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#860 by Lee Jay on 02 Apr, 2008 00:24
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rocketguy101 - 1/4/2008 6:21 PM
Looking at the pics you posted, I am amazed at the SRB attachment points. How large are the struts, 9-10 inches in diameter?
I really don't know, but from the images I'd somewhere closer to 20 inches. -
#861 by rocketguy101 on 02 Apr, 2008 00:37
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Lee Jay - 1/4/2008 7:24 PM
Quoterocketguy101 - 1/4/2008 6:21 PM Looking at the pics you posted, I am amazed at the SRB attachment points. How large are the struts, 9-10 inches in diameter?
I really don't know, but from the images I'd somewhere closer to 20 inches.I meant the SRB struts--sorry should have been clearer. Yeah, the OV struts appear to be about the same diameter as the LOX line, which is 17 inches dia (I read that somewhere).
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#862 by Lee Jay on 02 Apr, 2008 02:43
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rocketguy101 - 1/4/2008 6:37 PM
QuoteLee Jay - 1/4/2008 7:24 PM
Quoterocketguy101 - 1/4/2008 6:21 PM Looking at the pics you posted, I am amazed at the SRB attachment points. How large are the struts, 9-10 inches in diameter?
I really don't know, but from the images I'd somewhere closer to 20 inches.I meant the SRB struts--sorry should have been clearer. Yeah, the OV struts appear to be about the same diameter as the LOX line, which is 17 inches dia (I read that somewhere).
Not sure what you mean. Do you mean the attachment to the beam at the top? -
#863 by MKremer on 02 Apr, 2008 03:15
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rocketguy101 - 1/4/2008 7:37 PM
SRB thrust (and ET/orbiter weight) is thru the top SRB attachment, at the ET intertank crossmember structure. It's the opposite of the Shuttle/ET attachment - the SRB thrust forces are thru the upper attachment, with the bottom attachments handling side-load alignments.QuoteLee Jay - 1/4/2008 7:24 PM
Quoterocketguy101 - 1/4/2008 6:21 PM Looking at the pics you posted, I am amazed at the SRB attachment points. How large are the struts, 9-10 inches in diameter?
I really don't know, but from the images I'd somewhere closer to 20 inches.I meant the SRB struts--sorry should have been clearer. Yeah, the OV struts appear to be about the same diameter as the LOX line, which is 17 inches dia (I read that somewhere).
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#864 by rocketguy101 on 02 Apr, 2008 03:16
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They are shown in this picture http://mediaarchive.ksc.nasa.gov/detail.cfm?mediaid=25263 connecting the SRBs to the ET
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#865 by shuttlefan on 02 Apr, 2008 16:12
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Will the KIBO lab be the largest and heaviest payload the shuttle has ever carried? I imagine it's quite a tossup between KIBO and Chandra...
Also will there be any increased danger with such a huge payload in the unlikely event of an RTLS or TAL abort landing? -
#866 by Jorge on 02 Apr, 2008 17:14
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shuttlefan - 2/4/2008 11:12 AM
Will the KIBO lab be the largest and heaviest payload the shuttle has ever carried? I imagine it's quite a tossup between KIBO and Chandra...
Not even close. Chandra/IUS is the winner. Kibo isn't even the runner-up; several IUS payloads were heavier.
Kibo is possibly the heaviest carried to 51.6 degree inclination, but that is well short of what the shuttle can carry (and has carried) to 28.5.QuoteAlso will there be any increased danger with such a huge payload in the unlikely event of an RTLS or TAL abort landing?
No, the risk is considerably less than with heavier payloads like Chandra. Even STS-107 with the Spacehab Research Double Module had a higher projected RTLS landing weight than STS-124. -
#867 by Lee Jay on 03 Apr, 2008 01:37
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On that same note, which Shuttle flight has carried the most lead in the tail? I was a bit shocked by the amount on the last flight (stated on L2) but I have no idea if that was normal or abnormal.
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#868 by briguy700 on 03 Apr, 2008 01:53
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Thanks for the info on the attachment points guys !! Great photos and info. I guess I did underestimate their size !! :laugh:
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#869 by joema on 03 Apr, 2008 19:01
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cabbage - 27/3/2008 7:58 PM...assuming that they have largely cleared the atmosphere and there would be little drag from the SRBs could they not continue in powered flight for TAL (assuming they could successfully command ET SEP)? Is the deadweight of the SRBs a structural concern or a control issue?
The SRB casings are very heavy -- about 200,000 lb (91,000 kg) each. Separation is at roughly 150,000 ft (45.7 km) altitude.
Dynamic pressure (Q bar) is very low at SRB sep, about 0.25 psf. I don't know the drag coefficient of the SRB, but I doubt the total drag on each SRB is over a few dozen pounds force at that altitude/speed.
However the vehicle is still accelerating on SSMEs, so non-detached SRBs would suddenly impose reverse loads on the attach struts. Immediately after SRB sep, vehicle thrust/weight ratio is slightly less than 1:1. If the SRBs didn't detach, it would drop to about 0.77 to 1.
This implies at least four problems:
(1) The SRB attach struts which are mainly designed to support upward loads would suddenly be subjected to downward loads of nearly 2x the SRB casing weight
(2) The 400,000 of dead weight would alter the relationship of SSME thrust vector to vehicle center of mass. I don't know if the SSMEs have sufficient steering authority to compensate for that. The entire stack might pitch uncontrollably.
(3) The lower thrust:weight ratio would cause the vehicle to begin descending into the atmosphere
(4) The lower thrust:weight ratio would limit delta V and achievable range for aborts
I seriously doubt it's a survivable situation. If the structure didn't fail, they'd soon have aerodynamic/heat issues as they descended into the atmosphere with the ET and SRBs still attached.
Aside from all that, they wouldn't have the energy performance for a TAL abort.
If they commanded MECO immediately upon SRB sep failure, maybe in theory they could do an emergency quick ET sep, then glide down and ditch. I don't know if that's been studied or if the vehicle and separation dynamics would allow it. -
#870 by jeff122670 on 03 Apr, 2008 21:47
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i read a thread once on the launch processing system and the GLS (with respect to what G9, etc means)...
is there a manual on L2 or a thread somewhere about this stuff?
thanks
Jeff -
#871 by mkirk on 04 Apr, 2008 00:36
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joema - 3/4/2008 2:01 PM
Quotecabbage - 27/3/2008 7:58 PM...assuming that they have largely cleared the atmosphere and there would be little drag from the SRBs could they not continue in powered flight for TAL (assuming they could successfully command ET SEP)? Is the deadweight of the SRBs a structural concern or a control issue?
The SRB casings are very heavy -- about 200,000 lb (91,000 kg) each. Separation is at roughly 150,000 ft (45.7 km) altitude.
Dynamic pressure (Q bar) is very low at SRB sep, about 0.25 psf. I don't know the drag coefficient of the SRB, but I doubt the total drag on each SRB is over a few dozen pounds force at that altitude/speed.
However the vehicle is still accelerating on SSMEs, so non-detached SRBs would suddenly impose reverse loads on the attach struts. Immediately after SRB sep, vehicle thrust/weight ratio is slightly less than 1:1. If the SRBs didn't detach, it would drop to about 0.77 to 1.
This implies at least four problems:
(1) The SRB attach struts which are mainly designed to support upward loads would suddenly be subjected to downward loads of nearly 2x the SRB casing weight
(2) The 400,000 of dead weight would alter the relationship of SSME thrust vector to vehicle center of mass. I don't know if the SSMEs have sufficient steering authority to compensate for that. The entire stack might pitch uncontrollably.
(3) The lower thrust:weight ratio would cause the vehicle to begin descending into the atmosphere
(4) The lower thrust:weight ratio would limit delta V and achievable range for aborts
I seriously doubt it's a survivable situation. If the structure didn't fail, they'd soon have aerodynamic/heat issues as they descended into the atmosphere with the ET and SRBs still attached.
Aside from all that, they wouldn't have the energy performance for a TAL abort.
If they commanded MECO immediately upon SRB sep failure, maybe in theory they could do an emergency quick ET sep, then glide down and ditch. I don't know if that's been studied or if the vehicle and separation dynamics would allow it.
MY THOUGHTS ABOUT THE FAILURE OF THE SPACE SHUTTLE SOLID ROCKET BOOSTERS TO SEPARATE AS EXPECTED:
Okay I guess I should chime in here. I deliberately avoided this topic in hopes that it would die out, or someone who is far more knowledgeable would enter the discussion.
First off in my short time at JSC I never looked at this scenario, asked about it, or ever heard anyone else discuss it. Mainly that is because SRB SEP is a CRIT1 system that simply HAS TO WORK EVERY TIME.
Now a good Pilot or Engineer should always be skeptical if someone tells them that something can’t happen – in this case “one or both SRBs Failing to separate can’t happen” – however, my recollection is that our faith in this very robust system is high and there is little hope of salvaging the situation if the system doesn’t work as advertised. Maybe if I had been around long enough I would have had the time to get into some of the more ugly what ifs like this one.
Having said all of that, here is how I view the subject. Please keep in mind I don’t have the book answer for this so I am purely speculating based on what I know of shuttle systems. In the near future, if I come across some of the people who would actually have analyzed such a scenario, I will post what I learn from them in an update.
First off some of the variables that would affect the outcome include: Did one or both SRBs fail to separate? If only one separated, did it do so cleanly (no piece parts remaining or vehicle re-contact)? Did onboard Guidance mode from 102 to 103 (this would have an effect on how the vehicle steers itself, however, you are still screwed)?
No matter the answer to any of those questions the likely result is still a bad day. At SRB SEP the boosters are still producing some thrust (although it is tailing off quickly after PC<50) so if only one SRB separates you would have an asymmetric thrust condition and an LOC (loss of control).
Another problem is the flight control gains for the SSMEs are not designed for the extra mass, change in cg location, and resultant affect on the thrust vector that would occur if one or both boosters stayed with the stack.
My best guess is that you are most certainly on the LOC/BREAKUP CUE CARD in the back of the Ascent Checklist.
Best case would probably be that both SRBs stayed so as to prevent the asymmetry of thrust and mass. If by some miracle there is enough time to assess the situation, and the magnitude of the LOC (loss of control) isn’t too severe and rapid, then you would likely command MECO manually and execute a FAST SEP. There are several FAST SEP modes but the appropriate one here is to separated from the ET (and thus the entire shuttle stack) quickly and get the orbiter into a crew bail out condition – this is a 3 engine out contingency abort.
That’s about all I can add at this point, I hope it answers your questions. If anyone has more accurate info please feel free to correct me.
Mark Kirkman
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#872 by jcopella on 04 Apr, 2008 03:38
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jeff122670 - 3/4/2008 5:47 PM
i read a thread once on the launch processing system and the GLS (with respect to what G9, etc means)...
is there a manual on L2 or a thread somewhere about this stuff?
thanks
Jeff
There's nothing on L2 that's LPS- or GLS-related that I'm aware of. -
#873 by SiameseCat on 06 Apr, 2008 22:24
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Are the RCS thrusters throttleable, or can they only fire at full thrust?
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#874 by Jim on 06 Apr, 2008 22:58
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SiameseCat - 6/4/2008 6:24 PM
Are the RCS thrusters throttleable, or can they only fire at full thrust?
only full thrust. The duration is variable -
#875 by Lawntonlookirs on 10 Apr, 2008 14:00
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I was satching the NASA KSC TV feeds and saw this picture. I am assuming that it is the delevery of the SRB, or the preperation of sending them back to Utah. I am not sure.
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#876 by NavySpaceFan on 11 Apr, 2008 21:29
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Question about shuttle payload cannisters: Do the cannisters stay in the orbiter payload bay, or does the payload come out the bottom into the orbiter?
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#877 by DaveS on 11 Apr, 2008 22:05
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NavySpaceFan - 11/4/2008 11:29 PM
Question about shuttle payload cannisters: Do the cannisters stay in the orbiter payload bay, or does the payload come out the bottom into the orbiter?
None. The payload is removed from the canister in the PCR at the pad. Then untol the orbiter arrives at the pad, it is kept in the PCR by the so called Payload Ground Handling Mechanism or PGHM which is pronounced as "pigem".
Once the orbiter is safely harddown at the pad, the RSS swings around it and dock seals are inflated around the forward and aft bulkheads of the payload bay to maintain a clean room environment of the PCR after which the PCR doors are opened and then the orbiter payload doors are also opened.
Then the PGHM with the payload is moved into the payload bay of the orbiter after which the payload is attached to the orbiter payload bay instead of the PGHM.
Then the PGHM is backed away, orbiter payload bay doors and PCR doors are closed. Then in the launch countdown a few hours before RSS retract, the dock seals are deflated and a tile inspection is conducted to make no tiles or blankets was damaged during the inflation/deflation period.
The Paylad Transportation Canisters are Ground Support Equipment, just like the PGHM.
Edit: Attached a photo of the STS-95 payloads being loaded int othe payload bay of Discovery at pad 39B. PGHM with the payloads are to the left, the PLB is to the right.
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#878 by NavySpaceFan on 11 Apr, 2008 22:38
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Thanks Dave!!! I always wondered how that worked!
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#879 by C5C6 on 14 Apr, 2008 13:55
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hi, while watching STS-118 launch for the 118th time.....I can hear the PAO saying at 145 secs into the flight that both OMS are being burned for 90 secs to provide extra thrust in Endeavour's climb to orbit........is this accurate?? I didn't know the OMS where ignited during powered flight.......