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Space Forum / Shuttle / September 2005CEV and Stick
Has the final CEV design been chosen and what will it look like, the Lockheed design with small winglets or will it be a complete modular design like the Apollo spacecraft? As far as I know the launcher for the CEV will be a 2 stage launcher rocket composed of one solid rocket boster and one J2S/SSME upper stage. I believe this configuration can send the CEV to the moon using the upper stage? Would it be possible to just use the SRB to put the CEV in orbit only? I heard something about make two types of CEVs? I think they should just make one CEV design. I have read many posts in the past from people who dont like using the shuttle parts, SRBs, SSME, in the new spacecraft but rather use EELVs.(delta, titan, atlas) I dissagree, I believe the SRBs are safe. The initial explosion of Challenger came from gas entering into the SSMEs, but the SRBs did not cause the explosion. The SRBs did not explode first, right? ATK Thoikol said that SRBs donot explode. They burn at a "perscribed rate". Thats what it says somewhere on this website, which I like. http://www.safesimplesoon.com/default.htm > I have read many posts in the past from people who dont like using the > shuttle parts, SRBs, SSME, in the new spacecraft but rather use [quoted text clipped - 3 lines] > right? ATK Thoikol said that SRBs donot explode. They burn at a "perscribed > rate". Thats what it says somewhere on this website, which I like. The SSME's had absolutely nothing to do with the Challenger disaster. The disaster's root cause was a leaking SRB field joint. If you'd like to learn more, you can start here: Report of the Presidential Commission on the Space Shuttle Challenger Accident http://science.ksc.nasa.gov/shuttle/missions/51-l/docs/rogers-commission/table-o f-contents.html Jeff  SignatureRemove icky phrase from email address to get a valid address. >> I have read many posts in the past from people who dont like using the >> shuttle parts, SRBs, SSME, in the new spacecraft but rather use [quoted text clipped - 9 lines] > The SSME's had absolutely nothing to do with the Challenger disaster. The > disaster's root cause was a leaking SRB field joint. Oddly enough, an SRB leak won't have much effect on the proposed CEV...no tank to blow up! > Has the final CEV design been chosen and what will it look like ... No, but Griffin's big blueprint plan, which lays out the launch vehicles and an outline of the spacecraft, is being released during the next day or three, first to the White House, then to NASA Centers, then to the public next week. Keep your eyes on "www.nasawatch.com", "space.com", etc., for the latest. Early hints are that the plan is to develop an SRB-based CEV launcher quickly to replace shuttle. A Saturn V class shuttle derived launcher might follow in a decade or so. - Ed Kyle >Keep your eyes on "www.nasawatch.com", "space.com", etc., >for the latest. Thanks for the heads up. >Early hints are that the plan is to develop an >SRB-based CEV launcher quickly to replace shuttle. >A Saturn V class shuttle derived launcher might >follow in a decade or so. But only both, plus a return capacity, could really replace the shuttle... Dale > >Keep your eyes on "www.nasawatch.com", "space.com", etc., > >for the latest. [quoted text clipped - 8 lines] > But only both, plus a return capacity, could really > replace the shuttle... An unmanned SRB/SSME launcher would be able to boost about the same, if not more, payload mass into orbit as a space shuttle payload bay. A Progress-like unmanned CEV with a heat shield could be used to deliver and return mass. What has shuttle been returning to earth that couldn't return in a CEV? - Ed Kyle > What has shuttle been > returning to earth that couldn't return in a CEV? You ought to qualify that question with the word "lately" or "recently" else some smart a.s (like me) will respond: "LDEF, Palapa-B2 and Westar VI . . ." :-p Signature"Fame may be fleeting but obscurity is forever." ~Anonymous "I believe as little as possible and know as much as I can." ~Todd Stuart Phillips <www.angryherb.net> On 15 Sep 2005 07:10:32 -0700, in a place far, far away, "Ed Kyle" <edkyle99@hotmail.com> made the phosphor on my monitor glow in such a way as to indicate that: >Early hints are that the plan is to develop an >SRB-based CEV launcher quickly to replace shuttle. >A Saturn V class shuttle derived launcher might >follow in a decade or so. If that's the case, then it will never happen, since it will be quite clear by then that it's unneeded. > The initial explosion of Challenger came from gas entering into the SSMEs, > but the SRBs did not cause the explosion. The SRBs did not explode first, > right? You're partly correct, Ray. The SRBs did not explode prior to RSD, nor did they cartwheel. However, it's incorrect to exclude the SRBs as a cause of the explosion. The SSMEs effectively destroyed themselves, from operating with an oxygen-rich propellant mixture; but that was more a case of insufficient hydrogen (the fuel) "entering into the SSMEs." Challenger's Ghost >> The initial explosion of Challenger came from gas entering into the SSMEs, >> but the SRBs did not cause the explosion. The SRBs did not explode first, [quoted text clipped - 9 lines] > >Challenger's Ghost Now I'm confused. I thought the SRB leak burned through the external tank and the ET was what blew up. -- David (not an aerospace engineer) > Now I'm confused. I thought the SRB leak burned through the external > tank and the ET was what blew up. The SRB leak burned through the *structure* of the tank. The external tank *broke* up. Nothing "blew up" -- while the term "explosive burn" is occasionally applied, the fireball was not an explosion. See http://science.ksc.nasa.gov/shuttle/missions/51-l/docs/rogers-commission/ Chapter-3.txt for a comprehensive description of what happened. >> Now I'm confused. I thought the SRB leak burned through the external >> tank and the ET was what blew up. [quoted text clipped - 6 lines] >http://science.ksc.nasa.gov/shuttle/missions/51-l/docs/rogers-commission/ >Chapter-3.txt for a comprehensive description of what happened. I can see what you mean. --------------------- Pasted Text -------------------------- Within milliseconds there was massive, almost explosive, burning of the hydrogen streaming from the failed tank bottom and 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 46,000 feet, the Challenger was totally enveloped in the explosive burn. The Challenger's reaction control system ruptured and a hypergolic burn of its propellants 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. --------------------- Pasted Text -------------------------- But that first paragraph sure reminds me of the description of an FAE like a MOAB or BLU-82 except for having it's own oxidizer. http://www.answers.com/topic/thermobaric-weapon http://www.redrat.net/BUSH_WAR/moab.htm -- David >But that first paragraph sure reminds me of the description of an FAE >like a MOAB or BLU-82 except for having it's own oxidizer. > > There are very high quality photos of the launch and break-up here: http://www.aerospaceweb.org/question/investigations/q0122.shtml It's really surprising just how intact the crew compartment stayed during the break-up. Pat > >But that first paragraph sure reminds me of the description of an FAE > >like a MOAB or BLU-82 except for having it's own oxidizer. > > There are very high quality photos of the launch and break-up here: > http://www.aerospaceweb.org/question/investigations/q0122.shtml Your guys could use a few good clues about ethical photo annotation, Pat (e.g., with regard to wind direction and behavior, especially relative to FSS and MLP orientation): "But what was most unusual about this particular case was the direction of the wind, blowing towards the west-northwest. As a result, the super-cooled air descended directly into the lower portion of the right SRB and impinged upon the aft field joint. An illustration of the wind is depicted below atop a rear view of the Shuttle assembly." Obviously, Pat, there is a gross disparity between the arrows and "blowing towards the west-northwest." Regardless, this theory was thoroughly debunked at the time by an expert from the University of Florida at Gainesville. MSFC also debunked the "colder right SRB" theory quite early, via a temperature chart in one of the transcripts from the Rogers hearings. One Rogers hearing confirmed an ice-encased *left-aft* SRB. The record may even reflect the presentation of a photo of *that* particular ice to the Commission. You and your cohorts in the HORS can continue till doomsday to depict left as right, but it will never change what actually happened -- deliberate cold-soaking of the left SRB via cryogenic hydrogen which escaped from negligently installed facility plumbing. Challenger's Ghost > >> The initial explosion of Challenger came from gas entering into the SSMEs, > >> but the SRBs did not cause the explosion. The SRBs did not explode first, [quoted text clipped - 9 lines] > > Now I'm confused. No confusion was intended, at least on my part. > I thought the SRB leak burned through the external tank That was the conclusion of the Rogers Commission, not mine. I blame a tank-damaging SRB thrust imbalance at lift-off, followed by a worse imbalance for the tank explosion (neither caused by a leaking SRB). > and the ET was what blew up. It did, of course, but I've concluded that it was not the first thing to do so. I believe an explosion of the right OMS pod barely preceded it. (See, for example, <www.mission51l.com>.) Challenger's Ghost [snip] David wrote: >> Now I'm confused. John Wrote: >No confusion was intended, at least on my part. David Wrote: >> I thought the SRB leak burned through the external tank john Wrote: >That was the conclusion of the Rogers Commission, not mine. I blame a >tank-damaging SRB thrust imbalance at lift-off, followed by a worse >imbalance for the tank explosion (neither caused by a leaking SRB). David Wrote: >> and the ET was what blew up. John Wrote: >It did, of course, but I've concluded that it was not the first thing >to do so. I believe an explosion of the right OMS pod barely preceded >it. (See, for example, <www.mission51l.com>.) > >Challenger's Ghost I'm not an aerospace engineer so this brings to mind 2 questions. 1. What was the cause of the OMS pod exploding, aerodynamic forces, a malfunction in the pod, or something else? 2. Aren't some of the OMS pods pointed towards the ET. Wouldn't they be safed until the ET is separated so that they don't fire and burn the ET? Actually, I should also make sure I'm correct that an OMS pod is one of the things that sticks out and has several thruster bells on it pointed in different directions for maneuvering. IIRC, they use hypergolic fuel. Are the holes in the nose, small OMS thrusters, but not actually considered OMS pods. They sure look like thrusters, but I suppose they could be there for some instrumentation purpose. BTW, I've lurked off (mostly) and on for years, posting occasionally, so I know a little of the history of the group and John. OTOH, I've been posting lately and he seems to be willing to give a civil answer to a question and not criticize me for not being an aerospace engineer or not spending hours on google trying to find an answer before asking something that most people here could answer in a couple minutes without having to look anything up and probably in much simpler terms than any technical document I could find in google. I know many of you are mad at him because of his book. I haven't read it. To be honest, so many things happened so fast and were viewed from so far away or through limited telemetry that I don't see how anyone could be positive what happened, whether it be NASA, John, or the Rogers Commission. I'm certainly not qualified to get in the argument over the exact cause of Challenger, but I am interested in hearing what different people think and getting the occasional question answered on other topics. As for my background, it's programming. From CP/M and 8080 Assembler in the mid 70's, through writing firmware in assembler, writing support libraries and porting language runtimes (sometimes including emulating the 8080 CPU and MP/M) for other programmers to use in applications, writing C then C++ (started when it was a program which compiled C++ to C with dozens of parenthesis in each source line) to c# and some website and database programming. -- David > I'm not an aerospace engineer Neither is John Maxson. Google his name for all the evidence you need to know why most people have rightfully killfiled him. Signature"Fame may be fleeting but obscurity is forever." ~Anonymous "I believe as little as possible and know as much as I can." ~Todd Stuart Phillips <www.angryherb.net> On Thu, 15 Sep 2005 17:49:20 -0500, in a place far, far away, David Ball <davidbemail-1q04@yahoo.com.nospam> made the phosphor on my monitor glow in such a way as to indicate that: >>> The initial explosion of Challenger came from gas entering into the SSMEs, >>> but the SRBs did not cause the explosion. The SRBs did not explode first, [quoted text clipped - 12 lines] >Now I'm confused. I thought the SRB leak burned through the external >tank and the ET was what blew up.\ Nothing "blew up." The Shuttle was lost due to aerodynamic forces that destroyed the structural integrity of the Orbiter, as a result of its separation from the ET after it was destroyed by an impinging SRB. > Nothing "blew up." > > The Shuttle was lost due to aerodynamic forces that destroyed the > structural integrity of the Orbiter, as a result of its separation > from the ET after it was destroyed by an impinging SRB. In a repeat of the Challenger accident, what would the crew survival probability be, if they're in an inline mounted CEV (on top of an EDS on top of the ET) with escape system. On 16 Sep 2005 02:01:47 -0700, in a place far, far away, "Alex Terrell" <alexterrell@yahoo.com> made the phosphor on my monitor glow in such a way as to indicate that: >> Nothing "blew up." >> [quoted text clipped - 5 lines] >probability be, if they're in an inline mounted CEV (on top of an EDS >on top of the ET) with escape system. Much higher, since there would be no structure for a failed SRB to blowtorch away. That's what seems to be the appeal of the system. It costs just as much as a Shuttle flight (more, actually, when you take into account the other launches that you need to do to get equivalent payload), but it's safer. > On 16 Sep 2005 02:01:47 -0700, in a place far, far away, "Alex > Terrell" <alexterrell@yahoo.com> made the phosphor on my monitor glow [quoted text clipped - 15 lines] > into account the other launches that you need to do to get equivalent > payload), but it's safer. Agree - Though I was actually thinking of the SDHLV rather than the stick, so there is an ET to burn in to, an explosion of sorts might occur, but the escape tower should take them clear. >> On 16 Sep 2005 02:01:47 -0700, in a place far, far away, "Alex >> Terrell" <alexterrell@yahoo.com> made the phosphor on my monitor glow [quoted text clipped - 19 lines] > stick, so there is an ET to burn in to, an explosion of sorts might > occur, but the escape tower should take them clear. The escape tower is only for very low velocity escapes. It would look a lot like the Challenger if the system activated at Mach 1. The escape tower is only for very low velocity escapes. It would look a lot like the Challenger if the system activated at Mach 1. The escape tower system is for all conditions untill the stack is too high, where normal demating can occur. apollos tower always was jettisoned at that point. the purpose is to pull the capsule straight up away from the stack >> Agree - Though I was actually thinking of the SDHLV rather than the >> stick, so there is an ET to burn in to, an explosion of sorts might >> occur, but the escape tower should take them clear. > >The escape tower is only for very low velocity escapes. It would look a lot >like the Challenger if the system activated at Mach 1. Only if the designers are totally incompetent. The Apollo escape tower was jettisoned at about Mach 9, not because it was no longer usable but because it was no longer needed. Escape in the transonic region (circa Mach 1) and at maximum dynamic pressure (circa Mach 2) were two of the major design cases for it. (Pad escape drove total motor impulse, to get the capsule high enough for parachute deployment and far enough that the worst-case fireball wouldn't overheat the chutes. Transonic escape drove thrust, to get the capsule clear of the rocket despite the very high aerodynamic drag at Mach 1. Max-dynamic-pressure escape drove stability, because high aerodynamic loads plus loads from the escape-motor plume could overstress the capsule (a la Challenger) unless it stayed pointed pretty much into the wind. And near-vacuum escape adds issues of reentry stability -- they didn't want to rely on active attitude control still being functional. If memory serves, all four cases were tested successfully.) Signaturespsystems.net is temporarily off the air; | Henry Spencer mail to henry at zoo.utoronto.ca instead. | henry@spsystems.net >(Pad escape drove total motor impulse, to get the capsule high enough for >parachute deployment and far enough that the worst-case fireball wouldn't >overheat the chutes. > I never thought of that aspect- the radiated IR flux of an exploding Saturn V would have been tremendous. Pat >>> Agree - Though I was actually thinking of the SDHLV rather than the >>> stick, so there is an ET to burn in to, an explosion of sorts might [quoted text clipped - 20 lines] > rely on active attitude control still being functional. If memory serves, > all four cases were tested successfully.) I stand corrected. I was only aware of 2 of the 4 criteria you mentioned, but all 4 make sense. But how could they have possibly tested at Mach 9? I can't imagine any wind tunnel rig that could simulate the conditions you describe. >I stand corrected. I was only aware of 2 of the 4 criteria you mentioned, >but all 4 make sense. But how could they have possibly tested at Mach 9? I >can't imagine any wind tunnel rig that could simulate the conditions you >describe. To test something that's meant to take a capsule away from a rocket, you put the capsule on a rocket... The Little Joe II rocket was built specifically to take dummy Apollo CMs up to realistic test conditions for the escape system: first transonic, then max q, and then hypersonic at high altitude. I don't think they went quite up to Mach 9, but it wasn't really necessary -- once the capsule was high enough that aerodynamic forces were down to near zero, the exact velocity didn't matter much. (They did have to try twice for the high-altitude test: the first time, the Little Joe II went violently out of control at low altitude, which was annoying in terms of trying to get the high-altitude test done, but did show that the escape system would work successfully in a situation nobody had expected.) Signaturespsystems.net is temporarily off the air; | Henry Spencer mail to henry at zoo.utoronto.ca instead. | henry@spsystems.net With reference to Rand's comments elsewhere that crew shouldn't have more protection than a $billion cargo, would it make sense to give the more expensive cargos an escape launch system? >With reference to Rand's comments elsewhere that crew shouldn't have >more protection than a $billion cargo, would it make sense to give the >more expensive cargos an escape launch system? > I think Rand, like Robert MacNamara, knows the price of everything...and the value of nothing. ;-) Pat On Thu, 22 Sep 2005 16:52:51 -0500, in a place far, far away, Pat Flannery <flanner@daktel.com> made the phosphor on my monitor glow in such a way as to indicate that: >>With reference to Rand's comments elsewhere that crew shouldn't have >>more protection than a $billion cargo, would it make sense to give the [quoted text clipped - 3 lines] >I think Rand, like Robert MacNamara, knows the price of everything...and >the value of nothing. ;-) Can you expand on that topic? How many trillions of dollars should we spend to ensure that no astronaut ever dies? On 22 Sep 2005 13:25:45 -0700, in a place far, far away, "Alex Terrell" <alexterrell@yahoo.com> made the phosphor on my monitor glow in such a way as to indicate that: >With reference to Rand's comments elsewhere that crew shouldn't have >more protection than a $billion cargo, would it make sense to give the >more expensive cargos an escape launch system? Perhaps if they're as small as the crew module. The best escape system, of course, is a reliable space transport capable of safe abort... >With reference to Rand's comments elsewhere that crew shouldn't have >more protection than a $billion cargo, would it make sense to give the >more expensive cargos an escape launch system? If it were practical, yes. Unfortunately, they tend to be large and heavy, and you'd need quite a large escape system and rather a lot of added hardware. And since those cargos already tend to max out the largest available launchers... Signaturespsystems.net is temporarily off the air; | Henry Spencer mail to henry at zoo.utoronto.ca instead. | henry@spsystems.net >> Nothing "blew up." >> The Shuttle was lost due to aerodynamic forces that destroyed the >> structural integrity of the Orbiter, as a result of its separation >> from the ET after it was destroyed by an impinging SRB. >In a repeat of the Challenger accident, what would the crew survival >probability be, if they're in an inline mounted CEV (on top of an EDS >on top of the ET) with escape system. Somewhere in the range of eighty to ninety percent. If you've got a proper launch escape system, and you activate it any time before the whole stack actually explodes and/or tumbles, a Challenger accident won't hurt you. However, a launch escape system with enough oomph to get that job done, might kill you all by itself. And you still need a second or so of warning to use the escape system. So there are still lethal failure modes, and I'd be greatly skeptical of any engineer who said they could be reduced below the five-percent level. I'd dismiss out of hand any bureaucrat who made such a claim. Basically, a launch escape system is an ejection seat with a broader envelope. Ejection seats make military aircraft safer than they would otherwise be, but they are a desperate last resort and people still die in that business. Signature*John Schilling * "Anything worth doing, * *Member:AIAA,NRA,ACLU,SAS,LP * is worth doing for money" * *Chief Scientist & General Partner * -13th Rule of Acquisition * *White Elephant Research, LLC * "There is no substitute * *schillin@spock.usc.edu * for success" * *661-718-0955 or 661-275-6795 * -58th Rule of Acquisition * >However, a launch escape system with enough oomph to get that job done, >might kill you all by itself. And you still need a second or so of >warning to use the escape system. > Not necessarily- Mercury used an entirely automatic escape system (Gemini was manual, and Apollo was manual or automatic depending on the severity of the fault the vehicle status sensors detected.), and given the fact that a failure of a SRB could be extremely fast and cataclysmic, you'd probably want the stick to use a fully automatic system during first stage burn. Provided that the crew sat in their acceleration couches braced for LES firing until first stage separation occurred, there is no reason why you couldn't have the LES extremely quick firing. Of course this means that the crew won't be pushing buttons on the way up, but rather riding as passengers until first stage burn is completed. Pat >>However, a launch escape system with enough oomph to get that job done, >>might kill you all by itself. And you still need a second or so of >>warning to use the escape system. >Not necessarily- Mercury used an entirely automatic escape system >(Gemini was manual, and Apollo was manual or automatic depending on the >severity of the fault the vehicle status sensors detected.), and given >the fact that a failure of a SRB could be extremely fast and >cataclysmic, you'd probably want the stick to use a fully automatic >system during first stage burn. I was assuming a fully automatic escape system. It *still* takes finite time to clear the danger zone. Hopefully less time than it takes the danger to grow to non-survivable limits, but keep in mind the auto-escape can't be set on a hair trigger given that it has a non-trivial possibility of killing the crew all by itself. Signature*John Schilling * "Anything worth doing, * *Member:AIAA,NRA,ACLU,SAS,LP * is worth doing for money" * *Chief Scientist & General Partner * -13th Rule of Acquisition * *White Elephant Research, LLC * "There is no substitute * *schillin@spock.usc.edu * for success" * *661-718-0955 or 661-275-6795 * -58th Rule of Acquisition * >...Mercury used an entirely automatic escape system >(Gemini was manual, and Apollo was manual or automatic depending on the >severity of the fault the vehicle status sensors detected.), and given >the fact that a failure of a SRB could be extremely fast and >cataclysmic, you'd probably want the stick to use a fully automatic >system during first stage burn. The trouble is, as John has noted, the escape system itself is dangerous, so you would prefer activation to be manual if at all possible, to minimize false alarms. Mercury's fully-automatic system was a nightmare to develop and debug -- which is why Apollo's system was automatic only for three types of especially-severe failure -- and was justified mainly by vague fears of pilot incapacitation (on the part of influential but basically clueless kibitzers, not the design engineers). Signaturespsystems.net is temporarily off the air; | Henry Spencer mail to henry at zoo.utoronto.ca instead. | henry@spsystems.net >The trouble is, as John has noted, the escape system itself is dangerous, >so you would prefer activation to be manual if at all possible, to >minimize false alarms. Mercury's fully-automatic system was a nightmare >to develop and debug Given the state of the art in electronics at the time I could imagine it was, but today's abilities should allow a system of multiple independent sensors and independent control computers to examine performance data several times a second and vote on whether the escape system should be fired. > -- which is why Apollo's system was automatic only >for three types of especially-severe failure -- and was justified mainly >by vague fears of pilot incapacitation (on the part of influential but >basically clueless kibitzers, not the design engineers). > If you're going with a solid first stage, about the only thing that's going to be fast enough in case of a case rupture is a automatic system... you could have a manual system also, but that requires some pretty quick thinking on the part of the crew after they determine something's wrong. Pat >>...Mercury's fully-automatic system was a nightmare to develop and debug > [quoted text clipped - 3 lines] >several times a second and vote on whether the escape system should be >fired. The problem now is not so much the implementation details -- although things like voting algorithms for safety-critical decisions are *NOT* simple -- but the decision rules. It's one thing to deal with specific cases where you know what to look for, quite another to try to build a fully automatic system that can cope with even the weird ones. Again, bear in mind that you can't just activate whenever in doubt, because the escape process itself is dangerous. Apollo called this one correctly: leave the decision to the crew except for specific cases where a lethal problem could develop *very* quickly. >If you're going with a solid first stage, about the only thing that's >going to be fast enough in case of a case rupture is a automatic >system... Maybe. Depends on whether you can give some early warning of such cases, with suitable sensors. That is, what are the likely *causes* of case rupture, and how quickly do they develop? Remember too that an escape system does take some time to operate and get the spacecraft clear. A problem that strikes *too* suddenly may not be survivable even with automatic escape. Some sense of proportion is needed. If serious effort on automatic escape would only give you (say) a 5% chance of surviving a casing rupture, that effort is almost certainly better spent elsewhere. >you could have a manual system also, but that requires some >pretty quick thinking on the part of the crew after they determine >something's wrong. Well-trained crews can respond quickly. A single Saturn V engine failure just after liftoff could cause an Apollo launch to fall back onto the pad; that case was left to manual abort. Note also the Gemini 6 non-abort, where a well-trained commander decided (correctly) *not* to abort in a situation that superficially called for it. Signaturespsystems.net is temporarily off the air; | Henry Spencer mail to henry at zoo.utoronto.ca instead. | henry@spsystems.net >The problem now is not so much the implementation details -- although >things like voting algorithms for safety-critical decisions are *NOT* [quoted text clipped - 3 lines] >bear in mind that you can't just activate whenever in doubt, because the >escape process itself is dangerous. As near as I can see, the four basic failure modes of the stick's first stage would be: 1.) Case burn-through, as occurred on Challenger...this would be slow enough that a manual system would suffice. 2.) Catastrophic case rupture due to a pressure excursion inside the casing caused by abnormal propellant burn or a clogging of the internal bore or exhaust nozzle. This would probably require a fully automatic response. 3.) Failure of proper exhaust nozzle gimbal response, or the nozzle getting stuck in place during gimbaling. Again, you'd probably want the system to be automatic in this case. 4.) Disintegration of the nozzle assembly of the SRB. This would probably be slow enough to allow a manual system to be used, as it would probably not result in a immediate change in heading, and might well result in a net loss of thrust to the SRB. I'd still go fully automatic in all cases...but the thing is, given the SRB's really outstanding performance record to date (1 failure in 218 firings) I'd be quite confident to ride on it with no emergency escape system at all, especially after the Challenger fixes. As for the liquid upper stage- that's a case where engine shutdown would probably make a manual system a very viable idea...particularly given that it would occur in a thin enough atmospheric environment that simple CEV separation without use of a escape tower would be the most likely means of escape after engine shutdown or gimbal failure. Pat >1.) Case burn-through, as occurred on Challenger...this would be slow >enough that a manual system would suffice. Quite so. It doesn't happen in a hurry. >2.) Catastrophic case rupture due to a pressure excursion inside the >casing caused by abnormal propellant burn or a clogging of the internal >bore or exhaust nozzle. This would probably require a fully automatic >response. Gut feeling: that case is too fast even for automatic escape. Effort should go into minimizing the probability of it happening. >3.) Failure of proper exhaust nozzle gimbal response, or the nozzle >getting stuck in place during gimbaling. Again, you'd probably want the >system to be automatic in this case. This one's borderline. On the Saturn V, some cases of this caused automatic escape and others didn't. >4.) Disintegration of the nozzle assembly of the SRB. This would >probably be slow enough to allow a manual system to be used, as it would >probably not result in a immediate change in heading, and might well >result in a net loss of thrust to the SRB. It'll probably put the flame out, in fact. That propellant burns well only at high pressure, and has a strong tendency to go out on sudden pressure drops in particular. Again, manual control seems adequate. >I'd still go fully automatic in all cases... I wouldn't; the less you have to trust the automatic system, the better. >but the thing is, given the >SRB's really outstanding performance record to date (1 failure in 218 >firings) I'd be quite confident to ride on it with no emergency escape >system at all, especially after the Challenger fixes. Once, maybe. Not if I was going to do it with some frequency. That failure rate is good only by artillery-rocket standards. Signaturespsystems.net is temporarily off the air; | Henry Spencer mail to henry at zoo.utoronto.ca instead. | henry@spsystems.net > >I'd still go fully automatic in all cases... > > I wouldn't; the less you have to trust the automatic system, the better. Who would trigger the manual system? On what inputs would they trigger the manual system? If they're instructed to trigger the manual abort when three red lights and two orange lights show, then why would this not be codified and made automatic? >> >I'd still go fully automatic in all cases... >> I wouldn't; the less you have to trust the automatic system, the better. > >Who would trigger the manual system? Whoever's riding it. (If nobody's aboard, you probably don't care.) >On what inputs would they trigger the manual system? Depends on the kind of failure. The Saturn V Flight Manual has a table of failure types and what cues the crew uses to decide to abort. The rule is that there should be two independent sources confirming the need to abort, although Mission Control can light an ABORT light on the panel and that counts as one. (Mission Control is specifically charged with watching for slowly-developing problems, in particular.) For example, for an engine-out failure in the first few seconds, you abort on two out of three of: (a) one of the "thrust OK" lights on the panel (which are derived from pressure switches in the engines) goes out; (b) you feel a drop in acceleration and possibly a lurch sideways; (c) the ABORT light goes on. >If they're instructed to trigger the manual abort when three red lights >and two orange lights show, then why would this not be codified and >made automatic? Partly because, as above, some of the cues they're supposed to respond to are not just lights on the panel. Partly because one of their jobs is to decide how reliable the information is. And partly because they're also charged with deciding when unusual circumstances justify breaking the rules, one way or the other. Wally Schirra decided not to abort Gemini 6 because he didn't think the rocket had really left the pad, despite what the panel showed, and he was right. Signaturespsystems.net is temporarily off the air; | Henry Spencer mail to henry at zoo.utoronto.ca instead. | henry@spsystems.net >Who would trigger the manual system? > [quoted text clipped - 4 lines] >made automatic? > This reminds me of the concept of having the Dyna-Soar pilot manually fly the Titan to orbit based on the information that he was getting on his control panel about the actual heading compared to the planned one; at that point, you might just as well take the pilot out of the loop and let it ascend on autopilot, with manual piloting as a back-up in case something wasn't working right with the autopilot. Peering out of the CEV windows, I don't know how the crew is going to have better information on what the booster is up to than stage performance sensors would. I could see the crew being given the ability to manually abort if they think that the automatic system has missed something (say they suddenly smell smoke in the cabin) but not the other way around, where they can override the automatic system. Pat > > [quoted text clipped - 8 lines] > > Well, we haven't had one blow yet. >It'll probably put the flame out, in fact. That propellant burns well >only at high pressure, and has a strong tendency to go out on sudden >pressure drops in particular. Again, manual control seems adequate. > Which brings up a question- would a case rupture also cause the propellant to snuff out if it was limited to one segment like it was during the Thiokol test? > > [quoted text clipped - 3 lines] >I wouldn't; the less you have to trust the automatic system, the better. > Again though, I think it's going to be a case where the sensors tell the crew to abort, and they really won't have enough information on what's going on below them to second guess its advice, so they will almost certainly abort based on what it's telling them. But there is a time-lag inherent in this approach that could be fatal. Pat >>>2.) Catastrophic case rupture... >>Gut feeling: that case is too fast even for automatic escape. Effort >>should go into minimizing the probability of it happening. > >Well, we haven't had one blow yet. Yet. That doesn't mean it's impossible. There have been some quite spectacular fireworks displays from Titan SRBs. Thinking "this time is different" is a good way to lose your money and/or life. >>It'll probably put the flame out, in fact. That propellant burns well >>only at high pressure, and has a strong tendency to go out on sudden [quoted text clipped - 3 lines] >propellant to snuff out if it was limited to one segment like it was >during the Thiokol test? Depends on how big a hole it opens up, but the chances seem good. However, that won't affect the rupture itself, which is something that generally happens on a much shorter time scale. >>>I'd still go fully automatic in all cases... >>I wouldn't; the less you have to trust the automatic system, the better. > >Again though, I think it's going to be a case where the sensors tell the >crew to abort, and they really won't have enough information on what's >going on below them to second guess its advice... If so, that's a problem which needs solving, not a law of nature. (Sample: is there any reason *not* to give them full video coverage of the entire exterior? Why should they be the ones with the worst view?) I can see having to trust an automatic system for cases where there definitely isn't time for the crew to react, such as (probably) nozzle gimbal hard over near max q. But that should be the *only* reason for telling the crew that you don't trust them to get it right when their lives are at stake. Signaturespsystems.net is temporarily off the air; | Henry Spencer mail to henry at zoo.utoronto.ca instead. | henry@spsystems.net >>Well, we haven't had one blow yet. >> > >Yet. That doesn't mean it's impossible. Oh, I don't think it's impossible...I think that it is very, very unlikely though. > There have been some quite >spectacular fireworks displays from Titan SRBs. Thinking "this time is >different" is a good way to lose your money and/or life. > Different manufacturer and different design on the two SRBs though. Which is rather like saying that the Comet's failure rate should reflect upon the reliability of the 707. >> Again though, I think it's going to be a case where the sensors tell the >> [quoted text clipped - 7 lines] >the entire exterior? Why should they be the ones with the worst view?) > I imagine they will have cameras looking at the booster's exterior during ascent, as well as possibly video from Mission Control showing their view of it. But here's a question- since sensor data from the vehicle will be downloading to Mission Control as well as feeding itself into the CEV's flight computers from the same set of sensors, if the Big Red Light goes on in the CEV's cockpit, it will also be going on in Mission Control. And that will mean you can either trust your gut instincts and external views of the vehicle, or trust what your instruments are telling you and Mission Control...and they teach pilots to trust their instruments unless they are completely sure that they are wrong, and have complete confidence that their eyes aren't being deceived and there is indeed a problem with their instruments. If you don't see or feel something going wrong with the SRB, that doesn't mean that something isn't going wrong with it, and if it were me that abort switch would be getting pushed around one second after the BRL came on, no matter what I though the real situation was. For starters, it's going to take a few seconds to look for some problem on the external video, especially considering that you are going to be sitting in a vibrating crew compartment while you are doing it, then you are going to have to determine exactly why the BRL is on if nothing is wrong, and you frankly don't have that time if something really is wrong and you just haven't spotted it. >I can see having to trust an automatic system for cases where there >definitely isn't time for the crew to react, such as (probably) nozzle >gimbal hard over near max q. But that should be the *only* reason for >telling the crew that you don't trust them to get it right when their >lives are at stake. > I still would go with a fully automatic system with manual back-up activation if the crew thought that something was wrong that the LES wasn't picking up for some reason. But since (at least in my case) I'd be hitting the abort switch if the sensors told me to, I can't see any reason why I should be in the loop at all as it would only cause a delay in activating the escape system which could prove fatal. Pat > I still would go with a fully automatic system with manual back-up > activation if the crew thought that something was wrong that the LES [quoted text clipped - 3 lines] > at all as it would only cause a delay in activating the escape system > which could prove fatal. Seconded. Astronauts are passengers, doing a job once in orbit. Lots of Greetings! Volker > Well, we haven't had one blow yet. - Unknown NASA manager, after the 24th shuttle launch > 2.) Catastrophic case rupture due to a pressure excursion inside the > casing caused by abnormal propellant burn or a clogging of the internal > bore or exhaust nozzle. This would probably require a fully automatic > response. A case burst is thought to be not survivable (based on engineering analysis). That's from a PDF I've got titled "Reliability and Crew Safety Assessment for Solid Rocket Booster / J-2S Based Launch Vehicle". I believe you can find that PDF at: http://www.safesimplesoon.com/assets/documents/Reliability+CrewSafety.pdf The document also has a pretty detailed initial analysis of the different failure modes of "the stick" and what the survivability of each failure mode should be. Granted that this isn't quite "the stick" as currently envisioned (e.g. NASA wants an SSME powered upper stage for more payload than a J-2S would give), but it's closer than guess work. Jeff SignatureRemove icky phrase from email address to get a valid address. >A case burst is thought to be not survivable (based on engineering >analysis). That's from a PDF I've got titled "Reliability and Crew Safety [quoted text clipped - 3 lines] > >http://www.safesimplesoon.com/assets/documents/Reliability+CrewSafety.pdf Fascinating and chilling reading. D. SignatureTouch-twice life. Eat. Drink. Laugh. -Resolved: To be more temperate in my postings. Oct 5th, 2004 JDL >> A case burst is thought to be not survivable (based on engineering >> analysis). That's from a PDF I've got titled "Reliability and Crew Safety [quoted text clipped - 5 lines] > > Fascinating and chilling reading. I've tried to scan through it since lunch but I keep getting interrupted. Damn that real work! ;-) Signature"Fame may be fleeting but obscurity is forever." ~Anonymous "I believe as little as possible and know as much as I can." ~Todd Stuart Phillips <www.angryherb.net> >> > >I've tried to scan through it since lunch but I keep getting >interrupted. Damn that real work! ;-) > I downloaded it the first time it got mentioned around here- read it carefully. For the sake of conservatism, they _assume_ that a case rupture on ignition is a 100% fatal situation, but they also say that that might not be the actual case. On the Thiokol case rupture test, damage was limited to the segment that failed, and did not spread to the segments above or below it. The worst-case failure is the upper segment or top thrust dome of the SRB failing. Failures further down the SRB don't generate as damaging of shockwaves, and having it occur in flight rather than on the pad drives the pressure wave backwards, and further reduces the shock effect. If the case does rupture, it ruptures for a reason- either there is some structural flaw in the SRB casing (and they get very carefully checked for flaws) or there is a problem of some sort with the burning of the fuel grain leading to a pressure excursion that causes the case to fail due to being overstressed. And the grain is very carefully checked during production and assembly. The SRB is a proven design that has suffered 1 failure in 218 operational uses. That is an exceptionally good reliability for any rocket booster. We've had a case leak, but never a case rupture in operations. The Challenger leak was slow enough in its growth that it would have given plenty of time for the activation of a escape system- Hell, the SRB was basically intact even after the Challenger launch stack broke up. Pat >> 2.) Catastrophic case rupture due to a pressure excursion inside the >> casing caused by abnormal propellant burn or a clogging of the internal [quoted text clipped - 14 lines] >envisioned (e.g. NASA wants an SSME powered upper stage for more payload >than a J-2S would give), but it's closer than guess work. They say, though, "In fact, although it has been assumed here that all case bursts result in crew loss, the physical similarities of the consequences of most case b urst events indicate a potential high degree of survivability from most of these events." SignatureJosh "This is a devastating storm. This is a storm that's going to require immediate action now." -George W. Bush, four days after Hurricane Katrina > Mercury's fully-automatic system was a nightmare to develop and debug > -- which is why Apollo's system was automatic only for three types of > especially-severe failure -- and was justified mainly by vague fears > of pilot incapacitation (on the part of influential but basically > clueless kibitzers, not the design engineers). Henry, do you know whether the abort logic for both Mercury and Apollo done in analog, or had digital tech emerged sufficiently by the time Apollo flew that they were able to implement it in the GP computer? It doesn't sound like it from your description... I looked through the techniques they used to "program" the ejection seat sequence on Gemini (think it was one of the documents Rusty scared up), and was amazed at the way they used detonating cord & other bits-and-pieces to define the order & delays between each event. It sounded like a fun job... -- I was punching a text message into my | Reed Snellenberger phone yesterday and thought, "they need | GPG KeyID: 5A978843 to make a phone that you can just talk | rsnellenberger into." Major Thomb | -at-houston.rr.com >> Mercury's fully-automatic system was a nightmare to develop and debug >> -- which is why Apollo's system was automatic only for three types of [quoted text clipped - 3 lines] >done in analog, or had digital tech emerged sufficiently by the time >Apollo flew that they were able to implement it in the GP computer? Bits and pieces of it may have been technically digital, but there was no software in the abort logic -- it was pure hardware. Apollo really wasn't computerized except for navigation and maneuvering. The computer started out as purely the brains of the guidance/navigation system, with no other responsibilities. Later on it acquired one control job: Block I's CM autopilot was analog hardware, Block II's was software in the guidance computer. This was considered a bit daring and there was considerable debate about whether it was a good idea, but in the end it worked better that way. Most everything else was hard-wired, including many things we would do in software as a matter of course. Remember, the CSM was basically a 1961 design with various local upgrades. (I was once told -- haven't checked the numbers myself -- that close to 1/3 of the CM's total mass was electronics and electrical gear.) Signaturespsystems.net is temporarily off the air; | Henry Spencer mail to henry at zoo.utoronto.ca instead. | henry@spsystems.net > In article <1126861307.927304.247490@f14g2000cwb.googlegroups.com>, > Alex Terrell [quoted text clipped - 19 lines] > warning to use the escape system. So there are still lethal failure > modes, Put sensors on the stick to detect the leek. eg pressure sensors inside and / or IR video cams on the outside. A leek that would destroy the stick would take more than 1 sec to develop. > and I'd be greatly skeptical of any engineer who said they could > be reduced below the five-percent level. I'd dismiss out of hand any [quoted text clipped - 4 lines] > otherwise be, but they are a desperate last resort and people still > die in that business. SignatureJ.P. Kerslake B.Sc., F.B.I.S. Dyslexia Rules KO. "phone"01248-353264. e-mail Home=johnpercy@NOSPAMkerslakej2.freeserve.co.uk (remove NOSPAM) RiscStation Lite+. RiscOS 4.03 boot 1.03. MPro.3.27 DialUp 3.10. SpanStamp 1.02a > Put sensors on the stick to detect the leek. eg pressure sensors > inside and / or IR video cams on the outside. A leek that would > destroy the stick would take more than 1 sec to develop. That's "leak" . . . And on what engineering analysis do you base your conclusion? Signature"Fame may be fleeting but obscurity is forever." ~Anonymous "I believe as little as possible and know as much as I can." ~Todd Stuart Phillips <www.angryherb.net> >Put sensors on the stick to detect the leek. eg pressure sensors >inside and / or IR video cams on the outside. A leek that would >destroy the stick would take more than 1 sec to develop. > When I eat leeks, I generally get an abnormal rise in gas pressure an hour or so later, leading to dangerous venting. :-) Pat > Put sensors on the stick to detect the leek. eg pressure sensors > inside and / or IR video cams on the outside. A leek that would > destroy the stick would take more than 1 sec to develop. Which is one of the reason's no one's worried about a stick case leak--there's no external tank next door to burn into and blow up. On the other hand, a motor grain crack that causes a mere 10% increase in burning area would likely double the pressure inside the case instantly--not much time for protection there. I've partially come around on this one--but the extensive data on SRBs significantly reduces the risk of this kind of manufacturing error. Tom With a well designed capsule and escape tower what can go wrong? > With a well designed capsule and escape tower what can go wrong? How do you quantify the wellness of the design of the capsule and escape tower? Hint: With a well designed operating system and software, why do I still need a firewall? Lots of Greetings! Volker >With a well designed capsule and escape tower what can go wrong? With a well-designed launch vehicle, why would you need an escape tower for your capsule? Hint: "Well-designed" does not mean "infallible". All the things that can go wrong with a launch vehicle, can go wrong with an escape tower - which is, after all, a suborbital launch vehicle in its own right. Plus, all the failure modes unique to escape towers. The launch vehicle failure that requires use of an escape tower, can be so violent that no escape tower can open the distance fast enough for any capsule to survive. The escape tower can fail to launch when triggered. The crew and/or computer can fail to trigger the escape tower when needed. The crew and/or computer can trigger the escape tower when it is not needed. The escape tower can be triggered in a part of its operational envelope that has not been tested and contains hidden failure modes. The escape process can be violent enough to injure or kill the crew. And, of course, there's no escape tower to resort to when the escape tower fails. Signature*John Schilling * "Anything worth doing, * *Member:AIAA,NRA,ACLU,SAS,LP * is worth doing for money" * *Chief Scientist & General Partner * -13th Rule of Acquisition * *White Elephant Research, LLC * "There is no substitute * *schillin@spock.usc.edu * for success" * *661-718-0955 or 661-275-6795 * -58th Rule of Acquisition * >A leek that would > destroy the stick would take more than 1 sec to develop. O MY GOD! Killer onions from space! > In a repeat of the Challenger accident, what would the crew survival > probability be, if they're in an inline mounted CEV (on top of an EDS > on top of the ET) with escape system. Depends on the vehicle design. If it can land on parachutes as a dead mass, then yeah, survivability would be much better. (imagine if the Shuttle's crew cabin had had parachutes). But if the CEV depends on active control surfaces, perhaps some engines to propell it away from wreckage first, then survivability is less since you require some functioning systems to get the CEV to egress from stack and land properly. Chances of damage to CEV during initial explosion are less due to inline design, but not nill, especially if the failure occurs in the stage directly below the CEV. > > In a repeat of the Challenger accident, what would the crew survival > > probability be, if they're in an inline mounted CEV (on top of an EDS > > on top of the ET) with escape system. > > Depends on the vehicle design. In the event of a *real* aft burnthrough in the solid rocket, the stick will cartwheel quickly. Challenger's Ghost >The Shuttle was lost due to aerodynamic forces that destroyed the >structural integrity of the Orbiter, as a result of its separation >from the ET after it was destroyed by an impinging SRB. I looked at the description and pictures on the aerospaceweb.org website. OK, after looking at the article/pictures, I agree that the Shuttle portion of the stack was lost due to aerodynamic forces, although (due to lack of clear captioning on some of the photos) some would probably argue whether it was aerodynamic forces that started the aerodynamic breakup or a burnthrough to the RCS fuel removing the shuttle nose. I'm not trying to argue that. I should also probably mention that I have OCD (although it's extremely mild compared to 30-40 years ago), which can sometimes make you very literal about how something is described. The SRBs were destroyed using onboard self-destruct explosives after separating/coming loose from the stack, so that part of the stack is accounted for. Acknowledging that the shuttle portion of the stack was lost due to aerodynamic forces, and ignoring whether or not the shuttle was still attached to the ET at the time, what destroyed the ET? I keep seeing terms like "explosively burning vapor" which sounds a lot like the Daisy Cutter bombs the Air Force dropped from C-130's and detonated just above ground (avoiding making a crater) to clear out the trees and make an LZ for the helicopters. The difference seemingly being that the ET was traveling at supersonic speed so most of the "explosively burning vapor" was trailing out behind it, and it was so huge that it took a longer time to "explosively burn" all that fuel and oxidizer. If the ET was statically mounted on the pad without the rest of the stack and something like a small rocket motor was mounted sideways to create the burnthrough on the ground, would you describe the result as an explosion/blowing up? Is being supersonic, and so huge that it takes longer to be destroyed, the difference between blowing up and being called "explosively burning vapor"? Also, after seeing what foam traveling at about 500 MPH (I don't know the actual stack speed when the foam came off and accelerated to about 500 MPH before hitting the RCC) could do to Columbia, and seeing as Challenger was described as traveling at about 1,250 mph 76 seconds into the flight when the SRB rotation pushed the stack so that it's nose was no longer aligned with the airflow, one has to wonder if any ET parts came off and did some damage to Challenger as well. I'm still amazed they were able to figure out as much as they did about Challenger. Sorry to be such a pain. -- David > Acknowledging that the shuttle portion of the stack was lost due to > aerodynamic forces, and ignoring whether or not the shuttle was still [quoted text clipped - 7 lines] > huge that it took a longer time to "explosively burn" all that fuel > and oxidizer. Basically yes. The SRB pivoted into the O2 tank, opening it up, the entire tanke failed and burned. Basically, I believe the SRBs are safer, cheaper and more powerfull than a lot of hydrogen/oxygen engines. >> The initial explosion of Challenger came from gas entering into the >> SSMEs, [quoted text clipped - 11 lines] > > Challenger's Ghost Has anyone commented on the changes required for the SRB fuel burn? The shuttle SRB burns 3 mil pounds of thrust for a couple minutes. Will the Stick run a little less hot for a longer period of time? If not, what are the g-forces associated with the Stick? 5 or 6 G's would end the era of the citizen astronaut... > Has the final CEV design been chosen and what will it look like, the > Lockheed design with small winglets or will it be a complete modular design [quoted text clipped - 14 lines] > > http://www.safesimplesoon.com/default.htm > Has anyone commented on the changes required for the SRB fuel burn? The > shuttle SRB burns 3 mil pounds of thrust for a couple minutes. Will the > Stick run a little less hot for a longer period of time? If not, what are > the g-forces associated with the Stick? 5 or 6 G's would end the era of the > citizen astronaut... Heh, heh. No more senatorial astronauts, either. > Has anyone commented on the changes required for the SRB fuel burn? The > shuttle SRB burns 3 mil pounds of thrust for a couple minutes. Will the > Stick run a little less hot for a longer period of time? If not, what are > the g-forces associated with the Stick? 5 or 6 G's would end the era of the > citizen astronaut... They're putting a 100 tonne or so second stage on top of it (weighs as much as an orbiter), plus a 20-25 tonne payload, and the burn profile could be tweaked if needed, so the Gs won't be that bad. - Ed Kyle I read another article that supports your comment - quoting a maximum of 3g. The second stage is bigger than I thought. I've also seen varying quotes on the price of each launch of the Stick - but it looks to be around $250 mil. Unbelievable for a "simple" capsule design - especially for a capsule that can be reused up to 10 times, and with reusable solid boosters. I thought SRB's cost around $35 mil each. If they can't keep the cost down to $100 million per launch, then I have a hard time imaging Congress would approve it, in light of Katrina and Iraq. I've also seen a price tag of $500 million for the in-line heavy, but that's probably a bit more reasonable given a smaller number of launches and four times the throwweight. I suspect that NASA is gold-plating the CEV design. Is there a compelling reason for developing a capsule that carries more than 4 astronauts? > > Has anyone commented on the changes required for the SRB fuel burn? The > > shuttle SRB burns 3 mil pounds of thrust for a couple minutes. Will the [quoted text clipped - 9 lines] > > - Ed Kyle > I read another article that supports your comment - quoting a maximum of 3g. > The second stage is bigger than I thought. [quoted text clipped - 8 lines] > probably a bit more reasonable given a smaller number of launches and four > times the throwweight. Big rockets cost big bucks - and SRB-SSME or SRB-J2S will be the biggest rocket in the world once it is operating. At $250 million, the rocket would actually be pretty cheap compared to existing prices. At that price, it would be able to launch a shuttle's worth of payload for about 1/2 the price (or better). I suspect that the CEV payload will cost as much as the launch vehicle, or more. - Ed Kyle > I suspect >that the CEV payload will cost as much as the launch >vehicle, or more. Don't they all? Brian I still had sight in the 80's and the actual cause of that explosion was really very plain to see on the video. The joint leaked hot gas near the base of one SRB, this mounting eventually broke as it was melted. The top of the SRB thus swung in toward the tank as the bottom swung away, pivoting on the top fixing. The External tank was thus punctured, and you could clearly see the vapour coming out and with all that heat and exhaust about.... Bang, big time. If anything, it is the lack of a way to stop an SRB which is one of the problems, though I don't think you could have reacted early enough in the Challenger case anyhow. That problem was clearly due to launching with temperature parameters outside of the design range. All you can do with solids, is jettison them, you cannot turn them off. As for designs of vehicle, there is no 'right design' as I feel half the problem is that nobody is really sure what they want it to actually do! Assumedly, it will need to service the station, assuming the international community does not trash it, but if we are talking moon, then you will, I feel need two ships anyway, a living and working transport craft, and a lander and take off craft at the lunarend of things, much as with Apollo. So, it boilds down to what you want at the Earth end. if you could do a modular design, then the capsule is king, in my mind, but if its just a ferry and remains in one configuration much like the shuttle, then there are operational advantages to a fly back design, especially if you are going to bring back sensitive scientific equipment. Brian SignatureBrian Gaff....Note, this account does not accept Bcc: email. graphics are great, but the blind can't hear them Email: briang1@blueyonder.co.uk ______________________________________________________________________________________________________________ > Has the final CEV design been chosen and what will it look like, > the Lockheed design with small winglets or will it be a complete modular [quoted text clipped - 15 lines] > > http://www.safesimplesoon.com/default.htm > I still had sight in the 80's and the actual cause of that explosion was > really very plain to see on the video. [quoted text clipped - 12 lines] > > All you can do with solids, is jettison them, you cannot turn them off. I'm not aware of any launch vehicle that had the capability to jettison an SRB that was still firing. Furthermore, thrust termination of solid rocket boosters can be done, but it's so violent that you'd end up losing your payload anyway, so why bother trying? The only thing could could do is activate a launch escape system and get away from the launch vehicle. The only problem with that is how do you detect a problem? Unfortunately, large segmented solids have been known to go "boom", not just leak. When one of those goes "boom" you're talking about rupturing a pressure chamber that's essentially the size of the entire solid stage. That's a lot of energy released at once. > As for designs of vehicle, there is no 'right design' as I feel half the > problem is that nobody is really sure what they want it to actually do! [quoted text clipped - 9 lines] > are operational advantages to a fly back design, especially if you are going > to bring back sensitive scientific equipment. The CEV has rougly the same requirements as the CSM did. It goes up and down with a crew and/or cargo and needs to be able to rendezvous and dock with other modules in orbit. NASA also wants it to be reusable and far more capable in some ways than the CSM. It seems that what they want is something with the shuttle's capabilities, minus the large payload bay, the main engines, and the large wings. Because of this, I'm not convinced that a CEV plus the stick plus a SDHLV will require any less people (and money) than the shuttle does today. It's just a shell game where you move the cargo, SSME's, and SRB's to the SDHLV, a single SRB and SSME to the stick, and everything else that was the shuttle gets stuck into the CEV. Where's the cost savings? Where's the extra money going to come from to actually design, build, and launch the real payloads (i.e. a lunar lander, lunar base modules, and etc.)? Given NASA's track record with ISS, I think that we're going to end up with little more than flags and footprints while continuing shuttle/ISS costs. Jeff SignatureRemove icky phrase from email address to get a valid address. > Given NASA's track record with ISS, I think > that we're going to end up with little more than flags and footprints while > continuing shuttle/ISS costs. I'm not convinced of the "flags and footprints part either." Has anyone actually stopped to considered how many administrations will be involved before the plans come to fruition? And, just as important, the ballooning U.S. deficits as a result of Iraq for the past few years and now Katrina? Like, where did that extra $50-odd Billion-with-a-B come from that Congress authorized the other day? Hmmmm . . . Those bills will all come due in one form or another, and likely will result in a lot more than space exploration plans being cut out of future budgets. :-/ Signature"Fame may be fleeting but obscurity is forever." ~Anonymous "I believe as little as possible and know as much as I |
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