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Load and Go a Go
JF Mezei wrote on Tue, 21 Aug 2018
11:55:18 -0400: On 2018-08-21 05:06, Fred J. McCall wrote: Unnecessary. Any dummies will get the same g forces as the rest of the capsule. Do the seats/couches provide any G force reduction? Or are they "fixed" and protect the occupants by being perfectly moulded like on Soyuz? No. Seats can reduce 'jolt', but until we get antigravity no seat can reduce g forces. If there is some suspension provided by the seats to cushion landing, you will want to have human-like mass on the seats with G force sensors. Why? If the capsule doesn't exceed 3.5g, stuff in the capsule won't exceed 3.5g, either. Things that don't matter just don't matter. That doesn't matter. Ensuring that the capsule re-enters correctly when the mass it carries is that of a crew would be important. The unnecessary testing you suggest will take forever, since you would need to 'test' with from zero to seven passengers each weighing from 105 to 200 pounds, plus varying return cargo from zero to maximum capacity. A different mass means different F forces during re-entry interface and during the actual landing. Not enough different to matter. You act as if nothing is known and we just build the things and shoot them up there on a wing and a prayer. Not at all how it works. And it would presumably also test the software when firing thrusters to ensure it can handle the mass of the crew. You seem under the delusion that the crew will mass MORE than a cargo variant will carry. CG would still presumably be different. You seem to be trying to make the argument that the only way to man rate a system is to fly people on it, I said dummies, not people. They're not going to send you, Mayfly. -- "Some people get lost in thought because it's such unfamiliar territory." --G. Behn |
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Load and Go a Go
JF Mezei wrote on Tue, 21 Aug 2018
12:04:07 -0400: On 2018-08-21 06:32, Jeff Findley wrote: Yes. The rocket doesn't care what payload is on top when you're going through pre-launch procedures like fueling. In a cargo, you need not provide for emergency egress since the cargo is unlikely to get scared and want to exit ASAP if things go wrong. You need not provide that for a manned vehicle, either. Name one other than the Shuttle that did so. I assume that a bridge from tower to capsule will remain for some time during fueling to allow such egress. (or would SpaceX just train astronauts to press the big red button for capsule jettison and do away for emergency egress ? You assume incorrectly. The crew would probably never get a chance to 'push a button'. If telemetry detects a problem with the booster the capsule goes. Will SpaceX provide emergency egress joy ride in a basket down a long rope like for Shuttle? No. That would be stupid. I take it NASA will want astronauts all tucked in and hatches closed before fueling begins, or would it allow that operation to be done while fueling is happening? You need to stop 'taking' things and do some actual research instead of just bleating out stupid remarks. -- "Some people get lost in thought because it's such unfamiliar territory." --G. Behn |
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Load and Go a Go
Jeff Findley wrote on Tue, 21 Aug 2018
19:51:37 -0400: In article , says... On 2018-08-21 05:06, Fred J. McCall wrote: Unnecessary. Any dummies will get the same g forces as the rest of the capsule. Do the seats/couches provide any G force reduction? Or are they "fixed" and protect the occupants by being perfectly moulded like on Soyuz? Seats don't reduce G forces. If we could do that, we'd have literal anti-gravity beds here on earth so that patients in the hospital would never get bedsores. If there is some suspension provided by the seats to cushion landing, you will want to have human-like mass on the seats with G force sensors. Like Fred said, dummies. Specifically, instrumented "crash test" dummies. They're used in the aerospace industry as well as the automotive industry. They mimic the mass, strength, and etc of a human and are instrumented to measure the accelerations at various parts of the dummy's body. They're literally "off the shelf" items. Actually, I think the whole 'dummy test' scenario is unnecessary. Were dummies used to test the Shuttle or Apollo or Gemini or Mercury? -- "Insisting on perfect safety is for people who don't have the balls to live in the real world." -- Mary Shafer, NASA Dryden |
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Load and Go a Go
JF Mezei wrote on Tue, 21 Aug 2018
21:41:35 -0400: On 2018-08-21 19:51, Jeff Findley wrote: Like Fred said, dummies. Specifically, instrumented "crash test" dummies. Pardon me? I am the one who said that, with Fred, predictably satting it instrumented dummies woudln't be used because the aircraft already has instruments. Spacecraft, not aircraft. With regards to seats, springs and cushions would reduce impact of landing, woudln't it ? Not talking about anti gravity beds. So you're talking about 'jolt' and not 'g forces'. 'Jolt' isn't really an issue for any system I'm aware of other than Soyuz and derivatives that use a 'last blast' landing on dirt. Dragon V2 was never going to do that it that way, even when they were still planning on propulsive landings. Max g on capsules is during reentry, not landing, and it's sustained for some time so seats don't do jack. -- "Some people get lost in thought because it's such unfamiliar territory." --G. Behn |
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Load and Go a Go
In article ,
says... Will SpaceX provide emergency egress joy ride in a basket down a long rope like for Shuttle? No. That would be stupid. And yet that is exactly what they are doing. SpaceX will reuse the shuttle system, just attached higher on the fixed service structure. ULA will have its own version of the egress system which will consist of individual harnesses sliding along the ziplines instead of the larger multi-person basket(s) at pad 39A. https://www.floridatoday.com/story/t.../04/03/atlasv- rocket-boeing-starliner-astronauts-emergency-egress-system-commercial- crew/99972784/ Jeff -- All opinions posted by me on Usenet News are mine, and mine alone. These posts do not reflect the opinions of my family, friends, employer, or any organization that I am a member of. |
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Jeff Findley wrote on Wed, 22 Aug 2018
06:41:13 -0400: In article , says... Will SpaceX provide emergency egress joy ride in a basket down a long rope like for Shuttle? No. That would be stupid. And yet that is exactly what they are doing. SpaceX will reuse the shuttle system, just attached higher on the fixed service structure. ULA will have its own version of the egress system which will consist of individual harnesses sliding along the ziplines instead of the larger multi-person basket(s) at pad 39A. https://www.floridatoday.com/story/t.../04/03/atlasv- rocket-boeing-starliner-astronauts-emergency-egress-system-commercial- crew/99972784/ OK, I have to ask the obvious question. Why? If it's really an emergency, how long does it take to unbutton the capsule and get everyone out as opposed to just firing the escape system? -- "Insisting on perfect safety is for people who don't have the balls to live in the real world." -- Mary Shafer, NASA Dryden |
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Jeff Findley wrote on Wed, 22 Aug 2018
06:41:34 -0400: In article , says... Jeff Findley wrote on Tue, 21 Aug 2018 19:51:37 -0400: Like Fred said, dummies. I got the attribution wrong. You didn't say "dummies". Specifically, instrumented "crash test" dummies. They're used in the aerospace industry as well as the automotive industry. They mimic the mass, strength, and etc of a human and are instrumented to measure the accelerations at various parts of the dummy's body. They're literally "off the shelf" items. Actually, I think the whole 'dummy test' scenario is unnecessary. Were dummies used to test the Shuttle or Apollo or Gemini or Mercury? Monkeys were the human analog used to test Mercury. They had a lot of untested stuff, so needed a living analog to test with. The Russians used dogs for the same purpose. Gemini and Apollo had instrumented uncrewed test flights. Which is what I would expect Dragon V2 to do. I just don't see the necessity of dummies on those flights. The STS-1 was a mistake. There were several issues with that first flight that could have resulted in LOC. They didn't have a choice. Fly it unmanned and it was a guaranteed loss of vehicle, since the thing couldn't land without a pilot. For current uncrewed test flights using off the shelf crash test dummies (i.e. min size female and max size male) is the cheapest way to instrument the vehicle to see what accelerations the meat bags will have to endure. You get the same data without the dummies from sensors on the capsule. -- "Insisting on perfect safety is for people who don't have the balls to live in the real world." -- Mary Shafer, NASA Dryden |
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Load and Go a Go
JF Mezei wrote on Wed, 22 Aug 2018
14:09:45 -0400: On 2018-08-22 08:26, Fred J. McCall wrote: OK, I have to ask the obvious question. Why? If it's really an emergency, how long does it take to unbutton the capsule and get everyone out as opposed to just firing the escape system? Consider theye are also pad crews at some periods (the ones who tuck crews in, close hatches etc etc). They need some means of emergency egress as they do not have a capsule jettison system. But when they 'tuck the crew in' there's no fuel in the rocket, so there's not really anything that can 'go wrong' that would endanger ground crew. Besides, would such an emergency escape system have much utility for ground crew? They'd all have to gather where the basket is, get in, hope the basket has sufficient room for them all, then get away. Easier to just take cover in place. jeff mentioned that for Dragon itself, it is more likely an automated capsule jettison gets triggered than crews unstrapping themselves and leaving capsiule to take the joy ride down the zip line. Quite right, so the utility of the zip line is what, again? However, during crew ingress when the hatch is opened and there are both flilght cerws and pad crews in capsule, doubtful that the capsule jettison would be armed. So egress via bridge and then down the zip line more likely. But there's nothing to blow up, since there's no fuel in the rocket yet. With fueling happening after crew are strapped in and hatches closed, the odds of problems while crews get into capsule are much lower. Essentially non-existent. At the time crews will ingress, will any part of the stack be alreayd fueled? Or does fueling "at last minute" involved fueling not only stage 1, but also stage 2 and fuel inside Dragon ? Everything is empty but the hypergolic fuel in the capsule itself. If THAT goes wrong (and the odds of that are virtually zero), there is no escape. Capsule, basket, zip line, and all go up. So I'm still puzzled at the actual utility of such a system. -- "Insisting on perfect safety is for people who don't have the balls to live in the real world." -- Mary Shafer, NASA Dryden |
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