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#980
by
psloss
on 14 May, 2008 15:59
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Has the BFS ever been engaged during a shuttle mission?
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#981
by
DaveS
on 14 May, 2008 16:07
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psloss - 14/5/2008 5:59 PM
Has the BFS ever been engaged during a shuttle mission?
AFAIK, no. There was some talk prior to STS-1 to try out the BFS on one of the OFTs, but ultimately this did not happen.
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#982
by
pr1268
on 15 May, 2008 01:08
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Did OV-101 (Enterprise) have a fully-functional TPS? I'm curious after seeing the patchwork tiles on Enterprise in the famous Star Trek cast photo at Enterprise's roll-out (As seen on
Wikipedia's Enterprise Page). Thanks!
Edit: Corrected misspelled "functional".
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#983
by
pr1268
on 15 May, 2008 01:38
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If Vandenberg shuttle launches would have occurred, then would a polar orbit be the only possible launch orbit for the shuttle? I'm looking at the area in Google Earth and hypothesizing a launch from VBG whose orbit is inclined 75- or 80-degrees, and considering the orbiter's flight path in such a scenario: It seems that other than flying over some of the Channel Islands, such a launch would be over open water most the way. I even considered a launch more westward, but then I realized such an orbit would be retrograde. Any others' comments/thoughts?
Also, is there some literature (L2, NASA online, etc.) about the extraordinary requirements a polar orbit shuttle launch would incur? I've read about 109% on SSMEs, restricted payloads, etc., but I'm wanting more. Thanks!
P.S. I never realized how far away LC6 was from the VBG runway... Wow!
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#984
by
helentgl
on 15 May, 2008 01:56
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OV-101 did not have a thermal protetion system. It was not needed for the approach and landing test program. The tile pattern was for show.
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#985
by
Danny Dot
on 15 May, 2008 10:54
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mkirk - 14/5/2008 10:12 AM
snip
I don’t know about now, but at the time we immediately began to reassess performance cases and the Flight Rules concerning the ARD limits. MOD and the Training Division began to look at how we could gain more insight into performance hits such as this and naturally such cases were "en vogue" when it came to integrated simulations.
The LH2 leak on 93 was so small that it was below the ARD and Flight Rule limits used at that time.
snip
Mark Kirkman
It is good to know that training and MOD took a look at this issue after the flight. It was known when I was an instructor a "small" nozzle leak could cause hundreds of feet/sec of performance loss, but was too small to model in the ARD. I used to put in a "small" nozzle leak and kill and engine for an ATO. The result was a massive underspeed and typically a high energy TAL. NASA not correcting this problem tells me the culture that gave us Columbia and Challenger is alive and well at NASA.
Does anyone know what the performance margin was on STS-93? I understand it was very high.
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#986
by
Jim
on 15 May, 2008 13:55
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pr1268 - 14/5/2008 9:38 PM
If Vandenberg shuttle launches would have occurred, then would a polar orbit be the only possible launch orbit for the shuttle? I'm looking at the area in Google Earth and hypothesizing a launch from VBG whose orbit is inclined 75- or 80-degrees, and considering the orbiter's flight path in such a scenario: It seems that other than flying over some of the Channel Islands, such a launch would be over open water most the way. I even considered a launch more westward, but then I realized such an orbit would be retrograde. Any others' comments/thoughts?
Also, is there some literature (L2, NASA online, etc.) about the extraordinary requirements a polar orbit shuttle launch would incur? I've read about 109% on SSMEs, restricted payloads, etc., but I'm wanting more. Thanks!
P.S. I never realized how far away LC6 was from the VBG runway... Wow!
Polar is a generic term for high inclination orbits and there are not any exact ranges but 80-100 is good one. Most used sun synchronous orbits have inclination in the 98 degree range
The Shuttle could have flown 140 to 201 degrees azimuth from which corresponds to 56 to 104 degrees inclination. There were some range safety issues for 140 to 158 azimuths that would have to have been worked out
The 109% SSMEs and FWC SRB's were to prevent from restricting payloads.
\VAFB launches were the main design drivers for the shuttle 1000 nmi crossrange was from a VAFB abort once around. 32k lbs to 150 nmi at 98 degrees was the performance reference for the shuttle and not the 65k lbs due east payload . 65k lbs was for structure loading but the performance requirements of the VAFB mission would have equated to a 78k lb or so payload launched due east
The runway distance didn't matter since RTLS wouldn't start until after SRB sep
Just a note: It is VAFB and SLC-6
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#987
by
pr1268
on 15 May, 2008 14:30
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Jim - 15/5/2008 8:55 AM
Polar is a generic term for high inclination orbits and there are not any exact ranges but 80-100 is good one. Most used sun synchronous orbits have inclination in the 98 degree range
The Shuttle could have flown 140 to 201 degrees azimuth from which corresponds to 56 to 104 degrees inclination. There were some range safety issues for 140 to 158 azimuths that would have to have been worked out
Is the 98 degree inclination needed to accommodate the Earth's rotation and/or its orbit around the Sun? Please understand that I'm a total amateur at orbital mechanics!
The 109% SSMEs and FWC SRB's were to prevent from restricting payloads.
\VAFB launches were the main design drivers for the shuttle 1000 nmi crossrange was from a VAFB abort once around. 32k lbs to 150 nmi at 98 degrees was the performance reference for the shuttle and not the 65k lbs due east payload . 65k lbs was for structure loading but the performance requirements of the VAFB mission would have equated to a 78k lb or so payload launched due east
The runway distance didn't matter since RTLS wouldn't start until after SRB sep
Thank you for the interesting info. I gathered that polar orbits would have extra engineering requirements since the launch doesn't take advantage of the Earth's rotation velocity. I didn't even initially consider the AOA crossrange requirement.
Just a note: It is VAFB and SLC-6
Okay, I stand corrected. But, for the record, I was using the
FAA identifier for Vandenberg since I didn't know what acronym NASA uses, and I saw "LC6" identified on Google Earth. Thanks again for your reply.
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#988
by
Lawntonlookirs
on 15 May, 2008 14:53
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Speking about VAFB. If they did use VAFB for Shuttle flights, how were they going to recover the SRB if the launch took them over land instead of water. I admit I haven't read much about VAFB and the shuttle.
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#989
by
psloss
on 15 May, 2008 15:02
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Lawntonlookirs - 15/5/2008 10:53 AM
Speking about VAFB. If they did use VAFB for Shuttle flights, how were they going to recover the SRB if the launch took them over land instead of water. I admit I haven't read much about VAFB and the shuttle.
The launches wouldn't take the boosters over land.
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#990
by
Jim
on 15 May, 2008 16:11
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pr1268 - 15/5/2008 10:30 AM
1. Is the 98 degree inclination needed to accommodate the Earth's rotation and/or its orbit around the Sun? Please understand that I'm a total amateur at orbital mechanics!
2. Thank you for the interesting info. I gathered that polar orbits would have extra engineering requirements since the launch doesn't take advantage of the Earth's rotation velocity. See (gasp) wikipedia
1 Sun Synchronous orbits are certain combinations of altitude and inclination where that an object on that orbit passes over any given point of the Earth's surface at the same local solar time.
2. They need extra performance b
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#991
by
tnphysics
on 18 May, 2008 04:51
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It appears that certain abort trajectories violate range safety constraints. These trajectories involve RTLS aborts were the about-face is made using the SRBs, such as a triple-out SSME at T+0.01 sec.
How is this resolved? This would appear to be solvable, as the Orbiter glides, but the SRBs do not.
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#992
by
Jorge
on 18 May, 2008 05:32
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tnphysics - 17/5/2008 11:51 PM
It appears that certain abort trajectories violate range safety constraints. These trajectories involve RTLS aborts were the about-face is made using the SRBs, such as a triple-out SSME at T+0.01 sec.
How is this resolved? This would appear to be solvable, as the Orbiter glides, but the SRBs do not.
The "about-face" (Powered Pitch Around, or PPA) is never made using the SRBs. Three-out during first stage is a contingency abort, not an RTLS. It is also a black zone (orbiter survival not expected). If the orbiter does make it, the crew will bail out.
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#993
by
joema
on 20 May, 2008 00:05
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Jorge - 18/5/2008 12:32 AM
...Three-out during first stage is a contingency abort, not an RTLS. It is also a black zone (orbiter survival not expected)...
I was under the impression that "three out blue" is now considered a survivable contingency abort, with a documented procedure.
It was not survivable before the ET attach struts were beefed up a few years ago. I thought these struts were reinforced to eliminate this as a black zone.
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#994
by
mkirk
on 20 May, 2008 00:30
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joema - 19/5/2008 7:05 PM
Jorge - 18/5/2008 12:32 AM
...Three-out during first stage is a contingency abort, not an RTLS. It is also a black zone (orbiter survival not expected)...
I was under the impression that "three out blue" is now considered a survivable contingency abort, with a documented procedure.
It was not survivable before the ET attach struts were beefed up a few years ago. I thought these struts were reinforced to eliminate this as a black zone.
I don’t know anyone who would go on record and officially call any of the black zones survivable – hence the name black zone – as the testing/analysis rigor for contingency aborts are not the same as for the intact aborts.
I believe 3 out in first stage still has black zones - some of which are mission specific and would be a function of things such as cg location, OMS load etc...
As for beefing up the aft struts, I was not aware that work had been done. I think you are implying that if that work was done then the threat of the stack coming apart is minimized. That is only one of the issues with 3 out early in first stage. Another would be the threat of hang-up or re-contact with the ET during Separation. Separation in this case is a single separation from the entire stack (ET and SRBs) as a whole.
Mark Kirkman
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#995
by
Danny Dot
on 20 May, 2008 01:19
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mkirk - 19/5/2008 7:30 PM
joema - 19/5/2008 7:05 PM
Jorge - 18/5/2008 12:32 AM
...Three-out during first stage is a contingency abort, not an RTLS. It is also a black zone (orbiter survival not expected)...
I was under the impression that "three out blue" is now considered a survivable contingency abort, with a documented procedure.
It was not survivable before the ET attach struts were beefed up a few years ago. I thought these struts were reinforced to eliminate this as a black zone.
I don’t know anyone who would go on record and officially call any of the black zones survivable – hence the name black zone – as the testing/analysis rigor for contingency aborts are not the same as for the intact aborts.
I believe 3 out in first stage still has black zones - some of which are mission specific and would be a function of things such as cg location, OMS load etc...
As for beefing up the aft struts, I was not aware that work had been done. I think you are implying that if that work was done then the threat of the stack coming apart is minimized. That is only one of the issues with 3 out early in first stage. Another would be the threat of hang-up or re-contact with the ET during Separation. Separation in this case is a single separation from the entire stack (ET and SRBs) as a whole.
Mark Kirkman
I agree with Mark. 3 engines out early would result in the orbiter not having enough airspeed/altitude to get to a bail out. Contact with the SRBs would be another big problem.
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#996
by
joema
on 20 May, 2008 01:31
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mkirk - 19/5/2008 7:30 PM
...As for beefing up the aft struts, I was not aware that work had been done. I think you are implying that if that work was done then the threat of the stack coming apart is minimized. That is only one of the issues with 3 out early in first stage. Another would be the threat of hang-up or re-contact with the ET during Separation. Separation in this case is a single separation from the entire stack (ET and SRBs) as a whole...
I don't have definitive info on that, but I thought I read the struts were beefed up around 1999/2000 to handle the structural aspect of the "three out blue" case before max q.
Re orbiter sep from the entire stack, I didn't think that's planned for "three out blue". Rather the procedure is ride the SRBs to SRB sep, immediately afterwards do a fast sep from the ET, stabilize, reenter and bail out.
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#997
by
mkirk
on 20 May, 2008 02:12
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joema - 19/5/2008 8:31 PM
Re orbiter sep from the entire stack, I didn't think that's planned for "three out blue". Rather the procedure is ride the SRBs to SRB sep, immediately afterwards do a fast sep from the ET, stabilize, reenter and bail out.
Well you are making me doubt myself a little bit since I haven’t flown the SMS in 3 or 4 years and I haven’t flown Contingency Aborts in over 7 seven years. I really am starting to forget a lot of the details - of course it doesn't help that I have been learning and flying different aircraft over the last few years.
I will have to double check but I am pretty sure FAST SEP (form the entire stack) is commanded just prior to the time that SRB SEP would occur PC<50 + 2 seconds (nominally SRB SEP is PC<50 + 5 seconds). This is done owith the BFS because the setting of MECO Confirmed negates the PASS SRB SEP Sequence.
If you have access to a copy of the Ascent/Aborts Flight Procedures Handbook – Chris has a copy in L2 – then you can look in sections 2 and 4 for detailed information on the 3 Out bBue procedures. Also the Ascent Checklist – which is also in L2 and on the NASA public web – has the contingency abort Cue Card in section 10.
I will look at my notes and the above mentioned documents myself when I have more time and if I am wrong about what I said I will post a correction.
Mark Kirkman
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#998
by
pr1268
on 20 May, 2008 05:16
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I need help settling a debate with a friend. He says that the Shuttle's wings can stall in atmospheric flight. I say they can't, because of their delta wing design†. Who's right? Thanks!
†I gave the Aerospatiale/British Aerospace Concorde (which has a delta wing) as an example of a stall-proof wing. The instruction manual to Microsoft's Flight Simulator 2000 (which included the Concorde) mentions that the Concorde's wings cannot stall.
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#999
by
Lee Jay
on 20 May, 2008 05:38
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All wings can stall. Delta's just stall at a very high angle.
