STS Shuttle discussion thread

[sevenperforce]

5 minutes ago, PB666 said:

Err the inertial forces initiated when the booster hit the wing and a bunch of liberated RCS blew de f up.

We may have to agree to disagree on this. Booster impact with the wing would be described as a structural impact force or a debris impact force. "Inertial forces" do not refer to impact. 

"Liberated RCS" did not blow anything up. The OMS/RCS propellant would not have been "liberated" until after the structural failures.

[PB666]

1 minute ago, sevenperforce said:

We may have to agree to disagree on this. Booster impact with the wing would be described as a structural impact force or a debris impact force. "Inertial forces" do not refer to impact. 

"Liberated RCS" did not blow anything up. The OMS/RCS propellant would not have been "liberated" until after the structural failures.

It was described, go back and read.

[magnemoe]

4 hours ago, PB666 said:

Thanks but no thanks, it does not meet any useful requirments.

Abort system was oversize and you want an cargo bay below the crew compartment. 
You would also not need an heat shield on the escape module, abort is for launch or landing. Upper stage operations you have to get down below mach 3 before separate escape module 

[sevenperforce]

46 minutes ago, magnemoe said:

Abort system was oversize and you want an cargo bay below the crew compartment. 
You would also not need an heat shield on the escape module, abort is for launch or landing. Upper stage operations you have to get down below mach 3 before separate escape module 

Well, I was making it a LF abort system in stock. Making it smaller would not be a challenge.

Cargo bay would typically be right under the crew compartment, for obvious reasons, but stock parts don't have a structural adapter for that.

You do want a heat shield on the escape module, because Challenger. If the overall vehicle takes damage during ascent (or on orbit, due to meteoroid impact or whatever) that would render low-gee gliding re-entry risky, you ditch the orbiter and come in ballistic.

Capsule heat shield is single-use. You can have a door through it to get to the airlock and cargo bay, if you like.

Edited January 16, 2018 by sevenperforce

[tater]

What's the max crew any crew vehicle would really need for the foreseeable future?

[sevenperforce]

8 minutes ago, tater said:

What's the max crew any crew vehicle would really need for the foreseeable future?

7 has been standard, it seems. You could get away with 4 or 5. Below that, and the per-seat launch cost goes through the roof.

Edited January 16, 2018 by sevenperforce

[GoSlash27]

4 hours ago, mikegarrison said:

The real problem with shuttle safety was not that the orbiter was on the side of the stack. It was not the SRBs. It was not the foam. It was not the lack of a way to repair the orbiter in orbit.

The real problem was NASA had a terrible safety mentality.

mikegarrison,
 I agree with the safety mentality angle, but only in as far as they actually man-rated a launch vehicle that had the crewed reentry vehicle on the side instead of on top. All the other safety hazards stem from that fact. They could've mitigated the risks somewhat, but there's nothing you can do with that layout that's ever going to make it as safe as a more conventional layout.

Best,
-Slashy

[PB666]

https://spaceflight.nasa.gov/outreach/SignificantIncidents/assets/rogers_commission_report.pdf

"Just after liftoff at .678 seconds into the flight,  photographic  data  show  a  strong  puff  of  gray smoke was spurting from the vicinity of the aft field joint on the right Solid Rocket Booster"

" Solid   Rocket Boosters  were  increasing  their  thrust  when  the first flickering flame appeared on the right Solid Rocket Booster in the area of the aft field joint. This  first  very  small  flame  was  detected  on image enhanced film at 58.788 seconds into the flight.  It  appeared  to  originate  at  about  305  degrees  around  the  booster  circumference  at  or  near the aft field joint."

"One   film   frame   later   from   the   same camera,  the  flame  was  visible  without  image enhancement.  It  grew  into  a  continuous,  well - defined  plume  at  59.262  seconds.  At  about  the  same  time  (60  seconds),  telemetry  showed  a pressure    differential    between    the    chamber pressures in the right and left boosters. The right booster chamber pressure was lower, confirming the growing leak in the area of the field joint."

"As the flame plume increased in size, it was   deflected   rearward   by   the   aerodynamic slipstream     and     circum ferentially     by     the  protruding  structure  of  the  upper  ring  attaching  the    booster    to    the    External    Tank.    These deflections  directed  the  flame  plume  onto  the surface  of  the  External  Tank.  This  sequence  of  flame  spreading  is  confirmed  by  analysis  of  the  recovered  wreckage.  The  growing  flame  also  impinged on the strut attaching the Solid Rocket Booster to the External Tank"
"

Noting that the lower attachment point was being damaged.

"The  first  visual  indication  that  swirling  flame   from   the   right   Solid   Rocket   Booster breached   the   External   Tank   was   at   64.660 seconds when there was an abrupt change in the shape and color of the plume. This indicated that it  was  mixing  with  leaking  hydrogen  from  the External   Tank.   Telemetered   changes   in   the hydrogen tank pressurization confirmed the leak. Within  45  milliseconds  of  the  breach  of  the External    Tank,    a    bright    sustained    glow developed  on  the  black - tiled  underside  of  the Challenger between it and the External Tank."

"At  about  72.20  seconds  the  lower  strut  linking   the   Solid   Rocket   Booster   and   the External Tank was severed or pulled away from the weakened hydrogen tank permitting the right Solid  Rocket  Booster  to  rotate around the upper attachment  strut.
"

Page 68

"The  intertank  region  of  the  wreckage contained  buckling  in  the  fore  and  aft  direction  consistent  with  this  impulsive  thrust.  Similarly,  the  right  side  of  the  intertank  showed  signs  of crushing.  This  crushing  is  consistent  with  the rotational impact of the frustum of the right Solid Rocket Booster with the External Tank following complete  loss  of  restraint  at  the  aft  lower  strut attachment area.
"

The booster is now rotating around the forward support in the direction of the tank.

" At about the same   time,   the   rotating   right   Solid   Rocket Booster impacted the intertank structure and the lower  part  of  the  liquid  oxygen  tank.  These structures failed at 73.137 seconds as evidenced by  the  white  vapors  appearing  in  the  intertank  region.
"
Swithing to the material analysis

"There  was  evidence  that  during  the  breakup  sequence,  the   right   Solid   Rocket   Booster   struck   the outboard end of the Orbiter's right wing and right outboard elevon. Additionally, chemical analysis indicated  that  the  right  side  of  the  Orbiter  was sprayed by hot propellant gases exhausting from the hole in the inboard circumference of the right Solid  Rocket  Booster.
"
Page 67. ". The bottom side of the right wing showed  some  indentation  on  the  tiles  that  make  up    the    Thermal    Protection    System.    This indentation was consistent with impact with the right booster as it rotated following loss of restraint of one or more of its lower struts. The  frustum  of  the  nose  cone  of  the right Solid Rocket Booster was damaged (photo E) as if it had struck the External Tank, but there were no signs of thermal distress."

And back to the photo analysis
"
he upper photos show, from left to right, the left side of the orbiter (unburned), the right lower and upper rudder speed brake (both burned damaged) and left upper seed brake (unburned), confirmation that the fire was on the right side [the SRB defective side] of the stack" The outgas detected was that of the SRB.

IOW before the SRB detached it had already stricken the ET and the orbiter and had partially exploded down direction  upon impact.

"The right frustrum shows impact damage at top and burns along the base of the cone;  evidence indicates it was damaged when it impacted with the External Tank. "

"
Within milliseconds there was massive, almost   explosive,   burning   of   the   hydrogen streaming  from  the  failed  tank  bottom  and  the  liquid oxygen breach in the area of the intertank. At this point in its trajectory, while traveling at a Mach  number  of  1.92  at  an  altitude  of  46,O00  feet, the Challenger was totally enveloped in the explosive burn. The Challenger's reaction control system  ruptured  and  a  hypergolic  burn  of  its  propellant s  occurred  as  it  exited  the  oxygen -hydrogen  flames.  The  reddish  brown  colors  of  the  hypergolic  fuel  burn  are  visible  on  the  edge  of  the  main  fireball.
"
"The  Orbiter,  under  severe  aerodynamic   loads,   broke   into   several   large sections   which   emerged   from   the   fireball. Separate  sections  that  can  be  identified  on  film  include  the  main  engine/tail  section  with  the engines  still  burning,  one  wing  of  the  Orbiter,  and  the  forward  fuselage  trailing  a  mass  of umbilical  lines  pulled  loose  from  the  payload bay."

IOW, in our theoretical model in which such damage can occur randomly, there is nothing stopping the SFRB from striking the orbiter and exploding, in fact in the cold weather model it exactly struck the orbiter and it appear after it struck the ET that it was burning out something somewhere down the fulstrum. At the point it struck the orbiter approximately there is evidence of an reaction control fuel explosion as noted by the orange glow in the cloud, but it does not seemed to have burned the orbiter.

IN parting this conversation, a decaying SRB can under a variety of circumstances free itself from some core body and begin rotating or translocating in the direction of the PL vehicle. Thats what the report describes. Rocket had hole, hole got bigger, fried its attachment point twisted around the other fulstrom and struck to bodies in rapid succession amidst  large increasingly powerful explosions. Such that if the upper fulstrum, now under much more force breaks it can flying into any part of the orbiter or any other rocket core if that core happens to be along the vector of travel when it breaks.

Again the bad here is the SRB. In an ideal world if you can down throttle and you had adequate sensors you then do down throttle both engines and you separate them prematurely and let the range officer take care of them.

 

 

 

Edited January 16, 2018 by PB666

[PB666]

16 minutes ago, GoSlash27 said:

mikegarrison,
 I agree with the safety mentality angle, but only in as far as they actually man-rated a launch vehicle that had the crewed reentry vehicle on the side instead of on top. All the other safety hazards stem from that fact. They could've mitigated the risks somewhat, but there's nothing you can do with that layout that's ever going to make it as safe as a more conventional layout.

Best,
-Slashy

But with as many ice related incidence the risk created by the ice was obviously the highest, this is about risk, not whether you can make something perfectly safe (per other conversation about sucking it up). But as Tater very aptly points out, the problem begins on flight number 1 and no effective mitigation was employed after 100 flights, that is an administrative problem, not a structural problem. The shuttle was a complex launch system, it may have been too complex for NASA to manage, that in and of itself does not make the general design bad.

[mikegarrison]

17 minutes ago, GoSlash27 said:

mikegarrison,
 I agree with the safety mentality angle, but only in as far as they actually man-rated a launch vehicle that had the crewed reentry vehicle on the side instead of on top. All the other safety hazards stem from that fact. They could've mitigated the risks somewhat, but there's nothing you can do with that layout that's ever going to make it as safe as a more conventional layout.

Best,
-Slashy

Aerospace engineering is ALWAYS about compromises. The key is to work through them, figure out how to deal with the results, and not give up anything you don't have to give up. I'm OK if, after everything is said and done, the safest design is not chosen. If it were, the shuttle would have been made of steel and concrete and stuffed with pillows (non-flammable, of course), etc. etc. This is a space ship, and it's the 1970s. It's not going to be "safe" like sitting on your couch is safe.

But once you make those design compromises, don't compound them by making stupid operational compromises. And if you find out something isn't working, fix it. The whole point of redundant chains of safety is that if one link breaks, it's not supposed to cause the whole thing to fail. But that means that if one link breaks and nothing fails, you don't ignore it and say "Oh, I guess that link wasn't important". You have to keep all the links fixed up and working.

[Bill Phil]

21 minutes ago, GoSlash27 said:

mikegarrison,
 I agree with the safety mentality angle, but only in as far as they actually man-rated a launch vehicle that had the crewed reentry vehicle on the side instead of on top. All the other safety hazards stem from that fact. They could've mitigated the risks somewhat, but there's nothing you can do with that layout that's ever going to make it as safe as a more conventional layout.

Best,
-Slashy

Well, presumably LRBs would've been safer. And in all honesty, 1 launch failure in 135 launches is not a bad record. That's a 99.26% launch success rate, and considering the sheer complexity of the vehicle... that's a big accomplishment. Of course, there was also a reentry failure that was caused during launch, but the launch successfully inserted the payload into orbit. As a launch vehicle, the Shuttle stack was not bad at all. It's a shame that LRBs, 5 segment SRBs, and the cargo only variant were never developed.

In any case, let's all be thankful that the "death star" payloads were never launched...

[PakledHostage]

14 minutes ago, Bill Phil said:

And in all honesty, 1 launch failure in 135 launches is not a bad record. That's a 99.26% launch success rate, and considering the sheer complexity of the vehicle... that's a big accomplishment.

And as has been mentioned upthread, that 1 launch failure was largely attributable to management failures. From Page 83 of the Rogers Commission Report:

Quote

The decision to launch the Challenger was flawed. Those who made that decision were unaware of the recent history of problems concerning the O-rings and the joint and were unaware of the initial written recommendation of the contractor advising against the launch at temperatures below 53 degrees Fahrenheit and the continuing opposition of the engineers at Thiokol after the management reversed its position.

 

[GoSlash27]

38 minutes ago, PB666 said:

But with as many ice related incidence the risk created by the ice was obviously the highest, this is about risk, not whether you can make something perfectly safe (per other conversation about sucking it up). But as Tater very aptly points out, the problem begins on flight number 1 and no effective mitigation was employed after 100 flights, that is an administrative problem, not a structural problem. The shuttle was a complex launch system, it may have been too complex for NASA to manage, that in and of itself does not make the general design bad.

PB666,

 Oh, no. The general design was indeed bad. It was disappointingly bad from a cost- effectiveness perspective and appallingly bad from a safety perspective. All of the safety problems that were unique to the shuttle have been repeated ad nauseum upstream and I won't bother to rehash them here, but they *all* stem from having the (incredibly fragile) crewed reentry vehicle on the side of the stack instead of on top.  A lot of failure modes that could only happen because the crewed reentry vehicle was where it was, and a lack of abort options because the crewed reentry vehicle was where it was. There were many things they could have done to reduce the risks, but nothing could have been done to make it *as* safe as a conventional design.

Best,
-Slashy

[PB666]

Just now, GoSlash27 said:

 Oh, no. The general design was indeed bad. It was disappointingly bad from a cost- effectiveness perspective and appallingly bad from a safety perspective. All of the safety problems that were unique to the shuttle have been repeated ad nauseum upstream and I won't bother to rehash them here, but they *all* stem from having the (incredibly fragile) crewed reentry vehicle on the side of the stack instead of on top.  A lot of failure modes that could only happen because the crewed reentry vehicle was where it was, and a lack of abort options because the crewed reentry vehicle was where it was. There were many things they could have done to reduce the risks, but nothing could have been done to make it *as* safe as a conventional design.

That is an opine, not a fact.

[sevenperforce]

2 hours ago, magnemoe said:

Abort system was oversize and you want an cargo bay below the crew compartment. 
You would also not need an heat shield on the escape module, abort is for launch or landing. Upper stage operations you have to get down below mach 3 before separate escape module 

If you don't want to put a door in your heat shield, then you can do an off-axis crew cabin with dorsal and ventral hatches. Internal hatch opens to internal crew passageway with airlock at cargo bay; external hatch available for docking or post-landing egress. Escape motors on either side of the crew cabin.

[GoSlash27]

1 minute ago, PB666 said:

That is an opine, not a fact.

No, it is objective fact. If the crewed return vehicle is on top of the stack, then chunks disintegrating or falling off of the stack aren't going to destroy it. If it's on top of the stack, then it can be aborted with the crew throughout the launch and can be expected to reenter intact.
 The design *itself* was fraught with peril.

[Jaff]

An engineering marvel however 

 

imo of course

[GoSlash27]

Just now, Jaff said:

An engineering marvel however 

Indeed. Possibly the most amazing feat of engineering in history.

[tater]

40 minutes ago, Bill Phil said:

Well, presumably LRBs would've been safer. And in all honesty, 1 launch failure in 135 launches is not a bad record. That's a 99.26% launch success rate, and considering the sheer complexity of the vehicle... that's a big accomplishment. Of course, there was also a reentry failure that was caused during launch, but the launch successfully inserted the payload into orbit. As a launch vehicle, the Shuttle stack was not bad at all. It's a shame that LRBs, 5 segment SRBs, and the cargo only variant were never developed.

In any case, let's all be thankful that the "death star" payloads were never launched...

Columbia was mortally wounded during launch. She failed on reentry, but the spacecraft was hopeless from seconds after liftoff. I call that a launch failure. Doing a failure rate as a % of trips isn't terribly helpful, either. The difference between 1/135 and 2/135 is small done that way, but it's a substantial difference in risk.

 

20 minutes ago, PakledHostage said:

And as has been mentioned upthread, that 1 launch failure was largely attributable to management failures. From Page 83 of the Rogers Commission Report:

While true, it's also a design failure. Management farther upstream---at the decision point to go with "reusable" segmented, solid rocket motors---was also clearly a problem. We all know why the solids were chosen, too. The ugly way the sausage is made. It was not a choice about what was best, it was about DC.

 

[Jaff]

I think that skews my opinion of the shuttle tbh. It’s a glorious piece of engineering and spectacular in flight.

 

those 2 qualities can lead to me overlooking it’s obvious safety flaws

[tater]

17 minutes ago, PB666 said:

That is an opine, not a fact.

No, it's a fact.

The TPS damage was a problem from the very first flight, and persisted with every single flight until the end of the program, regardless of mitigation attempts. It was foam coming off, and impacting the orbiter. If the orbiter was not "downwind" of the main tank, then it could not have been impacted by foam.

Challenger could have been prevented by decision making at launch time alone. Columbia was doomed by the position of the orbiter. It's a marvel that we didn't lose any others. It was literally just chance where the foam impacted. A glancing blow one area, and the vehicle survived, as few cm another direction, and LOC.

Edited January 17, 2018 by tater

[GoSlash27]

2 minutes ago, tater said:

Challenger could have been prevented by decision making at launch time alone. Columbia was doomed by the position of the orbiter. It's a marvel that we didn't lose any others. It was literally just chance where the foam impacted. A glancing blow one area, and the vehicle survived, as few cm another direction, and LOC.

Agreed. And both could have been prevented by not having an airliner with all of the structural integrity of a soap bubble strapped to the side of an assembly with the chemical energy of a tactical nuke with no abort modes.

Best,
-Slashy

[tater]

Right after the destruction of Columbia, the Shuttle Program manager was saying that it could not have been a foam strike. Even then they would not believe that foam could damage the vehicle enough for a LOC incident.

They saw the foam as a problem, but not a danger all those years.

In retrospect, you have to wonder about their tile loss statistics, and the presumed cause. At the time (1990s and earlier), you'd hear that the acoustics of launch shook tiles loose, and they lost something like quite a few tiles per launch. But this was an assumption partially based on not thinking that expanding foam could really do much damage on impact. How many of those acoustically lost tiles were actually the result of foam strikes? We'll never know.

The shuttle's utility as a vehicle was certainly lowered after Columbia. If you really wanted to be safe, send crew to ISS on shuttle, and inspect shuttle for damage. If crippled, stay at ISS. Shuttle was an expensive way to get to ISS, though.

Strapped to a bomb doesn't even matter, except right after launch. Once the thing was really moving, most any separation from the stack would result in a RUD of the Orbiter.

Edited January 17, 2018 by tater

[PakledHostage]

9 minutes ago, tater said:

While true, it's also a design failure. Management farther upstream---at the decision point to go with "reusable" segmented, solid rocket motors---was also clearly a problem. We all know why the solids were chosen, too. The ugly way the sausage is made. It was not a choice about what was best, it was about DC.

As an engineer yourself, you know that is a ridiculous assertion... The shuttle isn't a car. It is as high performance a vehicle as ever existed. It is being imparted with literally megajoules of energy per kilogram during launch. It has to operate on razor thin margins or it wouldn't fly. Sure it is far from perfect and 20:20 hindsight has shown that there were areas that could have been improved from the outset. But compromises had to be made during its development and the people making those decisions probably:

a) weren’t dimwits
b) were privy to information that a bunch of armchair engineers on the internet aren’t considering in their criticisms

The people making those decisions back in the ‘70s also certainly didn’t have the benefit of hindsight that we all have today.

[GoSlash27]

9 minutes ago, PakledHostage said:

the people making those decisions probably:

a) weren’t dimwits
b) were privy to information that a bunch of armchair engineers on the internet aren’t considering in their criticisms

The people making those decisions back in the ‘70s also certainly didn’t have the benefit of hindsight that we all have today.

a) arguable. The people who made those decisions weren't engineers. They were lawmakers and bureaucrats.

b) false. c) Is closer to the truth, and directly contradicts b.

Best,
-Slashy

Edited January 17, 2018 by GoSlash27