Author Topic: Convair's 1962 Lunar Excursion Module proposal  (Read 9076 times)

Offline Daggerstab

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Convair's 1962 Lunar Excursion Module proposal
« on: December 31, 2012, 09:44:58 AM »
While trying to research the other thing, I came across these images of General Dynamics Convair's proposal for the Apollo (then) LEM:
http://www.flickr.com/photos/[email protected]/2217192111/in/set-72157603788534726/

There's a line drawing, one external and one internal view of a mock-up. I found the "beak" really amusing. Would they have called it "The Penguin"? :) The external shape of the cabin reminds me of an early tank turret.

I'll try to dig up more information and/or pictures later.

Offline ka9q

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Re: Convair's 1962 Lunar Excursion Module proposal
« Reply #1 on: December 31, 2012, 11:26:04 AM »
Interesting that they put the RCS thrusters on the end of long, deployable booms. That would have made rotational maneuvers much more propellant-efficient.

Of course, one can do rotational maneuvers with no propellant at all by using control moment gyros, but that would probably have been overkill for a spacecraft needing only a short mission life.

Any idea about the purpose of the "penguin beak"? It's not immediately obvious.


Offline Daggerstab

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Re: Convair's 1962 Lunar Excursion Module proposal
« Reply #2 on: December 31, 2012, 11:45:48 AM »
Interesting that they put the RCS thrusters on the end of long, deployable booms. That would have made rotational maneuvers much more propellant-efficient.

Of course, one can do rotational maneuvers with no propellant at all by using control moment gyros, but that would probably have been overkill for a spacecraft needing only a short mission life.

Another interesting point is that the RCS thrusters are asymmetric - the different units point in different directions.

Any idea about the purpose of the "penguin beak"? It's not immediately obvious.

From the text (quoted?) in the description of the images:
Quote
Docking was to have been achieved by a probe and drogue mechanism. The method was to allow the crew to take advantage of good visibility and not have to change positions. Controls, displays and cues would not change during docking. Once the probe was aligned with the drogue, it would be locked in place, and the LEM rotated 90 degrees for final mating and crew transfer.

So, I think the "beak" is a part of the docking mechanism and it's supposed to move on its "rail" to align the hatches and complete the docking. It's one of the reasons why the top of the lander reminded me of a tank turret - it resembles the mechanisms used to change gun elevation.

Offline Not Myself

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Re: Convair's 1962 Lunar Excursion Module proposal
« Reply #3 on: December 31, 2012, 12:17:40 PM »
While trying to research the other thing, I came across these images of General Dynamics Convair's proposal for the Apollo (then) LEM:
http://www.flickr.com/photos/[email protected]/2217192111/in/set-72157603788534726/

There's a line drawing, one external and one internal view of a mock-up. I found the "beak" really amusing. Would they have called it "The Penguin"? :) The external shape of the cabin reminds me of an early tank turret.

I'll try to dig up more information and/or pictures later.

Reading the post and then clicking on the link, it looked a lot less ridiculous than I was expecting :)

My first thought upon seeing the beak was that it looks like a giant on/off switch.  Which of course it isn't.
The internet - where bigfoot is real and the moon landings aren't.

Offline BazBear

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Re: Convair's 1962 Lunar Excursion Module proposal
« Reply #4 on: December 31, 2012, 02:32:07 PM »

Reading the post and then clicking on the link, it looked a lot less ridiculous than I was expecting :)

I agree. Whenever I think Convair, the first thing that pops in my head are Delta Darts/Daggers and Hustlers.
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Offline Sus_pilot

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Convair's 1962 Lunar Excursion Module proposal
« Reply #5 on: December 31, 2012, 02:56:58 PM »

Reading the post and then clicking on the link, it looked a lot less ridiculous than I was expecting :)

I agree. Whenever I think Convair, the first thing that pops in my head are Delta Darts/Daggers and Hustlers.

B-36's. 

Offline BazBear

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Re: Convair's 1962 Lunar Excursion Module proposal
« Reply #6 on: December 31, 2012, 03:54:36 PM »

Reading the post and then clicking on the link, it looked a lot less ridiculous than I was expecting :)

I agree. Whenever I think Convair, the first thing that pops in my head are Delta Darts/Daggers and Hustlers.

B-36's.
They are on my short list of "ugliest aircraft ever".
"It's true you know. In space, no one can hear you scream like a little girl." - Mark Watney, protagonist of The Martian by Andy Weir

My Youtube Apollo playlist http://www.youtube.com/watch?v=8SfyE9qsG8k&list=PL2aEC7cUMrGCNrtGMMWRXYob-kqCz2zz8

Offline ka9q

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Re: Convair's 1962 Lunar Excursion Module proposal
« Reply #7 on: December 31, 2012, 06:13:24 PM »
Another interesting point is that the RCS thrusters are asymmetric - the different units point in different directions.
I was looking at that. They can do an uncoupled yaw maneuver, but I don't see how they can do an uncoupled pitch or roll, i.e., one that doesn't also induce translation. There's also no way to do a Y-axis translation (using the same coordinates as the Grumman LM). There is, however, full redundancy for each thruster that does exist. That wasn't true for the Grumman LM, which would have had to use uncoupled maneuvers.




Offline ka9q

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Re: Convair's 1962 Lunar Excursion Module proposal
« Reply #8 on: December 31, 2012, 06:30:16 PM »
I found more pictures:

http://www.flickr.com/photos/sdasmarchives/tags/generaldynamicslunarexcursionmodule/

There are three more rocket engines mounted on the underside of the ascent stage that are hidden when it is still attached to the descent stage, which consists only of tankage. So the same engines would be used for both ascent and descent powered flight.

The two smaller engines on the side would have made it possible, with proper balancing of impulse, to do uncoupled roll maneuvers but I still don't see how to do an uncoupled pitch maneuver.

Offline Daggerstab

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Re: Convair's 1962 Lunar Excursion Module proposal
« Reply #9 on: December 31, 2012, 06:37:37 PM »
I found the same gallery - I had written quite a long post with commentary to individual pictures, but it's pointless now. :)

Offline ka9q

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Re: Convair's 1962 Lunar Excursion Module proposal
« Reply #10 on: December 31, 2012, 07:56:41 PM »
Overall I think NASA made the right choice selecting the Grumman design, but it also got changed a lot during development. Who knows what this one would have become if it had been selected. The use of the same engines for descent and ascent is an interesting way to save weight, but those extra medium-sized (backup?) engines might have used up much of the savings.

Offline Donnie B.

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Re: Convair's 1962 Lunar Excursion Module proposal
« Reply #11 on: December 31, 2012, 08:33:03 PM »
What I don't see is a hatch for egress on the surface.

Was the plan to go out through the top and down a rope ladder?  Or not to do EVAs at all?  Or maybe they hadn't worked out that detail yet...

I've often wondered why Grumman chose to go with separate descent and ascent engines.  It always seemed to be a lot of extra mass that you could shed just by leaving a hole in the bottom of the descent stage as in this design.  I have read Kelly's Moon Lander but I don't recall his addressing that specific design choice.

Offline ka9q

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Re: Convair's 1962 Lunar Excursion Module proposal
« Reply #12 on: January 01, 2013, 02:45:35 AM »
I've often wondered why Grumman chose to go with separate descent and ascent engines.
One good reason is to have the ascent engine as a backup to the descent engine if the latter fails.

Offline Daggerstab

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Re: Convair's 1962 Lunar Excursion Module proposal
« Reply #13 on: January 01, 2013, 09:19:59 AM »
Overall I think NASA made the right choice selecting the Grumman design, but it also got changed a lot during development. Who knows what this one would have become if it had been selected. The use of the same engines for descent and ascent is an interesting way to save weight, but those extra medium-sized (backup?) engines might have used up much of the savings.

The description of the images in the original Flick gallery calls them "standby thrust chambers":
Quote
Convair's proposed vehicle featured a single throttleable main engine backed by two standby thrust chambers. It was to be a partially staged configuration with a side-by-side crew arrangement and a probe-drogue docking mechanism. The lower structure held the descent tankage, which was to be depressurized 15 seconds prior to touchdown. The depressurized tankage, along with the crushable vehicle skirt, were to offer a back-up to the landing system in the event of a landing accident.
The engines were protected against landing damage through use of a crushable main engine nozzle skirt and the placement of the standby engines above the descent tankage.

The Russian LK also used a single engine, without any backups.

What I don't see is a hatch for egress on the surface.

Was the plan to go out through the top and down a rope ladder?  Or not to do EVAs at all?  Or maybe they hadn't worked out that detail yet...

I was wondering the same thing. It seems that there's a side hatch:
http://www.flickr.com/photos/[email protected]/2217192111/ (the line drawing shows an oval hatch over the RCS arm)
http://www.flickr.com/photos/sdasmarchives/7142967369/ (inside view towards the back of the cockpit, shows the open hatch)
http://www.flickr.com/photos/sdasmarchives/7142968041/ ("Angry Bird" side view, I think that the closed hatch is barely visible, as it's white-on-white)

Given the position of the hatch, I guess it would require a rope or a ladder on the nearest "back" leg.

Offline Count Zero

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Re: Convair's 1962 Lunar Excursion Module proposal
« Reply #14 on: January 01, 2013, 08:47:55 PM »

Reading the post and then clicking on the link, it looked a lot less ridiculous than I was expecting :)

I agree. Whenever I think Convair, the first thing that pops in my head are Delta Darts/Daggers and Hustlers.

B-36's. 

Lovely beast!  They had gear-reduction between the engine & props to keep the blade tips sub-sonic, and this gave them a very distinctive sound.  Time to watch Strategic Air Command, starring Jimmy Stewart, again!
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