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Off Topic => General Discussion => Topic started by: jfb on December 10, 2020, 01:18:16 PM

Title: Starship!
Post by: jfb on December 10, 2020, 01:18:16 PM
Moderately surprised to not see a thread on Starship, especially after yesterday's flight.  Despite the kaboom at the end, that was a spectacularly successful flight.  A real-world test of a new engine cycle, a new fuel, a new mode of flight, and they almost pulled it off on the first try. 

And, my God, this shot:

https://twitter.com/SpaceX/status/1336849897987796992

That's real time.  That's not slowed down.  It just looks slow because you're looking at a 12-story building falling at you. 

SN9 is already built, there are at least 6 more prototypes in various stages of completion, the first booster is under construction - 2021 is gonna be an interesting year in South Texas. 
Title: Re: Starship!
Post by: Bryanpoprobson on December 10, 2020, 04:19:42 PM
It’s like the rockets that were envisaged in the days of Flash Gordon.
Title: Re: Starship!
Post by: molesworth on December 10, 2020, 05:18:40 PM
Scott Manley (everyone's favourite manly Scot  ;)) has a nice moment-by-moment analysis of the flight.  Also a new term I've not heard before - "engine-rich exhaust"  ;D

https://www.youtube.com/watch?v=egHxiX40eJY
Title: Re: Starship!
Post by: raven on December 10, 2020, 05:35:45 PM
I've heard it before, but, yes, it is a good one, up there with 'Unplanned Rapid Disassembly' and 'Lithobraking*'. Still, the fact it went as well as it did is still stunning, and I am sure they will iron out the bugs in the end.
*yes, I know it's an actual term, but it still makes for a dandy euphemism
Title: Re: Starship!
Post by: smartcooky on December 10, 2020, 07:01:54 PM
I love SpaceX's rapid iteration philosophy, they will have a truckload of data from this flight

"SpaceX - We Crash to Learn"
Title: Re: Starship!
Post by: Peter B on December 10, 2020, 07:53:33 PM
Moderately surprised to not see a thread on Starship, especially after yesterday's flight.  Despite the kaboom at the end, that was a spectacularly successful flight.  A real-world test of a new engine cycle, a new fuel, a new mode of flight, and they almost pulled it off on the first try. 

And, my God, this shot:

https://twitter.com/SpaceX/status/1336849897987796992

That's real time.  That's not slowed down.  It just looks slow because you're looking at a 12-story building falling at you. 

SN9 is already built, there are at least 6 more prototypes in various stages of completion, the first booster is under construction - 2021 is gonna be an interesting year in South Texas.

Yeah, 90 degree rotation in about three seconds. That's going to be interesting for passengers.
Title: Re: Starship!
Post by: raven on December 10, 2020, 08:13:29 PM
I love SpaceX's rapid iteration philosophy, they will have a truckload of data from this flight

"SpaceX - We Crash to Learn"
It's like a real life Kerbal Space Program.
You got to admit, the explosions are even better IRL.
Title: Re: Starship!
Post by: smartcooky on December 11, 2020, 12:17:48 AM
Moderately surprised to not see a thread on Starship, especially after yesterday's flight.  Despite the kaboom at the end, that was a spectacularly successful flight.  A real-world test of a new engine cycle, a new fuel, a new mode of flight, and they almost pulled it off on the first try. 

And, my God, this shot:

https://twitter.com/SpaceX/status/1336849897987796992

That's real time.  That's not slowed down.  It just looks slow because you're looking at a 12-story building falling at you. 

SN9 is already built, there are at least 6 more prototypes in various stages of completion, the first booster is under construction - 2021 is gonna be an interesting year in South Texas.

Yeah, 90 degree rotation in about three seconds. That's going to be interesting for passengers.

Yes, but if you look carefully, you will see that the bottom pivots around the nose cone - the flaps at the bottom fold up while the flaps on the nose cone remain extended. The crew/passengers will be at or close to the centre of rotation.

I can think of a half dozen fairground rides I have been on that pitch and rotate more violently that this maneuvre will.
Title: Re: Starship!
Post by: Peter B on December 11, 2020, 01:39:26 AM
Moderately surprised to not see a thread on Starship, especially after yesterday's flight.  Despite the kaboom at the end, that was a spectacularly successful flight.  A real-world test of a new engine cycle, a new fuel, a new mode of flight, and they almost pulled it off on the first try. 

And, my God, this shot:

https://twitter.com/SpaceX/status/1336849897987796992

That's real time.  That's not slowed down.  It just looks slow because you're looking at a 12-story building falling at you. 

SN9 is already built, there are at least 6 more prototypes in various stages of completion, the first booster is under construction - 2021 is gonna be an interesting year in South Texas.

Yeah, 90 degree rotation in about three seconds. That's going to be interesting for passengers.

Yes, but if you look carefully, you will see that the bottom pivots around the nose cone - the flaps at the bottom fold up while the flaps on the nose cone remain extended. The crew/passengers will be at or close to the centre of rotation.

Yeah, I did see that, and fully accept the point you're making.

Still, if I've got my geometry right, the passengers are going to be rotating from sitting up to lying on their backs. Obviously they're going to be fully aware of what's about to happen, but I reckon it would still be a bit unnerving.

Quote
I can think of a half dozen fairground rides I have been on that pitch and rotate more violently that this maneuvre will.

Yeah, but you wouldn't have ridden any of them while wearing a spacesuit with all the attendant problems if you suddenly need to have a spew...  :o
Title: Re: Starship!
Post by: Dalhousie on December 11, 2020, 03:05:12 AM
Note that in September 2019 this flight was promised to be in October 2019.

At that time the flight was supposed to be to 18 km.  This has been gradually whittled down, first to 15 km then 12.5 km.

This flight was no higher or faster than a commercial airliner.

While useful data and experience would have been gained, the flight ended with the destruction of a testbed and the loss of three reusable engines.

This is still very early days for "Starship".  There is a long way to go before it is orbital capable.

Title: Re: Starship!
Post by: Zakalwe on December 11, 2020, 06:01:15 AM
Moderately surprised to not see a thread on Starship, especially after yesterday's flight.  Despite the kaboom at the end, that was a spectacularly successful flight.  A real-world test of a new engine cycle, a new fuel, a new mode of flight, and they almost pulled it off on the first try. 

And, my God, this shot:

https://twitter.com/SpaceX/status/1336849897987796992

That's real time.  That's not slowed down.  It just looks slow because you're looking at a 12-story building falling at you. 

SN9 is already built, there are at least 6 more prototypes in various stages of completion, the first booster is under construction - 2021 is gonna be an interesting year in South Texas.

Yeah, 90 degree rotation in about three seconds. That's going to be interesting for passengers.

Yes, but if you look carefully, you will see that the bottom pivots around the nose cone - the flaps at the bottom fold up while the flaps on the nose cone remain extended. The crew/passengers will be at or close to the centre of rotation.

Yeah, I did see that, and fully accept the point you're making.

Still, if I've got my geometry right, the passengers are going to be rotating from sitting up to lying on their backs. Obviously they're going to be fully aware of what's about to happen, but I reckon it would still be a bit unnerving.

Quote
I can think of a half dozen fairground rides I have been on that pitch and rotate more violently that this maneuvre will.

Yeah, but you wouldn't have ridden any of them while wearing a spacesuit with all the attendant problems if you suddenly need to have a spew...  :o

We are a fair way away from passenger-rated flights  :D AFAIK, the plans are to develop a methalox RCS system to perform the flip rather than the main engines.




Note that in September 2019 this flight was promised to be in October 2019.

At that time the flight was supposed to be to 18 km.  This has been gradually whittled down, first to 15 km then 12.5 km.

This flight was no higher or faster than a commercial airliner.

While useful data and experience would have been gained, the flight ended with the destruction of a testbed and the loss of three reusable engines.

This is still very early days for "Starship".  There is a long way to go before it is orbital capable.

Musk gave it a 30% chance of full success, so I think that the first flight exceeded his expectations. He expects losses and failures, in fact he positively encourages them. SN9 is almost ready to go and up to SN15 are in various stages of construction.
As for it not going higher or faster than a commercial airliner, I've got to say "so what"? It's flown higher and faster than the SLS boondoggle. It also flew higher and faster than this thing....

(https://www.afmc.af.mil/Portals/13/02_%20LLRV%20on%20Ramp.jpg)
Title: Re: Starship!
Post by: smartcooky on December 11, 2020, 06:57:00 AM
Musk gave it a 30% chance of full success, so I think that the first flight exceeded his expectations. He expects losses and failures, in fact he positively encourages them. SN9 is almost ready to go and up to SN15 are in various stages of construction.

Indeed. To steal part of a post from another poster on a different forum


Launch successfully - tick
Synchronize engine shutdowns and gimbaling to maintain the vehicle attitude during ascent - tick
Translation while maintaining attitude to prepare for the pitch-over maneuver at target altitude - tick
Reach target altitude - tick
Transition to bellyflop position - tick
Controlled descent - tick
Transition to upright position - tick
Relight engines - tick
On target to landing site - tick
Land without exploding - BOOM!

That's 9 out of 10. I'd call that a pass


As for it not going higher or faster than a commercial airliner, I've got to say "so what"? It's flown higher and faster than the SLS boondoggle.

100%. When are we going to see SLS fly? Are we going to see it fly, ever?

In 2017, Nasa set a target to launch SLS rocket in the December 2019-June 2020 window, with a total cost of $7.17 bn. That's gone, and they're not even close yet and that cost has now risen to $9.1 bn. Yep, boondoggle is right!

Some people just hate SpaceX because, well, you know, Elon!

Title: Re: Starship!
Post by: jfb on December 11, 2020, 08:08:54 AM
Note that in September 2019 this flight was promised to be in October 2019.

At that time the flight was supposed to be to 18 km.  This has been gradually whittled down, first to 15 km then 12.5 km.

This flight was no higher or faster than a commercial airliner.

While useful data and experience would have been gained, the flight ended with the destruction of a testbed and the loss of three reusable engines.

This is still very early days for "Starship".  There is a long way to go before it is orbital capable.

Musk always overpromises on dates.  That’s something that’s been known from early F9 days, to the point where I don’t pay attention to announced dates.  They also had to take some time to figure out how to actually build the thing - the first few iterations were pretty rough.

My understanding is that they reduced altitude to avoid having to deal with high level winds, which seems a reasonable precaution.  And for this test altitude only mattered to the degree they could test the belly flop. 

As for the engines, they’re chunking them out at a decent clip now.  The next prototype is already built and will be rolled to the pad next week, and the next flight could happen by early January.  There are at least six more prototypes in various stages of construction, so they have plenty of hardware to chew through as they start dialing this in.

Yes, they’re not orbit-capable yet and won’t be until the first booster is built, which is happening right now. 

But, damn -

and came this close to pulling it off on the first try. 
Title: Re: Starship!
Post by: Zakalwe on December 11, 2020, 10:13:47 AM
Note that in September 2019 this flight was promised to be in October 2019.

At that time the flight was supposed to be to 18 km.  This has been gradually whittled down, first to 15 km then 12.5 km.

This flight was no higher or faster than a commercial airliner.

While useful data and experience would have been gained, the flight ended with the destruction of a testbed and the loss of three reusable engines.

This is still very early days for "Starship".  There is a long way to go before it is orbital capable.

Musk always overpromises on dates.  That’s something that’s been known from early F9 days, to the point where I don’t pay attention to announced dates.  They also had to take some time to figure out how to actually build the thing - the first few iterations were pretty rough.

My understanding is that they reduced altitude to avoid having to deal with high level winds, which seems a reasonable precaution.  And for this test altitude only mattered to the degree they could test the belly flop. 

As for the engines, they’re chunking them out at a decent clip now.  The next prototype is already built and will be rolled to the pad next week, and the next flight could happen by early January.  There are at least six more prototypes in various stages of construction, so they have plenty of hardware to chew through as they start dialing this in.

Yes, they’re not orbit-capable yet and won’t be until the first booster is built, which is happening right now. 

But, damn -
  • New engine cycle, using
  • A new fuel, and
  • A new mode of flight

and came this close to pulling it off on the first try.

Musk time...  ;D
Joking aside, it's impossible to accurately forecast when you are doing what has never been done before. All you can do is stick a date out there and then crack on with doing the work. If the task has been done before by others, then it's (relatively) easy to make an accurate forecast. After all, you're just repeating an already accomplished task. This is what is so damn annoying about SLS...they are basically doing what has been done before. Hell, even the engines were there as leftovers from the SS.  Even with that and as many tax-payer dollars that they can eat,  there's not been a forecast given for the SLS that they haven't blown through. It's time that they officially called it what it is- a job-creation scheme funded by tax-payer dollars and a Shelby gravy-train.

In comparison, SpaceX are doing what no-one has done before. They developed the Raptor from the ground up in about 7 years. The engine is already a record breaker. Now they have flown a rocket in a configuration never seen before. It looks like they have their aerodynamic calculations nailed.
Also, the flip is pretty amazing. They had quite literally a second for the engines and control systems to capture the state of the craft, to correct the momentum and to get the thrust centred through the centre of mass. That's breath-taking control authority.

Say what you like about Musk, but the dude gets things done.
Title: Re: Starship!
Post by: molesworth on December 11, 2020, 12:09:52 PM
Looks like an accident in the assembly building, and SN9 has tipped over and hit the wall.  No word from SpaceX, but it could mean either a delay for repairs or bringing SN10 forward instead.  Either way it's probably going to hold things up for a while.

https://twitter.com/BocaChicaGal/status/1337424248260993024
Title: Re: Starship!
Post by: Jeff Raven on December 11, 2020, 05:58:13 PM
It’s like the rockets that were envisaged in the days of Flash Gordon.

Hadn't thought about it until you said it, but yeah, it really does.

Just FYI, if anyone has access to the Roku Channel, they have the Buster Crabbe Flash Gordon serials from the late 30s and early 40s on there.
Title: Re: Starship!
Post by: bknight on December 11, 2020, 07:50:09 PM
Those were fun to watch Saturday at the movies.
Title: Re: Starship!
Post by: LunarOrbit on December 12, 2020, 06:21:28 PM
If you wondered what SN8 was thinking, watch this:

https://youtu.be/aQ0PP0BoOpo
Title: Re: Starship!
Post by: JayUtah on December 12, 2020, 07:09:56 PM
If you wondered what SN8 was thinking, watch this:

OMG, why didn't I think of that?
Title: Re: Starship!
Post by: JayUtah on December 12, 2020, 07:10:57 PM
Looks like an accident in the assembly building, and SN9 has tipped over and hit the wall.

Somewhere on a thumb drive in a box somewhere I have my manufacturing blooper reel.  I sympathize.
Title: Re: Starship!
Post by: raven on December 12, 2020, 10:41:51 PM
LunarOrbit, that was absolutely brilliant! I nearly laughed myself out of my chair. Thanks so very much for sharing  ;D
Title: Re: Starship!
Post by: LunarOrbit on December 13, 2020, 09:01:17 AM
I wish I could take credit for it, but I found it on Twitter. It's perfect.
Title: Re: Starship!
Post by: cjameshuff on December 13, 2020, 11:58:19 AM
Musk gave it a 30% chance of full success, so I think that the first flight exceeded his expectations. He expects losses and failures, in fact he positively encourages them. SN9 is almost ready to go and up to SN15 are in various stages of construction.

Yeah, they probably expected to take 2-3 flights to get what they got from this one. That's at least a couple months of assembling, testing, and cleaning up prototypes.

And yes, it was done a year later than Elon hoped. It was also done with a much higher fidelity test article. In the meantime, they've already test fired vacuum-optimized and high-thrust versions of the engine that they weren't even planning to develop for the first orbital versions of Starship. Nobody's disappointed with the pace they're managing.

The airliner comparison makes no sense. This isn't an airliner trying for an altitude record.
Title: Re: Starship!
Post by: smartcooky on December 13, 2020, 12:44:21 PM
Musk gave it a 30% chance of full success, so I think that the first flight exceeded his expectations. He expects losses and failures, in fact he positively encourages them. SN9 is almost ready to go and up to SN15 are in various stages of construction.

Yeah, they probably expected to take 2-3 flights to get what they got from this one. That's at least a couple months of assembling, testing, and cleaning up prototypes.

And yes, it was done a year later than Elon hoped. It was also done with a much higher fidelity test article. In the meantime, they've already test fired vacuum-optimized and high-thrust versions of the engine that they weren't even planning to develop for the first orbital versions of Starship. Nobody's disappointed with the pace they're managing.

The airliner comparison makes no sense. This isn't an airliner trying for an altitude record.


Besides which, a new design of airliner on its first ever test flight goes nowhere near 41,000 ft.
Title: Re: Starship!
Post by: cjameshuff on December 13, 2020, 12:48:57 PM
Looks like an accident in the assembly building, and SN9 has tipped over and hit the wall.  No word from SpaceX, but it could mean either a delay for repairs or bringing SN10 forward instead.  Either way it's probably going to hold things up for a while.

https://twitter.com/BocaChicaGal/status/1337424248260993024

The stand apparently partially collapsed. They've got it straightened out with a crane...some visible damage to the fins. Steel can be patched up in ways you can't do with aluminum or composites...still might not be worth the time to do so. On the other hand, this might be an opportunity to make SN9 the first named Starship: Only Slightly Bent.

Here's SN8: https://www.flickr.com/search/?user_id=44124348109%40N01&sort=date-taken-desc&text=spacex&view_all=1

(And they've just landed a F9 first stage for the 69th time, the 7th time for this particular first stage.)
Title: Re: Starship!
Post by: smartcooky on December 13, 2020, 02:47:47 PM
Looks like an accident in the assembly building, and SN9 has tipped over and hit the wall.  No word from SpaceX, but it could mean either a delay for repairs or bringing SN10 forward instead.  Either way it's probably going to hold things up for a while.

https://twitter.com/BocaChicaGal/status/1337424248260993024

The stand apparently partially collapsed. They've got it straightened out with a crane...some visible damage to the fins. Steel can be patched up in ways you can't do with aluminum or composites...still might not be worth the time to do so. On the other hand, this might be an opportunity to make SN9 the first named Starship: Only Slightly Bent.

Oh, that is very good. You should tweet Elon and suggest it!

ETA: And if SN9 does not do as well as SN8 did, they could rename it "Funny, It Worked Last Time"
Title: Re: Starship!
Post by: Zakalwe on December 13, 2020, 03:25:41 PM
Maybe "Honest Mistake",  "Reasonable Excuse" or "Teething Problems"
Or if there's recriminations to be had "A Series Of Unlikely Explanations" or "Excuses And Accusations"
Title: Re: Starship!
Post by: Dalhousie on December 13, 2020, 04:14:53 PM
Musk gave it a 30% chance of full success, so I think that the first flight exceeded his expectations. He expects losses and failures, in fact he positively encourages them. SN9 is almost ready to go and up to SN15 are in various stages of construction.

Yeah, they probably expected to take 2-3 flights to get what they got from this one. That's at least a couple months of assembling, testing, and cleaning up prototypes.

And yes, it was done a year later than Elon hoped. It was also done with a much higher fidelity test article. In the meantime, they've already test fired vacuum-optimized and high-thrust versions of the engine that they weren't even planning to develop for the first orbital versions of Starship. Nobody's disappointed with the pace they're managing.

The airliner comparison makes no sense. This isn't an airliner trying for an altitude record.


Besides which, a new design of airliner on its first ever test flight goes nowhere near 41,000 ft.

You realise this is not the first flight of SS?
Title: Re: Starship!
Post by: Dalhousie on December 13, 2020, 04:29:12 PM
Note that in September 2019 this flight was promised to be in October 2019.

At that time the flight was supposed to be to 18 km.  This has been gradually whittled down, first to 15 km then 12.5 km.

This flight was no higher or faster than a commercial airliner.

While useful data and experience would have been gained, the flight ended with the destruction of a testbed and the loss of three reusable engines.

This is still very early days for "Starship".  There is a long way to go before it is orbital capable.

Musk always overpromises on dates.  That’s something that’s been known from early F9 days, to the point where I don’t pay attention to announced dates.  They also had to take some time to figure out how to actually build the thing - the first few iterations were pretty rough.

"Over promising to this degree" is lying.  Knowingly stating that a test article with poorly constructed mockup fins and nose cone will fly to 18 km in two months is lying.  Saying that an orbital flight will happen with six months.  And most people believe it. 

Quote
My understanding is that they reduced altitude to avoid having to deal with high level winds, which seems a reasonable precaution.  And for this test altitude only mattered to the degree they could test the belly flop. 

Maybe.  But was this announced at the time or is it after the event rationalisation?  Musk does a lot of that, see the rationalisation that the failure of the Mk1 SS (the samed one that was going to flyto 18 km in two months) during an initial tanking test.

Quote
As for the engines, they’re chunking them out at a decent clip now.  The next prototype is already built and will be rolled to the pad next week, and the next flight could happen by early January.  There are at least six more prototypes in various stages of construction, so they have plenty of hardware to chew through as they start dialing this in.

At the rate they are destroying them, they need to.  Eleven test articles have been made to date.  Of these three have been retired, one never completed, one was subjected to destructive testing.  The remainder were destroyed.accidently

Quote
Yes, they’re not orbit-capable yet and won’t be until the first booster is built, which is happening right now. 

There are many steps to do before orbital capability.  Alot more than have been done so far.

Quote
But, damn -
  • New engine cycle, using
  • A new fuel, and
  • A new mode of flight

How does that justify continued lying and fatuity?

Quote
and came this close to pulling it off on the first try.

With a little less haste and a little more care it might have succeeded.

If this had been any other rocket from any other organisation, would people here be calling this a great success(as opposed to a partial one)?
Title: Re: Starship!
Post by: Dalhousie on December 13, 2020, 04:32:11 PM
As for it not going higher or faster than a commercial airliner, I've got to say "so what"? It's flown higher and faster than the SLS boondoggle. It also flew higher and faster than this thing....

You have completely missed my point.  People are crowing over this being a high altitude test, when it it isn't.  As fpor SLS, I am confident it will achieve orbit a lot sooner than this thing.

Title: Re: Starship!
Post by: Peter B on December 13, 2020, 04:37:49 PM
Maybe "Honest Mistake",  "Reasonable Excuse" or "Teething Problems"
Or if there's recriminations to be had "A Series Of Unlikely Explanations" or "Excuses And Accusations"

"Mistakes were made".

IIRC it's the title of a book (but perhaps not a Culture ship).
Title: Re: Starship!
Post by: smartcooky on December 13, 2020, 05:01:33 PM
Musk gave it a 30% chance of full success, so I think that the first flight exceeded his expectations. He expects losses and failures, in fact he positively encourages them. SN9 is almost ready to go and up to SN15 are in various stages of construction.

Yeah, they probably expected to take 2-3 flights to get what they got from this one. That's at least a couple months of assembling, testing, and cleaning up prototypes.

And yes, it was done a year later than Elon hoped. It was also done with a much higher fidelity test article. In the meantime, they've already test fired vacuum-optimized and high-thrust versions of the engine that they weren't even planning to develop for the first orbital versions of Starship. Nobody's disappointed with the pace they're managing.

The airliner comparison makes no sense. This isn't an airliner trying for an altitude record.


Besides which, a new design of airliner on its first ever test flight goes nowhere near 41,000 ft.

You realise this is not the first flight of SS?

Do you realise that it was? The others you think were flights, were actually short hop tests of engined fuel tanks fitted with a thrust-puck to check hover stability and engine gimbaling control authority. This is the was the first test flight of SS complete with winglets, pitch over, belly flop and flip maneuver.

Title: Re: Starship!
Post by: Zakalwe on December 13, 2020, 05:53:42 PM
As for it not going higher or faster than a commercial airliner, I've got to say "so what"? It's flown higher and faster than the SLS boondoggle. It also flew higher and faster than this thing....

You have completely missed my point.  People are crowing over this being a high altitude test, when it it isn't.  As fpor SLS, I am confident it will achieve orbit a lot sooner than this thing.

I'm not seeing much "crowing " over it being a high-altitude test. More that it was a test of a never-before-flown landing profile. I just think it was a shame that there wasn't a Roadster on it as a mass simulator. ;D

SLS flying first? If, and that's a big if, it flies first then I'll be surprised if it flies more than once. Did you see the latest crock from the program? That it's going to take a year (!) to replace a failed power component in Orion? I nearly coughed a lung up laughing.

Also, show us on the doll where the South African billionaire touched you inappropriately. You sure are salty when it comes to Musk's projects!  ::)
Title: Re: Starship!
Post by: Zakalwe on December 13, 2020, 05:57:07 PM
Musk gave it a 30% chance of full success, so I think that the first flight exceeded his expectations. He expects losses and failures, in fact he positively encourages them. SN9 is almost ready to go and up to SN15 are in various stages of construction.

Yeah, they probably expected to take 2-3 flights to get what they got from this one. That's at least a couple months of assembling, testing, and cleaning up prototypes.

And yes, it was done a year later than Elon hoped. It was also done with a much higher fidelity test article. In the meantime, they've already test fired vacuum-optimized and high-thrust versions of the engine that they weren't even planning to develop for the first orbital versions of Starship. Nobody's disappointed with the pace they're managing.

The airliner comparison makes no sense. This isn't an airliner trying for an altitude record.


Besides which, a new design of airliner on its first ever test flight goes nowhere near 41,000 ft.

You realise this is not the first flight of SS?

Do you realise that it was? The others you think were flights, were actually short hop tests of engined fuel tanks fitted with a thrust-puck to check hover stability and engine gimbaling control authority. This is the was the first test flight of SS complete with winglets, pitch over, belly flop and flip maneuver.

Yeah, but they barely flew higher or farther than the original Wright Flyer so it sucks and can be ignored. ::)
Title: Re: Starship!
Post by: smartcooky on December 13, 2020, 05:59:12 PM
You have completely missed my point.  People are crowing over this being a high altitude test, when it it isn't.  As for SLS, I am confident it will achieve orbit a lot sooner than this thing.

I should hope so, its had a 5 year, 9 billion dollar head start!

Note that in September 2019 this flight was promised to be in October 2019.

At that time the flight was supposed to be to 18 km.  This has been gradually whittled down, first to 15 km then 12.5 km.

This flight was no higher or faster than a commercial airliner.

While useful data and experience would have been gained, the flight ended with the destruction of a testbed and the loss of three reusable engines.

You really have no idea of the concept of "testing" do you.

Here, perhaps this will help you to understand

https://www.youtube.com/watch?v=g79K-R7xTFo

"Over promising to this degree" is lying.  Knowingly stating that a test article with poorly constructed mockup fins and nose cone will fly to 18 km in two months is lying.  Saying that an orbital flight will happen with six months.  And most people believe it.

Remember when SLS was supposed to originally launch? Wasn't it late 2019? I guess they lied.
It's slipped (again) to April 2021 now, and I am confident they will miss that too, so they will have lied... again.
 
Quote
My understanding is that they reduced altitude to avoid having to deal with high level winds, which seems a reasonable precaution.  And for this test altitude only mattered to the degree they could test the belly flop. 

Maybe.  But was this announced at the time or is it after the event rationalisation?  Musk does a lot of that, see the rationalisation that the failure of the Mk1 SS (the samed one that was going to flyto 18 km in two months) during an initial tanking test.

The reduction to 12.5km was announced well ahead of time.

Quote
As for the engines, they’re chunking them out at a decent clip now.  The next prototype is already built and will be rolled to the pad next week, and the next flight could happen by early January.  There are at least six more prototypes in various stages of construction, so they have plenty of hardware to chew through as they start dialing this in.

At the rate they are destroying them, they need to.  Eleven test articles have been made to date.  Of these three have been retired, one never completed, one was subjected to destructive testing.  The remainder were destroyed.accidentally

Another term you fail to understannd.. Iterative Design Process

https://www.smartsheet.com/iterative-process-guide

I know you are a Musk/SpaceX-hater (you've made no effort to keep that a secret) but do you really have to go so far out of your way to find fault in everything they do?
Title: Re: Starship!
Post by: Zakalwe on December 13, 2020, 06:12:12 PM
How many test flights has the SLS flown so far?
That'd be none. Zero. Zilch. Even with nearly a decade of development and billions of dollars. Heck, Orion is 16 years in development and still isn't finished.

Title: Re: Starship!
Post by: cjameshuff on December 13, 2020, 06:45:14 PM
Remember when SLS was supposed to originally launch? Wasn't it late 2019? I guess they lied.
It's slipped (again) to April 2021 now, and I am confident they will miss that too, so they will have lied... again.

It was 2019 at one point, but originally:
https://www.nytimes.com/2011/09/15/science/space/15nasa.html
Quote
The first unmanned test flight is scheduled for 2017.
Title: Re: Starship!
Post by: smartcooky on December 13, 2020, 06:56:45 PM
Remember when SLS was supposed to originally launch? Wasn't it late 2019? I guess they lied.
It's slipped (again) to April 2021 now, and I am confident they will miss that too, so they will have lied... again.

It was 2019 at one point, but originally:
https://www.nytimes.com/2011/09/15/science/space/15nasa.html
Quote
The first unmanned test flight is scheduled for 2017.

More lies then?
Title: Re: Starship!
Post by: cjameshuff on December 13, 2020, 07:17:36 PM
Remember when SLS was supposed to originally launch? Wasn't it late 2019? I guess they lied.
It's slipped (again) to April 2021 now, and I am confident they will miss that too, so they will have lied... again.

It was 2019 at one point, but originally:
https://www.nytimes.com/2011/09/15/science/space/15nasa.html
Quote
The first unmanned test flight is scheduled for 2017.

More lies then?

Apparently! I mean, if you go by Dalhousie's definition...though maybe that only applies to Musk.
Title: Re: Starship!
Post by: raven on December 13, 2020, 07:21:34 PM
Guys, gals, and non-binary pals, can we hakuna our matatas?
There's several things to dislike about Elon Musk as a person, all too often he's an arrogant, selfish and downright petty prick, and, yes, things are taking longer than originally stated, but this is new territory here in several fronts, this is not surprising?
Right now, I just want to wish the fine people at SpaceX working on this project through this very difficult time the best of my hopes. They are creating innovation and bending iron around a dream. Whatever we may or may not feel about Elon Musk, there's no denying they're doing some very novel work here, and working out the bugs and technical issues is going to take time and effort, often longer than Mr. Musk tends to originally state. Regardless, however long it takes, it's still work worth doing, I say.
Title: Re: Starship!
Post by: jfb on December 13, 2020, 11:46:16 PM
As for it not going higher or faster than a commercial airliner, I've got to say "so what"? It's flown higher and faster than the SLS boondoggle. It also flew higher and faster than this thing....

You have completely missed my point.  People are crowing over this being a high altitude test, when it it isn't.  As fpor SLS, I am confident it will achieve orbit a lot sooner than this thing.

After a decade of development SLS/Orion had goddamned better reach orbit first, otherwise heads need to roll.  In the time it’s taken Boeing to figure out how to weld a tank, SpaceX has developed an entirely new engine cycle, designed a new conops based around it, and is flight testing hardware. 

SLS/Orion is currently closer to the pad than SH/SS, but is moving at a slower pace.  There is a chance, small but significant, that at least a prototype SH/SS stack reaches orbit before SLS/Orion. 
Title: Re: Starship!
Post by: smartcooky on December 14, 2020, 12:24:19 AM
Guys, gals, and non-binary pals, can we hakuna our matatas?
There's several things to dislike about Elon Musk as a person, all too often he's an arrogant, selfish and downright petty prick, and, yes, things are taking longer than originally stated, but this is new territory here in several fronts, this is not surprising?
Right now, I just want to wish the fine people at SpaceX working on this project through this very difficult time the best of my hopes. They are creating innovation and bending iron around a dream. Whatever we may or may not feel about Elon Musk, there's no denying they're doing some very novel work here, and working out the bugs and technical issues is going to take time and effort, often longer than Mr. Musk tends to originally state. Regardless, however long it takes, it's still work worth doing, I say.

And me.

While I know Musk is intelligent, and driven, I also think he is an egotistical dickhead. However, unlike some, I don't allow that to bias how I feel about what he does. I think Richard Wagner was a nasty, antisemitic piece of gutter trash, but I sure as hell love to listen to his music!!

I'm a rocket-head and space-nerd. I want ALL of them to succeed, SpaceX, Blue Origin,  RocketLab, ULA, NASA, Roscosmos, ESA... all of them. The more the better. I just don't get how ANYONE can call themselves a space enthusiast and not be in absolute awe at what SpaceX are doing right now, from landing 12 story high re-usable boosters on land and on ships at sea, through the Dragon Crew and Cargo capsules, to fast iteration development of the most ambitious rocket ever made, not just a two-stage, heavy lift, interplanetary launch system, but one that is 100% reusable!
Title: Re: Starship!
Post by: Zakalwe on December 14, 2020, 03:53:05 AM
Isn't it funny how the ones that cry the loudest about the cult of personality also are the ones to hate Musk the most? It's like Republicans wailing about stolen elections whilst at the same time doing their best to support a man who is actively trying to steal an election. I also wonder why we never here from these people about the personality traits of Bridenstein or Tony Bruno?

Personally I don't give a hot damn about Musk's personality. I can see that he is a petty arsehole, but given that I'm not looking for new friends it doesn't matter a jot to me. I'm also pretty sure that he doesn't give two figs about what I think of him either. I can admire and support his work without getting enraged by his antics. Admire the works, not the man.

I also do not get how disliking the man's personality leads to knocking his company's output? That carries the stench of cancel-culture about it. Again, the ones most likely to wail about cancel-culture are often the very one practising it in regards to Musk. His various companies are all doing remarkable things and are transforming the way the world works. Hell, the changes brought about by just one of his companies would probably be the lifes work of single person, never mind the massive changes brought to our world by SpaceX, Starlink, Tesla and (possibly in the future) Neuralink.

Title: Re: Starship!
Post by: jfb on December 14, 2020, 10:56:51 AM
As for it not going higher or faster than a commercial airliner, I've got to say "so what"? It's flown higher and faster than the SLS boondoggle. It also flew higher and faster than this thing....

You have completely missed my point.  People are crowing over this being a high altitude test, when it it isn't.  As for SLS, I am confident it will achieve orbit a lot sooner than this thing.

After a decade and close to $10 billion in development costs it had goddamned well better reach orbit first, or heads need to roll both at NASA and the major contractors (actually, those heads need to roll anyway regardless of who gets to orbit first, SLS has been an embarrassment of a program).  And that's without developing new engines (never mind an engine cycle that's never flown before), without figuring how to re-use the booster, without pioneering construction techniques to reduce cost, without spinning up a manufacturing facility from the ground up. 

With this one test SpaceX have accomplished in half the time far more than SLS will just by making orbit. 

And to further flog the equine carcass, the altitude wasn't the point of the test, the flight profile was the point of the test. 
Title: Re: Starship!
Post by: smartcooky on December 14, 2020, 01:54:16 PM
And to further flog the equine carcass, the altitude wasn't the point of the test, the flight profile was the point of the test. 

Indeed, it didn't really matter what altitude it got to, so long as it was high enough so that there was sufficient altitude for the vehicle to

a. pitch over into the "skydiver" position
b. reach terminal velocity during the descent
c. have sufficient flight (glide) time to demonstrate the required aerodynamic control authority of the wing-flaps
d. have sufficient height to carry out the "landing flip" maneuver.



Title: Re: Starship!
Post by: Obviousman on December 14, 2020, 03:14:48 PM
Did you see the latest crock from the program? That it's going to take a year (!) to replace a failed power component in Orion? I nearly coughed a lung up laughing.
I didn't hear about this (though I am not following the programme closely at all). Can you post a link to what happened, or explain it yourself?

Thanks in advance!
Title: Re: Starship!
Post by: cjameshuff on December 14, 2020, 03:53:12 PM
Did you see the latest crock from the program? That it's going to take a year (!) to replace a failed power component in Orion? I nearly coughed a lung up laughing.
I didn't hear about this (though I am not following the programme closely at all). Can you post a link to what happened, or explain it yourself?

Thanks in advance!

They've managed to bury parts of the power system so deeply and inaccessibly in the vehicle that it'll take 9 months to disassemble it, replace a part, and put everything back together, and 3 more to re-test everything: https://www.theverge.com/2020/11/30/21726753/nasa-orion-crew-capsule-power-unit-failure-artemis-i

They have a possible shortcut, but it's not clear if it'll work.
Title: Re: Starship!
Post by: jfb on December 14, 2020, 04:02:07 PM
Did you see the latest crock from the program? That it's going to take a year (!) to replace a failed power component in Orion? I nearly coughed a lung up laughing.
I didn't hear about this (though I am not following the programme closely at all). Can you post a link to what happened, or explain it yourself?

Thanks in advance!

They've managed to bury parts of the power system so deeply and inaccessibly in the vehicle that it'll take 9 months to disassemble it, replace a part, and put everything back together, and 3 more to re-test everything: https://www.theverge.com/2020/11/30/21726753/nasa-orion-crew-capsule-power-unit-failure-artemis-i

They have a possible shortcut, but it's not clear if it'll work.

The part itself isn't critical - they can fly without repairing it - but it does mean a loss of redundancy in a power and data unit, and that ups the risk factor. 

Between the low launch cadence and cost of the booster though, I don't think they have a choice - they can't afford to risk a mission failure over something this relatively minor.  As much as it will increase delay and cost, having to repeat the mission with a new booster and spacecraft will be significantly worse. 
Title: Re: Starship!
Post by: Glom on December 14, 2020, 06:36:51 PM
Musk has yet to be #MeTooed or similar things and hasn't tried to steal an election. That makes him a saint by the standards of famous people these days.

I also rather like his PayPal.
Title: Re: Starship!
Post by: molesworth on December 14, 2020, 06:43:30 PM
Guys, gals, and non-binary pals, can we hakuna our matatas?
There's several things to dislike about Elon Musk as a person, all too often he's an arrogant, selfish and downright petty prick, and, yes, things are taking longer than originally stated, but this is new territory here in several fronts, this is not surprising?
Right now, I just want to wish the fine people at SpaceX working on this project through this very difficult time the best of my hopes. They are creating innovation and bending iron around a dream. Whatever we may or may not feel about Elon Musk, there's no denying they're doing some very novel work here, and working out the bugs and technical issues is going to take time and effort, often longer than Mr. Musk tends to originally state. Regardless, however long it takes, it's still work worth doing, I say.
This ^   100%

We should all be celebrating the fact that we seem to be heading into a new age of spaceflight and exploration, with both government-funded and commercial launchers, multiple countries involved in developments and research, and lots of interesting prospects for the future.

I'm hoping that 2021 will be even more exciting for space-nerds like me than the past couple of years have been...  ;D
Title: Re: Starship!
Post by: jfb on December 15, 2020, 10:32:53 AM
Yeah, Elon is a garbage human being that I wouldn't touch with three barge poles nailed together.  That enmity is reserved for Elon as a person, though, not for his companies (to the extent they aren't behaving badly wrt labor and environmental practices, anyway). 

Starship is a genuinely exciting development in spaceflight, and if it took a narcissistic asshole to bring it to fruition, well, sometimes that's the price of progress (It's not like Henry Ford, Howard Hughes, Bill Gates, or Steve Jobs were ever candidates for Humanitarian of the Year). 
Title: Re: Starship!
Post by: LunarOrbit on December 15, 2020, 11:54:53 AM
Yeah, Elon Musk has proven himself to be somewhat of a bad person, but I don't understand the hate for SpaceX (or Tesla) or how anyone could see SN8 as a failure. After all, Wernher von Braun was a Nazi, but I can still appreciate NASA and recognize the major accomplishment of landing astronauts on the moon despite his involvement. ::)

SpaceX is iterating at a fast pace, at least as far as space programs are concerned, and SN8 accomplished everything they needed it to. It wasn't intended to fly again, and it wasn't going into a museum. It would have been scrapped even if it landed... all of the important data was obtained. The timelines they give aren't always achieved, but they are goals not promises. They don't owe anyone anything, so I don't know why anyone would be personally offended if a date isn't met.
Title: Re: Starship!
Post by: Zakalwe on December 15, 2020, 03:32:07 PM

Considering the recent tone of this thread, I thought that this is a timely article from Eric Berger:
https://arstechnica.com/science/2020/12/six-years-after-orions-first-spaceflight-america-still-waits-for-an-encore/

"So over its lifetime, and for $23.7 billion, the Orion program has produced:

    Development of Orion spacecraft
    Exploration Flight Test-1 basic vehicle
    The Orion capsule to be used for another test flight
    Work on capsules for subsequent missions"

Compared to:
"Over its history, we can reliably estimate that SpaceX has expended a total of $16 billion to $20 billion on all of its spaceflight endeavors. Consider what that money has bought:

    Development of Falcon 1, Falcon 9, and Falcon Heavy rockets
    Development of Cargo Dragon, Crew Dragon, and Cargo Dragon 2 spacecraft
    Development of Merlin, Kestrel, and Raptor rocket engines
    Build-out of launch sites at Vandenberg (twice), Kwajalein Atoll, Cape Canaveral, and Kennedy Space Center
    105 successful launches to orbit
    20 missions to supply International Space Station, two crewed flights
    Development of vertical take off, vertical landing, rapid reuse for first stages
    Starship and Super Heavy rocket development program
    Starlink Internet program (with 955 satellites on orbit, SpaceX is largest satellite operator in the world)

To sum up, SpaceX delivered all of that for billions of dollars less than what NASA has spent on the Orion program since its inception."

Says it all really.  Love or hate Musk but you cannot argue that he and his company delivers outstanding value for money.  He gets stuff done.
Title: Re: Starship!
Post by: smartcooky on December 16, 2020, 04:49:00 AM

Considering the recent tone of this thread, I thought that this is a timely article from Eric Berger:
https://arstechnica.com/science/2020/12/six-years-after-orions-first-spaceflight-america-still-waits-for-an-encore/

"The take-home message for policymakers is pretty simple, Garver said. Public-private partnerships and fixed-price contracts like those for commercial crew have been shown to work—and expensive, slow, cost-plus programs like Orion and the SLS are to be avoided in the future if at all possible."

Telling!

The problem with US government funded space projects is that they are government funded. That means the funding is subject to the whims and ambitions of 535 politicians whose primary goal is to get themselves re-elected every two to six years. It is for this reason, I believe that ultimately, the task of launching payloads and people into space, and the subsequent development of a long-term human presence in space beyond LEO will fall to private enterprise. Companies like SpaceX, Blue Origin, Boeing, RocketLab etc are the future of spaceflight. They are immune to the whims of politicians, unaffected by pork barreling, and largely self funded or funded by contract.

As Jim Bridenstein said on the eve of the SpaceX Crew Demo 2 mission earlier this year.... "The entire world is going to see us launching again, to the International Space Station...and this time, when we do it, it's different. In fact, NASA is a customer, and as a customer, we become one of many that will be using this crew vehicle, if all goes according to plan. We'll have a robust commercial marketplace for spaceflight, and that commercial marketplace could be sovereign countries, it could be individuals that want to go, maybe, on vacation to space. Which I know sounds crazy, but I'll tell you, and you know this, those folks are out there, and there are a lot of folks that are ready to do it."
Title: Re: Starship!
Post by: JayUtah on December 16, 2020, 01:14:20 PM
As you can imagine, these conversations are hard for me to participate in, not because I don't have opinions but because I have sympathy for interests on both sides of the question.

No, I don't care for Elon Musk as a person.  But he has the ability to attract talent and motivate them to do good things.  Yes, SpaceX is able to move faster on development for a number of reasons; comparing them to the established aerospace community is apples and oranges.  Yes, SLS is a hopeless mess, for the reasons already apparent.

In addition to the aerospace establishment being far more beholden to political whims than SpaceX (or any of the other privately held companies, for that matter), there are additional uncertainties that make progress difficult.  I have a long standing contract that is now on its fourth acquisition.  That is, the company we originally signed the contract with has been acquired three additional times in less than 20 years.  Now it's Northrop Grumman, in case you're wondering.  But each new acquisition brings a whole lot of disorganization and delay.

Nor is Boeing even remotely the same company I started contracting with more than 20 years ago.  That's all I should probably say about that.

Yes, I've been courted by SpaceX, but I don't want to work for Elon Musk.  And so far I haven't been courted into a role I think I would like.  Yes, we all cheer when SpaceX achieves another first, or when they deliver another payload to orbit.  Or I do, anyway.  This is because my attitude is the same as molesworth's.  Today's space operations require many different participants that operate on different footing, and we all have a part to play.  Just because I have to work really hard -- along with my colleagues -- to deliver my little piece of SLS despite all the challenges doesn't mean I'm not excited when SpaceX succeeds, or when the Falcon 9 Heavy takes flight.  Or even when one of the smaller, less prominent companies achieves a first for them.  This really is becoming the second Golden Age of aerospace, and I'm just happy to be here for it.
Title: Re: Starship!
Post by: jfb on December 17, 2020, 10:11:27 AM
In addition to the aerospace establishment being far more beholden to political whims than SpaceX (or any of the other privately held companies, for that matter), there are additional uncertainties that make progress difficult.  I have a long standing contract that is now on its fourth acquisition.  That is, the company we originally signed the contract with has been acquired three additional times in less than 20 years.  Now it's Northrop Grumman, in case you're wondering.  But each new acquisition brings a whole lot of disorganization and delay.

Ugh.  Been through the merger and acquisition process multiple times both within and without the military industrial complex.  In my case it rarely impacted anything (just changed who I ultimately reported to), but with one exception I never worked on anything "important" so it rarely affected schedule. 

Ironically, the one exception caused the schedule to be accelerated, because the acquiring company thought we were within a month of release, when the truth was we were closer to 6 to 8 months out.  Our project manager had a nasty habit of lying in his progress reports, claiming we were further ahead than we really were.  The new boss was not pleased, and we went into overdrive to get something released.
Title: Re: Starship!
Post by: 12oh2alarm on December 19, 2020, 03:49:29 PM
Say what you like about Musk, but the dude gets things done.

Some things. Others never. The Hyperloop is an engineering nightmare that will never fly commercially. He should have been honest about it before selling it.

He also tells people with a straight face that flying cars will use cold gas thrusters for the final few meters finding a parking spot. He's either stupid, or not really the prodigy everybody thinks he is. Physics is certainly not where he shines. Making money and impressing people, I give him that. And landing stages upright. He's da man.
Title: Re: Starship!
Post by: raven on December 19, 2020, 04:34:18 PM
He's good at bringing people together and getting folks excited about things, getting things funded that others might have thought laughable. Sometimes for good reasons, and others, like the Falcon 1st stage, not so much. At  his best, he's a Moist von Lipwig. At his worst, he's a Reacher Gilt, to reference Going Postal by the late, great, Sir Terry Pratchett.
Title: Re: Starship!
Post by: Zakalwe on December 20, 2020, 06:27:14 AM
Say what you like about Musk, but the dude gets things done.

Some things. Others never. The Hyperloop is an engineering nightmare that will never fly commercially. He should have been honest about it before selling it.


Can you please show where Musk sold Hyperloop? Here's a hint....the concept is explicitly open-source. Heck, the concept was first proposed in 1904 by Robert Goddard (https://en.wikipedia.org/wiki/Vactrain). How come no hate for him?

You would think that on a science-based forum people would make an effort to do a modicum of research before forming biased opinions, wouldn't you?
Title: Re: Starship!
Post by: cjameshuff on December 20, 2020, 11:52:24 AM
Say what you like about Musk, but the dude gets things done.

Some things. Others never. The Hyperloop is an engineering nightmare that will never fly commercially. He should have been honest about it before selling it.


Can you please show where Musk sold Hyperloop? Here's a hint....the concept is explicitly open-source. Heck, the concept was first proposed in 1904 by Robert Goddard (https://en.wikipedia.org/wiki/Vactrain). How come no hate for him?

You would think that on a science-based forum people would make an effort to do a modicum of research before forming biased opinions, wouldn't you?

And apparently launching payloads to orbit and landing the first stages for reuse afterward is all about what a smooth talker you are, having nothing to do with physics. ::)

Musk frequently discusses low-level technological details of his projects, demonstrating a depth of knowledge that company executives rarely show interest in acquiring, but some people seem desperate to reduce him to a smooth-talking money man...which is comical if you've actually seen him speak publicly.
Title: Re: Starship!
Post by: Zakalwe on December 20, 2020, 01:02:42 PM
Say what you like about Musk, but the dude gets things done.

Some things. Others never. The Hyperloop is an engineering nightmare that will never fly commercially. He should have been honest about it before selling it.


Can you please show where Musk sold Hyperloop? Here's a hint....the concept is explicitly open-source. Heck, the concept was first proposed in 1904 by Robert Goddard (https://en.wikipedia.org/wiki/Vactrain). How come no hate for him?

You would think that on a science-based forum people would make an effort to do a modicum of research before forming biased opinions, wouldn't you?

And apparently launching payloads to orbit and landing the first stages for reuse afterward is all about what a smooth talker you are, having nothing to do with physics. ::)

Musk frequently discusses low-level technological details of his projects, demonstrating a depth of knowledge that company executives rarely show interest in acquiring, but some people seem desperate to reduce him to a smooth-talking money man...which is comical if you've actually seen him speak publicly.

I don't get that either. Musk is a TERRIBLE public speaker. He's hesitant, stumbles over words and appears to hate talking in public. He's the very last person on the planet that I'd describe as a smooth-talker.  As for "Physics is certainly not where he shines".....he knew enough to get a degree in the subject at University.

It's a symptom of today's world...people just regurgitate whatever old nonsense that they've seen that aligns with their internal biases rather than doing a second of research. It's typical of the hoax-nutcases that this place semi-regularly debates. I find it a touch upsetting that people on "our side" of the debate follow the same pathway.

Title: Re: Starship!
Post by: smartcooky on December 20, 2020, 01:21:58 PM
Say what you like about Musk, but the dude gets things done.

Some things. Others never. The Hyperloop is an engineering nightmare that will never fly commercially. He should have been honest about it before selling it.


Can you please show where Musk sold Hyperloop? Here's a hint....the concept is explicitly open-source. Heck, the concept was first proposed in 1904 by Robert Goddard (https://en.wikipedia.org/wiki/Vactrain). How come no hate for him?

You would think that on a science-based forum people would make an effort to do a modicum of research before forming biased opinions, wouldn't you?

And apparently launching payloads to orbit and landing the first stages for reuse afterward is all about what a smooth talker you are, having nothing to do with physics. ::)

Musk frequently discusses low-level technological details of his projects, demonstrating a depth of knowledge that company executives rarely show interest in acquiring, but some people seem desperate to reduce him to a smooth-talking money man...which is comical if you've actually seen him speak publicly.

I don't get that either. Musk is a TERRIBLE public speaker. He's hesitant, stumbles over words and appears to hate talking in public. He's the very last person on the planet that I'd describe as a smooth-talker.  As for "Physics is certainly not where he shines".....he knew enough to get a degree in the subject at University.

It's a symptom of today's world...people just regurgitate whatever old nonsense that they've seen that aligns with their internal biases rather than doing a second of research. It's typical of the hoax-nutcases that this place semi-regularly debates. I find it a touch upsetting that people on "our side" of the debate follow the same pathway.


Indeed. You only have to watch his interviews with people Like Tim Dodd, Kara Swisher, Walt Mossberg and Satellite 2020 conference chair Jeffrey Hill to realise this is not just a well-briefed spokesman - this is  a man who actually understands the engineering and physics concepts behind everything he does.
Title: Re: Starship!
Post by: JayUtah on December 20, 2020, 02:02:40 PM
Consider the launch yesterday of SpaceX's second NRO payload.  Whatever you think of Musk, even to be able to bid on these contracts requires not only demonstrated reliability of the vehicle, but certain aspects about the company that have to meet very high standards.  This was important for SpaceX.  It's also important for the United States, since we need to have more than one company and more than one vehicle that can deliver these nationally critical payloads.
Title: Re: Starship!
Post by: smartcooky on December 20, 2020, 02:21:26 PM
The Hyperloop is an engineering nightmare that will never fly commercially.

... because the very idea of passengers traveling at hundreds of miles per hour in a metal tube is insane, and it would never work.

... Oh! Hang on!>

He should have been honest about it before selling it.

Wait? What? He didn't sell it because he never owned it. Its difficult to sell something that is Open Source.

Here's where Hyperloop is at as of last month.

https://www.youtube.com/watch?v=BeyEbwguRls
Title: Re: Starship!
Post by: 12oh2alarm on December 20, 2020, 04:45:56 PM
... because the very idea of passengers traveling at hundreds of miles per hour in a metal tube is insane, and it would never work.

... Oh! Hang on!>


Are you referring to airliners in the air? If so, please explain how that relates to pods in 500 miles long evacuated tubes.

Yes, the "hyperloop" idea is more than a 100 years old. And it's never been built for a reason: IT'S STUPID on so many levels. Commercial, security, safety to begin with.

As an answer to your video, here's an answer taking it apart.

https://www.youtube.com/watch?v=VrbstnzbhZA

And here's where Elon's stupidity and physics ineptitude is demonstrated. While the everyday astronaut makes a fool of himself as a fanboy at the same time. (I usually am fond of EA's clips, but BS must be called BS. That's how science works  :) We need to recalibrate our enthusiasm, when it goes overboard).

https://www.youtube.com/watch?v=znv0TQsR5jk

I'm willing to put my money where my mouth is. I get 100 bucks a year while a, say, 500 km evacuated loop (with commercial passenger service) does not exist, and you get 100 a year from the year it does, until either of us meets our maker. Any takers? Happy to negotiate the specs.

I really wonder why in this particular forum, with a lot of smart cookies, Elon isn't seen more critical where he clearly is talking nonsense. I do realize his achievements, but this man is not infallible and has a knack for pulling wool over people's eyes. That needs to be called out.
Title: Re: Starship!
Post by: Zakalwe on December 20, 2020, 05:37:40 PM
Again, where did Musk sell Hyperloop?
Title: Re: Starship!
Post by: smartcooky on December 20, 2020, 10:52:09 PM
... because the very idea of passengers traveling at hundreds of miles per hour in a metal tube is insane, and it would never work.

... Oh! Hang on!>


Are you referring to airliners in the air? If so, please explain how that relates to pods in 500 miles long evacuated tubes.

Yes, the "hyperloop" idea is more than a 100 years old. And it's never been built for a reason: IT'S STUPID on so many levels. Commercial, security, safety to begin with.

As an answer to your video, here's an answer taking it apart.

https://www.youtube.com/watch?v=VrbstnzbhZA

And here's where Elon's stupidity and physics ineptitude is demonstrated. While the everyday astronaut makes a fool of himself as a fanboy at the same time. (I usually am fond of EA's clips, but BS must be called BS. That's how science works  :) We need to recalibrate our enthusiasm, when it goes overboard).

https://www.youtube.com/watch?v=znv0TQsR5jk

I'm willing to put my money where my mouth is. I get 100 bucks a year while a, say, 500 km evacuated loop (with commercial passenger service) does not exist, and you get 100 a year from the year it does, until either of us meets our maker. Any takers? Happy to negotiate the specs.

I really wonder why in this particular forum, with a lot of smart cookies, Elon isn't seen more critical where he clearly is talking nonsense. I do realize his achievements, but this man is not infallible and has a knack for pulling wool over people's eyes. That needs to be called out.

Videos by "thunderf00t".... all that needs saying really.

IIRC is one of the naysayers who declared landing boosters was impossible. When SpaceX succeeded, those videos suddenly disappeared.

I place no store in what this guy says.

And no, while I have a few vices - gambling is one I have spurned for over over 65 years

PS: You failed to address the comments about the alleged sale of hyperloop made by Zakalwe and I.

Care to try.
Title: Re: Starship!
Post by: 12oh2alarm on December 21, 2020, 04:33:43 AM
Again, where did Musk sell Hyperloop?

I was under the mistaken impression, Elon sold the test track to Branson. Mea maxima culpa.

Other than that, I stand by my criticism of Elon as 90 % snake oil salesman,  5 % bigmouth, 4 % deep pocket and 1 % realist.
Title: Re: Starship!
Post by: 12oh2alarm on December 21, 2020, 04:54:02 AM
... because the very idea of passengers traveling at hundreds of miles per hour in a metal tube is insane, and it would never work.

... Oh! Hang on!>


Are you referring to airliners in the air? If so, please explain how that relates to pods in 500 miles long evacuated tubes.

Yes, the "hyperloop" idea is more than a 100 years old. And it's never been built for a reason: IT'S STUPID on so many levels. Commercial, security, safety to begin with.

As an answer to your video, here's an answer taking it apart.

https://www.youtube.com/watch?v=VrbstnzbhZA

And here's where Elon's stupidity and physics ineptitude is demonstrated. While the everyday astronaut makes a fool of himself as a fanboy at the same time. (I usually am fond of EA's clips, but BS must be called BS. That's how science works  :) We need to recalibrate our enthusiasm, when it goes overboard).

https://www.youtube.com/watch?v=znv0TQsR5jk

I'm willing to put my money where my mouth is. I get 100 bucks a year while a, say, 500 km evacuated loop (with commercial passenger service) does not exist, and you get 100 a year from the year it does, until either of us meets our maker. Any takers? Happy to negotiate the specs.

I really wonder why in this particular forum, with a lot of smart cookies, Elon isn't seen more critical where he clearly is talking nonsense. I do realize his achievements, but this man is not infallible and has a knack for pulling wool over people's eyes. That needs to be called out.

Videos by "thunderf00t".... all that needs saying really.They sat in Virgi

IIRC is one of the naysayers who declared landing boosters was impossible. When SpaceX succeeded, those videos suddenly disappeared.

I place no store in what this guy says.

And no, while I have a few vices - gambling is one I have spurned for over over 65 years

PS: You failed to address the comments about the alleged sale of hyperloop made by Zakalwe and I.

Care to try.

See my answer to Zakalwe.

Smartcookie, I really like you but I am deeply disappointed by your non-answer. Really, "he's a naysayer, I place no store in what this guy says." is your argument? What if I called you an Elon fanboy? Jay would pick us both apart for fallacies, and rightfully so.

Thunderfoot has a grasp of both engineering and physics (I'm merely a physicist). He provides back-of-the-envelope calculations which he uses to support his points. That's more than the average fan boy does or can even understand (not directed at you, I like you, space era brother). He buys expensive equipment to demonstrate in experiments (empirically, WHAT A CONCEPT!) what it takes to use cold gas thrusters for car levitation. Musk should go with his tail between his legs. That was one of many moments he let the 90% snake oil salesman out. If you feel otherwise, please argue (preferably with maths and physics), why you believe, flying cars can and should be built with cold gas thrusters to move a little bit around.
Title: Re: Starship!
Post by: Zakalwe on December 21, 2020, 06:33:01 AM
... because the very idea of passengers traveling at hundreds of miles per hour in a metal tube is insane, and it would never work.

... Oh! Hang on!>


Are you referring to airliners in the air? If so, please explain how that relates to pods in 500 miles long evacuated tubes.

Yes, the "hyperloop" idea is more than a 100 years old. And it's never been built for a reason: IT'S STUPID on so many levels. Commercial, security, safety to begin with.

As an answer to your video, here's an answer taking it apart.

https://www.youtube.com/watch?v=VrbstnzbhZA

And here's where Elon's stupidity and physics ineptitude is demonstrated. While the everyday astronaut makes a fool of himself as a fanboy at the same time. (I usually am fond of EA's clips, but BS must be called BS. That's how science works  :) We need to recalibrate our enthusiasm, when it goes overboard).

https://www.youtube.com/watch?v=znv0TQsR5jk

I'm willing to put my money where my mouth is. I get 100 bucks a year while a, say, 500 km evacuated loop (with commercial passenger service) does not exist, and you get 100 a year from the year it does, until either of us meets our maker. Any takers? Happy to negotiate the specs.

I really wonder why in this particular forum, with a lot of smart cookies, Elon isn't seen more critical where he clearly is talking nonsense. I do realize his achievements, but this man is not infallible and has a knack for pulling wool over people's eyes. That needs to be called out.

I do love it when smart people do not realise they are being trolled by someone who is an expert at Twitter trolling. Thunderfoot is a smart guy but he's got many blindspots, electric cars being one. He's also a guy that loves the sound of his own voice and can never be accused of using ten words when 500 will do the same job. His rant is based on a Musk tweet where the word "maybe" is used. Forgive me, but I'm not going to listen to 35 minutes of Thunderfoot's nonsense.A smart guy needs to be a touch smarter here.

As for him being infallible? Tu Quoque

Again, where did Musk sell Hyperloop?

I was under the mistaken impression, Elon sold the test track to Branson. Mea maxima culpa.

Other than that, I stand by my criticism of Elon as 90 % snake oil salesman,  5 % bigmouth, 4 % deep pocket and 1 % realist.

Apology accepted. Branson's organisation is one of a number of firms who are experimenting with the Hyperloop concept. Will it work? Who knows? The concept of loading people into a pressurised aluminium cylinder at transporting then at 10,000 metres is also dangerous, difficult and would have been considered madness a little over 100 years ago, and yet here we are doing it.

90% snake oil salesman?
    The first privately funded, liquid-fueled rocket (Falcon 1) to reach orbit (28 September 2008)
    The first privately funded company to successfully launch (by Falcon 9), orbit and recover a spacecraft (Dragon) (9 December 2010)
    The first private company to send a spacecraft (Dragon) to the International Space Station (25 May 2012)
    The first private company to send a satellite into geosynchronous orbit (SES-8, 3 December 2013)
    The first private company to send a probe beyond Earth orbit (Deep Space Climate Observatory, 11 February 2015)
    The first landing of a first stage orbital capable rocket (Falcon 9, Flight 20) (22 December 2015 1:39 UTC)[60]
    The first water landing of a first stage orbital capable rocket (Falcon 9) (8 April 2016 20:53 UTC)
    The development of the most powerful operational rocket as of 2020 (Falcon Heavy, first flight 6 February 2018)
    The first private company to send humans into orbit (Crew Dragon Demo-2, 30 May 2020)

Not bad for a snakeoil salesman. And that's only the achievements of one of his companies. Again, you are letting your hatred of a man who you have never and will never meet blind you to what he has achieved. That's not a great look at all.


Title: Re: Starship!
Post by: 12oh2alarm on December 21, 2020, 08:47:05 AM

90% snake oil salesman?
    The first privately funded, liquid-fueled rocket (Falcon 1) to reach orbit (28 September 2008)
    The first privately funded company to successfully launch (by Falcon 9), orbit and recover a spacecraft (Dragon) (9 December 2010)
    The first private company to send a spacecraft (Dragon) to the International Space Station (25 May 2012)
    The first private company to send a satellite into geosynchronous orbit (SES-8, 3 December 2013)
    The first private company to send a probe beyond Earth orbit (Deep Space Climate Observatory, 11 February 2015)
    The first landing of a first stage orbital capable rocket (Falcon 9, Flight 20) (22 December 2015 1:39 UTC)[60]
    The first water landing of a first stage orbital capable rocket (Falcon 9) (8 April 2016 20:53 UTC)
    The development of the most powerful operational rocket as of 2020 (Falcon Heavy, first flight 6 February 2018)
    The first private company to send humans into orbit (Crew Dragon Demo-2, 30 May 2020)

Not bad for a snakeoil salesman. And that's only the achievements of one of his companies. Again, you are letting your hatred of a man who you have never and will never meet blind you to what he has achieved. That's not a great look at all.

I don't hate the man and I have given Musk credit in this forum for his achievements (but you do know he's not the first to successfully land rockets upright?). For the new type of rocketry, "He's da man". Electric cars, yay, power to him.

That doesn't mean all of his big dreams will come true. And talking cold gas thrusters for flying cars is, I repeat (how do I say this politely?) complete and utter excrement. If you disagree, please address energy requirements, delta-v achievable, weight, safety issues.
If the man is so intelligent and honest, why does he talk publicly about it?

Guys, being critical of claims is one of the hallmark of science and engineering (as is using numbers!). One of the best tests a new idea in science is to ask your peers to come up with any and all arguments they can to shoot it down. If the idea stands that test, it may be one to explore further. Some of Musks utterings don't pass this test at all as the video shows.

I hear you guys making all sorts of excuses why you don't want to engage in Thunderfoot's video contents instead of attacking the arguments he brings forward against cold gas thrusters for flying cars. Let me add another non-technical one: regulation. You think authorities would allow flying cars to contain 1000 psi pressure vessels? Hell no! That's acting like some of the moon landing deniers here we love to take apart: rejecting arguments because you can't be bothered or you don't like the person. Do you call that a great look? You can do better than that.

I'm as much an technology enthusiast as many on this forum. But I am aware there is a cemetry of dead technological ideas. Some still-born, some connected to life-support for a few years before they die. Hyperloop is in a vegetative coma, if you ask me  :D Apart from a few laughably down-scaled technology demonstrations sold as "full scale", it is my belief the hyperloop is asphyxiating already. And cold gas thruster for Teslas (maybe even flying cars as such) are already dead and smelling. The emperor has no clothes here! I would so love to see Wernher rip Elon apart on this.
Title: Re: Starship!
Post by: Zakalwe on December 21, 2020, 10:28:45 AM

I don't hate the man and I have given Musk credit in this forum for his achievements (but you do know he's not the first to successfully land rockets upright?). For the new type of rocketry, "He's da man". Electric cars, yay, power to him.

You might not, but you're doing a pretty good impression of someone who does (see below).


I stand by my criticism of Elon as 90 % snake oil salesman,  5 % bigmouth, 4 % deep pocket and 1 % realist.


but you do know he's not the first to successfully land rockets upright?

Yes, thank you. However they were all low altitude test pieces  No-one to date has autonomously landed an orbital class booster other than SpaceX. And certainly no-one has developed that technology into a commercially viable proposition.
Probably the closest at the moment is Blue Origin, but the pinnacle of their achievements is just getting above the Karman line in a straight up-and-down. Doing it with an orbital class booster involves dealing with a magnitude or two more of energy. I'd estimate they they are at last 5 years, if not a decade, behind SpaceX



That doesn't mean all of his big dreams will come true.

No-one is claiming that they will.

And talking cold gas thrusters for flying cars is, I repeat (how do I say this politely?) complete and utter excrement. If you disagree, please address energy requirements, delta-v achievable, weight, safety issues.
If the man is so intelligent and honest, why does he talk publicly about it?

Like I said, its amusing to see smart people getting all het up when they are either being trolled or when they don't realise that people can shoot the breeze. At worst, you're cherry-picking like a conspiracy theorist and using a few words to try an discredit someone's achievements or character. A classic ad-hominem.


I hear you guys making all sorts of excuses why you don't want to engage in Thunderfoot's video contents instead of attacking the arguments he brings forward against cold gas thrusters for flying cars.

Thunderfoot got himself all puffed up about something someone said on Twitter? There's more important things to debate than that. AFAIK, the original cold-gas thruster piece was Musk's idea to accelerate the car from a standing start (after all, when you're building a two-seater hypercar that will do 0-60 in under two seconds, carries a 1,000 kWh battery and a top speed well in excess of 200MPH what else can you add to make it even more extreme). Personally I think that the idea of making it fly using cold-gas thrusters is nonsense, but it is exactly the sort of shooting-the-breeze nonsense that I would engage in if I was one of the richest men on the planet and had ideas busting out of my ass.
Like I said, you and Thunderfoot are reading way too much into idle chit-chat. It reminds me of hoax nuts who take what written on von Brauns gravestone and use that as evidence of a Moon landing conspiracy.

Hyperloop is in a vegetative coma, if you ask me  :D

I personally don't think that it will happen anytime soon. The basic science is sound, but I can't see it happening anytime soon (mind you, there were plenty of serious people in NASA laughing when SpaceX first talked about landing orbital class boosters). I have it in the same area as space elevators and skyhooks with the provisio that we can actually have the materials science to make smaller runs of Hyperloop. 



Title: Re: Starship!
Post by: cjameshuff on December 21, 2020, 02:01:06 PM
I don't hate the man

Suuure, you spend so much effort spreading baseless FUD about him for purely non-hateful reasons. Jealousy, envy? Or purely pragmatic financial gain, perhaps?

Snake oil makes a poor rocket propellant. Your characterization of Musk based on some cherry-picked comments and a completely fabricated story about Hyperloop is wildly at odds with his actual achievements and says more about your own motivations.
Title: Re: Starship!
Post by: cjameshuff on December 21, 2020, 02:17:54 PM
I personally don't think that it will happen anytime soon. The basic science is sound, but I can't see it happening anytime soon (mind you, there were plenty of serious people in NASA laughing when SpaceX first talked about landing orbital class boosters). I have it in the same area as space elevators and skyhooks with the provisio that we can actually have the materials science to make smaller runs of Hyperloop.

Naysayers focus a lot on the evacuated tubes when the real advantages of the Hyperloop concept were decentralization of the endpoints, routing in a three-dimensional network instead of a two-dimensional grid to reduce congestion issues, and dividing traffic into smaller "packets" to reduce wait times. None of these are particularly controversial. I think Musk will have a harder time disrupting the tunnel boring industry to the degree that he's managed with electric cars, space launch, and satellite internet, but The Boring Company doesn't seem to have trouble getting started on some projects using concepts shared with Hyperloop.
Title: Re: Starship!
Post by: smartcooky on December 21, 2020, 02:39:48 PM
Smartcookie, I really like you but I am deeply disappointed by your non-answer. Really, "he's a naysayer, I place no store in what this guy says." is your argument? What if I called you an Elon fanboy? Jay would pick us both apart for fallacies, and rightfully so.

Call me what you like, I don't care - I have a hide of a rhinoceros when it comes to name-calling in the internet.
 
Thunderfoot has a grasp of both engineering and physics (I'm merely a physicist). He provides back-of-the-envelope calculations which he uses to support his points. That's more than the average fan boy does or can even understand (not directed at you, I like you, space era brother).

The only thing I see Thunderfoot using is mockery to support his claims, for example, using snippets of "The Simpsons", and excursions into misleading holiday resort ads to take the piss - I don't find that either funny or particularly erudite - its the sort of crap that flat earthers and moon hoax deniers do in their videos. If he wants his viewers to take him seriously, then he needs to cut out the smart alec crap he puts in his videos, and treat the subject matter seriously.

Unlike you, I am not at all impressed with his "grasp of both engineering and physics", for example he claims that the occupants of the pod would not be able to breath and would die because the tube is at vacuum...he clearly hasn't heard of "pressurization"..... Oh wait he has, and he tries (and fails) to explain that too. He claims that an aircraft is sealed up at sea level pressure and while flying at 40,000 feet, the occupants are breathing sea level pressure air. This is completely wrong! Aircraft are pressurized at a pressure ratio usually about 5:1 to 7:1. An aircraft flying at about 40,000 has a cabin altitude of between 6,000 and 8,000 feet, i.e. the occupants are breathing air at the same pressure that they would be standing on a 6,000 to 8,000 foot hill.

So, why don't they just pressurize aircraft at sea level? Because the differential pressures between the aircraft and the cabin interior would be too high, and that would cause the aircraft structure to have to be much stronger (and therefore heavier) to be able to cope with the higher pressure differentials, reducing the aircraft's performance. However, in the case of a hyperloop tube and pod, weight and mass are not as important. A pod could be built strong enough to be pressurized to sea level with a very low pressure inside the tube. Someone with any kind of grasp of engineering would know that - he clearly doesn't.

He buys expensive equipment to demonstrate in experiments (empirically, WHAT A CONCEPT!) what it takes to use cold gas thrusters for car levitation. Musk should go with his tail between his legs. That was one of many moments he let the 90% snake oil salesman out. If you feel otherwise, please argue (preferably with maths and physics), why you believe, flying cars can and should be built with cold gas thrusters to move a little bit around.

We weren't talking about flying cars.

The thing is, the history of engineering and physics is replete with people who have had their ideas called stupid, crazy, infeasible, physically impossible... and then, they actually do it and make it work.

Heavier that Air flying machines (The Wright Brothers)
Rockets to the Moon (Wernher von Braun)
Power distribution using Alternating Current (Nikola Tesla)
Electric Lights (Thomas Edison)
Bringing rocket boosters back from space and landing then vertically (Elon Musk)

The inventors of these these were all told that these things were impossibilities from a physics and engineering standpoint. They were mercilessly mocked for continuing to waste their time and effort trying.

Then there are people who were brilliant in their fields of science and engineering, who got some of the fundamental principles completely wrong.

Robert Goddard put the nozzles of his rockets at the top because, as brilliant as he was, he didn't understand The Pendulum Fallacy.

Fred Hoyle (an otherwise brilliant astronomer) held a belief in his "Steady State" theory of the universe, despite the fact that it violated a fundamental principle of physics, - that matter cannot be either created or destroyed.

Simon Newcomb, one of the greatest scientific minds of his time....."aerial flight is one of the great class of problems with which man can never cope....  even if a man flew he could not stop. Once he slackens his speed, down he begins to fall. Once he stops, he falls as a dead mass.". Of course, Newcomb, brilliant as he was, did not understand the concept of an airfoil.

Just because an idea might seem crazy, does not mean it should not be investigated, because you never know what might be learned from trying...

"Many hypotheses proposed by scientists as well as by non-scientists turn out to be wrong. But science is a self-correcting enterprise. To be accepted, all new ideas must survive rigorous standards of evidence. The worst aspect of the Velikovsky affair is not that his hypotheses were wrong or in contradiction to firmly established facts, but that some who called themselves scientists attempted to suppress Velikovsky’s work. Science is generated by and devoted to free inquiry: the idea that any hypothesis, no matter how strange, deserves to be considered on its merits. The suppression of uncomfortable ideas may be common in religion and politics, but it is not the path to knowledge; it has no place in the endeavor of science. We do not know in advance who will discover fundamental new insights."
- Carl Sagan, circa1980
Title: Re: Starship!
Post by: smartcooky on December 21, 2020, 09:43:32 PM
...but you do know he's not the first to successfully land rockets upright

Sending rockets straight up, letting them fall straight down and landing them upright - piece of cake.

Launching rockets so that they pitch over and fly 50 to 150 km downrange, deploy a payload, flipping them 180° and bringing them back, entering the earth's atmosphere at thousands of kph, and landing them upright on a predetermined point, within a few metres - not so much!

What SpaceX has done is orders of magnitude more difficult from a physics and engineering viewpoint that anything Blue Origin has done so far.... and all of this after after ignorant naysayers like Thunderf00t and CSS mocked them for even suggesting it as a possibility

"People who declare that something cannot be done should get out of the way of people who are actually doing it!"
Title: Re: Starship!
Post by: Peter B on December 22, 2020, 12:55:14 AM
I don't hate the man and I have given Musk credit in this forum for his achievements (but you do know he's not the first to successfully land rockets upright?).

[SNIP]

I'm not involved in this argument, but I'm curious...

Who/what was the first? When was this? Are you talking about on Earth or on the Moon?
Title: Re: Starship!
Post by: smartcooky on December 22, 2020, 02:39:45 AM
I don't hate the man and I have given Musk credit in this forum for his achievements (but you do know he's not the first to successfully land rockets upright?).

[SNIP]

I'm not involved in this argument, but I'm curious...

Who/what was the first? When was this? Are you talking about on Earth or on the Moon?

Blue Origin's New Shepard.

https://www.youtube.com/watch?v=sij4ivRwHuQ
Title: Re: Starship!
Post by: 12oh2alarm on December 22, 2020, 05:47:36 AM
I don't hate the man and I have given Musk credit in this forum for his achievements (but you do know he's not the first to successfully land rockets upright?).

[SNIP]

I'm not involved in this argument, but I'm curious...

Who/what was the first? When was this? Are you talking about on Earth or on the Moon?

Who? McDonnell Douglas. When? 1993. Earth. Look for DC-X, e.g. here:

https://www.youtube.com/watch?v=39cjZTCay24

But when the Star Hopper does it a 27 years later, the space community goes into synchronized nerdgasm.
Title: Re: Starship!
Post by: 12oh2alarm on December 22, 2020, 06:25:21 AM
I don't hate the man

Suuure, you spend so much effort spreading baseless FUD about him for purely non-hateful reasons. Jealousy, envy? Or purely pragmatic financial gain, perhaps?

Snake oil makes a poor rocket propellant. Your characterization of Musk based on some cherry-picked comments and a completely fabricated story about Hyperloop is wildly at odds with his actual achievements and says more about your own motivations.

I don't hate the man. I ridicule him for claims he should be ridiculed about. (Racists are haters, e.g. If you think I'm a hater, please recalibrate your judgement).

Making fun of the powers that be is a well established method in all of history to separate the truth from wishful thinking.

As for baseless FUD, I have yet to see a valid technical argument against Thunderfoot's empirical experiments and calculations. So far I have seen these rebuttals (paraphrased):


I'm surprised no one seems to be willing to admit that all of these are vacuous. Most address Thunderfoot or me. None is technical. They strike me as textbook ad-hominems.

Could it be because we are right that the Hyperloop and Flying Teslas are a fundamentally dumb idea and we make good arguments that are hard to counter?

I can do witty quotes, too:

It is easier to fool the people, than to convince them they have been fooled. -- Attributed to Mark Twain
Title: Re: Starship!
Post by: Zakalwe on December 22, 2020, 07:42:38 AM
I don't hate the man and I have given Musk credit in this forum for his achievements (but you do know he's not the first to successfully land rockets upright?).

[SNIP]

I'm not involved in this argument, but I'm curious...

Who/what was the first? When was this? Are you talking about on Earth or on the Moon?

Who? McDonnell Douglas. When? 1993. Earth. Look for DC-X, e.g. here:


But when the Star Hopper does it a 27 years later, the space community goes into synchronized nerdgasm.

It may come as a massive shock to you (or maybe not) but many of us are aware of those trials.  Vertical Takeoff Vertical Landing concepts existed long before DC-X (hell, the Apollo LM was a VTVL craft!).

Space nerds tend to know their history and many are aware of DC-X, the Roton, NASA's Morpheus, the SpaceX Grasshopper and others.  People were excited then, just as they are now. I get excited when Blue Origin flies their New Sheppard and I no doubt will be excited if and when New Glenn and New Armstrong flies. However you seem to have a bitter taste in your mouth about SpaceX, probably due to your obvious dislike of it's founder.
Starhopper was interesting for many reasons- the speed of building, the construction methods and more importantly the first flight of a Raptor engine. That engine is a groundbreaking design and exciting for space nerds. It's a bit of a shame that your bitter hatred seems to stop you enjoying the spectacle of space technology advancing.

I don't hate the man

Suuure, you spend so much effort spreading baseless FUD about him for purely non-hateful reasons. Jealousy, envy? Or purely pragmatic financial gain, perhaps?

Snake oil makes a poor rocket propellant. Your characterization of Musk based on some cherry-picked comments and a completely fabricated story about Hyperloop is wildly at odds with his actual achievements and says more about your own motivations.

I don't hate the man. I ridicule him for claims he should be ridiculed about. (Racists are haters, e.g. If you think I'm a hater, please recalibrate your judgement).

Could it be because we are right that the Hyperloop and Flying Teslas are a fundamentally dumb idea and we make good arguments that are hard to counter?

Again, you are doing a damn fine impersonation of someone who does.

You, again, have missed the point about Thunderf00t's verbose video. He, and you are bunching your panties up over what someone who you both clearly dislike said when shooting the breeze with a third party. Look at it this way, if you wandered into a pub and overheard a conversation between two people would you spend hours asking people to debate your over-long fatuous video? Would you demand a full rebuttal? Or would you be sensible and realise that two people were chewing the fat and blue-skying? To me it appears that you are doing nothing more than sea-lioning (https://en.wikipedia.org/wiki/Sealioning).


(https://i.kym-cdn.com/photos/images/newsfeed/000/873/260/a5b.png)
Title: Re: Starship!
Post by: 12oh2alarm on December 22, 2020, 09:21:26 AM

It may come as a massive shock to you (or maybe not) but many of us are aware of those trials.  Vertical Takeoff Vertical Landing concepts existed long before DC-X (hell, the Apollo LM was a VTVL craft!).

Space nerds tend to know their history and many are aware of DC-X, the Roton, NASA's Morpheus, the SpaceX Grasshopper and others.  People were excited then, just as they are now. I get excited when Blue Origin flies their New Sheppard and I no doubt will be excited if and when New Glenn and New Armstrong flies. However you seem to have a bitter taste in your mouth about SpaceX, probably due to your obvious dislike of it's founder.
Starhopper was interesting for many reasons- the speed of building, the construction methods and more importantly the first flight of a Raptor engine. That engine is a groundbreaking design and exciting for space nerds. It's a bit of a shame that your bitter hatred seems to stop you enjoying the spectacle of space technology advancing.
...

I am a space nerd like everybody else here and you are attacking a straw man. I have nothing but praise for Elons rockets. I phoned my dying father to watch the first manned mission of his rocket going to the ISS this year, because in the Apollo era we did the same. History being made!

I ridicule the Hyperloop and Flying Teslas (the BFR for half orbits to the other side of the planet, hmmm). The Hyperloop is more than "shooting the breeze with a third party", right? (Maybe it is time to open a separate thread in the appropriate forum section.)

Peter B asked about the history of upright landing rockets and I provided a better answer, going further back than Smartcookie. And I'm chastised with a snide remark "come as shock" by you. But that's ok with me. Call me a hater if you want, since you are obviously capable of entering my mental inner self. If I punch hard I need to be prepared to take one.

I see my role now, after many years in this forum, as a critical thinker to hold a mirror up to some individuals. You've come close to an Elon cult that doesn't allow their leader to be called out when he hasn't done the math. You are full of confirmation bias when you only look at successes. How many ideas have failed? We don't know. Ideas that fail before the prototype stage usually are not made public. History is full of expensive bottomless technological failures. Some even consider the Space Shuttle to be one of them (I don't agree, but can see their point). When the garden variety moon landing denier pops up we hold them to account until they answer our questions and in extreme cases our great host boots them off the forum. Different standards, it seems when it comes to Elon. Then arguing on the technological issues is no longer needed. And refusal to engage in technical arguments is justified because watching videos, following the math presented there, is an offending burden. That's hypocrisy.
Title: Re: Starship!
Post by: Zakalwe on December 22, 2020, 09:35:17 AM

I ridicule the Hyperloop and Flying Teslas (the BFR for half orbits to the other side of the planet, hmmm). The Hyperloop is more than "shooting the breeze with a third party", right? (Maybe it is time to open a separate thread in the appropriate forum section.)

I was referring to the cold-gas thrusters on the upcoming Roadster, not Hyperloop.


You've come close to an Elon cult that doesn't allow their leader to be called out when he hasn't done the math. You are full of confirmation bias when you only look at successes.
Not at all. I've called out your obvious disdain for the man, your errors relating to the "sale of Hyperloop" and the basis for Thunderf00t's video.


And refusal to engage in technical arguments is justified because watching videos, following the math presented there, is an offending burden. That's hypocrisy.

And you've refused to address the point that the Thunderf00t video is pointless. You are also building a strawman when you try to make pout that everyone is saying that all of Musk's ideas succeed. No-one other than you is trying to propose that
Anyhoo, I think we've taken this particular seam to its finish.

By the way, I am deeply impressed with the work you do on the video interpolation and the recovery of other NASA data. Keep up that great work as it's impressive and adds to the canon.
Title: Re: Starship!
Post by: 12oh2alarm on December 22, 2020, 10:21:02 AM
By the way, I am deeply impressed with the work you do on the video interpolation and the recovery of other NASA data. Keep up that great work as it's impressive and adds to the canon.

Sorry mate, these kudos should go to someone else. Peace!
Title: Re: Starship!
Post by: smartcooky on December 22, 2020, 01:49:13 PM
I hear you guys making all sorts of excuses why you don't want to engage in Thunderfoot's video contents instead of attacking the arguments he brings forward

I did.

I gave you a specific example of where he has the engineering and physics wrong. You ignored it!

against cold gas thrusters for flying cars.

You're the only one who want to talk about flying cars.

Personally, I can't ever see it happening (at least not privately owned, self flown ones), but Musk is NOT the first person to propose them, and he won't be the last. I think the nearest we'll get is something like the air taxi currently under trials in New Zealand

https://www.stuff.co.nz/travel/news/113451046/the-flying-taxi-being-tested-in-new-zealand

34s to bypass the intro...

https://youtu.be/WAP0HklQ-Qo

Let me add another non-technical one: regulation. You think authorities would allow flying cars to contain 1000 psi pressure vessels? Hell no!

They already do!

This may come as a shock to you, but in this country, for at least 30 years, we have had warranted, registered, Land Transport Authority approved cars on the road that run on CNG (Compressed Natural Gas). The vehicle tank pressure is over 3,000 psi - and this is not an inert gas like nitrogen we're talking about here... CNG is highly combustible.
Title: Re: Starship!
Post by: Zakalwe on December 22, 2020, 02:11:34 PM
By the way, I am deeply impressed with the work you do on the video interpolation and the recovery of other NASA data. Keep up that great work as it's impressive and adds to the canon.

Sorry mate, these kudos should go to someone else. Peace!
Ah, my apologies. Mistaken identity.

Anyhoo, Happy Christmas.to you and yours.
Title: Re: Starship!
Post by: Zakalwe on December 22, 2020, 02:15:21 PM
I hear you guys making all sorts of excuses why you don't want to engage in Thunderfoot's video contents instead of attacking the arguments he brings forward

I did.

I gave you a specific example of where he has the engineering and physics wrong. You ignored it!

against cold gas thrusters for flying cars.

You're the only one who want to talk about flying cars.

Personally, I can't ever see it happening (at least not privately owned, self flown ones), but Musk is NOT the first person to propose them, and he won't be the last. I think the nearest we'll get is something like the air taxi currently under trials in New Zealand

https://www.stuff.co.nz/travel/news/113451046/the-flying-taxi-being-tested-in-new-zealand

34s to bypass the intro...

https://youtu.be/WAP0HklQ-Qo

Let me add another non-technical one: regulation. You think authorities would allow flying cars to contain 1000 psi pressure vessels? Hell no!

They already do!

This may come as a shock to you, but in this country, for at least 30 years, we have had warranted, registered, Land Transport Authority approved cars on the road that run on CNG (Compressed Natural Gas). The vehicle tank pressure is over 3,000 psi - and this is not an inert gas like nitrogen we're talking about here... CNG is highly combustible.

The handful of hydrogen fuel celled cars carry the H2 at huge pressures too. I believe that we are talking in the region of 10,000 Psi.
Title: Re: Starship!
Post by: 12oh2alarm on December 22, 2020, 03:42:53 PM

Let me add another non-technical one: regulation. You think authorities would allow flying cars to contain 1000 psi pressure vessels? Hell no!

They already do!

This may come as a shock to you, but in this country, for at least 30 years, we have had warranted, registered, Land Transport Authority approved cars on the road that run on CNG (Compressed Natural Gas). The vehicle tank pressure is over 3,000 psi - and this is not an inert gas like nitrogen we're talking about here... CNG is highly combustible.

This may come as a shock to you, but these cars don't fly, not even in your country. Lithobreaking incidents will be highly unlikely.

The danger/risk of high pressure containers in flying vehicles for the mass market is considerably different for regulators to be treating them differently (I would hope). Compare the average speed of CNG driven car collisions with the average terminal velocity of flying cars in trouble. Risk assessment for anything flying is by nature very different from assessment for road vehicles. Flying objects can go down anywhere (residential areas, stadiums, munition depots, nuclear power plants) while road vehicles typically don't stray too far from the sidewalk. We only let pilots fly after thorough training and exams, but allow any average Joe to drive a car if he can spell his name for a reason.
Title: Re: Starship!
Post by: 12oh2alarm on December 22, 2020, 04:09:09 PM
By the way, I am deeply impressed with the work you do on the video interpolation and the recovery of other NASA data. Keep up that great work as it's impressive and adds to the canon.

Sorry mate, these kudos should go to someone else. Peace!
Ah, my apologies. Mistaken identity.

Anyhoo, Happy Christmas.to you and yours.

No need to apologize. I need to apologize. The strict lockdown in my corner of the globe sometimes gets on my nerves. Yeah, lame excuse for riling you guys. But the mindless uncritical Musk worshipping can trigger me at times. I value scientific literacy as a foundation for judging claims, and more people need to be taught to be critical. It's okay to be critical of Thunderfoot as well, but what I have seen, more often than not he makes valid points and he's not a physics ignoramous. He knows limits imposed by thermodynamics and the rocket equation. His sarcastic style may not please everyone but I consider it fair game when he is up against star-struck interviewers and marketing departments with millions for snazzy CGI movies.

Thanks for the Christmas wishes, it means something to me. Wherever you are, all the best!
Title: Re: Starship!
Post by: Zakalwe on December 22, 2020, 04:33:12 PM
By the way, I am deeply impressed with the work you do on the video interpolation and the recovery of other NASA data. Keep up that great work as it's impressive and adds to the canon.

Sorry mate, these kudos should go to someone else. Peace!
Ah, my apologies. Mistaken identity.

Anyhoo, Happy Christmas.to you and yours.

No need to apologize. I need to apologize. The strict lockdown in my corner of the globe sometimes gets on my nerves. Yeah, lame excuse for riling you guys. But the mindless uncritical Musk worshipping can trigger me at times. I value scientific literacy as a foundation for judging claims, and more people need to be taught to be critical. It's okay to be critical of Thunderfoot as well, but what I have seen, more often than not he makes valid points and he's not a physics ignoramous. He knows limits imposed by thermodynamics and the rocket equation. His sarcastic style may not please everyone but I consider it fair game when he is up against star-struck interviewers and marketing departments with millions for snazzy CGI movies.

Thanks for the Christmas wishes, it means something to me. Wherever you are, all the best!

You make a good point re Coronavirus lockdowns. I've been working from home since mid-March and I've also been very strict on staying at home. 9 months of that allied.with the damp dark days here in Lancashire has had an effect on me. I've always prided myself on my mental strength but I can feel the grinding effects of dealing withCovid lockdown. I've receny taken a couple of weeks off work as I could feel my patience wearing thin and I knew that I may regret saying what I think.

Everyone take care in these times. Chill, have a break and stay safe.
Title: Re: Starship!
Post by: 12oh2alarm on December 22, 2020, 05:15:33 PM

Everyone take care in these times. Chill, have a break and stay safe.

Exactly. May Starship one day bring us photos like these, to append to the history of Moon and Mars landings. A clip as a Christmas gift for readers of this thread.
Someone put a ton of Apollo mission photos in a sequence, resulting in a kind of stop-motion movie of a mission. I like it (and didn't mind the game console music :-)

https://vimeo.com/141812811

Title: Re: Starship!
Post by: JayUtah on December 22, 2020, 05:33:00 PM
You make a good point re Coronavirus lockdowns.

...I can feel the grinding effects of dealing withCovid lockdown.

Another reason I'm so not jumping into this debate with both feet.  These things want to be talked about.  And they should be.  But it's easy to exhaust one's good nature these days, with so many demands on it coming from so many directions.
Title: Re: Starship!
Post by: smartcooky on December 22, 2020, 07:00:27 PM

Let me add another non-technical one: regulation. You think authorities would allow flying cars to contain 1000 psi pressure vessels? Hell no!

They already do!

This may come as a shock to you, but in this country, for at least 30 years, we have had warranted, registered, Land Transport Authority approved cars on the road that run on CNG (Compressed Natural Gas). The vehicle tank pressure is over 3,000 psi - and this is not an inert gas like nitrogen we're talking about here... CNG is highly combustible.

This may come as a shock to you, but these cars don't fly, not even in your country. Lithobreaking incidents will be highly unlikely.

The danger/risk of high pressure containers in flying vehicles for the mass market is considerably different for regulators to be treating them differently (I would hope). Compare the average speed of CNG driven car collisions with the average terminal velocity of flying cars in trouble. Risk assessment for anything flying is by nature very different from assessment for road vehicles. Flying objects can go down anywhere (residential areas, stadiums, munition depots, nuclear power plants) while road vehicles typically don't stray too far from the sidewalk. We only let pilots fly after thorough training and exams, but allow any average Joe to drive a car if he can spell his name for a reason.


Yeah, I'm calling BS on this. The number of vehicle accidents per occupant are greater than the number of aircraft accidents per occupant by several orders of magnitude
Title: Re: Starship!
Post by: smartcooky on December 23, 2020, 12:56:50 AM
Anyway, back to the interesting stuff...

SN9 is on the pad ready for testing

Here is Lab Padre's time-lapse of the move
 
https://www.youtube.com/watch?v=9ELfqbYJwSE
Title: Re: Starship!
Post by: raven on December 23, 2020, 04:30:31 AM
Totally needs the Thunderbirds theme. ;D But, yes, I'd rather get back to discussing the craft this topic is named for.
Title: Re: Starship!
Post by: AtomicDog on December 23, 2020, 09:14:16 AM
Totally needs the Thunderbirds theme. ;D But, yes, I'd rather get back to discussing the craft this topic is named for.

You mean this theme? When Starship finally takes a crew to Mars I want to see this theme playing in the background:

https://youtu.be/x8PR3QIwXHs
Title: Re: Starship!
Post by: JayUtah on December 23, 2020, 11:19:23 AM
Totally needs the Thunderbirds theme. ;D

Believe me, the Gerry Anderson fandom has been all over this since the beginning.
Title: Re: Starship!
Post by: raven on December 23, 2020, 04:26:10 PM
Totally needs the Thunderbirds theme. ;D But, yes, I'd rather get back to discussing the craft this topic is named for.

You mean this theme? When Starship finally takes a crew to Mars I want to see this theme playing in the background:

https://youtu.be/x8PR3QIwXHs

Meant more this one, but that works too! Thunderbirds had an interesting take on high tech. Sure, it caused problems, but they could be fixed, usually with other tech and a little ingenuity, and it loved it all the same.


Believe me, the Gerry Anderson fandom has been all over this since the beginning.
Colour me less than surprised.  8)
Title: Re: Starship!
Post by: jfb on December 23, 2020, 06:23:21 PM
Totally needs the Thunderbirds theme. ;D

Believe me, the Gerry Anderson fandom has been all over this since the beginning.

To wit:

Title: Re: Starship!
Post by: jfb on December 23, 2020, 06:36:26 PM
Anyway, back to the interesting stuff...

SN9 is on the pad ready for testing

Here is Lab Padre's time-lapse of the move
 
https://www.youtube.com/watch?v=9ELfqbYJwSE

Really interested in what sort of damage may be lurking after the fall in the high bay.  Based on the pictures I’ve seen the flaps took the brunt of the damage (and acted as crumple zones to limit damage to the body and the high bay).  Cryo proof and/or static fire may be interesting this time around. 

But beyond that, it’s one thing to fall over in the pad, it’s a whole other thing to fall over in a work area.  Thank God it didn’t happen while people were on scaffolds around it.  They need to beef up those supports or someone will get killed. 
Title: Re: Starship!
Post by: smartcooky on December 24, 2020, 04:41:37 AM
Totally needs the Thunderbirds theme. ;D

Believe me, the Gerry Anderson fandom has been all over this since the beginning.

To wit:




Best comment: Andy Denyer
Love it! But... No Jeff Bezos as the Hood?

(https://www.dropbox.com/s/j4j4awubvrbk1ir/BezosTheHood.jpg?raw=1)
Title: Re: Starship!
Post by: JayUtah on December 24, 2020, 05:42:03 PM
...it’s a whole other thing to fall over in a work area.  Thank God it didn’t happen while people were on scaffolds around it.  They need to beef up those supports or someone will get killed.

This is part of the luxury of SpaceX.  Had a similar accident occurred related to a contracted vehicle, the whole area would be shut down and subject to inspector general activity.  That would delay the process by a month or more.  But since the SpaceX Starship is a self-funded development effort, with no contracted customer yet, SpaceX only has to answer to OSHA (America's health-and-safety regulator), and then generally only if a worker injury occurred.  Yes, OSHA has an interest in workplace standards that might cause an injury, but less so.

I just skimmed the video of Starship assembly, so everyone please forgive me if I'm misrepresenting it.  But it looked like some parts of assembly and stacking were being done using general-purpose construction equipment.  Naturally almost none of that would be acceptable in the development of any other crewed space vehicle, if done under the auspices of a NASA contract to do so.  Now you can apply whatever judgment call you want to.  But this is part of how SpaceX is able to move so quickly.  And corner-cutting was honestly what delayed them in the ability to bid on many U.S. government contracts.  Obviously this raises the question of whether the controls and oversight that persist in competing programs is really necessary, and whether it really achieves the safety and quality goals that crewed space flight requires.  If anything this provides more data that helps us ask and answer these questions.
Title: Re: Starship!
Post by: Zakalwe on December 24, 2020, 06:15:04 PM


I just skimmed the video of Starship assembly, so everyone please forgive me if I'm misrepresenting it.  But it looked like some parts of assembly and stacking were being done using general-purpose construction equipment.  Naturally almost none of that would be acceptable in the development of any other crewed space vehicle, if done under the auspices of a NASA contract to do so.  Now you can apply whatever judgment call you want to.  But this is part of how SpaceX is able to move so quickly.  And corner-cutting was honestly what delayed them in the ability to bid on many U.S. government contracts.  Obviously this raises the question of whether the controls and oversight that persist in competing programs is really necessary, and whether it really achieves the safety and quality goals that crewed space flight requires.  If anything this provides more data that helps us ask and answer these questions.

They seem to be building their prototypes on a sandy, wind-swept shoreline, using cherry-pickers, big hammers and crowbars. It's fascinating watching them.....I nearly coughed up a lung when the rolled a $3 million Raptor engine under SN8 on the back of a pickup. They then used what looked like a butchered work platform to (jerkily) raise the Raptor up to install it on the thrust puck.

The same with loading SN9 onto the test stand.....a huge crane, some slings and two blokes on a couple of monster cherry-pickers. Boeing would have a stack of Statement of Works, Risk Assessments, lifting plans etc as high as the booster. However the ultimate end was the same, namely a booster on a test stand. Guess which one was completed first?

Their building process is the very antithesis of the hyper clean room assembly that you see elsewhere. And yet, they have made more test flights in a year than NASA/Boeing have with the SLS in 10 years.

Which approach works the best? Time will tell. I'm guessing that SpaceX are doing it this way so they can learn as fast as possible. Why make everything fancy when the chances are that it will end up in a pile of scrap? Once the design is worked out then they can crack on with making it look purty. They clearly know the process of building human-rated craft, so I am assuming that they will apply that set of knowledge once they work out how to fly the Booster and Starship.
Title: Re: Starship!
Post by: jfb on December 24, 2020, 07:47:45 PM
But it looked like some parts of assembly and stacking were being done using general-purpose construction equipment. 

Yup.  The joke among the Texas Tank Watchers is that the second company on Mars after SpaceX will be United Rentals. 

Title: Re: Starship!
Post by: molesworth on December 25, 2020, 12:33:21 PM
Yup.  The joke among the Texas Tank Watchers is that the second company on Mars after SpaceX will be United Rentals.

With all those red cliffs and buttes reminding me of the Road Runner cartoons, I think it might be Acme  ;D
Title: Re: Starship!
Post by: smartcooky on December 25, 2020, 02:57:18 PM
I just skimmed the video of Starship assembly, so everyone please forgive me if I'm misrepresenting it.  But it looked like some parts of assembly and stacking were being done using general-purpose construction equipment.  Naturally almost none of that would be acceptable in the development of any other crewed space vehicle, if done under the auspices of a NASA contract to do so.

Genuine question... why?

If a $5 million "general purpose" crane meets and exceeds all the specifications required to do the job, why is it necessary to design, build or buy a $50 million "special purpose" crane to do the exact same job? 
Title: Re: Starship!
Post by: Zakalwe on December 25, 2020, 03:10:17 PM
Because pork barrel politics.
Shelby has mouths to feed dontcha know...
Title: Re: Starship!
Post by: jfb on December 26, 2020, 11:08:32 AM
I just skimmed the video of Starship assembly, so everyone please forgive me if I'm misrepresenting it.  But it looked like some parts of assembly and stacking were being done using general-purpose construction equipment.  Naturally almost none of that would be acceptable in the development of any other crewed space vehicle, if done under the auspices of a NASA contract to do so.

Genuine question... why?

If a $5 million "general purpose" crane meets and exceeds all the specifications required to do the job, why is it necessary to design, build or buy a $50 million "special purpose" crane to do the exact same job?

Special-purpose equipment may be designed to make the process safer or more efficient, or to bake in a known level of reliability.  A general-purpose mobile crane can handle a lot of different tasks, but may not have a level of precision that a special-purpose crane can provide.

But...

SpaceX’s answer appears to be to tailor their design and process to accommodate commercial equipment rather than vice versa. 
Title: Re: Starship!
Post by: raven on December 26, 2020, 11:14:37 AM
There's a quite good Kerbal Space Program fanfic that explains the distinctly bodged appearance of the parts being due to the early Kerbal space program being operated out of a junk yard. I can't help but be reminded of that.
Title: Re: Starship!
Post by: smartcooky on December 26, 2020, 07:09:08 PM
I just skimmed the video of Starship assembly, so everyone please forgive me if I'm misrepresenting it.  But it looked like some parts of assembly and stacking were being done using general-purpose construction equipment.  Naturally almost none of that would be acceptable in the development of any other crewed space vehicle, if done under the auspices of a NASA contract to do so.

Genuine question... why?

If a $5 million "general purpose" crane meets and exceeds all the specifications required to do the job, why is it necessary to design, build or buy a $50 million "special purpose" crane to do the exact same job?

Special-purpose equipment may be designed to make the process safer or more efficient, or to bake in a known level of reliability.  A general-purpose mobile crane can handle a lot of different tasks, but may not have a level of precision that a special-purpose crane can provide.

But...

SpaceX’s answer appears to be to tailor their design and process to accommodate commercial equipment rather than vice versa. 

Thanks for this answer

I'm not necessarily buying the first part. I said if the commercially available GP equipment meets ALL of the required specifications (and that would necessarily include being able to do the job just as safely as the SP equipment would) then why the need to spend the extra to buy the SP equipment?

I am well versed in using specialist test equipment from my avionics days so I am certainly aware that having something built to do a specific task can make the job easier. For example, one of the pieces of equipment I use to work on was the APN59B weather radar out of a C-130. It had a test rig which plugged into an internal test port on the RT289 that allowed all the internal voltages and circuit board test points to be monitored with the turn of a rotary switch on the test panel. That job could just as safely be done by using a meter or oscilloscope and directly probing those points. In fact we had to do that sometimes because we only had one test rig, but would often have two RT units in the workshop at the same time.

As to the second part, yes, that seems to be the intent here. I am looking forward to seeing how they are going to go about stacking Starship on top of Super Heavy - "Bluezilla" they used on SN8 doesn't look as if it will lift high enough. Maybe they are going to build a Super-High Bay?
Title: Re: Starship!
Post by: JayUtah on December 27, 2020, 02:16:48 PM
So many great, thoughtful contributions here.  Again, this is hard for me to debate because a lot of it is my industry and I have to represent it fairly in public.  It's hard to distill insight away from its mixture with opinion, but I assume a fair amount of my opinion is part of why you guys would want me to answer.

But mostly, you folks have touched on items that would result in another wall of text were I to address all of them carefully.  I spent a lot of time yesterday baking, and thinking about how to respond in a way that's honest, respectful of others' opinions, informative, and shorter than book length.  I literally taught a class on this (tooling for advanced manufacturing) in college, so there is a plethora of thoughts to collect.  There is also a lot of historical background that we can't just ignore.  And some business stuff that I frankly let other people be experts in whereas I am not.
Title: Re: Starship!
Post by: molesworth on December 28, 2020, 04:27:42 PM
So many great, thoughtful contributions here.  Again, this is hard for me to debate because a lot of it is my industry and I have to represent it fairly in public.  It's hard to distill insight away from its mixture with opinion, but I assume a fair amount of my opinion is part of why you guys would want me to answer.

I'm sure a wee disclaimer along the lines of "not speaking in my professional capacity.." would suffice  ;)

I think all of us in the space industry have the same problem, and I certainly wouldn't want any thoughts I might have on the efficiency or fiscal wisdom of any agency, company or project to be seen as representing the views of my company...  :D
Title: Re: Starship!
Post by: jfb on December 29, 2020, 12:26:00 AM
I’d like to take back my earlier statement somewhat, because the more I think on it the less happy I am with it.

SpaceX are building their rockets and their rocket manufacturing facility concurrently.  They were stacking rockets before they had buildings in which to stack them.  They are using general-purpose construction equipment to build and stack starships because it was the quickest path to get hardware on the pad.

That is changing - they’re in the process of installing a permanent crane in the high bay.  They’ve bodged together a crawler-transporter out of ganged SPMTs, but at some point they may roll out a bespoke CT.  There are a number of jigs and customized welders in the tents for building the barrels, domes, and nosecones.  But even so, plenty of components are built off-site (I believe in Hawthorne) - the flaps, header tanks, downcomers, and of course the engines. 

And these are all still prototypes, not production vehicles.  They’re test beds for validating design and procedures.  Things are still in flux.

I can imagine as the manufacturing side gets tuned, we’ll see more specialized equipment and fewer United Rentals decals. 
Title: Re: Starship!
Post by: JayUtah on December 29, 2020, 12:27:08 PM
Indeed, just last night I saw a short video about the Starship launch pad. Along the way someone quoted someone at SpaceX saying they didn't know how to build Starship yet.  So yes, that casts the whole process of constructing flight-test articles in more favorable light.  You can dig up photos of early assemblies from the lunar module and space shuttle showing them being assembled with hand tools on plywood fixtures.  It's a matter of understanding where we are in the process.

Without delving into a lengthier response...

Generally you have to develop the thing you're building and the way you're going to build it together.  Fabrication and assembly methods place constraints on the design, and it's costly to ignore them until later.  So I'm just not sure where the Starship is in its development process.  If the contention is that one company outpaces all others, then you need to take careful stock of what they might be skipping and why.  My impression is that Elon Musk prefers a Silicon Valley style engineering development process, which is hardly surprising.  You work very quickly to build prototypes and proofs of concept, then you go back later and fill in the gaps, redesigning as necessary to accommodate things you learned during your initial work.  This seems to work well for software and electronics, although those of you who specialize in those fields can correct me.

But the manufacturability issues don't resolve themselves easily that way when the product is a costly physical engineering article.  The Falcon 9 acceptance was delayed because NASA inspectors kept finding nonconforrmant manufacturing and assembly processes.  The Tesla Model 3 was delayed for the same manufacturability reasons.  I drove a demonstration model and was impressed enough with it to plunk down the deposit for one.  A year went by, and then another year.  The price kept going up and the feature list kept getting shorter.  This was Tesla trying to figure out how to build it after it had already been "designed."  And lest this turn into a one-sided criticism, it's also the reason the Dreamliner was late.  Boeing tried to cut the same corners and paid the price in a costly redesign effort and delayed delivery.

That said, if you can afford to learn from failure then it's worth it to explore other development processes and see if you can find a better way.  So just because you aren't doing the same thing everyone else does doesn't mean you're doing it wrong.  It just means it falls somewhere else on the cost-benefit spectrum.  Now in the case of Falcon 9 you can clearly say that the manufacturing issues are resolved, because the delivery tempo is enviable.  But the question is how big a check Elon Musk had to write to fix the manufacturing variances?  And what if it had happened in a company where that sort of correction wasn't an option?

More importantly, manufacturability is not strictly an economic argument.  If you're going to do work for a national space agency, acceptance testing based on a manufactured product is the requirement.  And it's the same for some commercial customers (or more appropriately, their insurers).  A one-off, hand-built article isn't eligible for acceptance testing because a lot of the other requirements of a development and manufacturing process (which I'll get into in a separate post) have to be baked into the process.  The tests aren't just for the article, but for the way the article is being designed and built.  You have to demonstrate that you can make an article that passes various tests using a process that also satisfies certain criteria that pertain to the process.  You have to prove you can do it that way every time, not just for the article submitted for test.

So the answer to why Starship prototypes are currently being assembled with general purpose construction equipment is simply that it's not as far along in the development process as I had previously thought, and SpaceX have elected to accelerate to flight testing.  And from what I understand the objectives of these test flights to be, I have far less a problem with the construction methods now that the evidence seems to show not only that they're building up the actual production line, but that they're doing it fairly early in the process.  This is good, because it means they seem to be addressing a problem that has plagued Musk's companies before.
Title: Re: Starship!
Post by: smartcooky on December 29, 2020, 04:02:18 PM
Very good reply Jay, thank you

It seems obvious to me that SpaceX are using a "conceptual engineering" philosophy in the designing of Starship... they are trying things that are leading edge, never done before concepts, such as a 100% reusable rocket, a closed-cycle methalox engine and the flip maneuver to land upright, so this really is innovation on a grand scale. The idea seems to be to prove the concepts work before you spend billions on refined engineering, only to find that the concept is flawed and never going to work or is too difficult to reliably and safely engineer.

Was the video you watched the one by Primal Space? If so, you might remember they talked about how one of the static test fires kicked up material that damaged stuff inside the engine bay. This could be fixed by having water deluge and/or exhaust channels to prevent the shock-wave from doing this damage. However, the point needs to be made that the primary purpose of Starship is to fly humans to Mars, land them on the surface and then return them to earth. There will be no specially built launch pads, exhaust channels or water deluges on Mars. They are going to have to learn to handle this debris issue, so why not start now.
Title: Re: Starship!
Post by: Zakalwe on December 29, 2020, 05:02:14 PM
Its also worth considering that Falcon 9 was primarily designed to win contracts for SpaceX. Starship is being primarily designed to get to Mars. It's secondary purpose will be a heavy lift vehicle that may be used to lift Starlink satellites in order to build the network and generate the revenue that SpaceX needs to get to Mars. In other words, Starship's primary customer will be SpaceX.

Being their own customer means that they do not have to jump go through the myriad of hoops that, say, a contractor to a government agency will insist on.
Title: Re: Starship!
Post by: smartcooky on December 29, 2020, 05:36:19 PM
Its also worth considering that Falcon 9 was primarily designed to win contracts for SpaceX. Starship is being primarily designed to get to Mars. It's secondary purpose will be a heavy lift vehicle that may be used to lift Starlink satellites in order to build the network and generate the revenue that SpaceX needs to get to Mars. In other words, Starship's primary customer will be SpaceX.

Being their own customer means that they do not have to jump go through the myriad of hoops that, say, a contractor to a government agency will insist on.

True, but to be fair, NASA  have awarded them a $135 million contract to advance the design of the Starship for potential use as a crewed lunar lander in the Artemis program.
Title: Re: Starship!
Post by: JayUtah on December 29, 2020, 08:11:50 PM
The idea seems to be to prove the concepts work before you spend billions on refined engineering, only to find that the concept is flawed and never going to work or is too difficult to reliably and safely engineer.

Yes, Silicon Valley has been quite successful at large by following this model.  And you might ask why Boeing, Lockheed, Northrop Grumman, and others don't follow suit.  And the answer is long, but boils down largely to them being established, publicly-traded companies.  Private companies have a different risk landscape, and this factors into deciding who will build what.

Quote
Was the video you watched the one by Primal Space? If so, you might remember they talked about how one of the static test fires kicked up material that damaged stuff inside the engine bay.

I shuffled back through my history and can confirm it was theirs:  "SpaceX's Launch Pad Problem."  I think it might be the first video from them I've seen.  First, the idea of a coated concrete pad is a good advancement.  But without the coating, the heat spalling was pretty spectacular.  And I get the wisdom of using that behavior to figure out what a field landing and takeoff on Mars will need in terms of engineering.  They have money, an already-wrecked launch pad, and privately-funded prototypes to hammer to pieces if needed, and aren't really accountable to anyone for how that investigation goes.  This would have to be planned for much differently if NASA had wanted an established company to investigate it.  "Move fast and (literally) break things," has considerable value, but it's not always an option for complicated reasons, and that raises thoughtful questions.

Title: Re: Starship!
Post by: molesworth on December 30, 2020, 04:59:28 AM
My impression is that Elon Musk prefers a Silicon Valley style engineering development process, which is hardly surprising.  You work very quickly to build prototypes and proofs of concept, then you go back later and fill in the gaps, redesigning as necessary to accommodate things you learned during your initial work.  This seems to work well for software and electronics, although those of you who specialize in those fields can correct me.

I'll volunteer to be the one to correct you on this  ;D  As a software engineer of <ahem!> years, and working for a company that does everything from chip design up, I'd say it's widely accepted that careful design and testing results in much better quality for the end results.  There's an old saying that the earlier you find a bug, the cheaper and easier it is to fix.  (A couple of exceptions would be experimental prototypes where you want to quickly try ideas, and in my previous life as a game developer where getting the "gameplay" right was often more experimental - although the underlying "engine" tech had to be solidly designed.)

However, to my non-physical-engineering eyes, I don't think SpaceX is using a "throw it at the wall and see what sticks" approach at all.  To have gotten this far with what appears to be fairly mature spacecraft and engine designs leads me to believe they've spent a lot of time working on them.  Using off-the-shelf ground equipment like cranes and forklifts is perhaps more down to wanting to get things moving quickly rather than spending a lot of time building the infrastructure first.  I'll bet that there was quite a bit of similarly creative equipment use in the first years of most space programmes, including early and pre-NASA.
Title: Re: Starship!
Post by: molesworth on December 30, 2020, 06:44:12 PM
Oh, and if there was any doubt that Elon is quite, quite mad...

https://twitter.com/elonmusk/status/1344327757916868608 (https://twitter.com/elonmusk/status/1344327757916868608)
Quote
We’re going to try to catch the Super Heavy Booster with the launch tower arm, using the grid fins to take the load
:o
Title: Re: Starship!
Post by: Zakalwe on December 31, 2020, 04:38:25 AM
Oh, and if there was any doubt that Elon is quite, quite mad...

https://twitter.com/elonmusk/status/1344327757916868608 (https://twitter.com/elonmusk/status/1344327757916868608)
Quote
We’re going to try to catch the Super Heavy Booster with the launch tower arm, using the grid fins to take the load
:o

That'll make for an interesting YouTube stream!  :o
Title: Re: Starship!
Post by: bknight on December 31, 2020, 02:08:33 PM
Oh, and if there was any doubt that Elon is quite, quite mad...

https://twitter.com/elonmusk/status/1344327757916868608 (https://twitter.com/elonmusk/status/1344327757916868608)
Quote
We’re going to try to catch the Super Heavy Booster with the launch tower arm, using the grid fins to take the load
:o

There are quite a lot of challenges, but it isn't  impossible to slow a ship to landing speed and then latch a stand alone platfom then gently lower to the "ground"
Title: Re: Starship!
Post by: molesworth on December 31, 2020, 07:57:29 PM
Oh, and if there was any doubt that Elon is quite, quite mad...

https://twitter.com/elonmusk/status/1344327757916868608 (https://twitter.com/elonmusk/status/1344327757916868608)
Quote
We’re going to try to catch the Super Heavy Booster with the launch tower arm, using the grid fins to take the load
:o

There are quite a lot of challenges, but it isn't  impossible to slow a ship to landing speed and then latch a stand alone platfom then gently lower to the "ground"
The fine art of understatement...  ;D
Title: Re: Starship!
Post by: Peter B on December 31, 2020, 08:27:52 PM
Oh, and if there was any doubt that Elon is quite, quite mad...

https://twitter.com/elonmusk/status/1344327757916868608 (https://twitter.com/elonmusk/status/1344327757916868608)
Quote
We’re going to try to catch the Super Heavy Booster with the launch tower arm, using the grid fins to take the load
:o

Any illustrations of exactly what he has in mind?
Title: Re: Starship!
Post by: raven on December 31, 2020, 11:13:58 PM
Maybe I'm too nice to the guy, but a lot of the stuff he comes up with sounds like public spitballing, made public to keep the interest high and the conversation flowing.
Title: Re: Starship!
Post by: JayUtah on January 01, 2021, 12:24:12 AM
Maybe I'm too nice to the guy, but a lot of the stuff he comes up with sounds like public spitballing, made public to keep the interest high and the conversation flowing.

There's no question Elon Musk has revitalized enthusiasm for U.S. space enterprise.  He doesn't have shareholders or a board of directors at SpaceX to answer to, so he can play a unique role in that respect even if a substantial part of it is Harold Hill theatrics.  The pre-existing space infrastructure wasn't largely concerned with public interest or enthusiasm.  It didn't need it.  And I don't mean that arrogantly; we knew who our customers were and they knew who we were, and no one needed to advertise during the Superbowl.  Capturing the imagination of the American public was only a small part of the business model, so you got only the most basic public outreach efforts.

The problem is that the enthusiasm quickly became partisan.  It was characterized as SpaceX succeeding where other companies failed due to incompetence and lazy stagnation, which wasn't especially fair.  This doesn't mean everyone is entitled to share in the glory of one company's conspicuous innovation.  But a more properly directed surge in public enthusiasm could have led to more aggressive changes in the NASA funding model and a more credible change in marketing posture among existing companies to appeal differently to corporate customers.  So keeping the conversation flowing doesn't have to be rabidly adversarial.  Inevitably someone will say, "That's so bold!  Why isn't ULA thinking of similar things?"
Title: Re: Starship!
Post by: cjameshuff on January 01, 2021, 06:50:48 PM
I just skimmed the video of Starship assembly, so everyone please forgive me if I'm misrepresenting it.  But it looked like some parts of assembly and stacking were being done using general-purpose construction equipment.  Naturally almost none of that would be acceptable in the development of any other crewed space vehicle, if done under the auspices of a NASA contract to do so.

Genuine question... why?

If a $5 million "general purpose" crane meets and exceeds all the specifications required to do the job, why is it necessary to design, build or buy a $50 million "special purpose" crane to do the exact same job?

Special-purpose equipment may be designed to make the process safer or more efficient, or to bake in a known level of reliability.  A general-purpose mobile crane can handle a lot of different tasks, but may not have a level of precision that a special-purpose crane can provide.

But...

SpaceX’s answer appears to be to tailor their design and process to accommodate commercial equipment rather than vice versa.

Note that the big expensive SLS Vertical Assembly Center (which had to be rebuilt after they got it crooked the first time) didn't keep them from dropping a tank dome.

SpaceX isn't entirely avoiding custom equipment. They're building a gantry crane into the building they're constructing for putting together the booster, and will probably go back and install similar cranes elsewhere. They just didn't move forward with the crane construction until they had actual experience stacking Starship components to tell them what would be most useful. Their approach could be summarized as "try it and see what we really need", adding automation and special fixtures as needed. Musk seems to be very carefully avoiding the mistakes he made at Tesla with the Model 3, like the "fluff bot" he's mentioned that gave them so much trouble handling fiberglass mats which it turned out could be eliminated entirely from the design.
Title: Re: Starship!
Post by: smartcooky on January 02, 2021, 02:24:25 PM
Oh, and if there was any doubt that Elon is quite, quite mad...

https://twitter.com/elonmusk/status/1344327757916868608 (https://twitter.com/elonmusk/status/1344327757916868608)
Quote
We’re going to try to catch the Super Heavy Booster with the launch tower arm, using the grid fins to take the load
:o

Any illustrations of exactly what he has in mind?


Well, here is Scott Manley's take on catching boosters...

https://www.youtube.com/watch?v=lEAyjtIIccY
Title: Re: Starship!
Post by: molesworth on January 29, 2021, 05:00:36 PM
I don't know if it was prompted by the delay in SN9's launch, but we're now going to have two Starships on the pad at the same time!

(https://www.apollohoax.net/forum/index.php?action=dlattach;topic=1822.0;attach=1028)
Title: Re: Starship!
Post by: VQ on January 29, 2021, 05:16:44 PM
Well, here is Scott Manley's take on catching boosters...

More or less arbitrary to link:
https://xkcd.com/1244/
Title: Re: Starship!
Post by: JayUtah on January 29, 2021, 06:18:33 PM
I hope someone makes a poster out of that.  I see there's some SNAFU with the FAA over the SN9 launch, so I guess we have to wait.
Title: Re: Starship!
Post by: molesworth on February 02, 2021, 05:13:52 PM
Another decent flight with a failure at the end.  This time it looks like an engine failed to start properly (with several "coughs" trying to ignite) and another RUD.  It's a got job they've got another six or seven on the production line for further testing  ;)

(https://www.apollohoax.net/forum/index.php?action=dlattach;topic=1822.0;attach=1031)

eta : still can't figure out how to attach images correctly :)
Title: Re: Starship!
Post by: JayUtah on February 02, 2021, 05:25:19 PM
Another decent flight with a failure at the end.  This time it looks like an engine failed to start properly (with several "coughs" trying to ignite) and another RUD.

Yeah, I wasn't sure what the landing startup sequence was supposed to look like so I didn't know what to look for.  The sputtering was clearly evident though.  The commentator I heard said the pitchover would happen using two motors and then terminal descent would be on one motor.  The pitch error at the end was significant and indicated they didn't get enough pitch moment in time, which would be consistent with an underperforming motor.
Title: Re: Starship!
Post by: LunarOrbit on February 02, 2021, 05:33:30 PM
Looks like some kind of debris came out of the engine bay shortly before it crashed. Might be unrelated, but it probably shouldn't do that.
Title: Re: Starship!
Post by: bknight on February 02, 2021, 07:38:27 PM
I think that the two flights are similar that they both lacked proper fuel to the engines.  I saw a definirte  green huele comino off the engine indicating it was consumming itself.
Title: Re: Starship!
Post by: cjameshuff on February 02, 2021, 08:28:22 PM
I think that the two flights are similar that they both lacked proper fuel to the engines.  I saw a definirte  green huele comino off the engine indicating it was consumming itself.

Are you sure you're looking at SN9?

https://youtu.be/_zZ7fIkpBgs?t=703 (https://youtu.be/_zZ7fIkpBgs?t=703)

SN8's engines started up, but one showed clear, brilliant green in its exhaust. This was just a low-pressure jet of yellow flame...clearly subsonic, like maybe only the fuel turbopump was running. It could be that oxidizer pressure was low this time.

Some debris came out of the skirt, but the second engine continued to attempt to start and appeared to nearly succeed. I think it was just thermal blankets getting blown loose.

They previously did a series of static fires and engine swaps on SN9 that Musk described as something along the lines of "learning how to start Raptors". Looks like they're still tweaking that part of things.
Title: Re: Starship!
Post by: JayUtah on February 03, 2021, 04:01:59 PM
Inflight restarts are hard.  Starship has several hurdles.  The Raptor is a pump-fed engine, and turbopumps need a sufficiently high, sufficiently stable head pressure.  Starship has highly exciting flight dynamics just when you need liquids not to slosh in various tanks and pipes.

Previously, inflight restarts were obviated by having a hypergolic upper stage and bladder-pressurized propellant tanks.  No pumps to cavitate, no igniters to fail.  But hypergolics bring their own engineering problems with them.  And the available chemistry limits power and efficiency.  So restartable pump-fed or pressure-fed engines, with chemical or electrical ignition, has to be part of the vocabulary.  As with Apollo, pump-fed engines can be restarted by an ullage burn to "settle" the tanks, and a spark plug that ignites the preburner using propellants fed to it only by inertia from the ullage.  This works best when the vehicle isn't otherwise maneuvering.  And sometimes it involves several stages of ignition (i.e., using small igniter torches) based on how much propellant flow is possible from the previous step.  And multi-stage ignition sequences generally have to be very precisely timed.

Now complicate the fluid slosh by having your vehicle do Olympic diving maneuvers.  Head pressure fluctuations, gas voids, pump cavitation -- so much can go wrong.  It looks to me like the turbopumps just weren't getting a bite on the propellants, for whatever ultimate reason.  When they say they're still working out the mechanics of Raptor restarts, I don't doubt it for a second.  What they're trying to do is very hard.  If I have some time later, I'll look into the Raptor restart sequence and the Starship propellant feed system in more detail.

The two debris sheds look like the insulation blankets around the upper landing struts.  The debris looks like it's coming from the perimeter of the skirt, not the center.  And it's not the struts or footpads themselves -- at least the first one -- because all six footpads are still in place after the first shed.  Plus, the ease with which the slipstream slows them down suggests lightweight film, not heavy structure.  Losing insulation in the last five seconds of the flight would be inconsequential.  It may be planned for in SpaceX's flight profile.  I would be interested to see the slipstream turbulence models for the interior of the skirt.
Title: Re: Starship!
Post by: Peter B on February 03, 2021, 06:07:17 PM
Just a thought, but wouldn't it be easier to use the RCS to swing the vehicle upright, and then restart the engine? That way you have gravity on your side for draining propellant from the tanks.
Title: Re: Starship!
Post by: cjameshuff on February 03, 2021, 06:41:38 PM
Just a thought, but wouldn't it be easier to use the RCS to swing the vehicle upright, and then restart the engine? That way you have gravity on your side for draining propellant from the tanks.

Starship masses over a hundred metric tons. The current cold gas thrusters are nowhere near capable of doing that. They've talked about doing the flip using methox thrusters (the HLS landing thrusters might be a scaled-up relative of these), but if they can do it without dedicated thrusters, that's a whole thruster system they don't need...one capable of giving them comparable maneuverability to two gimbaled Raptors.

They're probably not that far from getting it working. SN8 had the engines light up and perform an essentially perfect flip, the problems came after that. SN9 had one engine not start, but there's many, many things that could cause that.
Title: Re: Starship!
Post by: cjameshuff on February 03, 2021, 11:06:37 PM
Inflight restarts are hard.  Starship has several hurdles.  The Raptor is a pump-fed engine, and turbopumps need a sufficiently high, sufficiently stable head pressure.  Starship has highly exciting flight dynamics just when you need liquids not to slosh in various tanks and pipes.

Even better, Raptor has two turbopumps to start, being a FFSC engine.


Now complicate the fluid slosh by having your vehicle do Olympic diving maneuvers.  Head pressure fluctuations, gas voids, pump cavitation -- so much can go wrong.  It looks to me like the turbopumps just weren't getting a bite on the propellants, for whatever ultimate reason.  When they say they're still working out the mechanics of Raptor restarts, I don't doubt it for a second.  What they're trying to do is very hard.  If I have some time later, I'll look into the Raptor restart sequence and the Starship propellant feed system in more detail.

They use smaller header tanks, one for LOX in the nose and one for LCH4 at the bulkhead between the LOX/LCH4 tanks. So they can basically have as little ullage space as they like. Too little ullage space might make pressure regulation difficult though.


The two debris sheds look like the insulation blankets around the upper landing struts.  The debris looks like it's coming from the perimeter of the skirt, not the center.  And it's not the struts or footpads themselves -- at least the first one -- because all six footpads are still in place after the first shed.  Plus, the ease with which the slipstream slows them down suggests lightweight film, not heavy structure.  Losing insulation in the last five seconds of the flight would be inconsequential.  It may be planned for in SpaceX's flight profile.  I would be interested to see the slipstream turbulence models for the interior of the skirt.

They also lost the skirt camera on the way up, so something might have come loose...but I'm thinking a cable harness or conduit, not part of the engine.
Title: Re: Starship!
Post by: Zakalwe on February 04, 2021, 03:01:27 AM
Perhaps the turbopumps don't like being rotated that fast? I would imagine that the gyroscopic precession effects on turbines spinning at the RPMs that turbopumps operate at would cause significant loads?
Title: Re: Starship!
Post by: cjameshuff on February 04, 2021, 08:15:42 AM
Perhaps the turbopumps don't like being rotated that fast? I would imagine that the gyroscopic precession effects on turbines spinning at the RPMs that turbopumps operate at would cause significant loads?

The engines are what perform the rotation, SN9 wasn't rotating at the time the second engine failed to ignite.
Title: Re: Starship!
Post by: bknight on February 04, 2021, 08:38:38 AM
I think that the two flights are similar that they both lacked proper fuel to the engines.  I saw a definirte  green huele comino off the engine indicating it was consumming itself.

Are you sure you're looking at SN9?

https://youtu.be/_zZ7fIkpBgs?t=703 (https://youtu.be/_zZ7fIkpBgs?t=703)

SN8's engines started up, but one showed clear, brilliant green in its exhaust. This was just a low-pressure jet of yellow flame...clearly subsonic, like maybe only the fuel turbopump was running. It could be that oxidizer pressure was low this time.

Some debris came out of the skirt, but the second engine continued to attempt to start and appeared to nearly succeed. I think it was just thermal blankets getting blown loose.

They previously did a series of static fires and engine swaps on SN9 that Musk described as something along the lines of "learning how to start Raptors". Looks like they're still tweaking that part of things.
Yes, I posted that after watching the launch.  After watching Scott Manley's slow mo video I correct my initial thoughts. I don't see any green engine consumption that occurred in SN-8.  It looked like the second engine just never ignited properly.  So they have to fix that.
Title: Re: Starship!
Post by: JayUtah on February 07, 2021, 01:25:35 PM
If I'm following social media correctly, it looks like the next idea is to light all three Raptors and shut down the least performant one, on the premise that this will improve the chances of getting two good engines for maneuvering and landing.  I'm interested to see whether it will work.
Title: Re: Starship!
Post by: raven on February 07, 2021, 06:26:16 PM
Sounds like something of a bodge and a kludge, but I'd like to see them try all the same.
Title: Re: Starship!
Post by: Obviousman on February 07, 2021, 06:31:00 PM
If I'm following social media correctly, it looks like the next idea is to light all three Raptors and shut down the least performant one, on the premise that this will improve the chances of getting two good engines for maneuvering and landing.  I'm interested to see whether it will work.

I saw that was posted to Elon Musk, asking why they didn't do that. His reply?

"Because we were dumb"! LOL!
Title: Re: Starship!
Post by: smartcooky on February 07, 2021, 06:47:13 PM
Flying rockets is damned hard... how many times did NASA blow up rockets on the pad or just after launch in attempting to get the bloody things to fly? Landing rockets is double-damned hard.. how many times did SpaceX try to land a rocket before they got one to stick? Was it seven? Eight?

And landing Falcon 9 boosters comparatively easy - the Falcon booster comes in tail first at multi-mach speed, already lined up to land, and with a bit of tricky sideways translation and an accurately timed burn that starts about 8,000 m of altitude, they park it on a dime

What they are trying to do with Starship is at least a whole order magnitude harder - descend rapidly "skydiver" fashion, then restart, flip and land in quick succession, all at low altitude - just a few hundred feet.

I have no idea why they dont pull the flip manouver at a higher altitude and just run the landing burn longer
Title: Re: Starship!
Post by: cjameshuff on February 07, 2021, 07:33:24 PM
Sounds like something of a bodge and a kludge, but I'd like to see them try all the same.

It's why they have three landing engines in the first place. They only want two for the actual landing and so they've only been starting two, but it sounds like having the redundancy implemented might have helped SN9. (Trying to start up a third engine when the fuel tank's pressure was already low would not have helped SN8.)
Title: Re: Starship!
Post by: cjameshuff on February 07, 2021, 07:47:54 PM
I have no idea why they dont pull the flip manouver at a higher altitude and just run the landing burn longer

It'd take a lot more propellant, and without two good engines to keep it straight, the vehicle would likely tumble out of control...it's not supposed to fly backwards at any significant airspeed. On SN8 the one landing engine was losing thrust near the end and on SN9 it couldn't even complete the flip without two engines...altitude would not have helped either.
Title: Re: Starship!
Post by: jfb on February 09, 2021, 11:12:51 AM
I have no idea why they dont pull the flip manouver at a higher altitude and just run the landing burn longer

The header tanks are only so big - I don't know what kind of margin they have right now, but I don't think they can start appreciably higher without increasing their size.

Which may ultimately be the answer - these are prototypes, they're meant to test out ideas under real-world conditions, and it may be their modeling was just plain wrong and they need to rethink the tankage or the plumbing or the engines.  They may use larger headers on 16/17/18/etc.  They may find out the current Raptor design just isn't robust enough to be swung around that violently and has to be tweaked. 

I would not expect a successful landing before SN15, and I would not be surprised if they had at least one kaboom after demonstrating a successful landing.  They are going to burn a lot of hardware before they get this figured out. 
Title: Re: Starship!
Post by: Zakalwe on February 09, 2021, 01:04:11 PM
I have no idea why they dont pull the flip manouver at a higher altitude and just run the landing burn longer

The header tanks are only so big - I don't know what kind of margin they have right now, but I don't think they can start appreciably higher without increasing their size.

Which may ultimately be the answer - these are prototypes, they're meant to test out ideas under real-world conditions, and it may be their modeling was just plain wrong and they need to rethink the tankage or the plumbing or the engines.  They may use larger headers on 16/17/18/etc.  They may find out the current Raptor design just isn't robust enough to be swung around that violently and has to be tweaked. 

I would not expect a successful landing before SN15, and I would not be surprised if they had at least one kaboom after demonstrating a successful landing.  They are going to burn a lot of hardware before they get this figured out.
i think that they have cut up a couple of prototypes that were in varying stages of being built. maybe that's the reason?
Title: Re: Starship!
Post by: smartcooky on February 11, 2021, 05:11:28 AM
I have no idea why they dont pull the flip manouver at a higher altitude and just run the landing burn longer

The header tanks are only so big - I don't know what kind of margin they have right now, but I don't think they can start appreciably higher without increasing their size.

Which may ultimately be the answer - these are prototypes, they're meant to test out ideas under real-world conditions, and it may be their modeling was just plain wrong and they need to rethink the tankage or the plumbing or the engines.  They may use larger headers on 16/17/18/etc.  They may find out the current Raptor design just isn't robust enough to be swung around that violently and has to be tweaked. 

I would not expect a successful landing before SN15, and I would not be surprised if they had at least one kaboom after demonstrating a successful landing.  They are going to burn a lot of hardware before they get this figured out. 

Let me start by saying I am not an aerospace engineer (although am a now retired aeronautical engineer - a different beast but with many points of convergence and commonality).

AIUI the whole (and sole) reason for the header tanks in the first place its to relight the Raptor engines due to the forces involved in the flip maneouvre to land creating a problm with fuel pressure from the main tanks. It seems to me that there is a more obvious solution; electric fuel booster pumps.

Peter Beck's "Electron" design at RocketLab uses electric fuel pumps powered by Li-Ion batteries. Why don't SpaceX take a leaf from RocketLab's book  - ditch the whole separate header tanks idea and use electric fuel booster pumps from the main fuel tanks to pressure-feed methalox to the Raptor engines? Is this idea perhaps so obvious that I am overlooking some even more obvious flaw in my thinking?
 
Title: Re: Starship!
Post by: molesworth on February 11, 2021, 05:30:54 AM
I have no idea why they dont pull the flip manouver at a higher altitude and just run the landing burn longer

The header tanks are only so big - I don't know what kind of margin they have right now, but I don't think they can start appreciably higher without increasing their size.

Which may ultimately be the answer - these are prototypes, they're meant to test out ideas under real-world conditions, and it may be their modeling was just plain wrong and they need to rethink the tankage or the plumbing or the engines.  They may use larger headers on 16/17/18/etc.  They may find out the current Raptor design just isn't robust enough to be swung around that violently and has to be tweaked. 

I would not expect a successful landing before SN15, and I would not be surprised if they had at least one kaboom after demonstrating a successful landing.  They are going to burn a lot of hardware before they get this figured out. 

Let me start by saying I am not an aerospace engineer (although am a now retired aeronautical engineer - a different beast but with many points of convergence and commonality).

AIUI the whole (and sole) reason for the header tanks in the first place its to relight the Raptor engines due to the forces involved in the flip maneouvre to land creating a problm with fuel pressure from the main tanks. It seems to me that there is a more obvious solution; electric fuel booster pumps.

Peter Beck's "Electron" design at RocketLab uses electric fuel pumps powered by Li-Ion batteries. Why don't SpaceX take a leaf from RocketLab's book  - ditch the whole separate header tanks idea and use electric fuel booster pumps from the main fuel tanks to pressure-feed methalox to the Raptor engines? Is this idea perhaps so obvious that I am overlooking some even more obvious flaw in my thinking?
With a similar disclaimer - I'm a semi-retired software engineer working on spacecraft data handling tech, but with a long-time interest in spaceflight...

As far as I understand it, the problem is the main tanks are large, and the small amount of fuel/lox left at landing would be moving about uncontrollably and unpredictably due to the flip.  Pumps may not be able to force through enough to relight the engines.

The header tanks are much smaller so should have less of an ullage problem, although pumps in addition to the nitrogen pressurisation may be worth looking into.  I haven't seen any report on why the engine on SN9 failed to relight, but it looked very different so may have been due to some other cause.  SpaceX have been pretty open about their development work so far, so I expect we'll hear more very soon.

I'd also add the comment that even 5 years ago I thought the chances of humans landing on Mars in my lifetime were vanishingly small.  Now I can see it happening within the next 10 - 15 years!   8)
Title: Re: Starship!
Post by: JayUtah on February 11, 2021, 03:15:14 PM
Yes, ullage is king here.  All the pumps in the world won't help you if the fluid you're trying to pump isn't anywhere near the pump inlet.  Not only do you have to consider pump head pressure, which you can solve with staged pumps, you have to consider that propellant slosh may deny you any use of pumps.  This is especially true if you have to plumb the tank for both horizontal and vertical operation.  The abstract principle of the header tank is very simple:  the fuller the tank, the less likely propellant slosh is a factor, and the less likely tank outlet location is a factor.  If the tank is sufficiently small, you can even introduce technologies like bladders, which effectively eliminate all the slosh, but I don't know if SpaceX are doing that.

So burning the Raptors longer on landing obviously means more propellant in header tanks that can't be touched until landing.  But since it all has to fit in the same fuselage, it means less fuel available for ascent -- the moneymaker.  Also, the flight dynamics would be altered by more mass in the header tanks.  And at a certain point, moving them around the fuselage for weight, balance, and moment-of-inertia purposes will typically either get you in structural trouble or plumbing trouble, or both.

And you aeronautical guys need to quit being so modest.  Fuel and oil flow paths and pumping strategies for high-performance aircraft are exactly the problems being solved here.  Rocketry used to be easy.  You were either ascending gracefully at 3+ g along the rocket axis, or floating in microgravity with no presumptions of favorable propellant placements.  Starship's propellant feed system reintroduces the problems of aircraft fuel-feed systems.  Hybrid thinking is needed.
Title: Re: Starship!
Post by: smartcooky on March 03, 2021, 06:26:46 PM
SN10 just nailed the landing!

Its leaning over a bit, but still upright!
Title: Re: Starship!
Post by: JayUtah on March 03, 2021, 06:33:39 PM
Any landing you walk away from...

Holy cow, lighting up all three Raptors worked.
Title: Re: Starship!
Post by: smartcooky on March 03, 2021, 06:54:35 PM
OH... it just exploded, on the pad!!!
Title: Re: Starship!
Post by: jfb on March 03, 2021, 09:09:43 PM
Fastest launch turnaround yet!

So between NSF, LabPadre, and SpaceX's own stream we have all the angles, and there are already a few postmortem videos. It looks like some of the landing legs did not deploy properly, and of those at least one failed to lock in place.  And it was a hard landing, you can clearly see it bounce on one of the LabPadre angles. 

But ... damn that was cool.  You could tell Innsprucker was waiting a few seconds to see if it would fall over before declaring it a success. 

Hopefully SN11 will land and not explode afterward, and SN15 should be solid all the way around.  And at some point there's going to be orbital testing with the full stack, which should be glorious to watch. 

This isn't going to get old for a while
Title: Re: Starship!
Post by: cjameshuff on March 03, 2021, 10:21:49 PM
Any landing you walk away from...

Holy cow, lighting up all three Raptors worked.

A bit different than I expected. I thought they'd shut down the third engine before doing the flip, maybe even before it fully started up if the first two were healthy. Instead they did the flip on all three (which I'd understood would be more thrust than they wanted during the maneuver) and went straight to one for the final landing burn.

Musk has mentioned that they're still working to get the Raptors burning reliably at lower thrusts, I wonder if they made some tweaks to reduce the minimum and allow the flip maneuver to be done with all three. Then they can just throttle up if one underperforms or fails to light, and pick a healthy engine to do the landing burn with.
Title: Re: Starship!
Post by: raven on March 03, 2021, 11:23:01 PM
OH... it just exploded, on the pad!!!
My mind went to the wonderful sequence with the transported, sorry, digitized Pig Lizard in Galaxy Quest (one of the best Star Trek Movies ever made.)

 Jason Nesmith : What? What was that?

Alexander Dane : Uh, nothing.

Jason Nesmith : I heard some squealing or something.

Gwen DeMarco : Oh, no. Everything's fine.

Teb : But the animal is inside out.

Jason Nesmith : I heard that! It turned inside out?

[the pig-lizard explodes]

Teb : And it exploded.
Title: Re: Starship!
Post by: Zakalwe on March 04, 2021, 04:26:59 AM
OH... it just exploded, on the pad!!!

Hey, look on the positives. SN10 is now the first Starship to flew twice!  ;D
Title: Re: Starship!
Post by: JayUtah on March 04, 2021, 10:07:36 AM
Teb : And it exploded.

Poor Jed Rees trying to keep a straight face...
Title: Re: Starship!
Post by: VQ on March 04, 2021, 12:27:15 PM
OH... it just exploded, on the pad!!!

Looked like it was leaking fuel from the hard landing, and the fire eventually led to tank rupture? Not a lot of fuel left based on the limited duration of the fireball.
Title: Re: Starship!
Post by: smartcooky on March 04, 2021, 02:38:20 PM
As usual, an excellent analysis from Scott Manley

https://www.youtube.com/watch?v=CF9mdMI1qxM
Title: Re: Starship!
Post by: JayUtah on March 04, 2021, 03:42:10 PM
Yes, great analysis by Scott.  The (temporary) landing leg attach points are fairly far up the skirt.  So if only some of them deployed, and if they are crushable structures, then it's entirely possible that the ones that lowered and locked "bottomed out" and may have punctured the bottom of the tank.

I want to see more on why the one Raptor doesn't seem to shut down cleanly.
Title: Re: Starship!
Post by: raven on March 04, 2021, 05:45:15 PM
SN8 we had an engine rich exhaust and rocket fall down hard, go boom.
SN9, second engine failed to really light properly, rocket fall down hard, go boom
SN10, manages to light all three, fall down a little too hard, landing legs don't quite work right, go boom  . . . later.
I'd say we're making progress, folks, and I don't mean that sarcastically.
Title: Re: Starship!
Post by: Peter B on March 04, 2021, 09:50:47 PM
SN8 we had an engine rich exhaust and rocket fall down hard, go boom.
SN9, second engine failed to really light properly, rocket fall down hard, go boom
SN10, manages to light all three, fall down a little too hard, landing legs don't quite work right, go boom  . . . later.
I'd say we're making progress, folks, and I don't mean that sarcastically.

Agree absolutely! After all, SN8 flew only four months ago.

Having said that, I have a couple of questions.

First, I got the impression that SN10 lifted off more slowly than the previous two flights. Would others agree with that? And if so, what might the likely explanation be? Lower thrust or a greater weight?

Second, these last three vehicles have only three engines while I understand the flight version is to have six engines. Obviously, a flight version is also going to be carrying a payload of some sort. That suggests to me a flight version is going to have greater mass at each end of the vehicle than these last three vehicles. And that in turn suggests to me the flight version would rotate more slowly for the same amount of torque. Are these assumptions correct (at least, would they be significant)? And if so, would it affect the altitude above ground at which the flip maneuver would start? And if so, how would that affect the software controlling the spacecraft?
Title: Re: Starship!
Post by: molesworth on March 05, 2021, 06:37:14 AM
Some interesting video and images from the clean-up, courtesy of NASA Spaceflight blow.  There a are a couple of close-ups of the landing legs, which don't look very substantial at all.  If a couple failed to deploy properly, the loads on the remaining ones would be much larger.

Also of note is a Boston Dynamics robot dog wandering around (I want one of those :) ) and the big crane (aka Bluto/Tankzilla) now at the pad, presumably for SN11 being rolled out on Monday.

Title: Re: Starship!
Post by: cjameshuff on March 05, 2021, 07:29:10 AM
SN8 we had an engine rich exhaust and rocket fall down hard, go boom.
SN9, second engine failed to really light properly, rocket fall down hard, go boom
SN10, manages to light all three, fall down a little too hard, landing legs don't quite work right, go boom  . . . later.
I'd say we're making progress, folks, and I don't mean that sarcastically.

Agree absolutely! After all, SN8 flew only four months ago.

Having said that, I have a couple of questions.

First, I got the impression that SN10 lifted off more slowly than the previous two flights. Would others agree with that? And if so, what might the likely explanation be? Lower thrust or a greater weight?

Second, these last three vehicles have only three engines while I understand the flight version is to have six engines. Obviously, a flight version is also going to be carrying a payload of some sort. That suggests to me a flight version is going to have greater mass at each end of the vehicle than these last three vehicles. And that in turn suggests to me the flight version would rotate more slowly for the same amount of torque. Are these assumptions correct (at least, would they be significant)? And if so, would it affect the altitude above ground at which the flip maneuver would start? And if so, how would that affect the software controlling the spacecraft?

Musk was talking about ongoing work to reduce the minimum thrust of the Raptors so they could have redundancy in the landing burn, and the original description of the redundancy described for the flip was to light all three engines and shut one down if they all came up properly. Instead, they did the whole flip with three engines, as well as part of the landing burn. Maybe they had a heavier propellant load or more ballast to compensate.

They'll probably have to adjust the landing maneuvers based on load, sure.
Title: Re: Starship!
Post by: jfb on March 05, 2021, 12:55:37 PM
The Raptors themselves still seem to be having teething issues, which isn't surprising given their complexity.  One was burning a little hot on ascent, and there seemed to be a little more soot in the exhaust. 

And that's without being whipped around in exciting and highly dynamic maneuvers.  I have to wonder how rapidly spinning turbopumps deal with that kind of torque. 

But, good Lord, the only thing that really needs to be ironed out is the landing - everything up to that point (transition to belly flop and descent) seems pretty well dialed in. 
Title: Re: Starship!
Post by: JayUtah on March 05, 2021, 01:38:03 PM
The problem of angular momentum in turbo pumps devolves quickly into a bearing problem and a guidance software problem.

If you have mechanical bearings like roller bearings, you generally don't have as much problem with gimbaling.  They can take the differential loading quite easily without loss of performance.  But fluid bearings are more efficient; they result in less power loss in the bearing.  They bring with them their own problems in how to manage the fluid pressure in the bearing.  But more importantly, when the pump rotor responds inertially to engine gimbaling by wanting to remain firmly oriented as before, it causes the bearing to have a much higher load on one side than the other.  Hydrodynamic bearings can compensate for this, given sufficient sophistication in the fluid inlet valves.  Hydrostatic bearings not so much.  So you need to make sure your chi-rate (the angular rate at which the gimbals operate) is clamped to that which your rotor bearings can stand.  Of course in Starship's case the rotors are turning relatively slowly since the engines are at minimal thrust.

The guidance question arises from everyone's classroom experiments with gyroscopes.  Trying to change the axis of a spinning mass results in a force at right angles to the rotation axis.  This means whipping the engines creates a parasitical moment in an unwanted direction.  Your rocket either has to have enough moment of inertia not to be bothered by it, or you have to program into your thrust-vector controller a correction that accounts for it.
Title: Re: Starship!
Post by: VQ on March 05, 2021, 09:18:27 PM
The guidance question arises from everyone's classroom experiments with gyroscopes.  Trying to change the axis of a spinning mass results in a force at right angles to the rotation axis.  This means whipping the engines creates a parasitical moment in an unwanted direction.  Your rocket either has to have enough moment of inertia not to be bothered by it, or you have to program into your thrust-vector controller a correction that accounts for it.

With multiple engines all gimballing at the same rate/angle (except for axial rotation control), couldn't one orient the turbos so the gyroscopic forces cancel?
Title: Re: Starship!
Post by: molesworth on March 06, 2021, 10:53:00 AM
The guidance question arises from everyone's classroom experiments with gyroscopes.  Trying to change the axis of a spinning mass results in a force at right angles to the rotation axis.  This means whipping the engines creates a parasitical moment in an unwanted direction.  Your rocket either has to have enough moment of inertia not to be bothered by it, or you have to program into your thrust-vector controller a correction that accounts for it.

With multiple engines all gimballing at the same rate/angle (except for axial rotation control), couldn't one orient the turbos so the gyroscopic forces cancel?

I might be getting it wrong, but I think the problem isn't the torque the pumps would exert on the rest of the rocket, which would be very small, but the forces they would put on their own bearings and other structures, which could cause problems or even failures.  (I'm not a mechanical engineer though, just a software wrangler with a fairly decent understanding of physics.)
Title: Re: Starship!
Post by: JayUtah on March 06, 2021, 11:22:31 AM
With multiple engines all gimballing at the same rate/angle (except for axial rotation control), couldn't one orient the turbos so the gyroscopic forces cancel?

Yes.  That's what the Saturn V did.  But when your engine configuration is dictated by other concerns, you have to think of different ways to solve the same problem.  But first you have to quantify the problem.  If, in some rocket, it's a second-order effect, you may find the drift to be within acceptable tolerance.  I don't know what order of effects the Starship engineers are dealing with.  My understanding is that the masses in a nearly-empty Starship are positioned to give it a large moment of inertia.

By the way, if you've ever flow a light propeller-driven airplane, this is something you deal with.  When you pitch up, the gyroscopic action of the propeller tends to make you yaw to the left.  After a while you just unconsciously apply a little right rudder when pitching up.  Similarly, if you gimble an engine for pitch, and it results in unwanted yaw, the subsequent yaw trim maneuver ends up affecting you in the pitch axis.  So in that simplified example, the axes are coupled.  But not in a way that precludes developing a control law for it.
Title: Re: Starship!
Post by: molesworth on March 06, 2021, 11:23:27 AM
An update from Musk (although it's not an official statement, just a tweet) :

https://twitter.com/elonmusk/status/1368016384458858500

Quote
Thrust was low despite being commanded high for reasons unknown at present, hence hard touchdown. We’ve never seen this before.

Next time, min two engines all the way to the ground & restart engine 3 if engine 1 or 2 have issues.
Title: Re: Starship!
Post by: JayUtah on March 06, 2021, 01:07:56 PM
...but the forces they would put on their own bearings and other structures, which could cause problems or even failures.

Right.  If you lay the typical turbo pump on its side and split it lengthwise (which happens in lots of museum exhibits), you can identify the bearing points typically as larger-diameter cylindrical regions of the rotor.  There are typically two.  Where they lie along the shaft is a matter of considerable engineering tradeoff.  To reduce eccentric loads from gyroscopic behavior, the bearings want to be as close to the inertial center of the shaft as possible.  But to meet flexure tolerances for the rest of the assembly, they want to be spaced farther apart.

At one end you have the turbine, which is just a pinwheel.  At the other end you have the pump impeller(s), which is just a propeller whose primary job is moving fluid.  There are parasitical thrust forces generated in the shaft.  The pinwheel, in addition to spinning, also pulls on its end of the shaft.  The impeller often wants to pull or push on its end of the shaft too.  So you either have to balance those forces, or provide for them in your bearing design.

Every part of any articulated assembly behaves inertially.  So even a "thing attached to another thing" has to accommodate inertial responses if the assembly is suddenly accelerated or rotated.  But spinning masses amplify the reaction magnitude.  If you try to alter the orientation of a spinning mass, the reaction -- applied at the bearing points, at right angles to the shaft -- is very strong.  The spinning mass really wants to stay in the same orientation.

In most bearing designs, you expect the distribution of mechanical load around the circumference of the bearing race to be consistent -- and ideally equal.  Of course in something like an earth vehicle wheel bearing you know that there's also a gravity load involved.  But the way the load across the communicating-surface boundary changes over time informs the bearing design.  In some cases, shifting the load to one side of the bearing -- and thus reducing it on the other side -- can change the overall friction as measured in resistance to the rotation.  For liquid-fueled engines, turbo pump speed has to be be rock steady, otherwise it induces combustion instability.

Roller bearings are like ball bearings.  The communicating surfaces are separated by rollers so that there's no sliding involved, just rolling.  This is the sledge-on-logs principle.  The upside of this type of bearing is that the measured friction doesn't vary much with gyroscopic load.  But the measured friction of this type of bearing is, on average, higher than with other kinds of bearings.  Normally that would just mean sizing the pump load appropriately to the turbine shaft power.  But roller bearings incur mechanical wear and so are not the best choice for rockets you hope to be reusable.  They also require more attention to mechanical tolerances and precision to engineer, since they have more moving parts.  Plus, you really need efficiency.  The F-1 turbo pump had to deliver as much power as the entire engine on an F-16 fighter.

The more popular choice is fluid bearings.  The broad theory here is that if you have two communicating surfaces operating in shear, and there is a film of fluid between them that possesses a certain viscosity, very magical things happen in that fluid depending on shear velocity and normal pressure, and induced fluid pressure.  The result is that the fluid film is substantially resistant to normal force (a force trying to mash the two surfaces together) and thus prevents the surfaces from mechanically touching.  And at the same time it offers very little resistance to the shear motion -- the plates sliding across each other.

Fluid bearings are divided into two types, depending on what's keeping the fluid between the surfaces.  Your car engine probably uses hydrostatic bearings.  A separate oil pump sucks oil from the oil pan, through the oil filter, and pumps it through passages in the engine block where it emerges from ports appropriately spaced in the the outer bearing surface.  The pressure from this pump is what keeps the rotor centered.  But the oil escapes freely from the bearing in these cases, to be replaced by new oil from the pump.  It's captured and allowed to flow back into the pan to be recirculated.

If the pump fails, or if the moment of inertia in the rotor exceeds pump-supplied pressure, the rotor's bearing surface will grind against the stationary bearing surface.  The result is a dramatic, sudden increase in rotational friction, damage to the bearing surfaces, and a sudden increase in differential torque along the bearing shaft.  You now also likely have metal particles in the oil, which may block smaller lubricant passages.  The additional problem for rocket engines is where to get the power to drive the external oil pump while the motor is starting up.  Your car solves this problem by designing the bearing so that a little bit of residual oil remains in the bearing to lubricate all its shafts for a few seconds until the oil pump supplies suitable pressure.  And since gravity isn't available to help capture the free oil, you need to plan for how to get the oil back to whatever reservoir your oil pump is drawing from.  You have to borrow solutions from high-performance aircraft engines.

Hydrostatic bearings simply operate in the presence of an ambient fluid.  The communicating faces are designed to create a standing fluid "wedge" as they shear across each other.  You may have experienced this effect also in your car in the more terrifying form of hydroplaning.  Your car tires interact with the road surface and the intervening fluid to create a wedge of water that is literally capable of supporting the weight of your car and preventing the rubber from meeting the road.  A hydrostatic bearing is in a perpetual state of hydroplaning.  But as you can imagine, the effect happens only at high shear velocities, so hydrostatic bearings have to carefully match the viscosity of the lubricant to the expected operating speed.

Maintaining the "wedge" requires a delicate balance of distance and force between the communicating surfaces, fluid viscosity, and shear velocity (which, in a throttlable engine, can vary greatly).  Liquid lubricants change viscosity as they change temperature.  The reactive strength of the "wedge" changes with velocity and normal force.

One of the most common applications of a hydrodynamic bearing is the thrust bearing on a ship.  The propeller turns and the propulsive force occurs axially along the shaft.  But where is it applied to the ship structure?  Without the thrust bearing it would apply somewhere inside the engine, which is no good.  To transmit the force explicitly to the ship structure, you attach a robust disc to the shaft, which turns along with it.  The disc, while rotating, presses against a plate with a hole in it to allow the shaft to pass through untouched.  The plate is attached to the ship frame.  The area between the thrust disc and the thrust plate is lubricated with a hydrodynamic bearing, which bears the tremendous load of propulsion entirely by itself.

But to accommodate the ways in which the dynamics of the fluid film might change, the plate is actually replaced with a pie-slice assembly in which each of the pie-slice sectors is able to be angled and positioned to optimize the fluid behavior.  This way the ship can operate at a wide variety of shaft speeds, a wide range of applied loads (e.g., what if the propeller comes half out of the water?), and a wide variety of fluid temperatures and pressures.

Obviously putting that sort of sophisticated assembly into a rocket engine turbo pump is problematic.  Also, there is a big difference between a ship's propellor rotating at 180 rpm and a pump shaft rotating at tens (or even more than one hundred) thousand rpm.  If you decide to go with hydrostatic bearings, you have to ensure that engine operation stays within the narrow range of "hydroplaning" afforded by your built-in parameters.  This could be part of what Musk says when he wants to operate the Raptors slower:  the pumps may literally not be able to build up the fluid "wedge" at such a slow speed.

Temperature is not trivial.  The pinwheel end of the rotor will quickly reach temperatures of several hundred degrees Celsius.  It's sitting in the flow of the preburners, which is as hot as a blowtorch.  While there are many ways to cool the turbine end, borrowed from jet engine technology, it is inevitable that heat will travel down the bearing shaft and raise the temperature of the hot-end bearing substantially.  Conversely, the pump impellers are sitting (at least in the LOX case) in cryogenic propellant.  As the propellant passes through the pump, the cold end of the shaft drops to well below zero Celsius.  This makes the mechanical engineering of the pump rotor... interesting.  Remember what I said about differential torque in a bearing strike?  Imagine that one end of the shaft is very hot (and therefore not as mechanically strong as it would be at room temperature).  Imagine the other end is very cold, and likely brittle.  Sometimes the shaft literally cannot absorb the sudden torque increase, and the pump wrings its own neck.

But it also complicates the choice of lubricants.  What liquid lubricants stay viscous enough at blowtorch temperatures to act as a proper fluid film?  What lubricants stay fluid enough at arctic temperatures to avoid turning into a useless paste.

In many cases the answer has been the propellants themselves, simply because no other fluid can coexist in the environment as a separate lubricant..  A surprising number of rocket engine pumps are designed to use their respective propellant fluids as the hydrostatic lubricant.  But that means all the design parameters shift to the mechanical and operational parameters.  The bearing faces have to be designed "just so," and the engine has to be operated "just so" to keep the bearing characteristics within the narrow envelope of the fluid behavior of LOX or RP-1 or liquid methane.  So when you add violent engine gimbaling to the equation, it becomes a very hairy problem.

Pump bearing failure is what killed the Antares rocket that used the NK-33 engines [Jay spits on the floor].  This is an incredibly important part of engine design.  And part of my early work as a graduate student, learning from the Rocketdyne H-1 and helping develop manufacturing methods for the rotor of the RS-25.

But the Raptor is a "full flow" engine.  This is actually a blessing in disguise.  Early engines were open-cycle.  What powered the pumps just got dumped overboard non-propulsively (the early Atlas) or co-opted as a secondary heat barrier (the F-1).  Closed cycle engines (the RS-25 and the NK-33 -- spit on floor again) burn some of one half of the propellant mix and all of the other to generate mechanical power, then directs the turbine exhaust to the injector where the rest of the other side of the propellant equation is added to complete the reaction propulsively in the thrust chamber.  You don't lose any thermal energy this way, making the engine much more efficient.

A full-flow engine actually has two independent pump assemblies.  Many prior designs pumped the fuel and oxidizer with impellers positioned on the same shaft.  The Raptor (and other engines) have two instances of staged combustion -- one for methane and another for liquid oxygen.  The problem with an oxygen-rich first combustion stage is that the hot oxygen attacks the metal of the engine itself.  If you use a fuel-rich first combustion stage, you get a fuel-rich exhaust, which isn't a chemical danger to the plumbing.  The Raptor does both, each in a separate preburner.  The oxygen-rich exhaust doesn't have far to travel before it enters the thrust chamber, so you limit its exposure to engine materials.

But I'm sure you've guessed by now that if you have two pump assemblies, you have two shafts.  And if you're smart, you arrange for those shafts to spin in opposite directions, so that the gyroscopic effects -- at least in terms of vehicle guidance -- cancel out.  You still have to be very smart about how you design the pump bearings.  But here the guidance problem I mentioned yesterday probably doesn't exist on Starship.
Title: Re: Starship!
Post by: cjameshuff on March 06, 2021, 02:24:55 PM
A full-flow engine actually has two independent pump assemblies.  Many prior designs pumped the fuel and oxidizer with impellers positioned on the same shaft.  The Raptor (and other engines) have two instances of staged combustion -- one for methane and another for liquid oxygen.  The problem with an oxygen-rich first combustion stage is that the hot oxygen attacks the metal of the engine itself.  If you use a fuel-rich first combustion stage, you get a fuel-rich exhaust, which isn't a chemical danger to the plumbing.  The Raptor does both, each in a separate preburner.  The oxygen-rich exhaust doesn't have far to travel before it enters the thrust chamber, so you limit its exposure to engine materials.

And since each preburner/turbine/pump only has one part of the propellant to pump, but has the full flow of that propellant as working fluid, it can run at relatively low temperature. There's been some rough third party estimates of Raptor's operating conditions...pressures get quite high, but temperatures are surprisingly low:
https://en.wikipedia.org/wiki/File:Raptor_Engine_Unofficial_Combustion_Scheme.svg

Additionally, you don't have any bearings sitting in a location with an oxidizer-rich environment on one side and a fuel-rich environment on the other, though that's probably more an issue for the seals separating those environments.

The downside: two interdependent turbopumps to start up and control, each pumping the lesser propellant consumed by the other.
Title: Re: Starship!
Post by: JayUtah on March 06, 2021, 08:01:14 PM
though that's probably more an issue for the seals separating those environments.

Yeah, I specifically left seals out of the discussion.  It was long enough already.
Title: Re: Starship!
Post by: Allan F on March 07, 2021, 02:27:24 AM
By the way, if you've ever flow a light propeller-driven airplane, this is something you deal with.  When you pitch up, the gyroscopic action of the propeller tends to make you yaw to the left.  After a while you just unconsciously apply a little right rudder when pitching up.  Similarly, if you gimble an engine for pitch, and it results in unwanted yaw, the subsequent yaw trim maneuver ends up affecting you in the pitch axis.  So in that simplified example, the axes are coupled.  But not in a way that precludes developing a control law for it.

Wasn't that  effect why the later WW I airplanes were really difficult to fly, because not only did the propeller rotate, the WHOLE ENGINE rotated with it? Having a big lump of metal equalling a large percentage of the plane's mass rotating, offset the stick and rudder imput by 90 degrees.
Title: Re: Starship!
Post by: molesworth on March 07, 2021, 07:24:17 AM
Thanks Jay - an excellent summing up of the technolgy, and its problems, as usual  :)  This really puts the scale of things into perspective :
... The F-1 turbo pump had to deliver as much power as the entire engine on an F-16 fighter.

I also spend quite a lot of time on boats, and know only too well the likely issues with prop shafts and associated bits 'n' pieces  ::)  In a similar "using the working fluid as lubricant" mode, we also have water-lubricated stern glans on some boats, and it's a balancing act to get enough lubrication to keep it cool, and not so much there's a perpetual drip into the bilge...
Title: Re: Starship!
Post by: JayUtah on March 07, 2021, 11:11:11 AM
Wasn't that  effect why the later WW I airplanes were really difficult to fly, because not only did the propeller rotate, the WHOLE ENGINE rotated with it? Having a big lump of metal equalling a large percentage of the plane's mass rotating, offset the stick and rudder imput by 90 degrees.

Yes, the old rotary engines.  Another mechanical engineering nightmare.  But we owe those early engineers a debt of gratitude.  The techniques they developed for a lubricant system that would operate with the engine in any orientation live on in today's jet engines and rocket motors.  To be sure, the rotary engine didn't recover its lube oil at all.  But the more traditional engines such as in the "Jenny" had to deal with the fact that the oil sump wouldn't supply oil to the pump if the airplane was inverted or in otherwise extreme maneuvers.
Title: Re: Starship!
Post by: JayUtah on March 07, 2021, 11:33:23 AM
There's been some rough third party estimates of Raptor's operating conditions...pressures get quite high, but temperatures are surprisingly low:
https://en.wikipedia.org/wiki/File:Raptor_Engine_Unofficial_Combustion_Scheme.svg

Yeah, I saw that.  Temperature really ends up being the problem because the whole point of any preburner is to generate pressure which can be converted to velocity to drive turbines.  You can't get rid of pressure because you want the pressure.  But the best ways we have of producing pressure also produce high temperatures.  The vocabulary of materials we can apply to contain pressure at very high temperatures is severely limited.  So lowering the temperature is a win.  I need to see if there is a later edition of Sutton and Biblarz (the quintessential authors on rocket propulsion for engineers) that deals with full-flow engines.

Another win that struck me this morning as I was putting the bacon in the oven was that if you have two separate pumps, the rotor in each case is less massive.  The gyroscopic effects that complicate bearing design increase in proportion to mass, so a lighter rotor won't incur as much reaction during gimbaling.  The F-1 rotor was massive.  And since the rotor is shorter, you can place the bearings closer together toward the center.  A shorter rotor is naturally stiffer too.  Depending on the actual parameters, you could conceivably get away with one large bearing at the center of the rotor.  That would be a major win.  But still, most engineers' gut feelings are that you need two bearings in all cases.  Or rather, two small bearings slightly separated from the center point of the rotor is still better than one.  But the farther you get from the center, the more susceptible a bearing will be to eccentric loads created by engine gimbaling.
Title: Re: Starship!
Post by: jfb on March 08, 2021, 05:09:10 PM
Thanks, Jay.  There's a reason I'm a code monkey and not a real engineer, but I appreciated and enjoyed the details you presented. 
Title: Re: Starship!
Post by: Zakalwe on March 09, 2021, 02:13:35 AM
SN11 now rolled out onto the pad. This one has the Raptors already installed, so possibly moving into cyro tests early?
Title: Re: Starship!
Post by: VQ on March 09, 2021, 02:49:36 PM
....The more popular choice is fluid bearings....

In some similar but stationary applications (turbine compressors and chillers) I see magnetically levitated bearings, which are very efficient. Are those too heavy to scale for use in rocket turbines?
Title: Re: Starship!
Post by: JayUtah on March 09, 2021, 08:05:54 PM
Too heavy, but also susceptible to thermal degradation.  Magnets function poorly when they get very hot.  Also, it generally requires an electricity source to energize the magnet.  That presents a startup problem.  But yes, magnetic bearings are generally really cool.
Title: Re: Starship!
Post by: molesworth on March 30, 2021, 10:33:55 AM
Well that didn't quite go as planned...  (SN11 launch that is.)

No info yet on what went wrong, but from the camera streams on NASA Spaceflight and Everyday Astronaut it looked like some big chunks of debris came down in and around the tank farm, which isn't a good thing.
Title: Re: Starship!
Post by: bknight on March 30, 2021, 07:25:14 PM
Maybe launching in the fog wasn't a good idea.
Title: Re: Starship!
Post by: Peter B on March 30, 2021, 08:13:30 PM
Maybe launching in the fog wasn't a good idea.

Obviously the fog made it hard to see what went wrong, but surely this sort of spacecraft couldn't be vulnerable to fog could it?

What I was wondering about was a diffuse orange flame with what appeared to be small but very bright points of origin from about 25 to 30 seconds after launch in the piping of the left hand engine.
Title: Re: Starship!
Post by: smartcooky on March 31, 2021, 12:57:23 AM
Maybe launching in the fog wasn't a good idea.

Falcon 9 boosters land on a barge 500 to 1000 km out in the Atlantic; the whole thing is autonomous from the time the rocket goes into "start-up" at T-60 seconds to landing around 11 minutes later. Starship test vehicles are also autonomous. Almost all of the information they get comes from telemetry. Fog will have little if any impact.
Title: Re: Starship!
Post by: Count Zero on March 31, 2021, 10:12:39 AM
Almost all of the information they get comes from telemetry.

But did they get usable telemetry?  It looked like they were having downlink problems (though I don't know how extensive they were).  One announcer said "we've lost all data," but he may have only been referring to signal loss after the vehicle was destroyed.

Telemetry can usually get you to the bottom of the problem, but visual tracking and recording can help a lot.  NASA had multiple ground cameras for all launches, not just the test flights.  In the Apollo days, they had multiple cameras trained on each stage.  On both fatal Shuttle launches, ground cameras provided early clues to what went wrong, which helped focus the investigations.

I was extremely surprised that SpaceX would think that visual tracking was optional/unnecessary.
Title: Re: Starship!
Post by: cjameshuff on March 31, 2021, 11:14:37 AM
Almost all of the information they get comes from telemetry.

But did they get usable telemetry?  It looked like they were having downlink problems (though I don't know how extensive they were).  One announcer said "we've lost all data," but he may have only been referring to signal loss after the vehicle was destroyed.

Telemetry can usually get you to the bottom of the problem, but visual tracking and recording can help a lot.  NASA had multiple ground cameras for all launches, not just the test flights.  In the Apollo days, they had multiple cameras trained on each stage.  On both fatal Shuttle launches, ground cameras provided early clues to what went wrong, which helped focus the investigations.

I was extremely surprised that SpaceX would think that visual tracking was optional/unnecessary.

They specifically mentioned they were still getting good telemetry in the earlier video dropouts.

If they were doing something substantially different they might be pickier, but the part it'd be most useful with is the part of flight they've had no trouble with, and the part they're having trouble with will mainly show in telemetry, with little outward sign (seeing SN10 come down hard wasn't very informative, for example). Also, this is the last test flight of its series of videos, SN15's been waiting for quite some time with many major upgrades (including engine mount changes that meant they had to use older Raptors on SN11), and it might be some time before there's better weather.
Title: Re: Starship!
Post by: apollo16uvc on March 31, 2021, 01:41:25 PM
Moderately surprised to not see a thread on Starship, especially after yesterday's flight.  Despite the kaboom at the end, that was a spectacularly successful flight.  A real-world test of a new engine cycle, a new fuel, a new mode of flight, and they almost pulled it off on the first try. 

And, my God, this shot:

https://twitter.com/SpaceX/status/1336849897987796992

That's real time.  That's not slowed down.  It just looks slow because you're looking at a 12-story building falling at you. 

SN9 is already built, there are at least 6 more prototypes in various stages of completion, the first booster is under construction - 2021 is gonna be an interesting year in South Texas.

Yeah, 90 degree rotation in about three seconds. That's going to be interesting for passengers.
Perhaps it is to tress-test all the design elements, engines, gimbaling and flaps.

If structural integrity holds up in those manoeuvres its set for less extreme ones.
Title: Re: Starship!
Post by: JayUtah on April 01, 2021, 11:28:32 AM
As we discovered in the theater, water fog can do a number on radio communications in certain bands, even in very small amounts.  So it doesn't surprise me that the video might have dropped out while the telemetry (ostensibly on a more robust frequency, and with data integrity checks in place) soldiered on.

The engine anomaly looks like it starts at around T+18, although the sudden deflagration doesn't occur until a few seconds later.  It looks to me like a fitting might have opened up.  The bright spots around the solid piping indicates the flame is hitting with considerable velocity, which then indicates a leak in high-pressure flow.  Unclear whether that relates to the ultimate explosion.  As Musk says, they won't know until they pick through the "bits."  Even well into the 21st century, sifting through wreckage is still part of the job.
Title: Re: Starship!
Post by: Peter B on April 01, 2021, 12:23:17 PM
As we discovered in the theater, water fog can do a number on radio communications in certain bands, even in very small amounts.  So it doesn't surprise me that the video might have dropped out while the telemetry (ostensibly on a more robust frequency, and with data integrity checks in place) soldiered on.

The engine anomaly looks like it starts at around T+18, although the sudden deflagration doesn't occur until a few seconds later.  It looks to me like a fitting might have opened up.  The bright spots around the solid piping indicates the flame is hitting with considerable velocity, which then indicates a leak in high-pressure flow.  Unclear whether that relates to the ultimate explosion.  As Musk says, they won't know until they pick through the "bits."  Even well into the 21st century, sifting through wreckage is still part of the job.

The bits of the rocket? Or the bits of the telemetry data?
Title: Re: Starship!
Post by: JayUtah on April 01, 2021, 04:29:31 PM
I guess it's applicable to both.  Yes, the telemetry is vital.  But so is visual inspection of the wreckage.  The telemetry tells you, for example, that pressure in various parts of the system fell below expected levels.  But physically looking at the pipes tells you where the leak happened, and maybe gives you clues to why.
Title: Re: Starship!
Post by: raven on April 01, 2021, 06:48:56 PM
As we discovered in the theater, water fog can do a number on radio communications in certain bands, even in very small amounts.  So it doesn't surprise me that the video might have dropped out while the telemetry (ostensibly on a more robust frequency, and with data integrity checks in place) soldiered on.

The engine anomaly looks like it starts at around T+18, although the sudden deflagration doesn't occur until a few seconds later.  It looks to me like a fitting might have opened up.  The bright spots around the solid piping indicates the flame is hitting with considerable velocity, which then indicates a leak in high-pressure flow.  Unclear whether that relates to the ultimate explosion.  As Musk says, they won't know until they pick through the "bits."  Even well into the 21st century, sifting through wreckage is still part of the job.

The bits of the rocket? Or the bits of the telemetry data?
Both, I am guessing. Interesting that the debris field is mostly in one direction.
Title: Re: Starship!
Post by: JayUtah on April 02, 2021, 12:26:11 PM
Debris-field dispersal has always fascinated me, in a morbid sort of way.  I've always admired the professional debris-dispersal analysts.  It seems at first glance like reading tea leaves.  But these guys really do have insightful ways of plotting backwards from debris positions and conditions to initial-failure scenarios.  You consider that heavy things like engine thrust chambers fall ballistically while drag-sensitive structures like nosecones are more susceptible to aerodynamic effects.

A second look at the skirt video convinces me that the engine we saw enveloped in flame was shedding hot metal.  The "sparks" are a combination of hot metal being ejected and high-temperature impingement on nearby surfaces.  (You see this in Apollo film of the Saturn V interstage jettison.  As it ventures into the J-2 plumes, the impingement shows up as markedly incandescent.). But some points of light can't be explained by impingement.  They are pieces of engine, piping, or structure being eroded by hot gas flow.

Since the kaboom happened so very shortly after engine relight, I'm guessing the sick engine failed.  The problem with that is the plumbing.  As others have pointed out, the Raptor operates at obscene chamber pressures.  That has to be echoed in propellant-feed systems, which also have to maintain high pressure.  If an engine separates entirely from the propellant feed system, you get a rapid loss of pressure in the propellant tanks.  If the vehicle structure relies on pressure in the tanks, the vehicle is likely to rupture and release propellant.  This is even more likely when the vehicle is under tremendous aerodynamic stress -- intentional or otherwise.

Another thing that can happen in high pressure engines is that once the feed pressure is gone, combustion fronts can race up the propellant lines and find their way to a more relatively enclosed component like a tank or an accumulator, resulting in a detonation instead of a mere deflagration.  The smoking gun here is the methane header tank, which was found in two pieces quite a ways apart.  This indicates that each half was on a different side of a high-energy event, like an explosion.  So whatever the root cause was, I'm betting the kaboom was in the methane header tank.
Title: Re: Starship!
Post by: Zakalwe on April 03, 2021, 07:04:22 AM
As we discovered in the theater, water fog can do a number on radio communications in certain bands, even in very small amounts.  So it doesn't surprise me that the video might have dropped out while the telemetry (ostensibly on a more robust frequency, and with data integrity checks in place) soldiered on.

The engine anomaly looks like it starts at around T+18, although the sudden deflagration doesn't occur until a few seconds later.  It looks to me like a fitting might have opened up.  The bright spots around the solid piping indicates the flame is hitting with considerable velocity, which then indicates a leak in high-pressure flow.  Unclear whether that relates to the ultimate explosion.  As Musk says, they won't know until they pick through the "bits."  Even well into the 21st century, sifting through wreckage is still part of the job.

The bits of the rocket? Or the bits of the telemetry data?

Both.
And in both cases I suspect that there are a lot of bits!  ;D
Title: Re: Starship!
Post by: bknight on April 04, 2021, 05:37:04 PM
As we discovered in the theater, water fog can do a number on radio communications in certain bands, even in very small amounts.  So it doesn't surprise me that the video might have dropped out while the telemetry (ostensibly on a more robust frequency, and with data integrity checks in place) soldiered on.

The engine anomaly looks like it starts at around T+18, although the sudden deflagration doesn't occur until a few seconds later.  It looks to me like a fitting might have opened up.  The bright spots around the solid piping indicates the flame is hitting with considerable velocity, which then indicates a leak in high-pressure flow.  Unclear whether that relates to the ultimate explosion.  As Musk says, they won't know until they pick through the "bits."  Even well into the 21st century, sifting through wreckage is still part of the job.

The bits of the rocket? Or the bits of the telemetry data?

Both.
And in both cases I suspect that there are a lot of bits!  ;D
Indeed. 
Title: Re: Starship!
Post by: smartcooky on April 04, 2021, 08:10:52 PM
Much as I am a keen supporter of SpaceX, I am just beginning to wonder if the Raptor Engine with its Full-flow staged combustion is just too damned complex, especially as its powered by methane & liquid oxygen.

AFAIK, the Raptor is the first FFSC engine to use methalox. Are SpaceX biting off more the they can chew, trying to do something that has never been tried before (the relight & flip landing maneuver) using an engine type that has never been tried before?
Title: Re: Starship!
Post by: raven on April 04, 2021, 09:19:32 PM
Much as I am a keen supporter of SpaceX, I am just beginning to wonder if the Raptor Engine with its Full-flow staged combustion is just too damned complex, especially as its powered by methane & liquid oxygen.

AFAIK, the Raptor is the first FFSC engine to use methalox. Are SpaceX biting off more the they can chew, trying to do something that has never been tried before (the relight & flip landing maneuver) using an engine type that has never been tried before?
Not a few people thought the same of landing the first stage. I have a feeling if you give them enough time to iterate, they'll solve the problems.
But I am optimistic that way.
Title: Re: Starship!
Post by: molesworth on April 05, 2021, 05:31:05 AM
Much as I am a keen supporter of SpaceX, I am just beginning to wonder if the Raptor Engine with its Full-flow staged combustion is just too damned complex, especially as its powered by methane & liquid oxygen.

AFAIK, the Raptor is the first FFSC engine to use methalox. Are SpaceX biting off more the they can chew, trying to do something that has never been tried before (the relight & flip landing maneuver) using an engine type that has never been tried before?

Like raven I'm optimistic that the problems can and will be solved.  It is a complex design, but if you look at it as an incremental step from existing designs it's only pushing a few new boundaries (although admittedly pushing them hard).

Borrowing a phrase from a previous push to space - "We do these things not because they are easy but because they are hard".  I think this applies here too, and looking at the challenges of getting to the Moon and Mars with regular, cheap and reusable launch systems, the easy options just aren't going to make it.
Title: Re: Starship!
Post by: Zakalwe on April 05, 2021, 06:49:13 AM
Much as I am a keen supporter of SpaceX, I am just beginning to wonder if the Raptor Engine with its Full-flow staged combustion is just too damned complex, especially as its powered by methane & liquid oxygen.

AFAIK, the Raptor is the first FFSC engine to use methalox. Are SpaceX biting off more the they can chew, trying to do something that has never been tried before (the relight & flip landing maneuver) using an engine type that has never been tried before?

Is there a viable alternative for a reusable Mars bound craft that will use ISRU for re-fuelling?

What they are doing has never been done before. That doesn't mean that their approach is flawed (how many times did the F-1 engine explode due to combustion chamber instabilities?). There's nothing in the laws of physics that deems what they are trying to do impossible, so it's an engineering problem. A challenging one, but one that I am sure they will overcome.
Title: Re: Starship!
Post by: cjameshuff on April 05, 2021, 10:44:42 AM
They've had what, two engine failures in four prototype test flights with 12 ignitions and 9 relight attempts, one of them just being a failure to start? And all four test flights performing a complete ascent burn, with the final engine running for about the same duration as a booster engine's launch burn. And on one flight the landing burn starved an engine of fuel leaving it oxygen-rich and short on cooling, and on another the fuel turbopump ingested helium, both cases just resulting in loss of thrust.

The Raptors are doing fine. It's not reasonable to expect the system in its current state to operate with high reliability, especially when doing something that no other rocket does. Things are going to break or fall short of the desired performance...this would happen even if the Raptors were perfect, because their performance is fundamentally tied to the performance of the propellant systems, which are extremely experimental.

As for this latest failure:
Quote from: Elon [email protected]
Ascent phase, transition to horizontal & control during free fall were good.

A (relatively) small CH4 leak led to fire on engine 2 & fried part of avionics, causing hard start attempting landing burn in CH4 turbopump.

This is getting fixed 6 ways to Sunday.
Title: Re: Starship!
Post by: jfb on April 05, 2021, 01:04:00 PM
Yeah, so far most of the issues haven't been with the Raptors so much as the plumbing - making sure they have good pressure during and immediately after the flip.  If they were doing the Grasshopper thing and going straight up and coming straight back down, they'd likely have nailed it on the first try with SN8.  But that rapid transition from horizontal to vertical just after ignition is causing issues with fuel pressure/flow. 

No doubt there are still issues with the engines themselves, but like cjameshuff pointed out, the ascent phase has gone well in all the flights. 

SN15 is supposed to have a bunch of improvements and redesigned components, so it may survive.  I expect they'll blow up a few more before they figure this out. 
Title: Re: Starship!
Post by: raven on April 05, 2021, 08:06:29 PM
Much as I am a keen supporter of SpaceX, I am just beginning to wonder if the Raptor Engine with its Full-flow staged combustion is just too damned complex, especially as its powered by methane & liquid oxygen.

AFAIK, the Raptor is the first FFSC engine to use methalox. Are SpaceX biting off more the they can chew, trying to do something that has never been tried before (the relight & flip landing maneuver) using an engine type that has never been tried before?

Like raven I'm optimistic that the problems can and will be solved.  It is a complex design, but if you look at it as an incremental step from existing designs it's only pushing a few new boundaries (although admittedly pushing them hard).

Borrowing a phrase from a previous push to space - "We do these things not because they are easy but because they are hard".  I think this applies here too, and looking at the challenges of getting to the Moon and Mars with regular, cheap and reusable launch systems, the easy options just aren't going to make it.
Certainly not on a long term basis. A flag and foot prints mission, a 'camping trip' as I like to call it, is far simpler logistically than setting up for long term exploration and habitation, but it also means the effort is somewhat 'thrown away' after.
Title: Re: Starship!
Post by: jfb on May 05, 2021, 06:43:17 PM
SN15 flight seems to have been successful - flew, flipped, landed, and it hasn't blown up yet.  Scary fire under the skirt after landing that took a long time to put out, but ... success?
Title: Re: Starship!
Post by: raven on May 05, 2021, 08:35:22 PM
Definitely a giant leap. I am sure they will work out the kinks in the next steps.
Title: Re: Starship!
Post by: Count Zero on May 06, 2021, 08:05:01 AM
Definitely a giant leap. I am sure they will work out the kinks in the next steps.

Like the video downlink?  ;)
Title: Re: Starship!
Post by: raven on May 07, 2021, 01:34:59 AM
Definitely a giant leap. I am sure they will work out the kinks in the next steps.

Like the video downlink?  ;)
Yeah, that would be nice, especially when they insist on flying in fog or lowish cloud cover.
Title: Re: Starship!
Post by: jfb on August 09, 2021, 01:58:28 PM
Tim Dodd, the Everyday Astronaut, scored a walkthrough of the Boca Chica site with Elon Musk as the tour guide.  The interview is over two hours long, so Dodd has broken it up into multiple segments, of which the first two have dropped:

Part 1 (https://www.youtube.com/watch?v=t705r8ICkRw)
Part 2 (https://www.youtube.com/watch?v=SA8ZBJWo73E)

Part 3 hasn't dropped yet, but that will be at the pad.

Elon talks about his engineering philosophy in Part 1, which in order is basically:


Anyway, cool interview.  A lot of stuff is still in flux and they're still changing parts of the design as they go.  Everything is still too heavy and needs trimming.  The primary goal for the orbital test flight is to not take out the launch pad (a.k.a. Stage 0).  The first few orbital ship prototypes are just meant to get to orbit, deorbit, and land - none of them will carry any payloads, so they're not worried about doors or payload bays yet. 
Title: Re: Starship!
Post by: Obviousman on August 09, 2021, 04:27:41 PM
That philosphy seems good to me.

Requirements... phew! I fight a regular battle of trying to get requirements from my people. Instead, they tell me what they want and when we give it to them, they say "That is exactly what we asked for. But it is not what we want".
Title: Re: Starship!
Post by: Peter B on August 09, 2021, 07:19:23 PM
That philosphy seems good to me.

Requirements... phew! I fight a regular battle of trying to get requirements from my people. Instead, they tell me what they want and when we give it to them, they say "That is exactly what we asked for. But it is not what we want".

I can see where you're coming from, but I've been at the other end of the stick. Or, more precisely, I've been an inadvertent customer for a product someone else designed for another customer, but I have to use the product without having had any say in the design. So for me it would be more like, "We didn't ask for this, and it's not what we want."

And I'd humbly suggest that's how it works in most of the world - products are rarely for a single customer, so an important part of the design process is should be working out who the customers really are and engaging all of them (to a realistic extent) in the design process.

A friend told me about a job request system which was introduced in his workplace. He was in a customer service area, so clients would use this JR system to ask for work to be done. Logically, the customers for this product would be the work area and the clients. But instead the customers were Management. They got exactly what they wanted - a cheap system with a reasonable suite of reports so they could check up on the efficiency of the work area. The clients got an unhelpful interface which made it slow to log requests. And the work area got a clumsy system which listed jobs in an order which was neither alphabetical or chronological, and so slowed down their work and annoyed clients because of the seemingly random order they completed job requests.
Title: Re: Starship!
Post by: jfb on August 10, 2021, 03:58:39 PM
Yeah.  My group used to be part of a much larger organization, and we were kind of the red-headed stepchild.  Our product is an online banking platform geared towards smaller community banks and credit unions, while the mothership was a payment processor.  All the processes and forms worked well for the payment-processing world, but were overly complex and tedious for our purposes.  Change requests required a two-week lead time, had to be approved at the VP level, and all kinds of other nonsense. 

Once we were spun off into our own company, we were able to adopt a much leaner process, such that we only need a day's lead time for CRs, and it's a lot easier to keep track of tickets. 
Title: Re: Starship!
Post by: Obviousman on August 10, 2021, 05:18:12 PM
Ha! So much of this resonates with me.

These days I am a Defence contractor and manage a USAF-owned software system called Patriot Excalibur, or PEX. It's an aviation resource management system. It's used by every flying unit in the USAF, as well as the majority of other USAF units. Since it has such a wide user base, it has to cater to many different types of operation (fighters, tankers, bombers, transport, etc), each with specific requirements. The system does this quite well, offering various options for each module to suit the user need.

We decided to use it in Australia since it was a good tool. Even then, we still had to make modifications to suit the Australian environment. Despite being a good tool, there are areas where the users complain and want changed. Command also uses PEX but mainly in the area of data mining, rather than flight scheduling / flying currency management.

So we have a fair few bugs / enhancements to address. We used to do this with Agile development, putting out a new release every 3 months but now we are shackled to Defence's processes, it takes us 6 months to generate the required paperwork for a release.

Still, not too bad, eh? Nope. The person in charge of the system for one of the Services stymies us. They are a very smart individual but have never been in uniform, have never been aircrew. And more often than not, we have suggestions for improvement to which the frontline workers say "Fantastic! Just what we want! When can we have it?" and this person says "They don't need that" and instead lobbies for some reporting tool, which is wanted only by a small group but is usually Command.

No wonder I am retiring!

[END RANT]
Title: Re: Starship!
Post by: Peter B on August 11, 2021, 03:41:40 AM
Ha! So much of this resonates with me.

...

So we have a fair few bugs / enhancements to address. We used to do this with Agile development, putting out a new release every 3 months but now we are shackled to Defence's processes, it takes us 6 months to generate the required paperwork for a release.

...

[END RANT]

6 months?

Sheer looxury!

My friend said his system has shortcomings which haven't been addressed in 20 years...
Title: Re: Starship!
Post by: Peter B on August 11, 2021, 05:35:15 AM
Having said all that, the video of the fully stacked starship was pretty impressive. The idea that it could be being launched within a year equally so.
Title: Re: Starship!
Post by: JayUtah on August 11, 2021, 09:45:43 AM
I know for a fact that the Starliner folks are looking at SpaceX with a fair amount of envy right now -- not necessarily for the technology differences, but for the differences in development posture.  Government-supervised development contracts mean a lot of overhead and oversight that SpaceX simply doesn't have to deal with for Starship.  Musk isn't saying anything that other engineers don't already know.  It's just that -- as many others of you have pointed out -- the pace at which you can do them and the decision to undertake them take so much more time when contractual strings are attached.