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Apollo Discussions => The Reality of Apollo => Topic started by: BILLR on October 13, 2012, 02:11:17 AM

Title: Emergency ejection of CM during the launch phase.
Post by: BILLR on October 13, 2012, 02:11:17 AM
How would this process play out?(on Apollo). I know the  commander had physical control in case of this event. How would this work in regards to procedures for the flight crew? Was there any point of flight in which the system was automatic or was it always at the commanders discertion.
Title: Re: Emergency ejection of CM during the launch phase.
Post by: raven on October 13, 2012, 03:21:13 AM
Unless you have some ulterior motive behind these questions, this would probably do better in the sub forum below this one.
Welcome to the Apollhoax forum, by the way. :)
Title: Re: Re: Emergency ejection of CM during the launch phase.
Post by: Glom on October 13, 2012, 04:27:48 AM
How would this process play out?(on Apollo). I know the  commander had physical control in case of this event. How would this work in regards to procedures for the flight crew? Was there any point of flight in which the system was automatic or was it always at the commanders discertion.

You refer to the Mode I abort? The launch escape tower would lift the CM away from the space vehicle and it would then parachute into the sea. Not really sure how much flying there was to be done.
Title: Re: Emergency ejection of CM during the launch phase.
Post by: Jason Thompson on October 13, 2012, 07:30:29 AM
This is probably better off in the 'reality' section.

How would this process play out?(on Apollo).

Once the abort is initiated the escape rocket fires, and small canards emerge from the top of the escape tower to provide some measure of stability and control. The Cm is separated and carried away. once the tower rocket motor burns out the tower and BPC are discarded, the parachutes on the Cm open and the CM drifts slowly back down to land in the sea. Recovery forces then pick up the crew.

Quote
I know the  commander had physical control in case of this event. How would this work in regards to procedures for the flight crew?

They just had to sit tight. There was little to do except pull the abort handle to initiate the abort, then sit back and ride it out.

Quote
Was there any point of flight in which the system was automatic or was it always at the commanders discertion.

The abort system had pressure sensors inside the various stages of the rocket, the idea being that a recorded sudden drop in pressure would indicate that the launch vehicle was breaking up. This would trigger an automatic abort, since the breakup would proceed too rapidly and catastrophically for the crew to react to in time to execute the move. The first test of the abort system was an inadvertent test of the automatic sequencer, as the little Joe II rocket started an uncontrolled roll and broke up. The abort motor triggered successfully. It wasn't what they were trying to test, but it did at least provide usueful data.
Title: Re: Emergency ejection of CM during the launch phase.
Post by: BILLR on October 13, 2012, 08:30:00 AM
Thanks guys. I did not notice the reality section. I have alot of questions on mission details. Reading thru flightdeck voice transcripts kind of does that to you.
Title: Re: Emergency ejection of CM during the launch phase.
Post by: Kiwi on October 13, 2012, 10:21:30 AM
Something I'd like to know about a similar thing that led up to Apollo, is:

Just how amazing (or otherwise) was Wally Schirra's non-pulling of the "chicken ring" during the first attempted launch of Gemini 6?
Title: Re: Emergency ejection of CM during the launch phase.
Post by: Echnaton on October 13, 2012, 05:45:41 PM
Its hard to say what is going through a guys mind at a time like that.  Don't screw up, has to be one of the top things.  After the loss of Liberty Bell 7 every astronaut must have been especially wary of the consequences of mistakes or even non-mistakes like happened to Grissom.   It is one thing when you are a test pilot in the desert, its another when you are a public figure on live TV.  But those guys had nerves of steel to put all the pressures away and keep a clear head when their missions and lives were on the line.
Title: Re: Emergency ejection of CM during the launch phase.
Post by: Count Zero on October 14, 2012, 09:04:48 PM
Something I'd like to know about a similar thing that led up to Apollo, is:

Just how amazing (or otherwise) was Wally Schirra's non-pulling of the "chicken ring" during the first attempted launch of Gemini 6?


See?  Who says you'll never get a medal if you just sit there doing nothing?

I also admire Pete Conrad for "doing nothing" on Apollo 12, when every alarm & light in the cockpit lit-up when they were struck by lightning.
Title: Re: Emergency ejection of CM during the launch phase.
Post by: ka9q on October 15, 2012, 02:05:43 AM
During Apollo first stage flight on the Saturn IB and V, emergencies could happen far too quickly for a human to react in time to survive, so an automatic "emergency detection system" (EDS) operated during this time. Its primary sensor was the "Q-ball" at the tip of the launch escape tower; it monitored angle of attack and rotation rates in roll, pitch and yaw, automatically initiating an abort if any exceeded preset limits. The Commander could also initiate an abort manually but it's hard to think of a failure that would require him to do so very rapidly if the EDS were working properly.

The classic example of a failure that woud cause the angle of attack to suddenly increase would be an "engine hardover", a failure of an engine gimbal (or of its hydraulic actuator) that forced it all the way over to one side.

Anything that caused the angle of attack to increase suddenly was especially critical because, near the max-Q (maximum aerodynamic pressure) phase at about T+90 sec an excessive angle of attack could quickly rip the entire stack apart. An uncontrolled angle of attack -- not the disintegration of the external tank -- destroyed Challenger in 1986. I can cite numerous examples of angle-of-attack breakups in unmanned rocket launches, particularly the Delta failure that occurred a few months after Challenger.

Angle of attack has to be kept essentially at zero until the stack is outside the sensible atmosphere. A "gravity turn" maneuver is generally used to allow a gradual pitchover while keeping angle of attack at zero. Only above the atmosphere is "closed loop guidance" usually enabled, allowing the stack to take whatever angle is required to meet its target orbit with the least amount of propellant.

The Apollo Q-ball was jettisoned along with the escape tower shortly after staging. The Commander would inhibit the EDS manually just before staging, as depicted in the movie Apollo 13. Beyond that point the stack was outside the atmosphere so any failure, even one that caused the stack to turn around, would not rip it apart from aerodynamic forces and the automatic EDS abort capability was no longer needed. If a manual abort were needed, the launcher engines would be commanded to shut down and the Service Propulsion System engine would push the CSM away from the failed launcher to a safe distance. Then the CM would separate from the SM and come down as if after a normal entry.

 

Title: Re: Emergency ejection of CM during the launch phase.
Post by: Glom on October 15, 2012, 02:16:08 AM
"EDS to manual. Inboard! Get ready for a little jolt fellas."

Da da da da da da. Da da da da da da. Da da da da da da. Da daaa!

"That was some little jolt."
Title: Re: Emergency ejection of CM during the launch phase.
Post by: smartcooky on October 15, 2012, 04:06:24 AM
I have a question.

During an STS launch, the whole vehicle does a "roll" just after liftoff. I think I understand the purpose of that roll; to orient the Orbiter so that it goes into orbit "tail down" and in the required trajectory for whatever orbital inclination is needed for the mission profile.

However, I notice in the transcripts of the Apollo missions, the stack begins a "roll program" about 15 seconds after launch, which becomes a "pitch program" at about 35 seconds; its clearly heard on the audio of the Apollo launches on YT, and faithfully reproduced in the movie Apollo 13 where we hear Tom hanks saying "Roll complete, and we are pitching"

While I understand the need to orient an asymmetrical stack like the STS  (Fuel Tank, SRBs and Orbiter), I don't understand why the Saturn V needs to roll. It is after all a long, round tube with symmetrical main engine placement (one in the centre and four around the outside).

Why does it need to roll? 
Title: Re: Emergency ejection of CM during the launch phase.
Post by: Glom on October 15, 2012, 04:53:48 AM
I believe it's so the astronauts are oriented with the right way.
Title: Re: Emergency ejection of CM during the launch phase.
Post by: gwiz on October 15, 2012, 09:44:42 AM
Once the abort is initiated the escape rocket fires, and small canards emerge from the top of the escape tower to provide some measure of stability and control.
Probably better to say the canards destabilise the stack so that it pitches over to fly heat-shield-first, which is the way you want to be flying when you deploy the parachutes.
Title: Re: Emergency ejection of CM during the launch phase.
Post by: Echnaton on October 15, 2012, 10:58:34 AM
Why does it need to roll? 

During launch, the rocket was flown with one axis being referenced to the ground, so, for instance, the pitch maneuver was always performed the same way.    Since each mission could have a different launch direction, each needed to be rolled slightly to get the orientation of the capsule correct to the ground.  One benefit of always having a roll program was that it didn't really matter how much of a roll you made so the orientation on the pad could be in a direction that facilitated access via the white room.
Title: Re: Emergency ejection of CM during the launch phase.
Post by: Peter B on October 15, 2012, 08:15:14 PM
During an STS launch, the whole vehicle does a "roll" just after liftoff. I think I understand the purpose of that roll; to orient the Orbiter so that it goes into orbit "tail down" and in the required trajectory for whatever orbital inclination is needed for the mission profile...

While I understand the need to orient an asymmetrical stack like the STS  (Fuel Tank, SRBs and Orbiter), I don't understand why the Saturn V needs to roll. It is after all a long, round tube with symmetrical main engine placement (one in the centre and four around the outside). Why does it need to roll?
My understanding is that the same reasons applied to both spacecraft.

Firstly, it placed the astronauts in a head-down attitude, so that they always had a view of the horizon out the window during launch.

Secondly, it ensured the astronauts' brains weren't starved of blood during acceleration.

However, I'm happy to be corrected by people who actually know this stuff.
Title: Re: Emergency ejection of CM during the launch phase.
Post by: Chew on October 15, 2012, 08:18:12 PM
I believe it's so the astronauts are oriented with the right way.

They flew heads down. Or did you mean the right way is upside-down?

Quote
000:00:16 Collins: Roger.

    [The Flight Plan calls for Frank to report to Mission Control the accomplishment of many of the events that occur during ascent. He has already reported lift-off and like many other commanders, has not reported the yaw maneuver. Frank does report the initiation of the roll and pitch program.]

    [Clear of all the pad's ironwork, the rocket can safely rotate around its longitudinal axis by 17.876° from its launch roll angle of 90 ° to its flight azimuth of 72.124°. With the roll completed, it will begin pitching over to fly along this bearing with the crew in a heads-down attitude. Link (http://history.nasa.gov/ap08fj/01launch_ascent.htm)
Title: Re: Emergency ejection of CM during the launch phase.
Post by: smartcooky on October 15, 2012, 11:37:54 PM
OK, understood guys, thanks

I guess it must have been too much to expect them to have built Pads 39A & B to launch the astronauts already in the right positions. I can imagine all sorts of engineering issues might have been involved including roll-out from the VAB, fuel lines and crew entry.

Another issue might have been (and I don't know how important this would have been for Apollo) the orbital inclination required for TLI.

The Moon's orbit is inclined by about 5° w.r.t. the ecliptic (which is itself inclined to the earth's axis of rotation by about 23°). The point (or node) where the Moon's orbit intersects the ecliptic precesses over a period of about 18.6 years (known as the Saros Cycle) so the Moon's maximum declination (north or south of the ecliptic) for any given month can vary from about 18° to 28°. This could mean that the orbital inclination for TLI may have been a quite different for each mission.

It would be interesting to compare the Moon's declination on each launch date for all the Apollo missions that actually went to the Moon to see if the Moon's declination figure was taken into account when calculating the launch window; i.e. did they pick dates at which the declination of the Moon was close to zero?
Title: Re: Emergency ejection of CM during the launch phase.
Post by: Chew on October 16, 2012, 12:11:37 AM
It would be interesting to compare the Moon's declination on each launch date for all the Apollo missions that actually went to the Moon to see if the Moon's declination figure was taken into account when calculating the launch window; i.e. did they pick dates at which the declination of the Moon was close to zero?

Everything was taken into account.

Launch info here: http://apollohoax.proboards.com/index.cgi?board=apollo&action=display&thread=1356

Moon info here: http://ephemeris.com/ephemeris.php
Title: Re: Emergency ejection of CM during the launch phase.
Post by: ka9q on August 17, 2013, 12:52:42 AM
Apollo lunar launch azimuths, and hence the resulting orbital inclinations, varied as a function of time during each launch window. Since the launch pad didn't rotate, the launcher had to perform a variable roll after liftoff.

The IMU on the CM had only 3 gimbals. During launch, the reference direction (REFSMAAT) was oriented so that the gimbal lock positions (think of the poles of a globe) coincided with 90 degrees of out-of-plane yaw. So as long as you rolled so that the spacecraft Z axis (running parallel to the astronauts in their couches) was in the orbit plane, yaw was kept small and there was no risk of gimbal lock.

Another reason (often the main one, in fact) to roll a launcher after liftoff is to keep various antennas pointing in the right directions. The Saturn V had probably a dozen VHF telemetry transmitters. It also had UHF range safety (destruct) receivers, but those had multiple antennas since you couldn't depend on them facing in the right direction when you needed to send the command.
Title: Re: Emergency ejection of CM during the launch phase.
Post by: BazBear on August 17, 2013, 01:14:39 PM
Something I'd like to know about a similar thing that led up to Apollo, is:

Just how amazing (or otherwise) was Wally Schirra's non-pulling of the "chicken ring" during the first attempted launch of Gemini 6?
Gemini used ejection seats, didn't it (like the early STS flights)? I think I'd have hung in there as long as possible too; punching out from the top a Titan II sitting on the pad seems a bit iffy to me :)
Title: Re: Emergency ejection of CM during the launch phase.
Post by: ka9q on August 17, 2013, 02:53:28 PM
Yes, Gemini had ejection seats. They were never used, and I've always wondered if they would have worked.
Title: Re: Emergency ejection of CM during the launch phase.
Post by: Allan F on August 18, 2013, 08:50:19 AM
Wasn't the stack too short for a parachute to work before flight? Not a good idea to fall down next to an exploding rocket, by the way.
Title: Re: Emergency ejection of CM during the launch phase.
Post by: ka9q on August 18, 2013, 08:53:55 AM
I don't know that much about ejector seats, but it's my understanding that they can be designed for zero-zero operation, i.e., you could eject from a plane sitting on the runway and survive. The rockets take the pilot high enough that his parachute has time to open.
Title: Re: Emergency ejection of CM during the launch phase.
Post by: Zakalwe on August 18, 2013, 12:05:33 PM
I don't know that much about ejector seats, but it's my understanding that they can be designed for zero-zero operation, i.e., you could eject from a plane sitting on the runway and survive. The rockets take the pilot high enough that his parachute has time to open.

AFAIK, some seats are rated as "zero, -20" as they can be ejected even if the aircraft is under water.

http://www.ejectionsite.com/eunderh2o.htm

Martin Baker seats were developed to use a compressed air system if the seat ejection was initiated, as the normal explosive charges could kill the pilots if fired underwater.
http://www.ejectorseats.co.uk/underwater_ejection.htm
Title: Re: Emergency ejection of CM during the launch phase.
Post by: Allan F on August 18, 2013, 01:16:28 PM
Appears from that site as the Gemini escape system was designed to fire the astronauts away from the pad fast enough to outrun a fuel explosion.
Title: Re: Emergency ejection of CM during the launch phase.
Post by: BazBear on August 18, 2013, 03:52:21 PM
Appears from that site as the Gemini escape system was designed to fire the astronauts away from the pad fast enough to outrun a fuel explosion.
I'm sure, but it still sounds a lot dicier to me than leaving in the protection of a capsule.
Title: Re: Emergency ejection of CM during the launch phase.
Post by: DataCable on August 19, 2013, 07:37:27 PM
I don't know that much about ejector seats, but it's my understanding that they can be designed for zero-zero operation, i.e., you could eject from a plane sitting on the runway and survive. The rockets take the pilot high enough that his parachute has time to open.
But wouldn't Gemini ejection seats launch horizontally?
Title: Re: Emergency ejection of CM during the launch phase.
Post by: Obviousman on August 20, 2013, 06:06:33 AM
This might be useful:

(http://upload.wikimedia.org/wikipedia/commons/b/b5/Gemini_ejection_-_sequence_of_events.jpg)

(http://history.nasa.gov/SP-4002/images/fig34.jpg)
Title: Re: Emergency ejection of CM during the launch phase.
Post by: ka9q on August 21, 2013, 12:17:37 PM
Would the astronaut's oxygen supply remain isolated after ejection? In the explosion of a Titan II rocket there would be large amounts of unburned fuel (Aerozine-50) and oxidizer (nitrogen tetroxide) that are quite toxic in even small amounts.

The brown clouds visible in the recent explosion of the Proton rocket are nitrogen tetroxide.


Title: Re: Emergency ejection of CM during the launch phase.
Post by: Obviousman on August 23, 2013, 04:55:26 AM
Absolutely.

I haven't seen details of the seat (I'll check, though) but all modern ejection seats have a 5 min O2 supply. This is normally disconnected during seat seperation but in light of the booster fuel and the fact they are wearing a pressure suit with helmet, I'd imagine that it remains connected.
Title: Re: Emergency ejection of CM during the launch phase.
Post by: Obviousman on August 23, 2013, 05:52:49 AM
Okay, the seat has an 1800 psi tank. It goes through a regulator and designed to keep the suit pressurised to 3.5 PSI above 35,000 feet and controls "0 to 5 inches water gage" if below 35,000. The O2 system starts automatically upon ejection by activation of a lanyard.

The O2 bottle is part of the seat egress kit, and stays with the astronaut after seat seperation.

Title: Re: Emergency ejection of CM during the launch phase.
Post by: ka9q on August 23, 2013, 09:28:54 AM
Thanks.

All the attention placed on survivable aborts during the "early days" makes the lack of same for the Shuttle even more striking.
Title: Re: Emergency ejection of CM during the launch phase.
Post by: Ranb on August 23, 2013, 07:08:18 PM
Would a crew ejection from the Columbia or Challenger accidents been survivable at all?

Ranb
Title: Re: Emergency ejection of CM during the launch phase.
Post by: VQ on August 23, 2013, 07:49:19 PM
Would a crew ejection from the Columbia or Challenger accidents been survivable at all?

Ranb
Columbia, no. They were still too fast for any current-technology space suit to protect them from the impinging plasma.

Challenger, yes. At breakup they were at ~50k feet and Mach 2, conditions less severe than the 1966 SR-71 ejection. However, the space shuttle design would have made ejection seats for all occupants very difficult if not impossible (three of the seven occupants sit in the mid deck, deep in the crew compartment).
Title: Re: Emergency ejection of CM during the launch phase.
Post by: smartcooky on August 24, 2013, 05:21:23 PM
Would a crew ejection from the Columbia or Challenger accidents been survivable at all?

Ranb
Columbia, no. They were still too fast for any current-technology space suit to protect them from the impinging plasma.

Challenger, yes. At breakup they were at ~50k feet and Mach 2, conditions less severe than the 1966 SR-71 ejection. However, the space shuttle design would have made ejection seats for all occupants very difficult if not impossible (three of the seven occupants sit in the mid deck, deep in the crew compartment).

So safely eject the whole crew of the shuttle, the designers would really have to have employed a crew capsule ejection system similar to that used on the F-111 Aardvark



I imagine such a system would be a technical nightmare to design and build with many, many problems, not the least of which would be the potential hull compromise where the capsule joins the rest of the fuselage.

In the case of Challenger, its moot as there was no opportunity to eject anyway because the crew had no, or insufficient warning of the explosion.
Title: Re: Emergency ejection of CM during the launch phase.
Post by: VQ on August 25, 2013, 03:36:20 AM
In the case of Challenger, its moot as there was no opportunity to eject anyway because the crew had no, or insufficient warning of the explosion.

I disagree. The crew module pressure vessel survived the breakup largely intact, and based on switch settings in the cabin at least some of the crew was usefully conscious immediately after the breakup. It is plausible that ejection seats (combined with SR-71 style pressure suits) could have saved the crew members in the upper deck.
Title: Re: Emergency ejection of CM during the launch phase.
Post by: smartcooky on August 25, 2013, 04:42:02 AM
In the case of Challenger, its moot as there was no opportunity to eject anyway because the crew had no, or insufficient warning of the explosion.

I disagree. The crew module pressure vessel survived the breakup largely intact, and based on switch settings in the cabin at least some of the crew was usefully conscious immediately after the breakup. It is plausible that ejection seats (combined with SR-71 style pressure suits) could have saved the crew members in the upper deck.


But that was my point...

"To safely eject the whole crew of the shuttle...."

Yes they were still conscious, but that was after the explosion took place.

I was talking in terms of a design (like the F-111) that allows the crew capsule to be ejected (the F-111 does not have ejection seats). For that to work, they would have to eject the capsule before the explosion.
Title: Re: Emergency ejection of CM during the launch phase.
Post by: Obviousman on August 25, 2013, 06:25:22 AM
A point of interest - the very early F-111s used ejection seats as the crew capsule still hadn't been certified.
Title: Re: Emergency ejection of CM during the launch phase.
Post by: ka9q on August 25, 2013, 06:50:59 AM
I know a lot of this was considered after Challenger. The F-111 capsule idea was specifically mentioned, but it was just too impractical, at least as a retrofit.

I guess like a lot of security and safety mechanisms, a launch escape system really has to be designed in from the beginning. It certainly was for Mercury, Gemini and Apollo.

If NASA really wants to be honest with itself, it should write a "lessons learned" report on the entire Shuttle program. Start with why it was built, how it was justified and sold, and what actually happened in its 30 years of flight. And follow that with an unflinching explanation of why there was such a huge gap between the promises and the reality, and how to avoid repeating those same mistakes in future programs. Otherwise they will be repeated.




Title: Re: Emergency ejection of CM during the launch phase.
Post by: ka9q on August 25, 2013, 07:07:07 AM
Columbia, no. They were still too fast for any current-technology space suit to protect them from the impinging plasma.
In other words, whatever heat shield you have simply has to work. Meaning it must be as small and simple as possible, and preferably protected from damage until right before use.
Quote
Challenger, yes. At breakup they were at ~50k feet and Mach 2, conditions less severe than the 1966 SR-71 ejection. However, the space shuttle design would have made ejection seats for all occupants very difficult if not impossible (three of the seven occupants sit in the mid deck, deep in the crew compartment).
Doesn't the B-52 eject two crew members downward? If the Shuttle had been laid out so that some of the occupants sat just above the bottom skin, maybe it would have been possible. But this would have required punching a hole through the silica tiles on the underside, complicating an already difficult piece of technology.

But even if you can get the crew quickly away from the orbiter, you have the problem of protecting them from a hydrogen/oxygen fireball and two still-burning SRBs that are flying without guidance. Those plumes are pretty wicked, and you don't have to get directly hit by one to be fried by the noise and thermal radiation.

Launch abort survivability is not easy. Remember the Aries-1 was sunk by an Air Force analysis showing that the Orion's parachutes would be fried by chunks of burning solid propellant were an abort to occur as a result of a first stage failure (which for solid rockets usually means "a sudden, dramatic explosion" -- the Challenger SRB failure was a very unusual mode).


Title: Re: Emergency ejection of CM during the launch phase.
Post by: smartcooky on August 25, 2013, 08:03:04 AM
A point of interest - the very early F-111s used ejection seats as the crew capsule still hadn't been certified.

I thought that was only the case in the TFX.

the Challenger SRB failure was a very unusual avoidable mode).

FTFY
Title: Re: Emergency ejection of CM during the launch phase.
Post by: Obviousman on August 26, 2013, 07:29:58 AM
F-111A aircraft 63-9766 through 63-9776 were all fitted with ejection seats.