Emergency ejection of CM during the launch phase.

[Obviousman]

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.

[ka9q]

Thanks.

All the attention placed on survivable aborts during the "early days" makes the lack of same for the Shuttle even more striking.

[Ranb]

Would a crew ejection from the Columbia or Challenger accidents been survivable at all?

Ranb

[VQ]

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).

[smartcooky]

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.

[VQ]

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.

[smartcooky]

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.

[Obviousman]

A point of interest - the very early F-111s used ejection seats as the crew capsule still hadn't been certified.

[ka9q]

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.

[ka9q]

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.

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).

[smartcooky]

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

[Obviousman]

F-111A aircraft 63-9766 through 63-9776 were all fitted with ejection seats.