Advanced Question ACES Bailout in a Capsule

[Astro SG Wise]

No, for much longer - the unburnt fuel/oxidizer of the onset/shutdown of the thruster firing would simply blow into the capsule with the exhaust of the thruster firing, once the capsule is open. Luckily, the astronaut already wears a pressure suit. sadly, you would need to decontaminate the astronaut before he could take off his ACES suit.


Also, you overestimate the thrust of the RCS there. The thrusters are designed for space and upper atmosphere and will loose a lot of thrust to ambient pressure. The capsule would still be tumbling a bit while the thrusters are busy preventing much worse - for a few seconds before running out of fuel.



No, the astronaut would be cremated long before he could pull the release handle.

You can say, as coarse rule of thumb: Deploying a personal parachute at any speed above Mach 0.5 is nearly impossible, above Mach 0.3 it is risky.

For any high speed egress, you have special stabilization systems that have only the job of bringing you into the range for a successful parachute deployment and use powerful pyrotechnical deployment systems (parachute mortars), that can deploy a parachute even at higher speeds.

But such parachute mortars are not possible in an ACES suit, for a good reason - just imagine accidentally firing one inside the capsule.

Well, the only reason I over-estimate RCS thrust is that I have seen it work in Orbiter, and I have seen it in real life (AKA EFT-1)! When Orion comes down, it is bottom down, head up, and stable. It wouldn't be "tumbling" unless something went wrong with the RCS. Good with the astronaut cremation :thumbup:.

On the decontamination of the suit, would the crew have enough air in their ACES for a rescue crew to get them and decontaminate the suits?

 

[Urwumpe]

When Orion comes down, it is bottom down, head up, and stable. It wouldn't be "tumbling" unless something went wrong with the RCS.

Take a look again at EFT-1 ... and remember that the drogues had been deployed at Mach 0.48 ...

Notice the tiny changes in the sky at the lower left corner? That is the normal tumbling which is still controlled by RCS during re-entry (The RCS does not fire all the time for keeping a perfect attitude, it only gets active when a certain attitude error is exceeded), in high altitude (drogues deploy at about 6.7 km altitude). At lower altitudes suitable for bail-out, the ambient pressure is much higher and the RCS thrust much lower.

 

[Astro SG Wise]

Take a look again at EFT-1 ... and remember that the drogues had been deployed at Mach 0.48 ...

Onboard camera captures Orion capsule return to Earth - YouTube

Notice the tiny changes in the sky at the lower left corner? That is the normal tumbling which is still controlled by RCS during re-entry (The RCS does not fire all the time for keeping a perfect attitude, it only gets active when a certain attitude error is exceeded), in high altitude (drogues deploy at about 6.7 km altitude). At lower altitudes suitable for bail-out, the ambient pressure is much higher and the RCS thrust much lower.

Yeah, I guess, but it still isn't the "tumbling" that would be a serious problem. Also, how easy is it to decelerate by body drag? Felix Baumgartner passed Mach 1.24 during his jump, and decelerated from that speed to a safe parachute deployment speed.

---------- Post added at 05:10 PM ---------- Previous post was at 05:07 PM ----------

...then again, Felix went into a spin ...

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So, In it's totality, should parachutes even be added on persons? Is it credible and or reasonable to add them just in the super duper last chance?

 

[Urwumpe]

So, In it's totality, should parachutes even be added on persons? Is it credible and or reasonable to add them just in the super duper last chance?

Neither credible, nor reasonable.

 

[Thunder Chicken]

Here is perhaps the story of the closest analogous situation, the failure of the Explorer balloon:

From [ame="http://en.wikipedia.org/wiki/Explorer_II"]http://en.wikipedia.org/wiki/Explorer_II[/ame]:

The balloon was launched from a canyon in the Black Hills of South Dakota—dubbed the Stratobowl—on July 28, 1934 and reached a near-record altitude of 18,475 m (60,613 ft)[3] before tears in the fabric led the crew to begin reducing their altitude. A rupture in the balloon resulted in a precipitous descent, followed by a spark that caused the hydrogen to ignite and destroy what was left of the balloon, leaving the capsule to plummet toward the ground at terminal velocity. The crew just managed to escape using their parachutes, with the last man bailing out at 500 feet (150 m) above the ground. Their capsule was almost completely destroyed upon impact.[2]

But note the following:

• Only 3 crewmembers
• Crewmembers were not encumbered with pressure suits
• Crewmembers were not strapped into couches
• The capsule was an open sphere, very little equipment impeding egress

 

[Astro SG Wise]

Right, makes sense. So, would NASA use the ACES suits just as exposure suits? Maybe a new suit, (changing the acronym).

 

[Star Voyager]

As far as I know, they're modifying the ACES for both launch/entry and EVA:

 

[Astro SG Wise]

Yeah, it does definitely save costs. Not only that, it saves weight, having one suit for everything, and ultimately, saves more cost. But, something I wouldn't get used to is spacewalking with the "pumpkin". Would the EVA version of the ACES be orange, or white?

 

[Andy44]

I thought they weren't suitable for EVA due to the inflation effect?

Mike Mullane talks in his book about a situation they were in where the shuttle's airlock wasn't working properly and Houston was weighing the option of depressurizing the cabin and using the side hatch, with the crew in the ACES suits. It was ruled out mainly because they were afraid the cockpit avionics would overheat without any air flow, but the only people supposed to actually go outside were to be wearing EVA suits; the ACES suits were to worn by people staying inside.

 

[dman]

Ejection seats are bulky, heavy and dangerous, so there won't be any.

Space shuttle COLUMBIA carried ejection seats for the first few test flights

Were later removed when COLUMBIA went operational . The crew worn
pressure suits for the test flights . For operational mission suits were dispensed with and crew used oxygen helmets

After CHALLENGER disaster NASA went back to using pressure suits
First model LES (Launch Entry Suits) were only only partial pressure
suits based on those worn by U2 and SR 71 pilots

In 1995 NASA went to the full pressure ACES suits

 

[DaveS]

For operational mission suits were dispensed with and crew used oxygen helmets

They were unpressurized air only, fed by manually activated Personal Egress Air Packs (PEAPs). Those were intended for on-pad emergency evacuation of the orbiter in case of toxic atmosphere present (fire/propellant leak). In flight, they were useless.

 

[Astro SG Wise]

I thought they weren't suitable for EVA due to the inflation effect?

Mike Mullane talks in his book about a situation they were in where the shuttle's airlock wasn't working properly and Houston was weighing the option of depressurizing the cabin and using the side hatch, with the crew in the ACES suits. It was ruled out mainly because they were afraid the cockpit avionics would overheat without any air flow, but the only people supposed to actually go outside were to be wearing EVA suits; the ACES suits were to worn by people staying inside.

Yeah, ACES is on the inside, sort of like the Apollo A7L.

 

[Andy44]

Space shuttle COLUMBIA carried ejection seats for the first few test flights

Were later removed when COLUMBIA went operational . The crew worn
pressure suits for the test flights . For operational mission suits were dispensed with and crew used oxygen helmets

After CHALLENGER disaster NASA went back to using pressure suits
First model LES (Launch Entry Suits) were only only partial pressure
suits based on those worn by U2 and SR 71 pilots

In 1995 NASA went to the full pressure ACES suits

Yes, Columbia had to be modified. Columbia also had a lot more room inside the cabin than most capsule designs.

And, as they later computed, had those ejection seats ever been used during launch they would've killed the crew by hurtling™ them through the SRB plume.

 

[dman]

Yes, Columbia had to be modified. Columbia also had a lot more room inside the cabin than most capsule designs.

And, as they later computed, had those ejection seats ever been used during launch they would've killed the crew by hurtling™ them through the SRB plume.

Thats why for the first 2 minutes until SRB burn out and jettison you were
along for the ride and no way to get off........

 

[Hlynkacg]

Thats why for the first 2 minutes until SRB burn out and jettison you were
along for the ride and no way to get off........

Post SRB sep the shuttle would be too high and too fast for the Ejection seat to do any good.

 

[Andy44]

Post SRB sep the shuttle would be too high and too fast for the Ejection seat to do any good.

To be fair, the ejection seats would likely have been useful during the subsonic glide phase, if say, the landing gear didn't lock or something.

But during the entire launch and ascent they were essentially useless.

 

[Urwumpe]

To be fair, the ejection seats would likely have been useful during the subsonic glide phase, if say, the landing gear didn't lock or something.

But during the entire launch and ascent they were essentially useless.

They would not even have been enough to haul the crew away from the stack during a pre-launch emergency. They had really just been for possible landing emergencies.

 

[C3PO]

IMHO an emergency bailout from a capsule is as sensible as base-jumping out of a car crash. A planned ejection like Vostok is totally different to an emergency bailout.

 

[Andy44]

IMHO an emergency bailout from a capsule is as sensible as base-jumping out of a car crash. A planned ejection like Vostok is totally different to an emergency bailout.

Well, it's not like it hasn't been done...

 

[C3PO]

Well, it's not like it hasn't been done...

SKYDIVING IN A CAR .. - YouTube

I'm pretty sure that's a planned jump.