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#140
by
corrodedNut
on 05 Aug, 2011 00:33
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#141
by
Herb Schaltegger
on 05 Aug, 2011 00:44
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WRT to a "live" abort test, it seems to me that this sort of thing is going to be crazy-expensive and at the same time crazy-followed by the aerospace media. As a result, it will only be done once. Therefore, you'd need to do this at the point in the overall flight profile that offers the most-challenging "corner condition" so that you can use the data to certify the flight envelope to the greatest extent possible for the effort expended. At first blush, doing the test at or very near to max-q is probably the best place to meet all the likely objectives.
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#142
by
Steve D
on 05 Aug, 2011 00:53
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WRT to a "live" abort test, it seems to me that this sort of thing is going to be crazy-expensive and at the same time crazy-followed by the aerospace media. As a result, it will only be done once. Therefore, you'd need to do this at the point in the overall flight profile that offers the most-challenging "corner condition" so that you can use the data to certify the flight envelope to the greatest extent possible for the effort expended. At first blush, doing the test at or very near to max-q is probably the best place to meet all the likely objectives.
Has anyone ever done this? Tested an abort at or near Max-Q? If the test fails how would that affect manned space flight? We have counted on a system that was never really put to the test and it didn't work?
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#143
by
kevin-rf
on 05 Aug, 2011 00:55
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Has anyone ever done this? Tested an abort at or near Max-Q? If the test fails how would that affect manned space flight? We have counted on a system that was never really put to the test and it didn't work?
I thought that was the point of the Little Joe flights during Apollo...
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#144
by
Jim
on 05 Aug, 2011 00:56
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Little Joe I and II and Big Joe
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#145
by
Rocket Science
on 05 Aug, 2011 00:56
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#146
by
Jim
on 05 Aug, 2011 01:02
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5xx has same Centaur but is inside the 5m fairing. Spacecraft load is partially carried by fairing structure.
Spacecraft load is not carried by the fairing
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#147
by
Lurker Steve
on 05 Aug, 2011 01:03
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WRT to a "live" abort test, it seems to me that this sort of thing is going to be crazy-expensive and at the same time crazy-followed by the aerospace media. As a result, it will only be done once. Therefore, you'd need to do this at the point in the overall flight profile that offers the most-challenging "corner condition" so that you can use the data to certify the flight envelope to the greatest extent possible for the effort expended. At first blush, doing the test at or very near to max-q is probably the best place to meet all the likely objectives.
3 test launches in one year is going to be expensive, but the abort test doesn't really add to the cost at all, since the launcher isn't reusable. I don't believe the CST-100 will be reusable at first either, so they are investing in 3 fully instrumented Atlas V 421 launchers and CST-100 capsules. But, they are also setting the bar on the requirements for Safety testing. Perhaps SpaceX and Dream Chaser will be required to perform the same abort tests before they are allowed to carry humans.
I have the same feeling about the ULA space act agreement. They didn't get any NASA funding, but they did get gain the ability to help set the NASA standards for human rating a launcher.
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#148
by
Jim
on 05 Aug, 2011 01:06
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...launching a full-up orbital Atlas with the intent to have range-safety blow it up mid-flight. That's ballsy.
A full live Centaur would not be required there.
But it will be since:
a. TLYF
b. It can't be flown empty
c. it can't be flown with different fluid
d. too much engineering to do the above
If it's really going to be TLYF, they should set up a red team that is entirely responsible for how and when the abort occurs. Their job is to kill the booster in the worst possible way at the worst possible time -- if they do their job right, the launch team will be as surprised as the rest of us when the abort occurs.
The launch team has no influence once T-0 is past. It also has no influence on the flight trajectory pre launch, they just loadvthe software
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#149
by
Steve D
on 05 Aug, 2011 01:07
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#150
by
Ronsmytheiii
on 05 Aug, 2011 01:11
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Nice pics... 
That is Atlas III, not Atlas V. Also, notice how Atlas V has not used the DEC before even though it was used for Atlas III.
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#151
by
Rocket Science
on 05 Aug, 2011 01:15
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Nice pics...
That is Atlas III, not Atlas V. Also, notice how Atlas V has not used the DEC before even though it was used for Atlas III.
Yup, 100% correct
I tagged the photos with that for clarity sake.
Regards
Robert
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#152
by
Rocket Science
on 05 Aug, 2011 01:17
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Some history...
http://history.nasa.gov/SP-4209/appb.htm
Just took a quick look at this. Seems like there was a high percentage of failures with the Little John tests.
That was pretty early in spaceflight history. If you look at the Apollo tests later on, they were very sucessful abort tests.
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#153
by
kch
on 05 Aug, 2011 02:23
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3 test launches in one year is going to be expensive, but the abort test doesn't really add to the cost at all, since the launcher isn't reusable. I don't believe the CST-100 will be reusable at first either, so they are investing in 3 fully instrumented Atlas V 421 launchers and CST-100 capsules.
How does the 421 configuration (2 engine Centaur and 1 solid) help you? Is it more payload to orbit?
It's 412 - PLF size, number of solids, number of engines on Centaur
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#154
by
clongton
on 05 Aug, 2011 02:34
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I am liking this very, very much
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#155
by
robertross
on 05 Aug, 2011 02:40
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I am liking this very, very much
Certainly some promising news of late, at least from the commercial side.
I really do wonder when they will step in and go with domestic RD-180 production. You would have to think in the next 2-3 years to get a head start.
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#156
by
PeterAlt
on 05 Aug, 2011 02:47
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It's becoming clear to me now that Boeing envisions ULA to be for crewed commercial - at least in regard to their own capsule - what USA was to shuttle - complete launch services, including payload processing, recovery, turnaround, and maintenance. I wonder if ULA would do the same for Orion/SLS, or if it's pretty much a given that USA would inherent this contract from the shuttle program?
On a side note for Chris Bergen, it would be a convenient idea if this site could place links at the button of the page at the end of articles saying something to the effect "Discuss this article", which would take visitors to the forum thread discussing the article (instead of forcing visitors to guess where the thread may be only to find a thread that forwards to another thread somewhere else).
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#157
by
Ronsmytheiii
on 05 Aug, 2011 02:58
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It's becoming clear to me now that Boeing envisions ULA to be for crewed commercial - at least in regard to their own capsule - what USA was to shuttle - complete launch services, including payload processing, recovery, turnaround, and maintenance. I wonder if ULA would do the same for Orion/SLS, or if it's pretty much a given that USA would inherent this contract from the shuttle program?
ULA is not permitted to do work on spacecraft. Either Boeing, USA, or even Atrotech would do CST-100 processing.
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#158
by
Proponent
on 05 Aug, 2011 02:59
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Raised eyebrow... I suspect if an RL-10 fails for any reason, the other will be shut down and an abort will occur. It is better to cut ones losses and safely recover the crew than push a bad situation and risk a LOM.
I think that's right. In the past, if only one RL 10 lit the Centaur became uncontrollable. See http://www.thespacereview.com/article/1321/1
I'm assuming that would be the same for a dual engined Centaur with Atlas V. In which case definite loss of mission.
If the engines could be vectored enough so that each acted through the vehicle's center of mass at ignition, then loss of control should be avoidable at the cost of a very small performance penalty (cosine losses for a short period after ignition). That would probably be over 10 degrees' worth of vectoring, though. Off hand, I seem to recall seeing 8 degrees of vectoring as a spec.
If one failed to ignite but loss of control was prevented by vectoring of the good engine, a horizontal translation would occur. I wonder whether that would create any difficulties in regard to separation from the first stage.
FWIW, the attached ULA study shows Atlas V 401 having slightly better LoM and LoC probabilities than the 402 (p. 7). For both configurations it is assumed that the probability of a failed abort (i.e., of LoM becoming LoC) is 0.1, suggesting that no single-engine abort mode is considered viable.
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#159
by
Proponent
on 05 Aug, 2011 03:04
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On a side note for Chris Bergen....
Berg
in, please.
