Methane dropped from CEV plans

#140 by Jim on 21 Apr, 2006 17:20
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impulse - 21/4/2006 12:28 PM Want to to know the solution to CEV weight problems? Eliminate the whole propulsion element entirely. It is totally superfluous for LEO ops. Existing EELV's can loft the CEV capsule with oodles of margin to orbit and the Centaur element just stays attached. It will have TONS of unburned propellant and you will be placed in a real orbit- not a bogus suborbital trajectory like CLV. Nearly unlimited power and cooling capacity during pre-dock operations and no pesky solar panels or giant radiators. Minor mods to the Centaur can provide months of orbital time with cryos or you can just ditch the propellant and use batteries and a simple RCS to deorbit the capsule at the end of mission. The key is that with an EELV you can now afford to visit the ISS roughly four times more often. Who cares about a docked requirement for 180 days? It is irrelevant.The whole CEV "TEI" propulsion concept in its present incarnation is a horrendous joke. It is a crutch to preserve an incompetent design for the CLV. The CLV just can't do what they need it to do so they create one of the most expensive kludges yet conceived.

1: Who says Centaur is the key? What about D-IV 2nd stage
2. Steel ballon around the ISS. Better to have a structurally stable Centaur/upperstage
3. EELV upperstages donot have the right sized engines for rendezvous nor proper number of thrusters.
4. Avionic integration would be a nightmare. EELV avionic only can fly the upperstage. You want the CEV to control the upperstage for rendezvous?
5. Minor mods were for days not months onorbit for the cryo stage.
6. The sub orbital injection by the CLV was for 2nd stage disposal, which would be used for EELV's

7. The CEV is designed for going to the moon. Additional mission is to go to the ISS. Moon drives the requirements, ISS gets what it can.

I agree that a modified EELV can be a CEV launcher
#141 by Smatcha on 21 Apr, 2006 21:28
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Jim - 21/4/2006 10:20 AM
I agree that a modified EELV can be a CEV launcher

Jim, what do think are the primary barriers (real and imaginary) that prevent the adoption of the EELV for CEV at NASA?
#142 by Kayla on 22 Apr, 2006 12:42
The only barrier is politics. OSP had the EELV’s as the baseline launch vehicle. Under Admiral Steidel the favored LV were EELV or derivatives.
#143 by Bruhn on 22 Apr, 2006 14:56
I don't know where this rumor got started that the CLV is having performance problems. The CaLV had some published performance problems but they are even more preliminary than the CLV is. If you eqivalence were NASA is on the Constellation program to where NASA was on the Saturn program, we are in about 1960. And we do not have near the same resources NASA had during the Space Race. The CLV has had exactly one design cycle so far. Now we are good, but we're not that good. It takes many design and test cycles to whittle the mass down while maintaining the appropriate margins of safety.

I realize people need something to talk about, but before you nail the coffin shut you might want to wait until at least PDR.

And in my copy of the ESAS report, EELVs were considered in the trade space. I can't remember why they were eliminated.
#144 by Jim on 22 Apr, 2006 16:03
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Bruhn - 22/4/2006 10:56 AMI don't know where this rumor got started that the CLV is having performance problems. The CaLV had some published performance problems but they are even more preliminary than the CLV is. If you eqivalence were NASA is on the Constellation program to where NASA was on the Saturn program, we are in about 1960. And we do not have near the same resources NASA had during the Space Race. The CLV has had exactly one design cycle so far. Now we are good, but we're not that good. It takes many design and test cycles to whittle the mass down while maintaining the appropriate margins of safety.I realize people need something to talk about, but before you nail the coffin shut you might want to wait until at least PDR.And in my copy of the ESAS report, EELVs were considered in the trade space. I can't remember why they were eliminated.

Politics

PDR is too late to find out you are going the wrong path. But anyways it isn't the Stick performance, it is the cost of certifying the 5 segment SRM, from $1B to $3B. Additionally, the Stick total cost was suppose to be $1B. This was compared to the Atlas Phase 2 CEV launcher which was at 1.7B
#145 by impulse on 22 Apr, 2006 23:30
1: Who says Centaur is the key? What about D-IV 2nd stage
Knock yourself out- but I think you will not like the B2 engine quite as much and a dual engine variant is not possible.

2. Steel ballon around the ISS. Better to have a structurally stable Centaur/upperstage
Lets see- that steel balloon is what got you the performance you needed to do this cheap. Anything else is a strict payload compromise and you get to pay for that. Lets recalibrate here- an upper stage is the ultimate racing car. It must deliver astounding delta V and not weigh anything. You can insist on inefficient structures but you get to pay for that in additional complexity elsewhere. Like a higher Isp engine or a lighter avionics suite. Simple lightweight structures are cheap and well understood. Why on earth would you ever move the weight burden over to a more complicated system?
Around ISS the tank pressures are maybe 5-10 psia- for a tank designed for over 50 psia. Not enough margin for you?

3. EELV upperstages donot have the right sized engines for rendezvous nor proper number of thrusters.
Adding thrusters to do 6 DOF operations is a trivial task using hardware that has already been flown. If you insist on rapid motion because you are an impatient pilot then you get to pay for that. As it is we can handily maneuver Centaur with 9lbf thrusters- we used to do it with 6lbf. For a vehicle that weighs many tons fueled with a variable Cg. Delta V on orbit can be done with larger thusters in the Aerojet stable.

4. Avionic integration would be a nightmare. EELV avionic only can fly the upperstage. You want the CEV to control the upperstage for rendezvous?
I can think of at least four solutions to this but recall that thrusters are commanded by an RCU that talks over a 1553 bus to a computer. With proper software you can hand over command to whatever computer you want to use. That is the beauty of a bus. The CEV will already be on this bus anyway so that you can watch the data and controls from the Centaur FTINU.

5. Minor mods were for days not months onorbit for the cryo stage.
This all depends on whether you plan on keeping cryos on board near ISS. Given that they are not required I would dump em. then you got no worries. Just about the worst cryo storage place within 1 AU of the sun is docked to the ISS. You cannot control vehicle attitude and are in a high heating environment clamped to a hot structure. Once you remove these constraints then all sorts of possibilities emerge. Storing LH2 in an arbitrary state is hard and expensive. Storing it with forethought about the environment is not that tough. It is far easier to store ice cream in an Alaska winter than in an Arizona summer.

6. The sub orbital injection by the CLV was for 2nd stage disposal, which would be used for EELV's
Unlike CLV the upper stage is light enough to take to orbit. It stays there until the CEV is ready to come home. Then you dump it like a Progress. The thing only weighs 2.5t and is a balloon as you said. Can't imagine a more "burn-up able" machine.

7. The CEV is designed for going to the moon. Additional mission is to go to the ISS. Moon drives the requirements, ISS gets what it can.
This is certainly a laudable goal but as of right now the storable system is a major compromise that had to be done to meet an ISS schedule- not a lunar task. This is a prime example of a cart before the horse decision. NASA will have their hands full just getting the CEV CM done inside the schedule. Everyone knows the storable decision was a major loss to extensibility for real Lunar and Mars missions. Eventually you must make a cryo system. It will cost hundreds of millions to develop an essentially dead-end stage. Why would you EVER do this? Only because the CLV is not up to the job- it is a suborbital gizmo and NEEDS another stage to complete the real job.
But to set the record straight it was never proposed to send an existing Centaur on a Lunar mission as a TLI stage. That too is a bad idea. What was proposed was the design of the Phase 1 Wide Body Centaur to do that task. That vehicle uses all existing technology and could be completed and flown multiple times long before the CEV CM ever is even ready for flight. It has the most reliable engines and a flight proven avionics suite. If you want to do a basic lunar mission it is a piece of cake to use even existing systems like the RCS. If you insist on jumping right into 180 day lunar orbit durations you will need a fancier propulsion system which also does not require magic but is more sophisticated. Total propellant load with boiloff reserves: 10mt. Yep this machine is half the size of a regular Centaur.

If I was proposing crazy sh*t then I could see NASA spending $10 billion to get a much better CLV. The present CLV architecture is worse along nearly every assessment axis: cost, performance, demonstrated reliability, development risk etc. The present NASA course is not rational for sensible, risk-averse people. It is fraught with gratuitous new hardware and untested teams. Please note this: the American people are a patient bunch when they believe you are doing the right thing for the right reasons. If, however, you are abusing this trust by making insider interest based decisions there can be a terrible price to pay. NASA is risking not only a bunch of money but its future on this vision.
#146 by simonbp on 23 Apr, 2006 04:57
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Jim - 22/4/2006 11:03 AM
Politics

Actually, it was safety.

On page 382 of the ESAS, there is a summary table of different Crew Launch Vehicle designs, including man-rated heavy versions of both EELVs, a 5.4 m and a 8 m Atlases, and the two SRB CLVs (4-seg SSME and 5-seg J-2). The probability for Loss Of Mission for the heavies is about 1 in 150; 1 in 134 for the 5.4 m; and 1 in 79 for the 8 m. The SRBs, though, both have a LOM of about 1 in 450. With numbers like those, the baseline CLV makes the EELVs look like genuine deathtraps...

Now, these numbers might be wrong, and if so please show me evidence to the contrary, but what we are talking about here is crew safety. The EELVs are very good at what they were designed to do, but the CEV is not a Lacross or a Navstar, and the loss of a launch vehicle (regardless of whether the crew survives or not) is not simply a financial write-off, but a national disaster that treatens the very existance of the manned space program.

The fact is, the CLV will be an entirely new vehicle because no existing LV in the world today could fulfill its requirements without significant modifications. With that in mind, NASA is taking the tack that any new vehicle should be driven by safety, regardless of whether it is the best from a cost or performance perspective. I'm reall pround of NASA for doing this, and hope that they don't back down simply because of slight cost issues (or political pressure to use the EELVs)...

Simon
#147 by Kayla on 23 Apr, 2006 13:26
As in most things ESAS, the reliability numbers were skewed to favor SDLV. These reliability numbers are coming from the same folks that gave us 1 in 10,000 for the Shuttle back in the 1980’s. I believe that they are still carrying 1 in 200 for Shuttle. I’m not trying to knock the Shuttle’s reliability record here. There are lots of different ways to account for the numbers, but the most optimistic is 1 in 87 based on the continuous successful streak prior to Columbia. For the launch vehicle industry 1 failure in 87 is very good but it is not the calculated 1 in 200. Now start with a new launch vehicle (as CLV is) and tell me that the folks at MSFC can do better analysis on CLV than they can for the veteran Shuttle?

Let’s look at the specifics in ESAS regarding reliability numbers:
1)   Existing EELV’s can’t close black zones. Bogus. EELV’s can shape their trajectories to satisfy NASA’s re-entry requirements. The trajectory folks at MSFC, JSC and KSC have conducted analysis corroborating this.
2)   Failure of the RL10 to start is a catastrophic failure. The RL10 engine has proven to be an extremely reliable engine dating back to the 1960’s. It has a low operating pressure, low temperatures and low turbine speeds. The catastrophic failure modes are few and far between. In some 30,000 hot fires and 400 flight engines there has only been 1 catastrophic failure. Specifically regarding start, AC-70 and 71 each had an engine fail to start. The engine had frozen N2 in it and couldn’t rotate, process changes eliminated this failure mode. Although this resulted in mission failure it would have been a benign environment from with the CEV could escape.
3)   ESAS assumes no benefit from engine out. The wide body Centaur option, proposed for all evolved Atlas’s, has sufficient control authority and performance to accommodate engine out from Start. In a start failure (or almost any other RL10 failure) the mission would still be successful. ESAS completely ignored any engine out ability for EELV’s. Somehow, however, NASA is assuming human rating the RL10 for the LSAM and taking advantage of engine out!
4)   The structural margins on EELV’s do not meet NASA’s required 1.4 factor of safety. The EELV’s were designed as a family of rockets. For Atlas V, the structure was designed to a factor of safety of 1.2 for the most demanding mission driven by the high dynamic pressure and acceleration of the Atlas 551. The Atlas HLV was proposed as the current Atlas V variant for launching CEV. Due to the low acceleration and low maximum dynamic pressure the structural factor of safety for this vehicle is over 2 (booster and Centaur)! But ESAS specifically states that EELV’s do not have the required structural margins. The Atlas Phase 2 single stick would also be designed with a launch vehicle family in mind and have even great structural margin in the single body configuration.
5)   ESAS puts the loss of mission estimate for the Atlas HLV at 1:149 while the Atlas Phase 2 single stick at 1:134. The Atlas phase 2 was specifically designed to be more reliable then the existing Atlas. The Atlas Phase 2 has 2 RD180s (3 for HLV), no separating LRBs (HLV has 2 LRB separation events) and the Atlas Phase 2 has partial engine out accommodation for the RD180s and full engine out on the RL10. The simplicity of the Phase 2 intuitively says it should be much more reliable.
6)   Although no longer part of NASA’s baseline, ESAS assumed an SSME for the upper stage on CLV. The SSME is truly the race horse of rocket engines. It is a high pressure, high speed machine. Yet ESAS assumes that there are no catastrophic failure modes during start. Likewise, ESAS assumes that the start failure rate is 1:3,333. Over the course of 116 (or so) Shuttle missions (348 engines) the Shuttle has had to abort 8 missions due to the lack of an SSME to start. From this one can derive the SSME as having a start failure rate of 1 in 44. As an air started engine, the lack of the engine to start is mission failure.

I can go on and on about miss representation in ESAS from reliability to cost to performance. Bottom line was the ESAS team was given an answer. Their job was to provide justification to pursue that answer.

I for one am cynical regarding calculated failure analysis. This sort of analysis does well for what one knows and can model. However, it has trouble with the unknowns. Historically, the design of a rocket hasn’t been the issue; it is the process of actually building the parts, assembling them into a launch vehicle and the environment. It is this environment that got Challenger and AC70 & 71 into trouble. It was the process for Columbia. Non of these are included in the reliability calculations.

I trust a rocket that is flying on a regular basis and can actually demonstrate its reliability. CLV, being designed strictly to fly crew to LEO will only fly 3 or 4 times per year. The CaLV will be lucky to fly twice per year. These rockets will never build up a sufficient number of flights to get a good handle on their actual reliability.

Having a common rocket support NASA exploration, robotic, science, the DoD missions and commercial satellites is the only way to build up sufficient rate to truly demonstrate the reliability of the rocket!!!

I’m not supporting EELVs or their derivatives strictly for their cost savings (which is huge), I’m supporting them because they are the more reliable solution!!!
#148 by Jim on 23 Apr, 2006 13:36
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simonbp - 23/4/2006 12:57 AM
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Jim - 22/4/2006 11:03 AMPolitics
Actually, it was safety.On page 382 of the ESAS, there is a summary table of different Crew Launch Vehicle designs, including man-rated heavy versions of both EELVs, a 5.4 m and a 8 m Atlases, and the two SRB CLVs (4-seg SSME and 5-seg J-2). The probability for Loss Of Mission for the heavies is about 1 in 150; 1 in 134 for the 5.4 m; and 1 in 79 for the 8 m. The SRBs, though, both have a LOM of about 1 in 450. With numbers like those, the baseline CLV makes the EELVs look like genuine deathtraps...Now, these numbers might be wrong, and if so please show me evidence to the contrary, but what we are talking about here is crew safety. The EELVs are very good at what they were designed to do, but the CEV is not a Lacross or a Navstar, and the loss of a launch vehicle (regardless of whether the crew survives or not) is not simply a financial write-off, but a national disaster that treatens the very existance of the manned space program.The fact is, the CLV will be an entirely new vehicle because no existing LV in the world today could fulfill its requirements without significant modifications. With that in mind, NASA is taking the tack that any new vehicle should be driven by safety, regardless of whether it is the best from a cost or performance perspective. I'm reall pround of NASA for doing this, and hope that they don't back down simply because of slight cost issues (or political pressure to use the EELVs)...Simon

Politics hiding behind precieved safety numbers. It is a case of generated reliability numbers to make a case (basically, how to lie with statistics) CLV is a jobs program, plain and simple It is the opposite of your last line. The ESAS uses politics in its favor, it keeps jobs in Huntsville, Utah, Florida, Louisana.
#149 by Jim on 23 Apr, 2006 14:24
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impulse - 22/4/2006 7:30 PM

1: Who says Centaur is the key? What about D-IV 2nd stageKnock yourself out- but I think you will not like the B2 engine quite as much and a dual engine variant is not possible.

2. Steel ballon around the ISS. Better to have a structurally stable Centaur/upperstageLets see- that steel balloon is what got you the performance you needed to do this cheap. Anything else is a strict payload compromise and you get to pay for that. Lets recalibrate here- an upper stage is the ultimate racing car. It must deliver astounding delta V and not weigh anything. You can insist on inefficient structures but you get to pay for that in additional complexity elsewhere. Like a higher Isp engine or a lighter avionics suite. Simple lightweight structures are cheap and well understood. Why on earth would you ever move the weight burden over to a more complicated system? Around ISS the tank pressures are maybe 5-10 psia- for a tank designed for over 50 psia. Not enough margin for you?

3. EELV upperstages donot have the right sized engines for rendezvous nor proper number of thrusters.Adding thrusters to do 6 DOF operations is a trivial task using hardware that has already been flown. If you insist on rapid motion because you are an impatient pilot then you get to pay for that. As it is we can handily maneuver Centaur with 9lbf thrusters- we used to do it with 6lbf. For a vehicle that weighs many tons fueled with a variable Cg. Delta V on orbit can be done with larger thusters in the Aerojet stable.

4. Avionic integration would be a nightmare. EELV avionic only can fly the upperstage. You want the CEV to control the upperstage for rendezvous?I can think of at least four solutions to this but recall that thrusters are commanded by an RCU that talks over a 1553 bus to a computer. With proper software you can hand over command to whatever computer you want to use. That is the beauty of a bus. The CEV will already be on this bus anyway so that you can watch the data and controls from the Centaur FTINU.5. Minor mods were for days not months onorbit for the cryo stage.This all depends on whether you plan on keeping cryos on board near ISS. Given that they are not required I would dump em. then you got no worries. Just about the worst cryo storage place within 1 AU of the sun is docked to the ISS. You cannot control vehicle attitude and are in a high heating environment clamped to a hot structure. Once you remove these constraints then all sorts of possibilities emerge. Storing LH2 in an arbitrary state is hard and expensive. Storing it with forethought about the environment is not that tough. It is far easier to store ice cream in an Alaska winter than in an Arizona summer.

6. The sub orbital injection by the CLV was for 2nd stage disposal, which would be used for EELV'sUnlike CLV the upper stage is light enough to take to orbit. It stays there until the CEV is ready to come home. Then you dump it like a Progress. The thing only weighs 2.5t and is a balloon as you said. Can't imagine a more "burn-up able" machine.

7. The CEV is designed for going to the moon. Additional mission is to go to the ISS. Moon drives the requirements, ISS gets what it can.This is certainly a laudable goal but as of right now the storable system is a major compromise that had to be done to meet an ISS schedule- not a lunar task. This is a prime example of a cart before the horse decision. NASA will have their hands full just getting the CEV CM done inside the schedule. Everyone knows the storable decision was a major loss to extensibility for real Lunar and Mars missions. Eventually you must make a cryo system. It will cost hundreds of millions to develop an essentially dead-end stage. Why would you EVER do this? Only because the CLV is not up to the job- it is a suborbital gizmo and NEEDS another stage to complete the real job. But to set the record straight it was never proposed to send an existing Centaur on a Lunar mission as a TLI stage. That too is a bad idea. What was proposed was the design of the Phase 1 Wide Body Centaur to do that task. That vehicle uses all existing technology and could be completed and flown multiple times long before the CEV CM ever is even ready for flight. It has the most reliable engines and a flight proven avionics suite. If you want to do a basic lunar mission it is a piece of cake to use even existing systems like the RCS. If you insist on jumping right into 180 day lunar orbit durations you will need a fancier propulsion system which also does not require magic but is more sophisticated. Total propellant load with boiloff reserves: 10mt. Yep this machine is half the size of a regular Centaur. If I was proposing crazy sh*t then I could see NASA spending $10 billion to get a much better CLV. The present CLV architecture is worse along nearly every assessment axis: cost, performance, demonstrated reliability, development risk etc. The present NASA course is not rational for sensible, risk-averse people. It is fraught with gratuitous new hardware and untested teams. Please note this: the American people are a patient bunch when they believe you are doing the right thing for the right reasons. If, however, you are abusing this trust by making insider interest based decisions there can be a terrible price to pay. NASA is risking not only a bunch of money but its future on this vision.

Can tell you work for LM. But anyways

1. Centaur and D-IV use the same engine. Just different nozzle. Any issues affecting one will affect the other. Dual engines for the Centaur only but a little extra thrust but not reliability or engine out capability

2. Mass fraction of the Centaur is not that much different than the Deltas. I have a chart from LM (at work) that shows this. It isnt worth the headaches for manrating. Also LW is going to structurally stable for future variants.

3. those thrusters are to small for small orbit change and the RL-10 is too big. Need mid range thrust and not thrusters

4. LM avoided any interconnection between OSP and Centaur stating too expensive and hard. Would have to start from zero to do this. Major software changes were just one thing.

5. Your proposal was long term storage. What would the CEV do for ISS undocking and deorbit, if no long term storage?

If it is a plausable option, why hasn't LM come forward with it. Never seen it in any studies.
#150 by Kayla on 23 Apr, 2006 15:30
NASA should learn from our current reliance on Soyuz and Proton that relying exclusively on a single rocket is nonsense. Since Columbia we have only had 2 Astronauts at ISS because of the lack of a US launch capability to the ISS. This is actually driven by lack of cargo. We have reduced the ISS to a holding pattern as we strive to recover.

In the future if we want a robust human space program in LEO or beyond we must have two launchers to maintain an assured access to space. At the development cost & schedule of the CLV we are stuck with nothing for the next 8 years, and then optimistically we will have 1 rocket at $500M/launch. Use of the EELV’s will allow 10 launches of the CEV for the same price as 4 launches of the CLV.

NASA should immediately contract with both Boeing and Lockheed Martin for crew and cargo launches on EELV supporting initially ISS and hopefully much sooner than 2018 for exploration missions. If other rockets are developed, and are reliable they should also be able to compete for this business.
#151 by Kayla on 23 Apr, 2006 15:31
NASA should learn from our current reliance on Soyuz and Proton that relying exclusively on a single rocket is nonsense. Since Columbia we have only had 2 Astronauts at ISS because of the lack of a US launch capability to the ISS. This is actually driven by lack of cargo. We have reduced the ISS to a holding pattern as we strive to recover.

In the future if we want a robust human space program in LEO or beyond we must have two launchers to maintain an assured access to space. At the development cost & schedule of the CLV we are stuck with nothing for the next 8 years, and then optimistically we will have 1 rocket at $500M/launch. Use of the EELV’s will allow 10 launches of the CEV for the same price as 4 launches of the CLV.

NASA should immediately contract with both Boeing and Lockheed Martin for crew and cargo launches on EELV supporting initially ISS and hopefully much sooner than 2018 for exploration missions. If other rockets are developed, and are reliable they should also be able to compete for this business.
#152 by Jamie Young on 23 Apr, 2006 15:34
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Kayla - 23/4/2006 10:30 AM

NASA should immediately contract with both Boeing and Lockheed Martin for crew and cargo launches on EELV supporting initially ISS and hopefully much sooner than 2018 for exploration missions. If other rockets are developed, and are reliable they should also be able to compete for this business.

So why are Boeing and Lockheed happily taking the millions off NASA to compete for the CLV/CEV etc? Why don't they come out and say "look, the plan in the ESAS isn't going to work. Here is what we suggest. Go with our suggestions or we're not going to get involved with the CLV."

Sure, business is business, but hasn't Lockheed being here before the X-33. Knowing it wouldn't work, but happy to take NASA money. When it came to them going on their own without NASA money, they pulled the plug. Is this going to happen again here?
#153 by James Lowe1 on 23 Apr, 2006 15:41
I think what Jamie is asking is have these companies protested the plans, with a suggestion of better concepts?
#154 by Bruhn on 23 Apr, 2006 16:46
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Kayla - 23/4/2006 8:26 AM

Now start with a new launch vehicle (as CLV is) and tell me that the folks at MSFC can do better analysis on CLV than they can for the veteran Shuttle?

I can say with overwhelming confidence that the answer to this question is YES. I say that because comparing the CLV to the STS analytically is apples to oranges. A rocket is an order of magnitude easier to analyze than something as complex as STS was. A rocket can be analyzed with 1960s technology. You know the Saturn 1/1B was much harder to analyze than the Saturn V was with the Redstone and Jupiter tanks strapped together. In the late 50's early 60's, analyzing the coupled dynamics of those tanks strapped together was a challenge.

There was no way a STS could be designed until the technology in analytical tools and computer technology was developed. Now you fast forward to today, and we are building a comparatively easy vehicle (analytically) AND we have all the latest analytical tools, AND we have all the heritage data, lessons learned, etc. So logically, the answer to your question is YES, MSFC can do better analysis on CLV than on STS.
#155 by Tap-Sa on 23 Apr, 2006 16:47
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Kayla - 23/4/2006 5:26 PM
Likewise, ESAS assumes that the start failure rate is 1:3,333. Over the course of 116 (or so) Shuttle missions (348 engines) the Shuttle has had to abort 8 missions due to the lack of an SSME to start. From this one can derive the SSME as having a start failure rate of 1 in 44. As an air started engine, the lack of the engine to start is mission failure.

Whaaat? Is this figure really somewhere in the ESAS report? If so then clearly it's from the same bogus factory that produced STS probability. Just what is that 80s STS probability times three Figures this round indicate that they have no real calculated origins, they just fell out of the sky when someone wished for a number indicating high reliability.

In addition to the actual SSME start failure rate mentioned in the quote, how can ESAS assume such stellar start reliability for airstarted SSME when the concept itself seems to turn into no-start? IOW how can you reliably quote probabilities to certain technology when you aren't even sure if it's doable?

So much for 1 in 450. Boeing and LM should contract Futron to come up with study stating EELV LOM figure of ... uh ... err ... 1 in 673! I'll allow Futron to quote me on that. Just between you and me, that too fell out of the sky, but at least it looks scientific and computed
#156 by Tap-Sa on 23 Apr, 2006 17:10
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James Lowe1 - 23/4/2006 7:41 PM

I think what Jamie is asking is have these companies protested the plans, with a suggestion of better concepts?

What reason would these companies have to guide NASA to do manned spaceflight 'right' ? They get their money anyway.

All the 'better' concepts have fundamental 'flaw'; they mean that many people, mainly at NASA, loose their jobs. And that seems to be ultimate no-no. Which is strange, given how large corporations have no problem sacking tens of thousands on a whim.
#157 by Kayla on 23 Apr, 2006 18:26
I haven’t stated anything about disagreeing with the CEV.

With regard to the CLV/CaLV industry has worked with NASA on EELV derived alternatives. However, with the change in the guard at HQ a year ago, it was made clear to industry that any company not directly supporting SDLV will not win future contracts (CLV, CEV, LSAM, everything) supporting exploration. With that threat industry has pulled back alternatives that are believed to be superior. No company can afford to be shut out of a market as large as exploration, even if they believe that better alternatives exist.
#158 by Chris Bergin on 23 Apr, 2006 18:45
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Kayla - 23/4/2006 7:26 PM

With regard to the CLV/CaLV industry has worked with NASA on EELV derived alternatives. However, with the change in the guard at HQ a year ago, it was made clear to industry that any company not directly supporting SDLV will not win future contracts (CLV, CEV, LSAM, everything) supporting exploration. With that threat industry has pulled back alternatives that are believed to be superior. No company can afford to be shut out of a market as large as exploration, even if they believe that better alternatives exist.

I've heard this a couple of times from Lockheed people and even NASA people. All the eggs in one basket, when the basket has holes in it, leads to a mess on the floor.
#159 by Tap-Sa on 23 Apr, 2006 19:24
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Kayla - 23/4/2006 10:26 PM
However, with the change in the guard at HQ a year ago, it was made clear to industry that any company not directly supporting SDLV will not win future contracts (CLV, CEV, LSAM, everything) supporting exploration.

Isn't there legistlation to prevent this kind of tyranny. This is clearly skewing of competition.