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#1940
by
psloss
on 17 May, 2009 15:47
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But for any single engine out abort, it does need extensive and expensive certification. In contingency cases the CDR can do what is needed to land the orbiter where ever he can, but a single engine out abort is NOT a contingency -- it must be fully certified. Believe it or not, RTLS is fully certified but not tested.
How much have single engine out ECALs been simulated, if at all? Seems like ECAL would eliminate the PPA and Vrel = 0 parts of RTLS, but would it mitigate the low(-ish) altitude / high(-ish) Q ET sep and the post-sep recovery conditions?
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#1941
by
kch
on 17 May, 2009 15:47
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...fully certified but not tested.
This seems like a near contradiction to me. 
Seems "certifiable" to me ...
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#1942
by
Danny Dot
on 17 May, 2009 18:16
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But for any single engine out abort, it does need extensive and expensive certification. In contingency cases the CDR can do what is needed to land the orbiter where ever he can, but a single engine out abort is NOT a contingency -- it must be fully certified. Believe it or not, RTLS is fully certified but not tested.
How much have single engine out ECALs been simulated, if at all? Seems like ECAL would eliminate the PPA and Vrel = 0 parts of RTLS, but would it mitigate the low(-ish) altitude / high(-ish) Q ET sep and the post-sep recovery conditions?
I think you are right on all accounts. No PPA and Vrel=0, but still high Q sep and aggressive post-sep recovery needed.
Danny Deger
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#1943
by
psloss
on 17 May, 2009 18:25
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No PPA and Vrel=0, but still high Q sep and aggressive post-sep recovery needed.
Do you recall what John Young liked about ECAL vs. RTLS? Was it not having to fly up-range (or "fall" up-range, as it were) or was it that and/or other things?
Thanks.
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#1944
by
Jim
on 17 May, 2009 20:34
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...fully certified but not tested.
This seems like a near contradiction to me.
Certified means analyzed. It means they would have the proper approaches looked at, time hacks documented, vel vs distance, etc
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#1945
by
Brian P
on 18 May, 2009 03:30
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They haven't used the LES since 1995. The new suit is called ACES (Advanced Crew Escape Suit).
Any reason they are orange or did nasa just like the color?
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#1946
by
Jim
on 18 May, 2009 11:41
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They haven't used the LES since 1995. The new suit is called ACES (Advanced Crew Escape Suit).
Any reason they are orange or did nasa just like the color?
It is for visibility in the water
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#1947
by
brahmanknight
on 18 May, 2009 18:52
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This is for shuttle and ISS EVAs ( maybe we need and EVA Q&A ). Is there a secure radio channel they can use if needed? As in, encrypted.
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#1948
by
Jim
on 18 May, 2009 18:59
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This is for shuttle and ISS EVAs ( maybe we need and EVA Q&A ). Is there a secure radio channel they can use if needed? As in, encrypted.
Nope, just the UHF channels
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#1949
by
Lee Jay
on 18 May, 2009 22:25
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...fully certified but not tested.
This seems like a near contradiction to me.
Certified means analyzed. It means they would have the proper approaches looked at, time hacks documented, vel vs distance, etc
I know what it means in this context, it's just weird to me compared to other contexts.
Example. How do you do crane certifications? Function and load test them!
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#1950
by
Jorge
on 18 May, 2009 22:36
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...fully certified but not tested.
This seems like a near contradiction to me.
Certified means analyzed. It means they would have the proper approaches looked at, time hacks documented, vel vs distance, etc
I know what it means in this context, it's just weird to me compared to other contexts.
Example. How do you do crane certifications? Function and load test them!
It is not weird at all in an aerospace context, and it goes back a long way. The X-15 ejection seat was "certified" to Mach 4 and 120 kft, but was never flight-tested in that environment.
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#1951
by
Lee Jay
on 19 May, 2009 01:43
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IIRC, when the Shuttle is docked at ISS and in attitude control, it does a sort of natural reboost by selecting thrusters that not only apply the needed torque but also are thrusting posigrade. Is the same true of the current HST mission STS-125? Has there been a natural reboost during this mission?
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#1952
by
Jorge
on 19 May, 2009 01:52
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IIRC, when the Shuttle is docked at ISS and in attitude control, it does a sort of natural reboost by selecting thrusters that not only apply the needed torque but also are thrusting posigrade. Is the same true of the current HST mission STS-125? Has there been a natural reboost during this mission?
It depends on the attitude. The "natural reboost" comes from the vernier RCS, all of which are either side- or down-firing. In order for this effect to raise the orbit, the orbiter must be oriented with the payload bay facing the velocity vector. So during the times in this mission when the orbiter has been pointed that way (which hasn't been often), there's been a free reboost.
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#1953
by
karizma23
on 19 May, 2009 04:01
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Sometimes while watching NASA.tv I hear the crew and MCC-H talk about jettisoning water from the Shuttle into space. Apparently it's pretty cool to see. Does anyone have any video of this? I'd love to see it. Thanks!
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#1954
by
MKremer
on 19 May, 2009 04:38
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#1955
by
karizma23
on 19 May, 2009 05:39
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Thank you.
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#1956
by
mmeijeri
on 19 May, 2009 12:51
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OK, here's that old chestnut again: reusing the ET on orbit. The foam insulation makes this impossible, but what if you were willing to take a major performance hit? Could you remove the insulation, accept the bad consequences and go ahead anyway? What bad things would happen? Or else use internal insulation, again accepting the performance hit. All the vehicle would have to do is to put itself in orbit, without any additional payload, although it would be nice if you still had some. I'm thinking self-launching space station, so perhaps with a Shuttle-C or an inline SDLV, so no orbiter and no lives at risk.
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#1957
by
Lee Jay
on 19 May, 2009 13:03
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What bad things would happen?
The whole tank would get covered in ice.
Or else use internal insulation, again accepting the performance hit.
Like having some pieces of that insulation flake off and make it to the main engines?
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#1958
by
mmeijeri
on 19 May, 2009 13:11
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The whole tank would get covered in ice.
So bad you couldn't launch or just that you'd lose a lot of performance? There wouldn't be an orbiter, so you wouldn't have to worry about any ice hitting it.
Like having some pieces of that insulation flake off and make it to the main engines?
Depends on how likely that is. But what if you covered the insulation with metal on the inside? Probably heavy, but what if you were willing to accept zero additional payload? Wasn't that the original plan with Skylab and S-II?
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#1959
by
elmarko
on 19 May, 2009 13:11
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Here's one that I think gets asked occasionally.
Rotating the shuttle with something on the end of the RMS. Problems with that? Rotational moments breaking things? It's been asked on another forum as they were rotating to sep attitude for HST release.
