Author Topic: (CONT): CLV - ONE J-2X Engine (not two J-2S)  (Read 50358 times)


Online Chris Bergin

RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #1 on: 04/08/2006 03:07 AM »
Last two comments from the locked (broken) thread:

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simonbp - 7/4/2006  9:49 PM

And at this point (prior to cutting any metal), you'd rather change the LV (or not change as the case may be) than drop mission requirements or conscienously leave a safety loophole...

Simon ;)

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SMetch - 8/4/2006  12:54 AM

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Jim - 7/4/2006  12:01 PM

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SMetch - 7/4/2006  2:37 PM
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Jim - 7/4/2006  11:24 AM"Delta IV wasn’t optimized for LEO it was optimized to send things intohigh orbit like where we are now try to go, for example the Moon."

This even makes the abort issue worse
I agree that there were few good options with regards to the heavy OSP.  A correctly sized CEV with a correctly sized man rated upper stage used for EML1 injection or abort will work with the EELV’s optimal trajectories.

That is the issue:  EELV’s optimal trajectories and manrating for aborts are incompatible

With a man rated vehicle capable of over 3,000 m/s DV after abort it’s not any issue.  The OSP was too heavy to have this high of a percentage of fuel after abort.  As such the only safe Delta IV trajectories were direct insertion ones which in turn required a higher thrust to lift ratio than the Delta IV as optimally designed for.  To get that higher thrust to weight ratio required the dumping of payload.

The OSP and CEV with an EML1 insertion stage are not the same thing.  The combined package may have the same mass at lift off but one is much less dependent on the main launch vehicle.  As such a more lofted trajectory can be used with the EML1 stage serving as an emergency abort module instead of its primary role as an EML1 injection stage.


Offline Jim

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #2 on: 04/08/2006 02:05 PM »
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SMetch - 7/4/2006  2:37 PM[With a man rated vehicle capable of over 3,000 m/s DV after abort it’snot any issue. The OSP was too heavy to have this high of a percentageof fuel after abort. As such the only safe Delta IV trajectories weredirect insertion ones which in turn required a higher thrust to liftratio than the Delta IV as optimally designed for. To get that higherthrust to weight ratio required the dumping of payload.

I am talking about mid fight aborts with the use of an escape tower.  These crushed the astronauts.

Offline MartianBase

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #3 on: 04/10/2006 01:28 AM »
Thanks Chris, I'm keen on seeing what's going on with these J-2X

but I'd  just like to go back to an earlier post on costs of the CEV+CLV and the reported hikeby nasawatch
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SMetch
   
Posted 6/4/2006 5:43 PM (#29546 - in reply to #29479)
Subject: RE: CLV - ONE J-2X Engin


publiusr - 6/4/2006 11:13 AM

Over at www.nasawatch.com is a claim from a 'reliable' source that the SRB mods would cost 1-3 billion. I wonder where that is coming from, and if it is even real.


It’s looking worse for the SRB based CLV.

NASA now needs to achieve a 57% lower $/kg in order to compete with Delta IV Heavy with that level of up front cost.

Then again ISS crew flights minus the fuel in the SM for EOI could be launched via a Delta IV Medium. At which point they would need to be 97% cheaper.

It seems to me we need to redirect the money currently going to the CLV to the Shuttle Derived Heavy Lift Vehicle.

Its beginning to feel like 80% of ESAS recommendations won't survive to the end of the year. I'll give the remaining 20% until 2008.

Methane Engines – Gone (Hypergolic)
Air Start SSME – Gone (New engine a J2 in name only)
5.5 Meter CEV or “SUV” – Gone (5 Meter maybe smaller)
4 Segment SRB CLV – Gone (5 Segment SRB CLV)
25MT Class SRB CLV – Prediction (Delta IV Med-ISS & Delta IV Heavy-Lunar)
EOR-LOR – Prediction (L1 Rendezvous – Direct Return)
4 Crew to Moon – Prediction (2 Crew to Moon)
Inline SDHLV with SSME's - Prediction (Shuttle-C with RS-68)

Then again maybe we'll let the Chinese beat us back to the Moon. They aren’t as constrained in their thinking as we are.

“We can’t go back to the Moon, not with the technology we have today.”

Has it really jumped from 1 billion to 3 billion or is that an exaggeration?

Offline Smatcha

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #4 on: 04/10/2006 03:17 PM »
Basically ATK is getting the US taxpayer to develop a yet another 25K class US based launcher.  We have two already why not three?  All the while we are dismantling the only heavy lift infrastructure we have now and will desperately need if we are every going to leave the gravity well of the Earth with men.

http://www.usspacenews.com/index.html

“We also have to do a considerable amount of analysis to make sure it's safe, and that we have not introduce an unknown into the SRBs performance.”

I can’t wait for when this one comes home to roost.  The CLV is top heavy already and getting worse with the new extension.  Its high center of gravity is approaching know control limits hence the addition of those side thrusters and fins you see in the design.  Then there is the matter of the crew access and LOX/LH2 stages being higher than the current tower.

Were are all the LockMart and Boeing lobbyists when you need them?

It’s a bad design that ignores current capabilities at the expense of what we desperately need.

Other than that its great.

“Do we want to go to the moon or not?”
John C. Houbolt - November 15, 1961
Question posed in Letter to Dr. Robert C. Seamans Jr, NASA Associate Administrator

Ralph Ellison “I was never more hated than when I tried to be honest”




Offline Smatcha

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #5 on: 04/10/2006 03:37 PM »
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Jim - 8/4/2006  7:05 AM

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SMetch - 7/4/2006  2:37 PM[With a man rated vehicle capable of over 3,000 m/s DV after abort it’snot any issue. The OSP was too heavy to have this high of a percentageof fuel after abort. As such the only safe Delta IV trajectories weredirect insertion ones which in turn required a higher thrust to liftratio than the Delta IV as optimally designed for. To get that higherthrust to weight ratio required the dumping of payload.

I am talking about mid fight aborts with the use of an escape tower.  These crushed the astronauts.

How is an escape tower abort off of an SRB based main stage different than a Delta?

How is an escape tower abort from a lofted trajectory different than a direct injection?

In our design, the escape towers role is to just get the crew away for the main vehicle as quickly as possible staying within their G limits, as all abort systems must do.  It’s the EML1 stages job then to either continue to Abort to Orbit or to shallow out the reentry at lower altitudes and speeds.  We fully understand that a lofted trajectory needs modification prior to CEV reentry in an abort situation at certain regions along its trajectory.  We are not “slamming” the CEV into the atmosphere at any point or under any abort scenario.

In summary, these issues are well understood and can be solved when your primary vehicle has a significant +3,000 m/s DV thrust capacity on board unlike the OSP.

Controlling a slender SRB based booster with such a large distances between its center of thrust, center of gravity and center of aerodynamic load on the other hand is not.
“Do we want to go to the moon or not?”
John C. Houbolt - November 15, 1961
Question posed in Letter to Dr. Robert C. Seamans Jr, NASA Associate Administrator

Ralph Ellison “I was never more hated than when I tried to be honest”




Offline kraisee

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #6 on: 04/10/2006 07:14 PM »
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SMetch - 10/4/2006  11:17 AM
The CLV is top heavy already and getting worse with the new extension.


While I agree that ATK is thoroughly gouging the taxpayer for this project, I don't think the Delta or Atlas derivatives are better.   Go have a look at the safety section of the ESAS report.   The pure numbers for how likely a liquid engine is expected to fail compared to SRB's is quite an eye-opener.   A single liquid engine like the extremely reliable SSME, is expected to fail about 5 times more often than an SRB.   The more liquid engines you use, the more likelyhood for failure too.   Add to that, liquid engines have far more catastrophic failure scenarios than SRB's do too, and I do think SRB's aren't a bad choice at all.

Also, there is one little thing which I'd like to correct...

Each of the segments in the SRB masses about 130 metric tons.   With the motor, and all the other items required, a the 5-seg SRB masses 731mT.

The Upper Stage "looks" bigger, but even when fully fuelled, it still masses only 144mT - which is only a little more than each segment of the SRB.

There's another 27mT of CEV and LES on top of that, but whichever rocket you use, you're going to need that :)

"The Stick" may appear a little unconventional, but it isn't "top heavy".

Ross.
"The meek shall inherit the Earth -- the rest of us will go to the stars"
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Offline dmc6960

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #7 on: 04/10/2006 07:16 PM »
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SMetch - 10/4/2006  10:37 AM

How is an escape tower abort off of an SRB based main stage different than a Delta?

How is an escape tower abort from a lofted trajectory different than a direct injection?

In our design, the escape towers role is to just get the crew away for the main vehicle as quickly as possible staying within their G limits, as all abort systems must do.  It’s the EML1 stages job then to either continue to Abort to Orbit or to shallow out the reentry at lower altitudes and speeds.  We fully understand that a lofted trajectory needs modification prior to CEV reentry in an abort situation at certain regions along its trajectory.  We are not “slamming” the CEV into the atmosphere at any point or under any abort scenario.

In summary, these issues are well understood and can be solved when your primary vehicle has a significant +3,000 m/s DV thrust capacity on board unlike the OSP.

Controlling a slender SRB based booster with such a large distances between its center of thrust, center of gravity and center of aerodynamic load on the other hand is not.

I dont believe you are understanding the problem SMetch.  If I'm understanding Jim correctly, the most energy efficient way into orbit, is up, then over.  This is why the upper stage engines on Delta IV require less thrust than the weight of the payload they are propelling.  If you put a manned spaceship on this trajectory, you would already be pushing your G-limits during the initial ascent.  If an abort becomes necessary, the acceleration required on top of what was already occuring for a safe abort, became lethal.

If you changed the trajectory to go both over and up from the get go, acceleration for abort is now possible without being lethal, but you've lost launch vehicle performace. This loss of performace brought Delta IV to its very limits of lifting which is what gave OSP some of its problems. This is why the EELV have been frowned upon for manned lift this go-around.  Am I right Jim?  (nice name BTW).

I also dont understand why you're talking about having 3000 m/s DV on the vehicle after escape?  Only the command module will be ejected with an escape tower, NOT the service module.  There goes all your DV.  I also dont understand your "slamming into the atmoshpere"  statement.  What you are slamming is people's guts, into the backs of the people, under an escape option from an optimal Delta IV trajectory.
-Jim

Offline kraisee

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #8 on: 04/10/2006 07:48 PM »
Not to mention that for a regular 20+mT EELV, the cost is still very high - $254m per flight - and that is for the non-man-rated version too.   Man rated ones would cost a lot more AND are not as safe as "The Stick" according to industry trade studies.   See p. 507 (Section 6.11.1) of the ESAS report for some of the trade study results into these different vehciles.

If "The Stick" costs anywhere near the $100m per flight they keep on talking about, it'll pay for itself veryy quickly, even with the extra $2Bn in development costs.

Ross.
"The meek shall inherit the Earth -- the rest of us will go to the stars"
-Robert A. Heinlein

Offline BogoMIPS

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #9 on: 04/10/2006 08:08 PM »
Hi everyone.

Assuming the NasaWatch article about the CLV cost balooning from $1Bn to $3Bn is accurate (probably is), is it safe to assume that a large chunk of that cost has to do with the 5th segment, and the different propellant?

Maybe ATK/NASA should concentrate on a proof of concept with the as-is 4-segment booster with the necessary modifications (forward skirt, RCS, etc.) first.  Granted, such a launcher may not be adequate for the CEV's lunar mission, but the vehicle seems to have the necessary capabilities for the ISS.

Also, if the cost per launch and pLOV are as much lower for these vehicles as ESAS has claimed, then I'm sure the commerical launch industry would latch onto the vehicle quickly as a cheaper, safer options for orbiting unmanned payloads.

Doesn't solve the problem of getting us back to the Moon, but keeps us in LEO.

Offline hyper_snyper

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #10 on: 04/10/2006 08:14 PM »
The inflation in cost is due to the 5th seg addition.  Which doesn't make any sense to me.  As was stated elsewhere, ATK should internalize some of this cost, it shouldn't overburden an already buckling NASA budget.

Also, if launching the CLV is supposed to be relativley inexpensive shouldn't it pay for itself after a few launches?

Offline kraisee

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #11 on: 04/10/2006 08:33 PM »
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BogoMIPS - 10/4/2006  4:08 PM

Hi everyone.

Assuming the NasaWatch article about the CLV cost balooning from $1Bn to $3Bn is accurate (probably is), is it safe to assume that a large chunk of that cost has to do with the 5th segment, and the different propellant?

The news article Chris wrote today about the Lunar Reference Architecture coming in too heavy to be sent to the moon as-it-is, also mentions that the SRB's are going back to the same fuel as currently used on Shuttle SRB - PBAN instead of the newer HTPB.   I'm guessing this is a cost issue being "announced" as quietly as can possibly be done.   Oops, I just made it noticable.   Sorry.   ;)

Personally, I think ATK is price-gouging for all its worth.

They have already been allocated (not bid for) the contract to produce the CLV's SRB's, and the CaLV is already polanned to use precisely the same boosters too.   So I'm betting they feel ultra-confident they are the only organisation NASA can turn to in order to produce the SRB's in time for NASA to fly CEV by 2014.   Knowing that, I believe they are reaming the taxpayer for all they can squeeze out.

I don't know what the solution is, but I think NASA should take control of the SRB R&D program itself.   ATK should be relegated to merely a "metal bender" to build the casings and motor components to NASA specifications.   That way NASA can contract-out the work to whomever they want if costs start balooning rediculously out of control like seems to be occurring at present.

For that matter, I think that's the approach NASA should be taking for managing all the elements of the VSE.

I for one am getting real sick of the vast expense the "contractor empire" charges for their work.   It is certainly not competative *at all*, and seems to be hugely expensive for the items they turn out.   Its amazing just how much money it makes for these compains though...

Ross.
"The meek shall inherit the Earth -- the rest of us will go to the stars"
-Robert A. Heinlein

Offline kraisee

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #12 on: 04/10/2006 08:37 PM »
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hyper_snyper - 10/4/2006  4:14 PM

The inflation in cost is due to the 5th seg addition.  Which doesn't make any sense to me.  As was stated elsewhere, ATK should internalize some of this cost, it shouldn't overburden an already buckling NASA budget.

Also, if launching the CLV is supposed to be relativley inexpensive shouldn't it pay for itself after a few launches?

If ATK are going to triple development costs, I want to hear some real specifics as to WHY.

They are, after all, the organisation which proposed "The Stick" in the first place, and who did ALL the original pre-ESAS costing estimates for this entire plan.   They have said all along, amazingly until they got a contract in their sticky hands, that this could be done for one figure, and now they want triple?

There's such a fishy smell about this...   Anyone else noticing it?

Ross.
"The meek shall inherit the Earth -- the rest of us will go to the stars"
-Robert A. Heinlein

Offline Jim

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #13 on: 04/10/2006 09:44 PM »
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SMetch - 10/4/2006  11:37 AM How is an escape tower abort off of an SRB based main stage different than a Delta?
No different
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How is an escape tower abort from a lofted trajectory different than a direct injection?
 Big difference

It has nothing to do with the actual escape rockets.
It has nothing to do with the acceleration of the vehicle at the time of abort.
It has nothing to do with how much DV you have in the upperstage and whether it is direct or suborbital injection.  Those are end state differences.

 It all has to do with velocity vs altitude in the early parts of the  trajectory

The black line is a EELV trajectory.  It flies steeply to get out of the Earth's gravity well and then uses its efficent low thrust second stage engine.  Unfortunately, aborts like the red line, subject the crew to unsurvivable g-loads.   The aqua line is the shallow traj of the shuttle and SRB CLV.  Aborts are similar to the blue, where the g-loads are less stressful.

EELV's, with modified shallow trajectories, lose 25-33% of their standard lift capability.



Offline mkirk

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #14 on: 04/10/2006 11:11 PM »
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Jim - 10/4/2006  4:44 PM

Quote
SMetch - 10/4/2006  11:37 AM How is an escape tower abort off of an SRB based main stage different than a Delta?
No different
Quote
How is an escape tower abort from a lofted trajectory different than a direct injection?
 Big difference

It has nothing to do with the actual escape rockets.
It has nothing to do with the acceleration of the vehicle at the time of abort.
It has nothing to do with how much DV you have in the upperstage and whether it is direct or suborbital injection.  Those are end state differences.

 It all has to do with velocity vs altitude in the early parts of the  trajectory

The black line is a EELV trajectory.  It flies steeply to get out of the Earth's gravity well and then uses its efficent low thrust second stage engine.  Unfortunately, aborts like the red line, subject the crew to unsurvivable g-loads.   The aqua line is the shallow traj of the shuttle and SRB CLV.  Aborts are similar to the blue, where the g-loads are less stressful.

EELV's, with modified shallow trajectories, lose 25-33% of their standard lift capability.




That is a good explanation Jim!

I get asked this question a lot and some how I always end up in discussion of energy mangement, high and slow, black zones, g loads, etc...It would have taken me 2 pages to say what you said with a couple of colored lines and a few sentences.

Mark Kirkman
Mark Kirkman

Online wannamoonbase

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #15 on: 04/10/2006 11:59 PM »
Looks like the best answer (which I greatly dislike) is not sending humans into space  :(
SpaceX, just a few things planned for 2018: FH, Starlink Prototypes, Block 5, Dragon 2, Increased launch rate.

Offline Avron

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #16 on: 04/11/2006 03:28 AM »
Quote
kraisee - 10/4/2006  4:37 PM

There's such a fishy smell about this...   Anyone else noticing it?

Ross.

Same old... Same old...  then who would be playing games,  there is a lot of money for the taking and the game is to take as much as you can, as fast as you can, and deliver zero in return.. the perfect buisness...

So why no two J-2S you ask? Why not two boosters, hell why not three, looks like we will be needing a lot more lift that was in the original vision, or should that just be proposal...

Specific Impulse I understand... but don't understand its meaning...

Jim.. another cool graph may help.. please..

Offline Smatcha

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #17 on: 04/11/2006 04:46 PM »
Quote
Jim - 10/4/2006  2:44 PM

Quote
SMetch - 10/4/2006  11:37 AM How is an escape tower abort off of an SRB based main stage different than a Delta?
No different
Quote
How is an escape tower abort from a lofted trajectory different than a direct injection?
 Big difference

It has nothing to do with the actual escape rockets.
It has nothing to do with the acceleration of the vehicle at the time of abort.
It has nothing to do with how much DV you have in the upperstage and whether it is direct or suborbital injection.  Those are end state differences.

 It all has to do with velocity vs altitude in the early parts of the  trajectory

The black line is a EELV trajectory.  It flies steeply to get out of the Earth's gravity well and then uses its efficent low thrust second stage engine.  Unfortunately, aborts like the red line, subject the crew to unsurvivable g-loads.   The aqua line is the shallow traj of the shuttle and SRB CLV.  Aborts are similar to the blue, where the g-loads are less stressful.

EELV's, with modified shallow trajectories, lose 25-33% of their standard lift capability.




Agreed

The ESAS report states;

“Both Atlas and Delta single-engine upper stages fly highly lofted trajectories, which can produce high “deceleration loads” on the crew during an abort and, in some case, can exceed crew load limits as defined by NASA Standard (STD) 3000, Section 5.  Depressing the trajectories flow by these vehicles will require additional stage thrust to bring peak altitudes down to levels that reduce crew loads enough to have sufficient margins for off-nominal conditions.”

The key term is “deceleration loads”

The basic problem is that if an abort occurs during the red portion of the EELV trajectory the CEV will be on a very ballistic (i.e. highly elliptical) return trajectory.  This is okay for nuclear missiles but not okay for people.  The “deceleration loads” will be extreme as the capsule effectively slams into the atmosphere.  Think of it as the difference between a belly flop off of a high board into a pool vs. releasing the handle in water skiing gradually re-entering the water.  The total kinetic energy might be the same but the experience is very different.  The reentry angle is very narrow for the CEV due to G-limits and heat shield capabilities.  

My main point is that since the CEV contains a man rated EML1 insertion stage the additional DeltaV required to make orbit during the red portions of the curve can be achieved by re tasking this stage to replace what was originally supposed to come from the now aborted main stage.

Jim, what happens when you add up to a 3200 m/s deltaV after abort from the EML1 insertion stage?

“Do we want to go to the moon or not?”
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Question posed in Letter to Dr. Robert C. Seamans Jr, NASA Associate Administrator

Ralph Ellison “I was never more hated than when I tried to be honest”




Offline Jim

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #18 on: 04/11/2006 08:59 PM »
There is no stage attached to the CEV during those aborts.  It just is the capsule.

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #19 on: 04/11/2006 09:28 PM »
Quote
Jim - 11/4/2006  1:59 PM

There is no stage attached to the CEV during those aborts.  It just is the capsule.

Exactly, run your curves with a 3,200 m/s delta V after abort.  Our trajectory models show us safely in orbit.  The mission is toast because we used the EML1 injection fuel saving the crew but that’s okay.  Mission failure “is” an Option if it means the crew survives.

In fact in the baseline CLV SRB Stick approach the CEV’s TEI stage is used to abort to orbit after the tower is jettisoned following a successful 2nd stage ignition in the advent of a latter 2nd stage failure.  The identical approach was in place for Apollo, they didn't carry their LAS all the way into orbit either.

Come to think of it the CLV stick could pursue a more lofted trajectory as well with their current design if they wanted to increase the CLV efficiency and save alot money by not needing the 5 segment SRB after all.  Of course doing that would negate a lot of the arguments as to why the EELV’s were going to kill everyone.  What a tangled web we weave when at first……
“Do we want to go to the moon or not?”
John C. Houbolt - November 15, 1961
Question posed in Letter to Dr. Robert C. Seamans Jr, NASA Associate Administrator

Ralph Ellison “I was never more hated than when I tried to be honest”




Offline Jim

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #20 on: 04/12/2006 03:30 AM »
Just talked to some people and the "black" region of the EELV trajectories was eliminated at the end of the OSP program.  The loss of lift capability was reduced from the order 25-33% to 5-15%.  Use of the suborbital injection, like the stick, would make it better.   The larger (heavies) EELV's would still be required. 




Offline Smatcha

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #21 on: 04/12/2006 03:17 PM »
Quote
Jim - 11/4/2006  8:30 PM

Just talked to some people and the "black" region of the EELV trajectories was eliminated at the end of the OSP program.  The loss of lift capability was reduced from the order 25-33% to 5-15%.  Use of the suborbital injection, like the stick, would make it better.   The larger (heavies) EELV's would still be required. 




So where do we stand?  Could the TEI stage on the SRB based CLV or the (TLI/EML1) stage on the EELV suffice to get us out of the danger zone for a safe emergency return of the crew.

If so then the Delta IV (Med for ISS and Heavy for Lunar) could be used instead of the SRB/CLV freeing up funds to develop truly non-inventory items like the LSAM.  “Lunar Sooner” as opposed to "Lunar Latter" or maybe "Lunar Never".

Or maybe the Chinese will do something to kick us into high gear just like Sputnik did.

“You can waste anything except time and the crew.”
“Do we want to go to the moon or not?”
John C. Houbolt - November 15, 1961
Question posed in Letter to Dr. Robert C. Seamans Jr, NASA Associate Administrator

Ralph Ellison “I was never more hated than when I tried to be honest”




Offline Jim

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #22 on: 04/12/2006 03:23 PM »
The current CEV.

Medium class EELV's (especially Deltas) will never work

Heavy class or modifications to put the current CEV LEO.

Adding more upperstages would muck them up and doesn't help the aborts.  Makes them worst - Lower thrust to weight ratios in the lower stage.

Offline Manel

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #23 on: 04/12/2006 10:51 PM »


Why build the CLV ?

An External Tank with 3-4  RS-68  (no solids)  plus a Service Module with a delta V of 3.500 fps suffices to orbit the CEV

Get rid of the Stick!

Offline R&R

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #24 on: 04/12/2006 11:14 PM »
Quote
Jim - 13/4/2006  9:23 AM

The current CEV.

Medium class EELV's (especially Deltas) will never work

Heavy class or modifications to put the current CEV LEO.

Adding more upperstages would muck them up and doesn't help the aborts.  Makes them worst - Lower thrust to weight ratios in the lower stage.

What's the problem with the Medium class Delta-IV's?

Offline kraisee

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #25 on: 04/13/2006 04:13 AM »
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R&R - 12/4/2006  7:14 PM

What's the problem with the Medium class Delta-IV's?

The next-smallest Delta IV below the Heavy is the "Medium+ (5.4)".   It can only loft 13.5mT to LEO (185km, 18,5deg), and CEV is going to be more like 20-22mT.

The Atlas V (without SRB's) can only put 10.3mT into space.   SRB's boosters can be attached too, but you start adding degrees of extra complication (read: noticably less safe and noticably more expensive), but with the maximum possible five SRB's attached, you can loft 20mt.

Ross.
"The meek shall inherit the Earth -- the rest of us will go to the stars"
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Offline quark

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #26 on: 04/13/2006 06:03 AM »
The Atlas V with 5 SRB's (Atlas V 551 configuration) just launched the Pluto mission and passed a rigorous nuclear certification process (for the RTG on the spacecraft).  The SRB's are monolithic (no case joints) and very reliable.  The price increase for the solids is less than the performance increase so the price per kg is less on the 551 configuration.

The Atlas V HLV lifts 28 mT to LEO in a triple body configuration.  It has been developed but not flown.

Folks have been asking for the Atlas evolution chart.  Here is a version presented at the AIAA JPC last summer in Tuscon.  The phase 2 Atlas is a family that contains a single body vehicle perfect for the CLV (25 mT to LEO) and a three body vehicle that lifts 70mT.  This gives a three launch solution for a moon mission.  Costs are a small fraction of the current CLV budgets.  These vehicles can actually get to orbit, delivering the CEV to LEO, not a ballistic -30X100.

This whole debate of EELV vs SDLV for CLV could be settled simply and fairly with a competition (what a concept).  Let Lockheed, Boeing and ATK come to the table with firm proposals to meet NASA's requirements: performance, human rating, etc.  That was Adm Steidle's approach before Griffin fired him...


Offline quark

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #27 on: 04/13/2006 06:45 AM »
The notion that EELV's can't meet black zones is a myth propogated by ATK on their "safe, simple, soon" website.  It reflects a profound misunderstanding of the issue.  EELV trajectories are lofted to optimize performance but more fundamentally because the range safety community won't allow an initial orbit (called the parking orbit) with perigee less than 80nm.  Typical EELV trajectories target a perigee of around 90nm.  Check out the CLV stick delivery orbit: -30X100nm.  It's only an orbit if you're deep sea diving.  :)  If you fly an EELV to a low perigee transfer orbit and then do a second burn, all black zone (abort loads) issues evaporate.  And with essentially no performance loss.

Whoever thinks that the stick will cost $100M is doing serious drugs.  The SRB by itself is $100M based on shuttle data.  So, I guess if everything else is free...

Oh by the way, the ESAS study is a joke.  Put 25 shuttle guys in a room for 3 months and ask them to pick a launch system. Small wonder they came up with shuttle derived as the answer.  Especially since they're out of a job if they pick anything else.  Please, no one cite ESAS as a technical authority.  It was rigged to spit out the politically correct answer.

Without becoming any more sarcastic, let me reiterate:  the fair way to settle the debate is to hold a competition.  Let the best rocket win.

Offline gladiator1332

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #28 on: 04/13/2006 02:47 PM »
Quote
quark - 13/4/2006  2:45 AM

The notion that EELV's can't meet black zones is a myth propogated by ATK on their "safe, simple, soon" website.  It reflects a profound misunderstanding of the issue.  EELV trajectories are lofted to optimize performance but more fundamentally because the range safety community won't allow an initial orbit (called the parking orbit) with perigee less than 80nm.  Typical EELV trajectories target a perigee of around 90nm.  Check out the CLV stick delivery orbit: -30X100nm.  It's only an orbit if you're deep sea diving.  :)  If you fly an EELV to a low perigee transfer orbit and then do a second burn, all black zone (abort loads) issues evaporate.  And with essentially no performance loss.

Whoever thinks that the stick will cost $100M is doing serious drugs.  The SRB by itself is $100M based on shuttle data.  So, I guess if everything else is free...

Oh by the way, the ESAS study is a joke.  Put 25 shuttle guys in a room for 3 months and ask them to pick a launch system. Small wonder they came up with shuttle derived as the answer.  Especially since they're out of a job if they pick anything else.  Please, no one cite ESAS as a technical authority.  It was rigged to spit out the politically correct answer.

Without becoming any more sarcastic, let me reiterate:  the fair way to settle the debate is to hold a competition.  Let the best rocket win.

A competition would give us the answer, but that approach would take even more time and money. We need to start cutting some metal so we no longer have paper rockets.

I agree that the ESAS was a bit one-sided and the best polotical choice was the one selected. THe SDLV's keep several NASA centers alive and originally it looked like the Shuttle facilities at KSC would need only minor modifications to handle the new launch vehicles. Now even that it changing.

I like the "Stick" design, it seems simple, however, things are becoming much more complex than ATK originally proposed. I just hope they are correct about the estimates on safety, as that will make all of this worth it. But I think NASA should look into other concepts while they still have time. We are not too late in the game to cancel the Stick and go with something else. And possibly in the end, they may find that the Stick is the best choice.

Another thing that I am concerned about is the fact that the CEV is being designed around the launch vehicle. Instead of looking for ways to increase performance or look ofr a design that works as prmised, we are cutting dow non the CEV, and possibly shrinking the LSAM. I can't see how ATK is still a contractor when in their proposal they state our launch vehicle can do all of this, and then one year later we find that it can no longer fulfill the requirements. Yes things have changed on the CEV that have made it heavier, however, why pick a Launch Vehicle that just squeaks by in terms of ability to lift the CEV. HIstory shows that wegiht is always something that goes up, so this should have been taken into consideration when the Stick was chosen.

Offline Smatcha

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #29 on: 04/13/2006 02:53 PM »
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kraisee - 12/4/2006  9:13 PM

Quote
R&R - 12/4/2006  7:14 PM

What's the problem with the Medium class Delta-IV's?

The next-smallest Delta IV below the Heavy is the "Medium+ (5.4)".   It can only loft 13.5mT to LEO (185km, 18,5deg), and CEV is going to be more like 20-22mT.

The Atlas V (without SRB's) can only put 10.3mT into space.   SRB's boosters can be attached too, but you start adding degrees of extra complication (read: noticably less safe and noticably more expensive), but with the maximum possible five SRB's attached, you can loft 20mt.

Ross.

Yes with all the Fuel for TEI.  Why? If you are only going to the ISS.  This is yet another ridiculous design problem surrounding the stick.  The stick cannot dump payload without exceeding the G-Limits.  That’s why it must send up such a heavy combined package up to the ISS just to hold it down, whoa big stick.  Fuel for Station reboost spare me, what are we trying to do send the ISS to the EML1.  Hey not a bad idea at least it would be more useful there.

When you put in the lower cash flow for a Delta IV Med for ISS missions and a Delta IV Heavy for Lunar the NPV of the stick was bad enough at 1 Billion now it’s 3 Billion.

I agree its time to stick it to the stick.

“Do we want to go to the moon or not?”
John C. Houbolt - November 15, 1961
Question posed in Letter to Dr. Robert C. Seamans Jr, NASA Associate Administrator

Ralph Ellison “I was never more hated than when I tried to be honest”




Offline gladiator1332

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #30 on: 04/13/2006 02:59 PM »
It's just that without help from Boeing and Lockheed that will never happen.

Offline Smatcha

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #31 on: 04/13/2006 03:13 PM »
Quote
Jim - 12/4/2006  8:23 AM

The current CEV.

Medium class EELV's (especially Deltas) will never work

Heavy class or modifications to put the current CEV LEO.

Adding more upperstages would muck them up and doesn't help the aborts.  Makes them worst - Lower thrust to weight ratios in the lower stage.

There are two primary factors that need to both happen in order to make a CEV/EELV combo work.  The first is that the overall package CEV+Other weight cannot reduce the Thrust/Weight Ratio any further if anything we want to move this up.  Two, a significant portion of CEV+Other must be fuel.  As in previous posts, TEI fuel could be re-tasked in an emergency to abort the CEV into Orbit.

This abort to Orbit utilizing the attached TEI stage is nothing new.  It was and is the baseline approach in Apollo and now the Stick after Tower Jettison.  To suggest this approach to save the crew is off limits to the EELV is foolish.

Speaking of foolish, making the CEV+Other so heavy that an EELV couldn’t lift it for political reasons doesn’t make for good physics or economics either.

“Can NASA design something heavier than they can lift?”

According LRA-0 they can.

At the end of the day we are all on the same team and we want NASA to be successful.  It’s just that we are not going to get there if continue to let the politicians, both internal and external to NASA, muck this up.  A little more orbital mechanics and economics and a little less powerpoint and politics if you please.
“Do we want to go to the moon or not?”
John C. Houbolt - November 15, 1961
Question posed in Letter to Dr. Robert C. Seamans Jr, NASA Associate Administrator

Ralph Ellison “I was never more hated than when I tried to be honest”




Offline Jim

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #32 on: 04/13/2006 04:04 PM »
Quote
quark - 13/4/2006  2:45 AMThe notion that EELV's can't meet black zones is a myth propogated by ATK on their "safe, simple, soon" website.  It reflects a profound misunderstanding of the issue.  EELV trajectories are lofted to optimize performance but more fundamentally because the range safety community won't allow an initial orbit (called the parking orbit) with perigee less than 80nm.  Typical EELV trajectories target a perigee of around 90nm.  Check out the CLV stick delivery orbit: -30X100nm.  It's only an orbit if you're deep sea diving.  :)  If you fly an EELV to a low perigee transfer orbit and then do a second burn, all black zone (abort loads) issues evaporate.  And with essentially no performance loss.Whoever thinks that the stick will cost $100M is doing serious drugs.  The SRB by itself is $100M based on shuttle data.  So, I guess if everything else is free...Oh by the way, the ESAS study is a joke.  Put 25 shuttle guys in a room for 3 months and ask them to pick a launch system. Small wonder they came up with shuttle derived as the answer.  Especially since they're out of a job if they pick anything else.  Please, no one cite ESAS as a technical authority.  It was rigged to spit out the politically correct answer.Without becoming any more sarcastic, let me reiterate:  the fair way to settle the debate is to hold a competition.  Let the best rocket win.

It isn't that easy.  But there are ways around it. 

Offline quark

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #33 on: 04/14/2006 03:20 AM »
It may not be easy, but anything else is harder.  To drive everything off the point design of the stick will eventually sink the entire exploration program.  No one wants to see that happen.  MSFC is only now beginning to realize how hard the stick will be to fly and the cost to develop a new system that is essentially a clean sheet.  

Competition works.  The AF got two complete launch families, the Delta IV and the Atlas V for a total cost to the USG of $1B.  Of course, the contractors invested heavily, but even including that the total cost was probably around $5B and the AF got two complete systems with rockets from MLV up to HLV and two sets of launch pads at both coasts.  My guess is that the development cost of the CLV is approaching $10B for one system and one pad.

Competition was NASA's choice for the CEV.  Why not the CLV?  It seems backwards.  In the arena where private industry has tremendous capabilities and very recent experience (launch system development) NASA chose to go in-house for design and fat sole source contracts.  In the arena where no one has any relevent recent experience (capsules) NASA chose to compete.  Could it be that they knew that their own rookie team paired with ATK stood little chance against two seasoned, lean development contractors?

The technical issues to be faced by the stick are just beginning to surface:
1.  The most fundamental requirement for any LV is performance.  How many tons can you get to orbit?   Per ESAS the stick's capability was 27mT to 60X160.  After the baseline change in January, the performance dropped to 23mT to -30X100.  Rumors are that it is headed to around 20mT to that same sub-LEO orbit.  The CEV contractors are going crazy.  They had to take weight out and add propellant on to make up the shortfall.  There is NO performance requirement---it's whatever the stick can manage.
     As an aside, due to the mass of the upper stage, the performance of the stick drops off dramatically as the orbit altitude is increased.  To the ISS orbit, it's less than the Atlas V 551 (the stick's performance is less than the Delta IV or Atlas V HLV to any orbit).  To a commercial GTO, the stick performs like a low end Atlas or Delta.  To GSO, the stick has negative performance.  Bottom line is that the stick is pretty much useless for anything except sub-LEO

2.  The 5-seg SRB is far harder than anyone thought (hence the 3X cost increase).  The unique issues associated with taking a motor designed to ba a strap-on and making it a core have not bubbled up yet.  Heard a rumor that the 1.4 factor of safety can not now be met requiring a case redesign or a waiver.  Loads and load paths are completely different.  Propellant formulation and propellant grain design are new.  The TVC has much different requirements. as well and a brand new roll control system has to be developed.

3.  The upper stage is a huge challenge.  The engine might as well be a clean sheet design.  Think any of the engineers are still around?  or the vendors?  One thing we've learned over the years is that all rocket engines or motors contain much "secret sauce"---stuff the vendor knows that is required to make it work, but never written down.  Cryogenic upper stages are the most complex part of modern rockets.  There are lots and lots of systems that have to work together and that are almost impossible to analyze.  Pressurization, chill down, vent, propellant utilization, pnuematics, RCS, etc, etc.  Marshall has zero experience with cryo upper stages and has studiously avoided asking for help.
     By the way, if you believe the RFI, the mass fraction of the CLV upper stage is better than Centaur!!  That despite the fact that it has an intertank (vs common bulkhead) and is made of thick walled aluminum, vs pressure stabalized stainless steel.

4.  The stick is 300 ft tall.  That has adverse implications in a lot of areas.  GSE has to has to run up 300 ft.  Think of chilling down the LH2 fill line over that span.  You have to lift the CEV up that far.  You have to have 300 ft elevators to get crew up there. stability on the pad during ground winds will be very problematic.  Control stability during atmospheric flight will be very difficult.  Static elastic loads will be huge.  The systems implications go on and on.

5.  Aerodynamic vibration environments will be a huge issue, especially for the avionics.  Shuttle avionics are burried inside the orbiter, isolated from aeroacoustics.  The stick design has avionics mounted to the skin just below the CEV.  That is a terrible place.  It will be very hard to design avionice boxes to survive that.

MSFC will be faced with these problems and more.  And they have little experience to deal with them.  I haven't even talked the programatic problems yet.  There are many, but I'll touch on one.  The vehicle design team is isolated from the ground design team and both are isolated from the production organization.  For both the Atlas V and Delta IV developments, airborne, ground and production were fully integrated from the beginning operating under one management and system engineering authority.  It makes no sense to design something that can't be built or operated at the launch site.

Bottom line is that the current path is a disaster.  The longer we continue, the less likely the exploration program will survive the administration change.  And if exploration dies, there is a good chance NASA as an agency will die with it.

So a long winded way to reiterate: compete the CLV based on a firm set of requirements that enables a viable CEV and a viable lunar mission.

Offline rsp1202

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #34 on: 04/14/2006 04:16 AM »
My early questions over The Stick's viability had more to do with it looking like a kludge, and requesting some technical justification that this thing would fly. I certainly wanted it to; with the CLV being first up in the new lineup, it had better perform as advertised or all other bets were off. The pro's responding to my concerns (in much less detail than you've provided) were very reassuring that it would, and I chose to defer to their best judgements. So I'm extremely interested to hear any responses you might receive regarding your detailed dissection, which raises many disturbing questions.

Offline Propforce

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #35 on: 04/14/2006 05:16 AM »
Quote
Manel - 12/4/2006  3:51 PM

Why build the CLV ?

An External Tank with 3-4  RS-68  (no solids)  plus a Service Module with a delta V of 3.500 fps suffices to orbit the CEV

Get rid of the Stick!


I think a lot of people missed what you were saying.  A core CaLV (ET tank diameter with 3 or 4 RS-68, and a J-2X upper stage) could replace the CLV and certainly get rid of the SRBs.  


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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #36 on: 04/14/2006 05:48 AM »
Quote
quark - 13/4/2006  8:20 PM

Competition works.  The AF got two complete launch families, the Delta IV and the Atlas V for a total cost to the USG of $1B.  Of course, the contractors invested heavily, but even including that the total cost was probably around $5B and the AF got two complete systems with rockets from MLV up to HLV and two sets of launch pads at both coasts.  My guess is that the development cost of the CLV is approaching $10B for one system and one pad.

Competition was NASA's choice for the CEV.  Why not the CLV?  It seems backwards.  In the arena where private industry has tremendous capabilities and very recent experience (launch system development) NASA chose to go in-house for design and fat sole source contracts.  In the arena where no one has any relevent recent experience (capsules) NASA chose to compete.  Could it be that they knew that their own rookie team paired with ATK stood little chance against two seasoned, lean development contractors?

You make a lot of sense.  The EELV competition started with 4 or 5 prime contractors, including ATK, and it was through a series of reviews from lots of smart people that eventually was down-selected down to 2 companies.  Competition has always bring out this country's best.  

But that leaves two problems for Griffin, not to mention that was the approach from the guy that he took the job over,  that is what to do with the existing standing civil service army at NASA?  Also, what to do with the high cost of termination liability with the existing Shuttle contractors?  It was rumored to be upwards of billions of dollars just to terminate the Shuttle contract.


Quote
3.  The upper stage is a huge challenge.  The engine might as well be a clean sheet design.  Think any of the engineers are still around?  or the vendors?  One thing we've learned over the years is that all rocket engines or motors contain much "secret sauce"---stuff the vendor knows that is required to make it work, but never written down.  Cryogenic upper stages are the most complex part of modern rockets.  There are lots and lots of systems that have to work together and that are almost impossible to analyze.  Pressurization, chill down, vent, propellant utilization, pnuematics, RCS, etc, etc.  Marshall has zero experience with cryo upper stages and has studiously avoided asking for help.
     By the way, if you believe the RFI, the mass fraction of the CLV upper stage is better than Centaur!!  That despite the fact that it has an intertank (vs common bulkhead) and is made of thick walled aluminum, vs pressure stabalized stainless steel.


An even bigger challenge is to have MSFC assume they have the design knowledge and the system integration experience to build an upper stage !!!  With all the risk avoidance NASA has taken with the VSE, perhaps the biggest risk is assuming the existing NASA workforce know how to design and build a rocket !!  Meanwhile, little to no interaction with those who really know how - the INDUSTRY - and simply ignore their experience and expertise, is the highest risk of all.  

For the sake of this country's civil space program, the smart thing NASA can do is to engage with the people who are best at what they do -- design and build launch vehicle everyday.  Instead of keeping the industry at arm's length, embrace them and solicit their input on the CLV design and not treat them like a "build-to-print" machinging house (Steve Cook are you listening ????).


Quote
5.  Aerodynamic vibration environments will be a huge issue, especially for the avionics.  Shuttle avionics are burried inside the orbiter, isolated from aeroacoustics.  The stick design has avionics mounted to the skin just below the CEV.  That is a terrible place.  It will be very hard to design avionice boxes to survive that.

That's attributable to the previous point -- a lack of experience.  It will not be obvious until when the quotes comeback with much higher cost, vehicle dry weight go up as result, and boxes start to come back failing qualification tests.  But by then the decision makers will move on and NASA can blame the industry for failing to deliver on-cost, on-schedule, and meet-performance.  The story will continue.......


Quote
MSFC will be faced with these problems and more.  And they have little experience to deal with them.  I haven't even talked the programatic problems yet.  There are many, but I'll touch on one.  The vehicle design team is isolated from the ground design team and both are isolated from the production organization.  For both the Atlas V and Delta IV developments, airborne, ground and production were fully integrated from the beginning operating under one management and system engineering authority.  It makes no sense to design something that can't be built or operated at the launch site.

At risk of repeating myself, this is again due to a lack of integration experience.  From what I've heard, MSFC could not even agree with JSC on system level requirements.  This will only drag the program out and worse, an ill-defined requirements that will result in requirement creep which will further delay schedule, add risk, and increase cost for the program.


Quote
Bottom line is that the current path is a disaster.  The longer we continue, the less likely the exploration program will survive the administration change.  And if exploration dies, there is a good chance NASA as an agency will die with it.

So a long winded way to reiterate: compete the CLV based on a firm set of requirements that enables a viable CEV and a viable lunar mission.

I agree.  But I am not optimistic, not until enough higher up people begin to see the things are FUBAR, which will only result in the cancellation of the CLV program.

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #37 on: 04/14/2006 12:01 PM »
I agree on using EELV's but remember they were optimized for GTO and the stick was for LEO.  There are some manrating issues with the EELV's.   One of which was trying to avoid the 3 body Heavys.  A lot of work was done for OSP and the real driver was what are the manrating requirements.  Here is a list of some of the issues that need to be resolve:

1.  Survivable trajectories.  This was resolved at the end of OSP with some performance loss
2.  1.25 vs 1.4 factor of safety
3.  launch pad mods (redundancy and crew access)
4.  Avionics redundancy
5.  Back up flight software
6.  Spacecraft/Crew control of the launch vehicle
7.  Redundancy

Offline gladiator1332

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #38 on: 04/14/2006 03:19 PM »
I played around with the launch vehicle concepts shown in the ESAS and came up with the following "plan". For starters, a Delta IV Heavy would be used for the unmanned orbital testing of the CEV. The Delta IV Heavy has one flight under its belt, and is therefore much more further along in development than the Atlas V Heavy.

This plan will get the CLV out of the way, and since that means more funding available for the CaLV, therefore we could assume it will be developed much sooner. For manned orbital testing and ISS missions, a manned variation of the CaLV would be used, basically the CaLV without the SRBs.

For lunar missions, the "Two launch" plan would be used. The CEV and LSAM are launched on one CaLV and the EDS is launched on the other. Instead of using 5 segment SRBs on the CaLV, 4 segment SRBs will be used instead. Too much time and money would speant to upgrade to the 5 segment SRB.

This is a much simpler way to return to the Moon, as we no longer have to develop two launch vehicles. Everything is derived from the same CaLV design. With the RS-68 engine and the 4 segment SRB, these vehicles will be cheaper to develop and launch.

Offline mong'

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #39 on: 04/14/2006 03:36 PM »
sounds like a plan

that makes me think: with the recent changes, did anyone give a serious look at the 2 launch architecture outlined in the ESAS report ? could be a solution to the decrease in payload of the CaLV, with 2 launch you could put like 200 tons in LEO, that would allow the use of a pretty big LSAM

Offline HailColumbia

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #40 on: 04/14/2006 03:37 PM »
CEV will be required to perform ISS missions, a CaLV is overkill just to put a CEV into LEO.
-Steve

Offline RedSky

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #41 on: 04/14/2006 04:01 PM »
Quote
HailColumbia - 14/4/2006  10:37 AM

CEV will be required to perform ISS missions, a CaLV is overkill just to put a CEV into LEO.

I still don't know why it *has* to be considered "overkill"?   If STS had continued (i.e., no ESAS/CEV/OSP...)... just to deliver  and pickup crew... that wasn't considered overkill.  Why?  Because it would also bring up supplies, food, water, experiment racks, etc.  Why wouldn't the extra capacity of a CEV launch on a (man-rated) CaLV also be used for that purpose... say, with a Leonardo-style (but disposable) module.  The CEV would dock nose first w/the module... sep from the last stage... then rendez w/ISS.  Then, either dock the module to ISS or pass it off to the robotic arm.  It basically is just like the STS bringing up Leonardo/Donetello etc.

How are large parts (gyro's, new/replacement experiment racks, etc) ever to be brought up to ISS after STS then?  Once core complete is done... ISS still will need suplies and replacement parts that may be too much just for ATV and Progress.  Yes, there's COTS... but where's the contingency if nothing from the private sector is proposed or available?





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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #42 on: 04/14/2006 04:45 PM »
If the mid-heavy CaLV were developed first with just 4 seg SRBs for CEV/ISS+resupply (instead of the stick)... then that give enough lead time to develop the 5-seg version for a 2-launch lunar mission option.  The main core would already have been in existance for CEV/ISS missions.  It also would help keeping a CaLV from being cancelled before lunar missions... since it already would be basically in use.  If we just have a stick and CaLV/Lunar missions are cancelled... then what?

Perhaps NASA should just look at one mid-heavy SDLV: first 4-seg, then upgraded when needed to 5-seg.  (of course... no SMSE's as on this illustratrion).  Especially with the current costs of CLV stick soaring. I really think this strategy would be most cost effective, and help make it more difficult to cancel future lunar missions due to developing then a "whole new booster" for just it.   So if a mid-heavy CaLV is "overkill" for ISS... just replan the mission to the booster capabilities (as in the STS vs Soyuz).  Especially if ISS is going to a crew of 6, I'm sure the extra capacity of a mid-CaLV/CEV crew+resupply mission could be advantageous.





Offline Jim

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #43 on: 04/14/2006 05:06 PM »
Quote
RedSky - 14/4/2006  12:01 PM
Quote
HailColumbia - 14/4/2006  10:37 AMCEV will be required to perform ISS missions, a CaLV is overkill just to put a CEV into LEO.
I still don't know why it *has* to be considered "overkill"?   If STS had continued (i.e., no ESAS/CEV/OSP...)... just to deliver  and pickup crew... that wasn't considered overkill.  Why?  Because it would also bring up supplies, food, water, experiment racks, etc.  Why wouldn't the extra capacity of a CEV launch on a (man-rated) CaLV also be used for that purpose... say, with a Leonardo-style (but disposable) module.  The CEV would dock nose first w/the module... sep from the last stage... then rendez w/ISS.  Then, either dock the module to ISS or pass it off to the robotic arm.  It basically is just like the STS bringing up Leonardo/Donetello etc.How are large parts (gyro's, new/replacement experiment racks, etc) ever to be brought up to ISS after STS then?  Once core complete is done... ISS still will need suplies and replacement parts that may be too much just for ATV and Progress.  Yes, there's COTS... but where's the contingency if nothing from the private sector is proposed or available?

The unmanned CEV is the logistics for the ISS.  COTS is a backup for it.  CEV plus MPLM is a no-no. Cargo and crew are to be  separated

Offline Jim

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #44 on: 04/14/2006 05:09 PM »
Quote
RedSky - 14/4/2006  12:45 PMIf the mid-heavy CaLV were developed first with just 4 seg SRBs for CEV/ISS+resupply (instead of the stick)... then that give enough lead time to develop the 5-seg version for a 2-launch lunar mission option.  The main core would already have been in existance for CEV/ISS missions.  It also would help keeping a CaLV from being cancelled before lunar missions... since it already would be basically in use.  If we just have a stick and CaLV/Lunar missions are cancelled... then what?Perhaps NASA should just look at one mid-heavy SDLV: first 4-seg, then upgraded when needed to 5-seg.  (of course... no SMSE's as on this illustratrion).  Especially with the current costs of CLV stick soaring. I really think this strategy would be most cost effective, and help make it more difficult to cancel future lunar missions due to developing then a "whole new booster" for just it.   So if a mid-heavy CaLV is "overkill" for ISS... just replan the mission to the booster capabilities (as in the STS vs Soyuz).  Especially if ISS is going to a crew of 6, I'm sure the extra capacity of a mid-CaLV/CEV crew+resupply mission could be advantageous.

Why not just an EELV for CLV and let CLaV go off on its own and be optimized for the lunar mission

Offline mong'

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #45 on: 04/14/2006 05:19 PM »
Really interesting analysis Redsky

The more I think about it, the more find that a 2 CaLV, No CLV method is the way to go. Both for the lunar and ISS missions, plus the increased capacity of a 2 CaLV mission could be handy for flights to mars

Offline RedSky

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #46 on: 04/14/2006 05:22 PM »
Quote
Jim - 14/4/2006  12:09 PM
Why not just an EELV for CLV and let CLaV go off on its own and be optimized for the lunar mission

I thought EELV launch traj and performance didn't support CEV aborts, etc.  Plus, I'm really afraid if some core version of a CaLV isn't  developed early for CEV/ISS... then its not *ever* going to be developed in the forseeable future due to coming harsh budget restraints, a "we've done that before" attitude" with Wal-Mart landers,  etc.  I feel if its not already there in some form... we are going to lose the moon for a long, long time.

Offline Jim

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #47 on: 04/14/2006 05:29 PM »
Quote
RedSky - 14/4/2006  1:22 PM
Quote
Jim - 14/4/2006  12:09 PMWhy not just an EELV for CLV and let CLaV go off on its own and be optimized for the lunar mission
I thought EELV launch traj and performance didn't support CEV aborts, etc.  Plus, I'm really afraid if some core version of a CaLV isn't  developed early for CEV/ISS... then its not *ever* going to be developed in the forseeable future due to coming harsh budget restraints, a "we've done that before" attitude" with Wal-Mart landers,  etc.  I feel if its not already there in some form... we are going to lose the moon for a long, long time.

EELV or a derivitive with trajectory adjusted for aborts

Online wannamoonbase

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #48 on: 04/14/2006 05:39 PM »
QUOTE]

Why not just an EELV for CLV and let CLaV go off on its own and be optimized for the lunar mission
[/QUOTE]

This is a good idea.  It looks like Shuttle Derived technology has lots of limitations and the decision to use it was obviously political.  Use an EELV derived vehicle for CEV and take the next 3 or 4 years to really come up with a CaLV that answer the technical needs not political of the VSE.    Its going to have to be big, powerful and affordable.  Not an easy thing and something you certainly don't want to hamstring with loads of political baggage.
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Offline kraisee

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #49 on: 04/14/2006 06:12 PM »
I think there's three reasons NASA isn't using the EELV's.

The first one is political.   NASA is deliberately trying to keep the maximum number of current STS-related jobs going.   Yet NASA really has no guarantee the next government will even approve the development of a Heavy Lifter at all (STS must retire before that choice is made, so that decision isn't going to happen until 2010 ish).   So, ahead of that decision, they seem to be trying to protect jobs at places like ATK and MAF by developing the CLV using (largely) STS-derived elements.

That way, everyone is in a job when the CaLV decision comes around, so there is an easy transition to building extra SRB's at ATK, and new fuel tanks at MAF without having to create all-new infrastructures and preserving the maximum of current STS jobs.

The second is also political.   NASA had to get into bed with the USAF in the 1970's in order to be able to build Shuttle.   That relationship compromised the design fatally because then there were two organisations pulling in two different directions for what they wanted.   I don't think NASA wants any sort of external relationship issues at all with the designs involved in the Lunar program.   They want 100% control over the specifications this time, so won't get themselves involved in any rockets with largely military funding involved.   Further, they don't want to use the RD-180 engine for a very similar reason - the licencing issues are not yet solid, and they do not want any foreign government to be in a position to interrupt production of any vital components required for the VSE.

The third is a safety issue.   There's a simple rule: The more parts you have in a design, the more things there are which can go wrong.   This rule is often referred to as "Keep It Simple, Stupid" or K.I.S.S. and has been at the core of the VSE after the over-complexity of the Shuttle system directly resulted in the loss of Columbia.

The CLV has one 'big dumb solid', and one single liquid engine for the upper stage.   It just doesn't get any simpler than that in the rocket business.

The Delta IV Heavy, has three main engines and one upper stage engine.   In very basic terms:   That's four engines.   Which is twice the number of engines which could go wrong.

The Atlas-V 551 has five boosters, one main engine and an upper stage engine.   That's 7 engines which could go wrong, or 3.5 times the number of engines which must run perfectly for a successful flight.

Further, none of the EELV engines are based on designed which have ever been man-rated before.

The return to PBAN propellant for the 5-seg SRB's will make that stage a pure evolutionary upgrade to the already proven man-rated SRB's we use on Shuttle today.   Also the J-2X is based on an already man-rated engine which has flown successfully 87 times before, 63 times manned.

Also, while there's a lot of bad feeling about the SRB's after the Challenger incident, the fact is that the failure modes for SRB's are a lot less catastrophic than for liquid engines.   Page 413 of the original ESAS report shows information about which components were the riskiest for the flight of the original 4-seg/SSME spec'd CLV.   The solid constituted only 12% of the overall risk of the flight. It was the lone SSME (one of the most reliable liquid engines ever produced I might add) which constituted the lion's share of the risk at 64%.   That is more than 5 times more likely to fail than the SRB.   Even the staging was considered more risky than the SRB, at 21%.

The SRB's got a lot of bad press from Challenger which lives in peoples imaginations to this day.   But the facts indicate that they are more reliable than liquid systems because they are fundamentally so much simpler.   They just have far fewer parts in their designs which can go wrong.   Further, when SRB do fail, their failure modes are typically a lot more benign than liquid engine failures.   The best example is the most obvious one - a burn-through event like Challenger had, would NOT cause the loss of a CLV/CEV.

But when liquid engines "let-go", they have a tendency not to be so sympathetic - as Space-X recently demonstrated for all to see; just one little component failure in a relatively simple design for a liquid engine can cause some really interesting fireworks displays.

Ross.
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Offline Jim

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #50 on: 04/14/2006 06:31 PM »
The Spacex failure was easily detected and a manned vehicle would have sensed it and aborted.  The engine did not explode.  It just shut down, just like Apollo 13.

It doesn't have to be a current EELV.  The Atlas X (5.4m phase 2) could do it with engine out capability.  Its cost was near the stick.

The Atlas and Titan ICBM's were manrated.  They were not satellite launchers, which have better records.  The RS-68 was built for producability and low part count, and it has high margins.   The SSME is the exact opposite.  With some research and maybe a little redesign, the RS-68... Wait a minute, the RS-68 being used for the CaLV and the CaLV is supposed to be manrated.

Solids do have nasty failures.  Look at the second to last Titan 34D out of VAFB.  It was some fireworks

Reliabilty numbers, in the ESAS, were used to make a case.  Let an independ group derive them and I bet they would be different

The employment "requirement" may kill VSE/ESAS if it costs too much

It might come down to use it (EELV) or lose it (VSE)

Offline yinzer

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #51 on: 04/14/2006 06:44 PM »
Quote
kraisee - 14/4/2006  11:12 AM
But the facts indicate that they are more reliable than liquid systems because they are fundamentally so much simpler.   They just have far fewer parts in their designs which can go wrong.   Further, when SRB do fail, their failure modes are typically a lot more benign than liquid engine failures.   The best example is the most obvious one - a burn-through event like Challenger had, would NOT cause the loss of a CLV/CEV.

But when liquid engines "let-go", they have a tendency not to be so sympathetic - as Space-X recently demonstrated for all to see; just one little component failure in a liquid engine can cause some really interesting fireworks displays.

Ross.

I thought that the SpaceX rocket landed more or less completely intact in a lagoon; certainly it came out of things a lot better than the Delta II that took out all those cars in the parking lot in 97, or the Titan IV SRB that took out large chunks of the mountain when it managed to detonate during a ground firing, or the Titan 34D that blew up 8 seconds into flight back in 86.  Even when the Delta III had the RL-10 blow up during second stage flight, the payload survived essentially intact, no?

For most launch vehicles today, LOC and LOM are one and the same.  For solids, this doesn't really change anything, but for liquids, it sort of hides a lot of operational flexibility that exists, along the lines of "the engine is clearly not long for this world, so let's point the sucker into the wind, shut it down, cut it loose."  An abort where you have to get away from a shut-down liquid stage is going to be a lot gentler than an abort where you need to get away from a lit SRB...

But, none of this is as important as MSFC being able to build cool rockets and ATK workers keeping their jobs.
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Offline dmc6960

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #52 on: 04/14/2006 07:34 PM »
Quote
yinzer - 14/4/2006  1:44 PM

I thought that the SpaceX rocket landed more or less completely intact in a lagoon; certainly it came out of things a lot better than the Delta II that took out all those cars in the parking lot in 97, or the Titan IV SRB that took out large chunks of the mountain when it managed to detonate during a ground firing, or the Titan 34D that blew up 8 seconds into flight back in 86.  Even when the Delta III had the RL-10 blow up during second stage flight, the payload survived essentially intact, no?


Anyone know where to find some videos of that 34D incident or other videos besides the small SFN one of the '97 Delta II (perhaps from further away?)

Also, SpaceX's Falcon 1 DID land mostly intact without any explosions.  If you go to spacex.com and look at the onboard camera video from their updates page, you'll find a much more complete video of the flight than the one on this website (which was recorded from the live feed, missing many frames during the engine shutdown).  There is no eruption off to the side of the rocket, it simply tips onto its side when the engine shuts off and falls down.
-Jim

Offline yinzer

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #53 on: 04/14/2006 07:59 PM »
Quote
dmc6960 - 14/4/2006  12:34 PM
Anyone know where to find some videos of that 34D incident or other videos besides the small SFN one of the '97 Delta II (perhaps from further away?)

Also, SpaceX's Falcon 1 DID land mostly intact without any explosions.  If you go to spacex.com and look at the onboard camera video from their updates page, you'll find a much more complete video of the flight than the one on this website (which was recorded from the live feed, missing many frames during the engine shutdown).  There is no eruption off to the side of the rocket, it simply tips onto its side when the engine shuts off and falls down.

There are at least four videos of the Titan 34D incident out there; the Aerospace Corporation did an analysis of plume dynamics using 3 range cameras and an amateur video shot from a few miles north of the launch.  HOWEVER, I remember their being some concern about videos of spysat launches, in case the fairing failed and people could see what the satellite looked like before the rocket blew up; as such I'd be surprised if the videos were on the web.  I certainly couldn't find them, but there may be more photos in the report available here.  Ten bucks for a PDF... how curious are you?

And CNN has a video of the Delta failure here, which may or may not be the SpaceflightNow one.
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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #54 on: 04/14/2006 08:24 PM »
I personally like the Spiral idea better as we would then have the one common launcher rather than two. This drastically simplifies things, as two vehicles could be twice the problems. If we find a problem with the cargo version, we can fix it on the manned version as well.

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #55 on: 04/14/2006 08:38 PM »
Quote
mong' - 14/4/2006  1:19 PM

Really interesting analysis Redsky

The more I think about it, the more find that a 2 CaLV, No CLV method is the way to go. Both for the lunar and ISS missions, plus the increased capacity of a 2 CaLV mission could be handy for flights to mars

The only thing against a 2 CaLV plan is that using it to get to the ISS is overkill.  But that could be solved if COTS is used as crew cargo transport to ISS.  Then, just use NASA systems to get to the moon and Mars.  That way you "force" commerical enterprise to begin to make their presence in space.  NASA builds the ISS, the commercial sector then takes over.  NASA goes to the moon and builds a base, the commerical sector than takes oves once NASA is ready for Mars.  And you keep this process going with NASA as the trialblazer (the tip of the spear, if you will) with the commercial peanut gallery filling in the back as we spread outward.

Offline RedSky

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #56 on: 04/14/2006 09:08 PM »
Quote
Jim - 14/4/2006  12:06 PM
CEV plus MPLM is a no-no. Cargo and crew are to be  separated

This makes sense for a system like STS, where you *can't* launch heavy cargo loads without a crew.   STS needs a crew to fly it, and has no safe abort mode during powered SRB flight.  A mid-heavy man-rated CaLV can launch cargo unmanned.  But if used to launch a manned CEV on a mission anyway, I can't see why that "no-cargo" rule applies.  It's seems to be taking the spirit of the rule to an unreasonable extreme.  Yes, have a system that doesn't require a crew to launch cargo.  But if you're launching a crew anyway... why not use any excess capability (of a mid-heavy CaLV) for cargo also?   Besides, the CEV wouldn't have to be scaled back from the originally conceived plan (5.5m vs 5m etc which is now too heavy for SRB CLV).

(Iron-clad "rules" usually have a resonable exception.)

Offline kraisee

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #57 on: 04/14/2006 11:07 PM »
Quote
yinzer - 14/4/2006  2:44 PM

I thought that the SpaceX rocket landed more or less completely intact in a lagoon; certainly it came out of things a lot better than the Delta II that took out all those cars in the parking lot in 97, or the Titan IV SRB that took out large chunks of the mountain when it managed to detonate during a ground firing, or the Titan 34D that blew up 8 seconds into flight back in 86.  Even when the Delta III had the RL-10 blow up during second stage flight, the payload survived essentially intact, no?

Yes, but the Delta-II you mention also didn't destroy it's payload - at least, not until it hit the ground! :)

The key issue is that liquid engines rely on a lot more parts to function correctly.   When any rocket engine decided to go bang, it's going to be a bad day for everyone involved.

However, the most critical things are a) How often will a given launch vehicle fail, and b) If it does fail how likely are any crew to survive that failure?


Quote
For most launch vehicles today, LOC and LOM are one and the same.  For solids, this doesn't really change anything, but for liquids, it sort of hides a lot of operational flexibility that exists, along the lines of "the engine is clearly not long for this world, so let's point the sucker into the wind, shut it down, cut it loose."  An abort where you have to get away from a shut-down liquid stage is going to be a lot gentler than an abort where you need to get away from a lit SRB...

An SRB can be 'pointed into the wind' in a fashion too.

PBAN propellant burns at a much slower rate than a liquid tank can explode, and if it is not directed through a nozzle, it loses most of its force.

The Upper Stage would be emergency-separated just as a series of explosive charges along the length of the booster (the range safety system would be designed to do this) would essentially 'slice' the case of the SRB along its length, releasing the burning fuel to the atmoshpere and essentially sending the case away at right-angles to the direction of flight.

The booster essentially stops flying upwards iinstantly because the thrust is no longer directed through the motor nozzle at the bottom.    Because of the venting "burn" through th enew hole, the remains of the booster would actually get a little bit of momentum 'sideways' or even 'downwards' and would take it away from the trajectory of the rest of the launcher.   The Second Stage would not be ignited in such an abort, and would essentially provide a little bit of a "buffer zone" allowing the CEV to get away on the escape system.

The split would be a very clean cut, and does not produce any shrapnel (unlike a liquid stage explosion) either, so is considered a surprisingly safe method of instantly stopping a solid booster in mid-flight.

I understand this is one of the methods being considered for CLV right now.

Ross.
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Offline R&R

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #58 on: 04/14/2006 11:47 PM »
Quote
kraisee - 15/4/2006  12:12 PM

I think there's three reasons NASA isn't using the EELV's.

The second is also political.   NASA had to get into bed with the USAF in the 1970's in order to be able to build Shuttle.   That relationship compromised the design fatally because then there were two organisations pulling in two different directions for what they wanted.

All this was happening at the beggining when STS was being designed.  EELV is essentially complete, anything more would be evolution strictly for NASA, the Air Force already has what it needs.  NASA could have just as much oversight as they need to be happy and keep a lot of Civil Servants on the payroll.

Quote
The CLV has one 'big dumb solid', and one single liquid engine for the upper stage.   It just doesn't get any simpler than that in the rocket business.

Big and dumb?  Are you kidding?  The Shuttle SRB's have never had to handle sole Pitch and Yaw of the engine and never had Roll control.  That addition is going to be very complex not to mention it's now going to be controlled from the second stage that doesn't yet exist.

Quote
The Delta IV Heavy, has three main engines and one upper stage engine.   In very basic terms:   That's four engines.   Which is twice the number of engines which could go wrong.

The Atlas-V 551 has five boosters, one main engine and an upper stage engine.   That's 7 engines which could go wrong, or 3.5 times the number of engines which must run perfectly for a successful flight.

With that logic the Falcon 9 (9 engines) is doomed.  But really the RS68 is a tried and true engine with 0 failures.  At least 2 dozen have been test fired at Stennis and have flown on the first 4 launches (6 engines), 6 more are installed on boosters at the launch sites and several more are installed or waiting to be installed at the factory.  The early engine cutoff on the Heavy Demo was not an engine problem in fact it wasn't an ECO sensor problem, it was cavitation at the LOX feed inlet.

The RL10-B2 on the US has also had an excellent record for Delta-IV and the RL10 is the Centaur engine also with an exceptional record.

As for the solids on both EELV’s they are single segment which would be more reliable than 4 or 5 segment shuttle SRB’s which by the way could arguably have a hgher failure rate than expendable SRM’s in as many launches if you take into account the number that had blow by before Challenger.  Fact, there have been 0 failures of SRM's on EELV’s.

I don't know too much about the RD-180 but it has been great on the Atlas so far.

Quote
Further, none of the EELV engines are based on designed which have ever been man-rated before.

Man rating has more to do with the redundancy of the Avionics and Controls.  It also means having more than one for engine out redundancy.  Besides the RS68 is simpler than the SSME so it should be more man friendly for that.
 :)

Offline kraisee

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #59 on: 04/15/2006 07:02 AM »
While I agree with a lot of your comments, the simple fact remains that choosing EELV's for CEV would mean the loss of thousands of jobs currently working SRB systems at ATK in Utah and also at KSC.

Further, if no new liquid stage is required, what are all the ET workers still recovering from Katerina at MAF, who are also now facing the 6-7 year long 'gap' between STS and CaLV, going to be doing during that down time?

Ditto for many at MSFC who are overseeing the CLV upper stage development, and people at Stennis who will be dusting off the J-2 test stands again.

Without the CLV there is no work for any of these people to be doing for at least the first half of the CaLV development time.   There won't even be any contracts left in place which would fund the payroll for all those people, because Shuttle will have closed its doors already.

Thousands of experienced space engineers would lose their jobs and an awful lot of expertise would evaporate in precisely the same fashion as happened after Apollo.   Then they'd have other jobs when NASA would be wanting them back again maybe four years later.   Most of the Apollo guys who had been laid off gave NASA the bird when they came calling eventually for Shuttle, and damn right too.

If NASA did go with EELV's for launching CEV, I dare say it would pi$$ off a lot of the politico's in Utah, Texas, Florida, Louisiana, Mississippi and Alabama where most of those job losses would actually occur.

Now, can anyone riddle me this:   Which of the states are currently the backbone of political support for NASA?   Oh yeah, the answer would be: Utah, Texas, Florida, Louisiana, Mississippi and Alabama...   What I'm saying is that we might want to be very careful not to risk destroying our primary political support structures in these times of economic down-turn and budget cuts across most agencies in the US Gov.   NASA got a budget increase recently, mainly thanks to these guys pulling for NASA.   I'd prefer to avoid stabbing these folk in the back now.


Having said all of that, I am still very strongly in favour of a second-tier system being created so we don't have to rely on CLV alone to loft the CEV.

We've all been sitting ring-side to the problems with having a complete dependancy on a single manned launch system.   CLV is an arguably good first-tier solution because it fulfils all of the requirements fairly well: capacity, reliability, economics, political and employment.   An EELV (or even commercial launchers perhaps) would be great as a second manned launch system for CEV.   They would provide a system-wide redundancy for the program itself and near-enough guarantee that the US can continue to launch manned missions, even when the next national disaster comes along - which we all know will happen sooner or later.

I would strongly support an initiative to have a backup launch system because it would work in everyone's interests.   It would also expand the program beyond the current Vision, which I think is a valuable thing we should all be trying to do.   Of course, we still need to convince the law makers to fund such extra development.   Hmmm...   I wonder if the DoD need manned space access?   Perhaps they could fund the development of a manned capsule launcher based on an EELV, and just buy CEV's off the shelf for that role. :)

Ross.
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Offline Jim

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #60 on: 04/15/2006 03:15 PM »
"Hmmm... I wonder if the DoD need manned space access? Perhaps theycould fund the development of a manned capsule launcher based on anEELV, and just buy CEV's off the shelf for that role."

They were going to do that before and it was called Blue Gemini.  The DOD has no manned requirements.  They try and keep failing to justify it.

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #61 on: 04/15/2006 03:16 PM »
As I said before it may come done to "Use it" (EELV) or "Lose it" (VSE)

Offline R&R

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #62 on: 04/15/2006 04:34 PM »
Much discussion has been about the political aspects, representation from Texas, Mississippi, Alabama, Florida, California, Utah.  Getting rid of the Shuttle SRB's ans External Tank in leiu of a EELV won't eliminate that support too greatly.  I'm crazy you say?  Well lets think about it.  Using EELV means higher production at Decatur where the Bossters and Second Satges are built, now for Delta-IV and soon under ULA for Atlas V too.  That means more Alabama jobs plus NASA would still need a fair sized work force at MSFC to oversee and suport unique design requirements.  They might need some jobs in Denver since that's where all the ULA engineering will be.  Thr RS68 are built and tested at Stennis so Missippi keeps a fair number of jobs.  JSC will always be Mission Control so not much changes there.  I personnally think it's a big waste of money to put any CEV assembly there.  Speeking of CEV if all that assembly and integration is at KSC as has been stated then the losses there are not as large as they might look like.  If NASA wanted to keep some of the Launch processing team around they could go with stacking an EELV on the MLP and launching from SLC-39.  Bottom line if NASA keeps any number of Jobs at any of their locations they will keep the political support because no Senator or Congressman wants to have to answer why they did not support keeping Space related jobs in their districts.

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #63 on: 04/15/2006 04:50 PM »
I looked ove rthe ESAS further and I came up with three basic plans, all of which get rid of the CLV.

Plan A uses the lighter variants of the Atlas V outlined in ESAS. The standard Atlas V Heavy is sued for all LEO and ISS flights. Lockheed has the Atlas V Heavy ready to go, they just need the green light to begin production. And since hardware hasn't already been built, it would be easier to make modifications, as compared to the Delta IV Heavy which is already being produced and launched. For the Lunar flights, the Altas Phase 3A would provide 94 mT of payload, deffinatly enough to launch te CEV and LSAM on one flight and the EDS on another. I like the Phase 3A vehicles because they are smaller but deliver a similar amount of payload when comapred to the Atlas Phase X.

Pland B still uses the Altas V Heavy for ISS and LEO flights. This plan is similar to the SDLV "Plan C" however, it uses all EELV derived launch vehicles. A lighter version of the Atlas Phase X vehicle is used to launch the CEV and LSAM. It can lift 70 mT of payload. The much larger version of the Atlas Phase X would be used to lift the EDS and cargo. The added Atlas boosters allow it to lift 95 mT.
I prefer Plan B over Plan A because it is the basic plan that NASA currently has with the CLV/CaLV, however, instead of lifting 25 mT or less, the Phase X CLV can lift 70 mT. The Phase X CaLV uses the same boosters that will be used on the Atlas V Heavy. The Phase 3A vehicles, while smaller, require multiple boosters, therefore increasing the chances of LOM. If NASA decides to go with EELV derived vehicles, Plan B is deffiantly the way to go, as it allws them to stick with the original ESAS plan, but with new launch vehicles capable lifting much more.

Plan C I outlined in an earlier post and is similar to Plan B, except is uses SDLV's. Whether Plan B is better than Plan C, comes down to which one could be done for less, as they both have similar capabilites.




Offline kraisee

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #64 on: 04/15/2006 06:02 PM »
Quote
gladiator1332 - 15/4/2006  12:50 PM

I looked ove rthe ESAS further and I came up with three basic plans, all of which get rid of the CLV.

What were the specific reasons why ESAS did not choose any of those?

I'm guessing a combination of cost & time for development, cost/mission and safety considerations, but I don't have time to read the report right now.

Ross.
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Offline Jim

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #65 on: 04/15/2006 06:15 PM »
Quote
R&R - 15/4/2006  12:34 PMMIf NASA wanted to keep some of the Launch processing team around they could go with stacking an EELV on the MLP and launching from SLC-39.  Bottom line if NASA keeps any number of Jobs at any of their locations they will keep the political support because no Senator or Congressman wants to have to answer why they did not support keeping Space related jobs in their districts.

The EELV would be processed by the respective company.  Not KSC or its contractors.  "SLC" only applies to CCAFS and VAFB pads not LC-39.  Anyways EELV on LC-39 was shown to be counterproductive and more costly.

Offline kraisee

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #66 on: 04/15/2006 06:51 PM »
Okay, looks like I don't have to go out after all, so I'll do a summary of why those options were not chosen - all according the information provided in the ESAS report.

Plan A:

Atlas-V Heavy Crew lifter:
- LOC: 1 in 957, half of CLV's 1 in 1,918.

Atlas Phase 3A (5.4m core) Cargo lifter:
- Lower performance; 94mT, 12mT below CaLV w/out EDS.
- Considerably more expensive to develop and fly.   Various breakdowns range between 1.08 to 2.25 times for all costs.
- LOC: 1 in 612, third of 1 in 2,021 for 1.5 solution.

Plan B:

Atlas-V Heavy Crew lifter:
- LOC: 1 in 957, half of CLV's 1 in 1,918.

Atlas-X (8m core) Crew Lifter:
- Payload capacity 70mT, 36mT lower than CaLV w/out EDS.
- A second Crewed lifter duplicates a lot of capabilities.
- LOC: 1 in 614, third of CLV's 1 in 1,918.
- Facilities cheaper (0.92), all other costs more expensive varying between 1.71 - 2.36 times CaLV costs.

Atlas-X (8m core) w/ 2 x Atlas-V boosters Crew/Cargo Lifter:
- Payload capacity 94mT, 8mT lower than CaLV w/out EDS.
- All costs higher than CaLV, ranging between 1.08 and 1.33 times .
- LOC: 1 in 536, quarter of 1 in 2,021 for 1.5 solution.


Plan C:

ET-Derived Crew lifter w/out boosters:

Can't find any figures in the ESAS report for this launcher, so can't comment on costs or reliability.

Does "appear" to offer direct upgrade path to CaLV though, so shared costs and reliability look good in the absence of any reference figures.

CaLV derivative Crew/Cargo lifter w/ 4 SSME's instead of 5:
- Payload capacity 97mT, 9mT lower than CaLV w/out EDS.
- LOC: 1 in 915, half of 1 in 2,021 for 1.5 solution.


All the options above will require a 2-cargo lifter solution for all Lunar missions, which doubles all the costs for each Lunar mission compared to the ESAS 1.5 solution.

Crew Safety never gets above 1 in 1,000 in any of those options, which is half the safety rating for the ESAS vehicles.

I personally would like to see more information on the ET-derived Crew lifter though, because I think it might offer a second-tier launch system as a backup for CEV launching.

When I get some time, I'll try running some numbers on that vehicle.

Ross.
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Offline Jon_Jones

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #67 on: 04/15/2006 09:56 PM »
what would it be like if we:

took 3 SRB's../ put them in a tube (with a radius slightly larger than 1 SRB diameter) and called it stage 1.

took some liquid stage about 8m in diameter with 1-3 J-2x engines, put it on top and called it stage 2.

Scaled up the CEV to 6.5 m diameter and incorporated either a longer SM that used LH2 or a fat stubby one using a cheaply thrown together Methane system.

I think, above all else... having a bigger CEV is just plain cool, especially if I fly in one somewhere down the line. seriously, I have no idea about how much added risk putting three SRB's in a tube (essentially dynamite in a can) and calling it a stage 1 would be. but I look at it (from an ignorant outsider's perspective) that 3 SRB's = 3 times the thrust of the stick's first stage.
And I look at it as increasing the production of SRB by 1 per launch over the rate used with STS. maybe this will have economic benefits???
and since I boldly decreed 3 SRB's, lets assume that they would create and acceleration that was way to high for the current mass of original stage 2 + CEV
I say the best way around this is to increase the mass of Stage 2 + CEV.

would it be bad, crazy, good, or ??? if we made a larger liquid stage and then a larger CEV. the second stage wouldn't grow in height, but in diameter. maybe then we could shave some of the total height and save of the distance that the cryogenic LH2 and LOX have to travel up a tower and reduce the height astronauts have to go up. (reason being... if I was and astronaut... the closer to ground when I had to escape the launch complex... the better?).


what do you think?
please tell me,,, this is how I learn.
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Offline Jim

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #68 on: 04/15/2006 10:58 PM »
There are better ways to make a first stage.  Clustering SRB's isn't one of them.   Tube idea would be unworkable (stacking the SRB's in the can, production and transportation of the can)

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #69 on: 04/16/2006 12:09 AM »
For some reason I hadn't thought of staking the SRBs. and a cluster of SRBs is also out. Maybe I have not been listening well enough, but does it now seem that the SRB stage of the CLV is not going to be able to put the CEV into a usable orbit. I've seen 30X100 in a few places. This strikes me as a highly disconcerting pair of dimensions. This seems like a highly elliptical orbit and a seriously low one at that. Is 30 Nautical Miles even considered space? Is that close enough to ... what was it... 100km?
Is this thing going to be skimming or skipping across the atmosphere? (assuming no further burns to get a better orbit.) Can the SM hold enough power to get the thing into a better orbit then that?

I'm trying to understand the math involved. I don't know much of anything about this though. Let’s speak of the Isp for a first stage that could carry CEV and maybe one of the uncertain designs for the second stage.

I know that "Essentially, the higher the specific impulse, the less propellant is needed to gain a given amount of momentum. In this regard a propulsion method is more fuel-efficient if the specific impulse is higher. This should not in any way be confused with energy-efficiency, which can even decrease as specific impulse increases, since many propulsion systems that give high specific impulse require high energy to do so."

I've seen it also as "twice the net power to produce an acceleration of 1 m/s2 to a mass which at Earth has a weight of 1 N"
and essentially as a change in momentum divided by weight of propellant which may have something to do with the time derivative of propellant.

and we all know that your first stage should be the heaviest.. and looking at rocketry from a momentum standpoint (and force as defined as the derivative of momentum with respect to time) this seems to make good sense. Ok, so this thing is going and the SRB has a moderately good Isp... it goes for about 2min 20 sec or so and we get some average acceleration, which you prefer to call delta V.. (which I admit makes more sense than calling it an acceleration, because its such a long and drawn out time interval)
then we get to the separation and the candle is still lit so we need extra separation boosters to get the Upper stages away from the SRB.

Now what I what to know, after all our long and drawn out discussion, is... does the stick have the power to lift a second stage and CEV to height where that second stage, whose mass and therefore contribution to the delta V have all been determined by the lifting power of the SRB, does that second stage stand a chance, with a J-2x engine of getting the CEV into a decent orbit.. or is this choice of SRB looking like a the wrong choice for the job from a rocket scientist's perspective????

and in all our calculations, do we include drag. what is the drag for a rocket. is it somewhere around 1/4 or 1/8 the area time the velocity squared.... does this affect things? I know there are a several seconds where the thing is in the thick parts of the atmosphere... does this have much effect?
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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #70 on: 04/16/2006 02:58 AM »
Quote
kraisee - 15/4/2006  2:51 PM

Okay, looks like I don't have to go out after all, so I'll do a summary of why those options were not chosen - all according the information provided in the ESAS report.

Plan A:

Atlas-V Heavy Crew lifter:
- LOC: 1 in 957, half of CLV's 1 in 1,918.

Atlas Phase 3A (5.4m core) Cargo lifter:
- Lower performance; 94mT, 12mT below CaLV w/out EDS.
- Considerably more expensive to develop and fly.   Various breakdowns range between 1.08 to 2.25 times for all costs.
- LOC: 1 in 612, third of 1 in 2,021 for 1.5 solution.

Plan B:

Atlas-V Heavy Crew lifter:
- LOC: 1 in 957, half of CLV's 1 in 1,918.

Atlas-X (8m core) Crew Lifter:
- Payload capacity 70mT, 36mT lower than CaLV w/out EDS.
- A second Crewed lifter duplicates a lot of capabilities.
- LOC: 1 in 614, third of CLV's 1 in 1,918.
- Facilities cheaper (0.92), all other costs more expensive varying between 1.71 - 2.36 times CaLV costs.

Atlas-X (8m core) w/ 2 x Atlas-V boosters Crew/Cargo Lifter:
- Payload capacity 94mT, 8mT lower than CaLV w/out EDS.
- All costs higher than CaLV, ranging between 1.08 and 1.33 times .
- LOC: 1 in 536, quarter of 1 in 2,021 for 1.5 solution.


Plan C:

ET-Derived Crew lifter w/out boosters:

Can't find any figures in the ESAS report for this launcher, so can't comment on costs or reliability.

Does "appear" to offer direct upgrade path to CaLV though, so shared costs and reliability look good in the absence of any reference figures.

CaLV derivative Crew/Cargo lifter w/ 4 SSME's instead of 5:
- Payload capacity 97mT, 9mT lower than CaLV w/out EDS.
- LOC: 1 in 915, half of 1 in 2,021 for 1.5 solution.


All the options above will require a 2-cargo lifter solution for all Lunar missions, which doubles all the costs for each Lunar mission compared to the ESAS 1.5 solution.

Crew Safety never gets above 1 in 1,000 in any of those options, which is half the safety rating for the ESAS vehicles.

I personally would like to see more information on the ET-derived Crew lifter though, because I think it might offer a second-tier launch system as a backup for CEV launching.

When I get some time, I'll try running some numbers on that vehicle.

Ross.

I don't think you can base your entire decision on the odds of LOM or LOC. Just because some statistic states that once every 600 missions a crew is going to die, does not mean that it has to happen. With the LES and a safer configuration, your odds on any of these launch vehicles are much better when compared to the Shuttle. And where did ESAS get these numbers from. For one thing, how did they figure that an SRB has a 1 in 1000 odds of LOC. Did they base that off of the current Shuttle SRB? But were not dealing with your standard Shuttle SRB anymore. Many changes have been made to the CLV, and no one really knows what effects that will have on safety.
I agree that the Phase 3A plan is riskier, and it seems to be a waste to use so many boosters and engines when something much more simple can get the job done.

Sure I'd love to have the 1 in 1000 odds, but at what cost? Do you want great odds and a boring mission with a two man lander. Or would you rather take 1 in 600 odds, still much better than the Shuttle, and really explore the Moon.

And for the Atlas Phase X crew lifter, you stated above that it lifts 70mT, which is less than the CaLV. Yes it is lower than the CaLV, however, it lifts nearly 3 times more than the current CLV. And the only reason the Atlas V Heavy is used for ISS, I felt that 70mT of lift is a bit overkill for transporting crew to the ISS.

I really feel that either Plan B or Plan C is the way to go, as they both provide more than enough lift to really explore the Moon. Face it the 1.5 launch plan is dead. We need to launch the CEV and LSAM on the same launcher and launch the EDS and cargo on another. A two launch plan costs more, but you deffinatly get more for your money. (Hmm, maybe we should call it the "McDonald's Plan"...it's better than "Walmart")


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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #71 on: 04/16/2006 03:46 AM »
So lets say we stick with the SDLV idea and get rid of Plan A and B. I'm now looking at two more possible choices within Plan C.

NASA can go with the two launch plan outlined in ESAS where there is a manned version of the CaLV. This provides the most lift and would deffiantly solve the current problems. However, launching just the CEV and LSAM, or in the case of ISS flights, just the CEV on a CaLV could be seen as overkill.

I prefer another plan which uses a smaller Inline SDLV to launch the crew. Think of it as a larger CLV. It would have a 5 RS-68 core, like the CaLV, and a J-2S upperstage. I am unsure how much this vehicle would be able to lift, but deffinatly much more than the current CLV. I am debating whether the CEV and LSAM should be launched on the CLV and just the EDS and cargo on the CaLV.

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #72 on: 04/16/2006 04:25 AM »
Quote
Jon_Jones - 15/4/2006  8:09 PMFor some reason I hadn't thought of staking the SRBs. and a cluster of SRBs is also out. Maybe I have not been listening well enough, but does it now seem that the SRB stage of the CLV is not going to be able to put the CEV into a usable orbit. I've seen 30X100 in a few places. This strikes me as a highly disconcerting pair of dimensions. This seems like a highly elliptical orbit and a seriously low one at that. Is 30 Nautical Miles even considered space? Is that close enough to ... what was it... 100km? Is this thing going to be skimming or skipping across the atmosphere? (assuming no further burns to get a better orbit.) Can the SM hold enough power to get the thing into a better orbit then that? and in all our calculations, do we include drag. what is the drag for a rocket. is it somewhere around 1/4 or 1/8 the area time the velocity squared.... does this affect things? I know there are a several seconds where the thing is in the thick parts of the atmosphere... does this have much effect?

Last question, first.  Yes drag is take into account.

First question.  The CEV does put itself in the final orbit, the SM is sized for this

Offline gladiator1332

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #73 on: 04/16/2006 05:20 AM »

Offline kraisee

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #74 on: 04/16/2006 01:14 PM »
Quote
gladiator1332 - 15/4/2006  11:46 PM

So lets say we stick with the SDLV idea and get rid of Plan A and B. I'm now looking at two more possible choices within Plan C.

I think its the only one with any real chance of being an alternative, so okay :)


Quote
NASA can go with the two launch plan outlined in ESAS where there is a manned version of the CaLV. This provides the most lift and would deffiantly solve the current problems. However, launching just the CEV and LSAM, or in the case of ISS flights, just the CEV on a CaLV could be seen as overkill.

Yeah, thats the killer right there.   CaLV is going to cost somewhere around $1Bn per flight.   CLV's target price was $100m per flight.

So ISS flights increase in launch-vehicle price alone, by 10 times for every ISS flight, and also increase by 40% overall for Lunar missions if you go with CaLV as the crew launcher.

For the potential cost of just three CaLV crew launches to ISS, you pretty-much pay for developing "The Stick" and then you can do both types of mission safer and more economically.

Even if you have to use 2 CaLV's for lunar missions to get double the payload to Lunar Orbit Injection (LOI), the cost savings using The Stick you make on ISS flights alone are enough to pay for all the extra CaLV's you need for the Lunar program.

1.5 solution, annual LV costs:
4 x ISS missions using:
 1 x CLV @ $100m
2 x Lunar missions taking ~50mT to LOI using:
 1 x CLV @ $100m
 1 x CaLV @ $1Bn
TOTAL: $2.6Bn

2.0 solution, annual LV costs:
4 x ISS missions using:
 1 x CaLV @ $1Bn
2 x Lunar missions taking ~100mT to LOI using:
 1 x CaLV (manned) @ $1Bn
 1 x CaLV (unmanned) @ $1Bn
TOTAL: $8.0Bn

2.5 solution, annual LV costs:
4 x ISS missions using:
 1 x CLV @ $100m
2 x Lunar missions taking ~100mT to LOI using:
 1 x CLV @ $100m
 2 x CaLV @ $1Bn
TOTAL: $4.6Bn


Quote
I prefer another plan which uses a smaller Inline SDLV to launch the crew. Think of it as a larger CLV. It would have a 5 RS-68 core, like the CaLV, and a J-2S upperstage. I am unsure how much this vehicle would be able to lift, but deffinatly much more than the current CLV. I am debating whether the CEV and LSAM should be launched on the CLV and just the EDS and cargo on the CaLV.

An aside: The CaLV is still currently being assumed to be powered by five SSME's.   The alternative arrangement under consideration is to use four RS-68's.

So the approach we're talking about is fundamentally designing the CaLV as the heavy lifter.   Then removing the SRB's and seeing what exactly the same main core (and EDS if required) can do alone - right?   By designing the main core only once for both vehicles you'd certainly reduce the development costs.

Tomorrow I will try to 'run some numbers' and get some real figures for what that configuration can actually do, with both SSME & RS-68 power.

What I will say though is that it's an intriguing idea, but I suspect it won't be feasible.   I don't think the thrust to weight ratio for the core stage, without boosters, will be enough to get it off the ground.

I'm guessing, but I think you'd end up having to reduce the fuel capacity to make the vehicle light enough to get off the pad, but when you reduce the fuel load, you then reduce the amount of time which the stage will be able to burn for, and thus reduce the amount it will be able to climb and accelerate.   Then an Upper Stage is definately required - which adds even more mass at the Pad when you start, so you just end up in a vicious circle.   Its just a "feeling" right now, but I susect its a losing proposition.   We'll see if there's any paydirt though when I get a chance to run some figures.

Ross.
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Offline kraisee

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #75 on: 04/16/2006 01:48 PM »
Quote
Jon_Jones - 15/4/2006  8:09 PM
...
Now what I what to know, after all our long and drawn out discussion, is... does the stick have the power to lift a second stage and CEV to height where that second stage, whose mass and therefore contribution to the delta V have all been determined by the lifting power of the SRB,

Remember that fundamentally it is the two SRB's which do most of the initial lifting of the 750ton External Tank and 115ton Orbiter on every Shuttle flight.   The risk with the CLV was actually how to tame the enormous power of the SRB down to a point where it wouldn't leap off the pad and boost the crew up at an intollerable 7 or 8g!

The solution was the mass of the fairly large upper stage - which was necessary anyway.   The weight of that stage slows things down to a much more tollerable 2.5-3g launch.


Quote
does that second stage stand a chance, with a J-2x engine of getting the CEV into a decent orbit.. or is this choice of SRB looking like a the wrong choice for the job from a rocket scientist's perspective????

While the CLV is bound to cause discussion, the SRB & J-2X solution is an arguably good solution for launching crew.

It can certainly do the job of lofting a medium-capacity (~20mT) payload to orbit and does a pretty good job of reducing the complexity of the overall rocket system in a bid to maximise reliability and safety.   It has the advantage of also maintaining some of the current STS workforce after that system is retired, which is a very politically astute move for NASA at this time.

If the world were very different, and NASA actually had the chance to go for a completely blank drawingboard, I personally think something better could be devised.

For my money, I'd make two big dumb boosters; a medium-class and a really-heavy-class.   They would be single-stage to orbit.   They would be all-liquid powered and would provide for engine-out capability.   Later designs would utilise a very large toroidal aerospike design, powered by a collection of engines, each feeding a "section" of the engine bell. And that aerospike design would be able to be utilised as a TPS for re-entry, allowing the stage to retian some H2 in the tanks, which during re-entry would turn gaseous and provide a degree of "bouyancy" allowing the stage to float down more gently before being recovered and then being re-used.

But that's a "perfect world" solution for me, and we don't live in that perfect world, we live in this one instead.

Quote
and in all our calculations, do we include drag. what is the drag for a rocket. is it somewhere around 1/4 or 1/8 the area time the velocity squared.... does this affect things? I know there are a several seconds where the thing is in the thick parts of the atmosphere... does this have much effect?

Drag does have a significant effect, largely during the first few minutes of any launch.   After that, the atmosphere is a lot thinner and the effects of drag roll off considerably.   Drag is still noticable, and is a factor to be carefully considered up to about 250,000ft, so it's very difficult to model accurately.

Ross.
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Offline Jim

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #76 on: 04/16/2006 01:53 PM »
"An aside: The CaLV is still currently being assumed to be powered byfive SSME's. The alternative arrangement under consideration is to usefour RS-68's."

Not true, quite the opposite

Offline R&R

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #77 on: 04/16/2006 11:40 PM »
Quote
Jim - 17/4/2006  7:53 AM

"An aside: The CaLV is still currently being assumed to be powered byfive SSME's. The alternative arrangement under consideration is to usefour RS-68's."

Not true, quite the opposite

There's been a fair amount of copy from reliable press that seems to show NASA leaning to RS68 for money reasons.  Have you foun something more afirmative that they're not?

Offline Jim

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #78 on: 04/17/2006 12:43 AM »
Quote
R&R - 16/4/2006  7:40 PM
Quote
Jim - 17/4/2006  7:53 AM"An aside: The CaLV is still currently being assumed to be powered byfive SSME's. The alternative arrangement under consideration is to usefour RS-68's."

Not true, quite the opposite
There's been a fair amount of copy from reliable press that seems to show NASA leaning to RS68 for money reasons.  Have you foun something more afirmative that they're not?

I was referring to the first sentence.  RS-68 is now the baseline

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #79 on: 04/17/2006 11:19 AM »
Quote
Propforce - 14/4/2006  7:16 AM

Quote
Manel - 12/4/2006  3:51 PM

Why build the CLV ?

An External Tank with 3-4  RS-68  (no solids)  plus a Service Module with a delta V of 3.500 fps suffices to orbit the CEV

Get rid of the Stick!


I think a lot of people missed what you were saying.  A core CaLV (ET tank diameter with 3 or 4 RS-68, and a J-2X upper stage) could replace the CLV and certainly get rid of the SRBs.  


_______________


       We don´t need an upper stage to orbit the CEV !!

       An External Tank with 4 RS-68 can propel a 25 mTons CEV at  8.600 meters/ps

       At separation, the Service Module burns to put a  18 mTons CEV into earth orbit

       This single stage (almost) CLV is the first step to build a bigger CaLV,  with 2 RSRB and EDS


Offline yinzer

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #80 on: 04/17/2006 04:33 PM »
Quote
kraisee - 16/4/2006  6:14 AM
Yeah, thats the killer right there.   CaLV is going to cost somewhere around $1Bn per flight.   CLV's target price was $100m per flight.

So ISS flights increase in launch-vehicle price alone, by 10 times for every ISS flight, and also increase by 40% overall for Lunar missions if you go with CaLV as the crew launcher.

It's been reported elsewhere on this site that Goddard was told launching RLEP2 on a CLV would cost them $457M.  It'd be truly impressive if there was already a 400% per-flight cost overrun without a massive reduction in flight rates, like what happened to EELV.

Which also makes me wonder, what was the last time that MSFC designed (or had a significant role in) a piece of new or new-ish rocket-propelled hardware that actually flew?
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Online wannamoonbase

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #81 on: 04/17/2006 05:13 PM »
Quote
Manel - 17/4/2006  6:19 AM

       We don´t need an upper stage to orbit the CEV !!

       An External Tank with 4 RS-68 can propel a 25 mTons CEV at  8.600 meters/ps

       At separation, the Service Module burns to put a  18 mTons CEV into earth orbit

       This single stage (almost) CLV is the first step to build a bigger CaLV,  with 2 RSRB and EDS


I thought the CEV with SM and CM was 25 mT not 18?  What is 18 mT, is that less 7mT of fuel?
SpaceX, just a few things planned for 2018: FH, Starlink Prototypes, Block 5, Dragon 2, Increased launch rate.

Offline Jim

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #82 on: 04/17/2006 05:18 PM »
Quote
Manel - 17/4/2006  7:19 AM
Quote
Propforce - 14/4/2006  7:16 AM
Quote
Manel - 12/4/2006  3:51 PMWhy build the CLV ?An External Tank with 3-4  RS-68  (no solids)  plus a Service Module with a delta V of 3.500 fps suffices to orbit the CEVGet rid of the Stick!
I think a lot of people missed what you were saying.  A core CaLV (ET tank diameter with 3 or 4 RS-68, and a J-2X upper stage) could replace the CLV and certainly get rid of the SRBs.  
_______________       We don´t need an upper stage to orbit the CEV !!       An External Tank with 4 RS-68 can propel a 25 mTons CEV at  8.600 meters/ps       At separation, the Service Module burns to put a  18 mTons CEV into earth orbit       This single stage (almost) CLV is the first step to build a bigger CaLV,  with 2 RSRB and EDS


 Need the fuel (25 T) for the lunar mission

Offline Manel

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #83 on: 04/17/2006 06:46 PM »
Well Jim,  but I´m talking about missions to the ISS

Also you get a mini-CaLV as first step to the heavy CaLV

Then, let me copy from gladiator  - post 30882

    =For lunar missions, the "Two launch" plan would be used. The CEV and LSAM are launched  
      on one CaLV and the EDS is launched on the other. Instead of using 5 segment SRBs on  
      the CaLV,  4 segment SRBs will be used instead. Too much time and money would spent  
      to upgrade to the 5 segment SRB.  

This is a much simpler way to return to the Moon, as we no longer have to develop two launch vehicles. Everything is derived from the same CaLV design. With the RS-68 engine and the 4 segment SRB, these vehicles will be cheaper to develop and launch.=

Offline kraisee

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #84 on: 04/17/2006 07:49 PM »
Quote
Jim - 17/4/2006  7:53 AM

"An aside: The CaLV is still currently being assumed to be powered byfive SSME's. The alternative arrangement under consideration is to usefour RS-68's."

Not true, quite the opposite

I hate having to waste my time on pedantic BS like this, but...

Go dig out your copies of the LRA stuff from last week.   That's is an internal engineering report with all the latest changes to the ESAS itemised, and it is dated April 3rd 2006.

Unless something else has been released in the last two weeks which I missed, I think it contains the most up-to-date specifications being provided to technical study teams inside NASA itself.   That's good enough for me.

I won't repost the images themselves as Chris has chosen to remove it from the site because it shows only a small portion of the investigations being conducted currently, but I'll quote the section about changed assumptions for the CaLV from the original ESAS report.   It was on page 4:-

Quote
* CaLV
 - Booster propellant changed from HTPB to PBAN
 - Core stage engine mass increased based on RS-25festimate
 - EDS stage engines changed from 2 J-2S+ to 1 Block II J-2X
 - Payload Shroud mass increase

To be very precise, RS-25 is the designation for the SSME, and the 'f' designation actually refers to the still hypothetical 'disposable' variant we know from the ESAS report.

Now, don't get me wrongL I personally believe that the switch will happen to RS-68, and I think it's a good idea.

But that document shows that engineering teams studying critical analysis within NASA *right now* appear to still be assuming use of the SSME for all their investigative work.   So, unless there's another more recent document someone can identify, the switch to RS-68 has not been made officially YET.

So, I stand by my previous statement: "An aside: The CaLV is still currently being assumed to be powered by five SSME's. The alternative arrangement under consideration is to use four RS-68's."

Ross.
"The meek shall inherit the Earth -- the rest of us will go to the stars"
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Offline Jim

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #85 on: 04/17/2006 08:13 PM »
5 RS-68's
33 ft diameter
1 J-2X

LRA stuff is one study

Can't said anymore or the source document.  But those are the marching orders

Online Chris Bergin

RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #86 on: 04/17/2006 08:17 PM »
We are aiming to update the "state of play" on developmental processes this week...on the hardware.

Offline edkyle99

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #87 on: 04/17/2006 09:08 PM »
Quote
Jim - 17/4/2006  3:13 PM

5 RS-68's
33 ft diameter
1 J-2X

LRA stuff is one study



Is this a CLV description, or a CaLV core stage description?

 - Ed Kyle

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #88 on: 04/17/2006 09:13 PM »
CaLV obviously.  5 RS-68s on the CLV?  Where would you put them? ;)

Offline edkyle99

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #89 on: 04/17/2006 09:23 PM »
Quote
hyper_snyper - 17/4/2006  4:13 PM

CaLV obviously.  5 RS-68s on the CLV?  Where would you put them? ;)

On the bottom of the new 10 meter diameter first stage, of course!
 - Ed Kyle

Offline kraisee

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #90 on: 04/18/2006 12:00 AM »
I think what he meant was the arrangement.   Thing Saturn-V; four square around the perimiter, one in the center.

-R.
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Offline Jim

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #91 on: 04/18/2006 12:28 AM »
Quote
Jim - 17/4/2006  4:13 PM5 RS-68's
33 ft diameter
1 J-2X

LRA stuff is one study

Can't said anymore or the source document.  But those are the marching orders
CaLV configuration

Offline kraisee

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #92 on: 04/18/2006 12:34 AM »
Okay, Gladiator - I've run some numbers on that ET launcher.   It's basic at this stage still, but it's accurate enough to prove or disprove the concept.

I'm bumed.   I liked this idea of an ET-derived booster.   It "kinda" works, but has one very serious problem which appears to kill the idea stone cold.   Let me explain.

First, configurations...

You must have a second stage, One stage just doesn't work for the reasons I guessed at previously.   I tried configs of both four and five RS-68's on the main core.   4 RS-68's doesn't work at all.

I've used the standard configuration of hardware for the CaLV for all hardware calculations, minus the boosters of course.   The optimum condition is to put only about 800tons of propellant on board the main stage so it is not filled compared to full CaLV flights.   Just for comparison, Shuttle has about 730tons in the ET.   Then you put about 100-120 tons of propellant in a standard EDS stage.   Having an optimised upper stage based on the EDS improves things by less than 5mT of final payload, so I've ignored that option due to the massive duplication of costs required.

The first stage must be throttled down in the latter part of its flight to ensure you don't exceed 3g conditions.   Left alone it peaks around 4.2g!

I simply cut the throttles to 60% just as the stage reaches 3g around 190secs.   This cut could actually be achieved either by throttling all engines down to minimum flight-rated spec, or simply turning two of the five engines off early - kinda like the Saturn-V first stage did.   Doesn't really matter which way you do it, the result is the same.

However, the dynamic pressure this vehicle experiences is a total killer for this launcher.

Even throttling the 5 RS-68's down to 60% thrust between 50 and 120secs it suffers from a massive dynamic over-pressure problem peaking at 1,100lb/sq ft about 113 seconds into the flight.   As was just mentioned over on another thread, ~800lb/sq ft is the absolute max you should ever consider for a launcher, and you need to fly manned launchers noticably below that to give the escape system some "headroom" to operate in.

Just for comparison, CLV and CaLV have been designed to both operate below 600lb/sq ft.

So, ignoring that the thing would tear itself completely apart due to the pressure conditions, if it could fly an optimised flight profile, it can theoretically loft about 56mT to the ESAS reference orbit of 30x160nM, 28.5degree.

Mythbusters would probably declare this launcher "Busted", sorry.

Ross.
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Offline kraisee

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #93 on: 04/18/2006 01:42 AM »
Hold that... I'm playing with some clever throttling around ahead of the max-q which is improving the situation considerably.

I'll continue playing and post result when I can.

Ross.
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Offline edkyle99

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #94 on: 04/18/2006 01:59 AM »
Quote
kraisee - 17/4/2006  7:34 PM

Okay, Gladiator - I've run some numbers on that ET launcher.   It's basic at this stage still, but it's accurate enough to prove or disprove the concept. ...

You must have a second stage, One stage just doesn't work for the reasons I guessed at previously.   I tried configs of both four and five RS-68's on the main core.   4 RS-68's doesn't work at all.

I've used the standard configuration of hardware for the CaLV for all hardware calculations, minus the boosters of course.   The optimum condition is to put only about 800tons of propellant on board the main stage so it is not filled compared to full CaLV flights.   Just for comparison, Shuttle has about 730tons in the ET.   Then you put about 100-120 tons of propellant in a standard EDS stage.   Having an optimised upper stage based on the EDS improves things by less than 5mT of final payload, so I've ignored that option due to the massive duplication of costs required....

However, the dynamic pressure this vehicle experiences is a total killer for this launcher.


What about a crew launcher sized for a 25 tonne to LEO payload (mass injected
into LEO) powered  by only 3 RS-68s with a J-2X upper stage?  430 tonnes of
propellant in an ET-diameter, but shorter-than-ET, Stage 1 with a 490 tonne
gross.  90 tonnes propellant in Stage 2 with a 100 tonne gross.  Or so.  (Maybe
Stage 2 works as a TLI stage in a bigger launcher.)  The whole deal weighs
about 620 tonnes at liftoff with a 1.44 T/W ratio.

 - Ed Kyle

Offline Damon Hill

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #95 on: 04/18/2006 02:20 AM »
Think Atlas-Original: arrange three or four of the RS-68s in a jettisionable
ring with a center sustainer.  Adds some complexity and a staging event,
but it should shed a useful amount of mass and allow of some range of
payload capacity based on the number of engines used and perhaps
propellant loading/tankage stretch?

I seem to recall discussion that such an arrangement with SSMEs had a
pretty good SSTO payload.

Offline simonbp

RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #96 on: 04/18/2006 02:24 AM »
Quote
Damon Hill - 17/4/2006  9:20 PM

Think Atlas-Original: arrange three or four of the RS-68s in a jettisionable
ring with a center sustainer.  Adds some complexity and a staging event,
but it should shed a useful amount of mass and allow of some range of
payload capacity based on the number of engines used and perhaps
propellant loading/tankage stretch?

I seem to recall discussion that such an arrangement with SSMEs had a
pretty good SSTO payload.


Hehe, anyone up for a 200 ft Al-Li balloon tank? :)

We can call it "Atlas on Steroids" and let the media try and figure that one out!

Simon ;)

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #97 on: 04/18/2006 02:37 AM »
If you're getting useful payload without dropping the engines, why bother?  Just more to go wrong, and more stuff to develop.

Oh, if the high dynamic pressure is coming about due to excessive liftoff thrust, and depending on how hard it is / how flexible your analysis code is, it might be worth playing around with nozzle extensions to reduce sea-level thrust while picking up Isp further down the trajectory.

Now I'm really interested to see if this thing works out...
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Offline kraisee

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #98 on: 04/18/2006 02:38 AM »
Quote
edkyle99 - 17/4/2006  9:59 PM

What about a crew launcher sized for a 25 tonne to LEO payload (mass injected
into LEO) powered  by only 3 RS-68s with a J-2X upper stage?  430 tonnes of
propellant in an ET-diameter, but shorter-than-ET, Stage 1 with a 490 tonne
gross.  90 tonnes propellant in Stage 2 with a 100 tonne gross.  Or so.  (Maybe
Stage 2 works as a TLI stage in a bigger launcher.)  The whole deal weighs
about 620 tonnes at liftoff with a 1.44 T/W ratio.

 - Ed Kyle

Cost for developing a whole new large-scale first stage is prohibative.

There is a sound reason for trying this with the core of CaLV due to cost savings, but not to develop a whole new stage.

Ross.
"The meek shall inherit the Earth -- the rest of us will go to the stars"
-Robert A. Heinlein

Offline kraisee

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #99 on: 04/18/2006 08:07 AM »
Quote
kraisee - 17/4/2006  9:42 PM

Hold that... I'm playing with some clever throttling around ahead of the max-q which is improving the situation considerably.

I'll continue playing and post result when I can.

Ross.

Nope.   Can not get it to work even close to safely.

Busted.

And the 3-RS-68 engine'd version Ed mentions is basically just a Delta-IV Heavy in a slightly different "package".

It certainly wouldn't be able to loft an EDS stage, so you'd have to use something like the current D-IV Heavy upper stage and man-rate it - so at that point why not just use the Heavy as it is and save yourself a lot of extra costs duplicating it all over again.

Probably should mention that it isn't anywhere near as safe as the CLV either...

Ross.
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Offline gladiator1332

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #100 on: 04/18/2006 01:34 PM »
Bummer...oh well...thanks for looking into it.  :)

Offline edkyle99

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #101 on: 04/18/2006 05:52 PM »
Quote
kraisee - 17/4/2006  9:38 PM

Quote
edkyle99 - 17/4/2006  9:59 PM

What about a crew launcher sized for a 25 tonne to LEO payload (mass injected
into LEO) powered  by only 3 RS-68s with a J-2X upper stage?  430 tonnes of
propellant in an ET-diameter, but shorter-than-ET, Stage 1 with a 490 tonne
gross.  90 tonnes propellant in Stage 2 with a 100 tonne gross.  Or so.  (Maybe
Stage 2 works as a TLI stage in a bigger launcher.)  The whole deal weighs
about 620 tonnes at liftoff with a 1.44 T/W ratio.

 - Ed Kyle

Cost for developing a whole new large-scale first stage is prohibative.

There is a sound reason for trying this with the core of CaLV due to cost savings, but not to develop a whole new stage.

Ross.

All righty then.  How about using a CaLV core stage, shorn of one or
two (RS-68) engines and only partially loaded with propellant?  Still
430 tonnes of propellant in the first stage, but the gross mass would
be higher - perhaps 522 tonnes now.  Make up for the shortfall with
a slightly heavier second stage - 103.5 tonnes propellant and 115 tonnes
gross.  Thrust to weight is now 1.34, but the first stage could be identical
to the CaLV core except for the pulled engines.
 
While the second stage would not be the full EDS stage planned for
the CaLV, it would be about the right size for a TLI-only (no ascent
burn to Earth orbit) stage.  

 - Ed Kyle

Offline edkyle99

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #102 on: 04/18/2006 06:17 PM »
Quote
kraisee - 18/4/2006  3:07 AM

And the 3-RS-68 engine'd version Ed mentions is basically just a Delta-IV Heavy in a slightly different "package".

It certainly wouldn't be able to loft an EDS stage, so you'd have to use something like the current D-IV Heavy upper stage and man-rate it - so at that point why not just use the Heavy as it is and save yourself a lot of extra costs duplicating it all over again.

Probably should mention that it isn't anywhere near as safe as the CLV either...

Ross.

There is one significant difference between the ET-based 3-RS-68 version I
mentioned and a Delta IV Heavy.  Delta IV Heavy puts a much larger
percentage of propellant mass into the 3xCBC "first" stage compared
to the second stage - 600 tonnes in the first stage versus only 27+ tonnes in
the upper stage.  Delta IV Heavy gross mass exceeds 725 tonnes.  The
concept I mentioned only weighed 620 tonnes (or 670 tonnes if a CaLV
core was used) with a heavier second stage (90 tonnes propellant) and a
lighter first stage (430 tonnes propellant).  The heavier upper stage
supports a higher-thrust engine, which is needed to handle NASA's manned
ascent trajectories.

Delta IV Heavy could be turned into an equivalent design by only partially
loading its otherwise unchanged CBC stages with propellant and by topping
it with a new upper stage similar to the planned CLV second stage.  The
new upper stage would be needed anyway to handle the non-lofted ascent
trajectory.

As for safety, the ESAS report listed the LOC probability of the ET-based
designs to be nearly 1/1000 - about 15-20 times safer than the current
U.S. human launch system, though only half as safe as the CLV.  But do
any of us really believe those numbers?

 - Ed Kyle

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #103 on: 04/18/2006 06:44 PM »
Quote
edkyle99 - 18/4/2006  1:17 PM
As for safety, the ESAS report listed the LOC probability of the ET-based
designs to be nearly 1/1000 - about 15-20 times safer than the current
U.S. human launch system, though only half as safe as the CLV.  But do
any of us really believe those numbers?

Given the different ways that a liquid rocket can fail catastrophically compared to a solid rocket, I think the safety numbers of a purely-solid first stage are not unreasonable.  Whether they are truly 1/1600 or whatever, who knows, but with a proper escape system, it does look a heckuvalot safer than a liquid first stage.

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #104 on: 04/18/2006 07:23 PM »
Quote
BogoMIPS - 18/4/2006  2:44 PM
Quote
edkyle99 - 18/4/2006  1:17 PMAs for safety, the ESAS report listed the LOC probability of the ET-based designs to be nearly 1/1000 - about 15-20 times safer than the current U.S. human launch system, though only half as safe as the CLV.  But do any of us really believe those numbers?
Given the different ways that a liquid rocket can fail catastrophically compared to a solid rocket, I think the safety numbers of a purely-solid first stage are not unreasonable.  Whether they are truly 1/1600 or whatever, who knows, but with a proper escape system, it does look a heckuvalot safer than a liquid first stage.

Not true.  Most SRM failure modes give no ro little indication that they are happening, hence an abort system does no good.

Liquids can give you indications that you can shutdown and abort from.  A liquid engine with high margins (ie not an SSME) could degrade more "gracefully"

Offline kraisee

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #105 on: 04/18/2006 07:46 PM »
Quote
edkyle99 - 18/4/2006  2:17 PM
As for safety, the ESAS report listed the LOC probability of the ET-based
designs to be nearly 1/1000 - about 15-20 times safer than the current
U.S. human launch system, though only half as safe as the CLV.  But do
any of us really believe those numbers?

 - Ed Kyle

That's a fair point.

I don't per-se believe that there will only be one loss of crew in every 1,918 flights of the CLV.   I think the loss will be a lot higher than that.

But I *DO* believe the comparison between the figures is pretty close.   A vehicle with 1 in 500 LOC is probably four times more dangerous than one with an LOC of 1 in 2,000.   A vehicle with 1 in 1,000 LOC is probably half as safe as one with 1 in 2,000.   And any vehicles around 1 in 2,000 are probably about as safe as any other around 1 in 2,000.

So, I think those figures, while not necessarily what we'll find in reality, are still the best possible means of comparing the safety of the different vehicles.

For my money, I'll be surprised if we fly CEV 200 times without loss of life.   It's a new vehicle, and it'll have problems we aren't expecting.   BUT, it is based on a lot of vehicle components which have real flight history behind them, so lessons have already been learned, so I think CLV and CaLV are both already ahead of the game in terms of evolutionary development across the life of a vehicel system.

Ross.
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Offline kraisee

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #106 on: 04/18/2006 08:07 PM »
I can't find any hard-fact data on a direct comparison between solid and liquid rocket engine reliability.

I assume the ESAS figures are all based on some fact-based analysis from somewhere.   It certainly seems to indicate that the SRB's are significantly less likely to fail than comparable liquid engined first stages, but I have personally never seen any analysis which offers conclusions one way or the other.

Without hard-data, we're actually all just reduced to making guesses on here.   I'd like to have some real facts to work with instead of just the usual supposition.

So, does anyone out there have real hard data on comparing these things accurately which can be released for us to all examine?

Ross.
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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #107 on: 04/18/2006 08:27 PM »
Quote
kraisee - 18/4/2006  4:07 PMI can't find any hard-fact data on a direct comparison between solid and liquid rocket engine reliability.I assume the ESAS figures are all based on some fact-based analysis from somewhere.   It certainly seems to indicate that the SRB's are significantly less likely to fail than comparable liquid engined first stages, but I have personally never seen any analysis which offers conclusions one way or the other.Without hard-data, we're actually all just reduced to making guesses on here.   I'd like to have some real facts to work with instead of just the usual supposition.So, does anyone out there have real hard data on comparing these things accurately which can be released for us to all examine?Ross.

Look at Futon or some of the other beltway bandits.  (Aerospace Corp, Anser, Rand, etc). 

But anyways, you are going to find the same basic premise:  You can use statistics to prove your point anyway you want.

Offline yinzer

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #108 on: 04/18/2006 09:49 PM »
Quote
kraisee - 18/4/2006  1:07 PM

I can't find any hard-fact data on a direct comparison between solid and liquid rocket engine reliability.

I assume the ESAS figures are all based on some fact-based analysis from somewhere.   It certainly seems to indicate that the SRB's are significantly less likely to fail than comparable liquid engined first stages, but I have personally never seen any analysis which offers conclusions one way or the other.

Without hard-data, we're actually all just reduced to making guesses on here.   I'd like to have some real facts to work with instead of just the usual supposition.

So, does anyone out there have real hard data on comparing these things accurately which can be released for us to all examine?

Ross.

The sample size isn't really big enough to have hard data either way.  Reliability seems to come mainly from flying frequently enough to wring out design bugs.  

"Liquid rocket engine" is also an incredibly broad category. The Viking motor on the Ariane 4 flew 783 times, with one failure.  By the end of the production run, they weren't even test firing the motors, just installing them straight from the factory.  The RL-10 has also been incredibly reliable, probably due to comparatively low internal pressures and temperatures along with a generally simple design.  Staged combustion engines have been somewhat less reliable, with the SSME having one in-flight shutdown in 300 flights, the Block D / DM having numerous shutdowns and failures to ignite, and the RD-120 (Zenit 2nd stage) blowing up, failing to light, or shutting down prematurely on a semi-regular basis.

As I've pointed out before, it's important to keep in mind that there's been very little effort expended in letting liquid rocket engines handle failures gracefully; indeed the ESAS report recommends doing the exact opposite in several places ("inhibit SSME redlines" means "run the thing until it blows up").

There's been similarly little effort in letting stages handle failures gracefully.  People frequently mention that liquid rocket stages can release a lot more energy if they explode, but they don't point out that liquid rocket stages historically explode only when they are deliberately blown up, or when the main engine is deliberately run until it self-destructs, which is kind of the same thing.

The study Futron did for SpaceX is available www.spacex.com/FutronDesignReliability.pdf">here, for what it's worth.
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Offline mkirk

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #109 on: 04/18/2006 10:00 PM »
Quote
kraisee - 18/4/2006  3:07 PM

I can't find any hard-fact data on a direct comparison between solid and liquid rocket engine reliability.

I assume the ESAS figures are all based on some fact-based analysis from somewhere.   It certainly seems to indicate that the SRB's are significantly less likely to fail than comparable liquid engined first stages, but I have personally never seen any analysis which offers conclusions one way or the other.

Without hard-data, we're actually all just reduced to making guesses on here.   I'd like to have some real facts to work with instead of just the usual supposition.

So, does anyone out there have real hard data on comparing these things accurately which can be released for us to all examine?

Ross.


This link is about the best you will find in the public domain.  It is from the SAIC report that everyone started quoting early last year.

http://www.safesimplesoon.com/assets/documents/Reliability+CrewSafety.pdf

Like Jim said you have to step back an look at it with a healthy dose of skepticism...just like the Futron study.

Although I should in the interest of full disclosure add that I am on the "solids" side of the current debate.

Mark Kirkman
Mark Kirkman

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #110 on: 04/19/2006 12:04 AM »
Do solids have a history of exploding?I belive the reason why many question the solid first stage is the memory of Challenger. That is something that NASA will have to constantly face, I can't remember a Shuttle launch where I haven't let out a sigh of relief after the SRBs fall away. Even though the cause of Challenger was fixed, the SRBs are still thought of as dangerous.

Offline edkyle99

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #111 on: 04/19/2006 01:12 AM »
Quote
gladiator1332 - 18/4/2006  7:04 PM

Do solids have a history of exploding?I belive the reason why many question the solid first stage is the memory of Challenger. That is something that NASA will have to constantly face, I can't remember a Shuttle launch where I haven't let out a sigh of relief after the SRBs fall away. Even though the cause of Challenger was fixed, the SRBs are still thought of as dangerous.

The two big Titan SRM failures (Titan 34D-9 in 1986 and 403A-K11 in 1993)
got my attention.  34D-9 happened at T+16 seconds, right above the pad.  
K11 happened more than a minute and a half into the flight.  Then, of course
there is the more recent (1997) Delta 241 failure, where an SRB let go only
7 seconds after liftoff at the Cape.  Another Delta SRB failure happened in
1977 (D134), and an SRB failed on a Thor SLV-2A Agena D  in 1963.  
Delta 228 suffered a more benign SRB problem in 1995 when one of its
SRBs failed to separate, causing Koreasat 1 to enter a low orbit.  Japan's
H-IIA-6F suffered a similar problem in 2003 (tho caused by a nozzle burn
through rather than a separation system issue), but with more severe
consequences - the rocket had to be RSO'ed after 11 minutes.

 - Ed Kyle

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #112 on: 04/19/2006 01:33 AM »
There have been Minuteman failures also.

Offline BogoMIPS

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #113 on: 04/19/2006 01:44 AM »
The two Titan 34D failures you cite are both cases where an SRM failure was alongside a liquid rocket.  The strap-on SRM failures you cite are along the same lines as well.  Once the solid's failure causes the liquid rocket to fail, you've got both explosions happening, so limiting analysis to one seems tough.

Any good resources on the 'net about the 34D-9 failure?  I'd like to learn more about this, so I'm not talking out my exhaust nozzle right now. ;)

As long as we don't start looking at sticking the CEV atop the CaLV, the comparison of these systems to CLV, to me, doesn't seem 100% fair.  I will agree that solid motors can fail spectacularly, just as liquids can.  The question is how likely will that be, and how survivable is it when it happens?

I need to do some more research on failures of launches with of linear (i.e. no strap-on/parallel engines), solid-only first stages.  I haven't done enough reading to be sure, but other than ICBMs, I can't think of many other systems that have used that configuration previously.

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #114 on: 04/19/2006 02:08 AM »
Quote
BogoMIPS - 18/4/2006  9:44 PMThe two Titan 34D failures you cite are both cases where an SRM failure was alongside a liquid rocket.  The strap-on SRM failures you cite are along the same lines as well.  Once the solid's failure causes the liquid rocket to fail, you've got both explosions happening, so limiting analysis to one seems tough.Any good resources on the 'net about the 34D-9 failure?  I'd like to learn more about this, so I'm not talking out my exhaust nozzle right now. ;)As long as we don't start looking at sticking the CEV atop the CaLV, the comparison of these systems to CLV, to me, doesn't seem 100% fair.  I will agree that solid motors can fail spectacularly, just as liquids can.  The question is how likely will that be, and how survivable is it when it happens?I need to do some more research on failures of launches with of linear (i.e. no strap-on/parallel engines), solid-only first stages.  I haven't done enough reading to be sure, but other than ICBMs, I can't think of many other systems that have used that configuration previously.

Conestoga one and only flight was a control failure
Athena- no propulsive failures.

I will let you research the following:
Scout
Pegasus
Taursus

You won't find many solid only space vehicles

Your premise that the Titan IV and Delta/Thor failures are different because they were close to a liquid core is flawed.  They all were catastrophic before they affected the core vehicle.  Challenger is the only one that wasn't.

Offline edkyle99

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #115 on: 04/19/2006 03:13 AM »
Quote
BogoMIPS - 18/4/2006  8:44 PM

The two Titan 34D failures you cite are both cases where an SRM failure was alongside a liquid rocket.  The strap-on SRM failures you cite are along the same lines as well.  Once the solid's failure causes the liquid rocket to fail, you've got both explosions happening, so limiting analysis to one seems tough.

Any good resources on the 'net about the 34D-9 failure?  I'd like to learn more about this, so I'm not talking out my exhaust nozzle right now. ;)

As long as we don't start looking at sticking the CEV atop the CaLV, the comparison of these systems to CLV, to me, doesn't seem 100% fair.  I will agree that solid motors can fail spectacularly, just as liquids can.  The question is how likely will that be, and how survivable is it when it happens?

I need to do some more research on failures of launches with of linear (i.e. no strap-on/parallel engines), solid-only first stages.  I haven't done enough reading to be sure, but other than ICBMs, I can't think of many other systems that have used that configuration previously.

Not in depth, but the following link provides a description of the failure.  

http://www.fas.org/spp/military/program/cape/Cape1fn.htm

"TITAN 34D was launched from Vandenberg on 18 April 1986
TITAN 34D-9 exploded eight seconds after lifting off Space Launch Complex 4 (East) on April 18th.
Upper sections of the vehicle's solid rockets and bare fuel showered the launch pad, causing severe
damage to launch facilities nearby. In some instances, large steel fragments were blown 3000 feet
from the point of impact. The explosion also created a toxic cloud that rose to an altitude of 8000 feet
before it was blown out over the Pacific Ocean. The AFSC Inspector General's Office selected the
ESMC Commander, Brigadier General (Selectee) Nathan J. Lindsay, to serve as the president for
the Mishap Investigation Board. The Board issued its final progress report on 9 June 1986, and that
report suggested a variety of potential causes, mostly related to solid propellant/insulation
debonding."

That's how I remember it.  Propellant/insulation debonding.  They added a lot of NDT
procedures to the prelaunch cycle.  That still did not prevent the K-11 failure, which
was caused by a faulty repair of an SRM.

 - Ed Kyle

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #116 on: 04/19/2006 03:04 PM »
Here is additional history on the big Titan solids.

5-Segment SRMs (Titan 3C,D,E):  130 flown on 65 missions, no SRM failures

5.5-Segment SRMs (Titan 34D, Titan 3 Commercial):  38 flown on 19 missions, one SRM failure

7-Segment SRMs (Titan 4A):  44 flown on 22 missions, one SRM failure

3-Segment SRMUs (Titan 4B):  34 flown on 17 missions, no SRMU failures

Totals:  246 SRM/SRMUs flown, 2 failures

The disconcerting thing about the Titan solid motor failures is that they
occurred relatively late in the program - after more than 130 had
flown without failure.

 - Ed Kyle

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #117 on: 04/20/2006 07:16 PM »
What were the actual causes for the two failures you mention?

Specifically, are the Shuttle SRB's susceptible to similar failures due to common/similar designs?

Ross.
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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #118 on: 04/20/2006 07:26 PM »
Quote
kraisee - 20/4/2006  3:16 PMWhat were the actual causes for the two failures you mention?Specifically, are the Shuttle SRB's susceptible to similar failures due to common/similar designs?Ross.

Delamination.  The segments are xrayed, but.....
and bad repair


Offline edkyle99

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #119 on: 04/21/2006 01:43 AM »
Quote
kraisee - 20/4/2006  2:16 PM

What were the actual causes for the two failures you mention?

Specifically, are the Shuttle SRB's susceptible to similar failures due to common/similar designs?

Ross.

According to "Space Systems Failures" by Harland and Lorenz (Praxis Publishing, 2005), the Titan 34D-9 failure was suspected to have been caused by the delamination of "rubber insulation" that allowed "hot gas in the motor to make contact with the steel casing, weakening it sufficiently for the 700-psi pressure to open a hole 7-inches in diameter".

The Titan 4 failure was also caused by a case burn through.  At the factory, after the propellant mix had been poured into a motor segment, the segment was capped by a "rubbery material designed to retard erosion of the field joint".  This was called a "restrictor".  Occasionally, a void (debonding) would form between the propellant and the restrictor, requiring a repair.  Just such a repair was performed on one of the SRM segments for this Titan.  This repair just happened to be the most extensive ever - involving more than 5,000 square inches of the restrictor's surface.  There were actually multiple voids in this case, so the procedure was modified to repair multiple voids at once by using a "large, pie shaped patch".  It was assumed that the patch would be sealed by transient pressures, but, as it turned out, it was *opened*.  Result?  Casing burn through.  

After the accident, 14 repaired SRM segments (it happened a lot) were pulled for inspection.  No large surface repairs were attempted again.

 - Ed Kyle

Offline kraisee

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #120 on: 04/21/2006 04:37 AM »
From that brief description, the 34D-9 failure sounds somewhat similar to the event which took Challenger.   Assuming it was in the same "family" of failure modes, am I right in thinking the boosters were redesigned to erradicate this problem in a similar way as the Shuttle SRB's were re-designed?

That should have stopped such occurences.

Maybe someone on the forum could confirm whether or not there has been any reported cases of casing damage to any flown SRB's since STS-51L, or on any Titan flights since the 34D-9 failure?   We seem to assume that the much publicised modifications did actually fix the problems completely.   Does the evidence show that they did?

As for the Titan 4 failure, the Titan boosters have an external appearance quite similar to the Shuttle SRB's, so are they also susceptible to this same sort of issue?   If so, did any of the lessons learned on the Titan program migrate across to the Shuttle program?

I'm trying to get more of an understanding of process behind "mitigation of failure" in each of the two programs, and if there was any commonality between the various systems where saftey lessons could be cross-polinated.

Ross.
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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #121 on: 04/21/2006 04:39 AM »
both started x-raying the segments.  Titan-IV was done at the launch site.  Titan segments were not redesigned like the shuttle, since they were not manrated.  No Titan boosters were recovered

Offline edkyle99

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #122 on: 04/21/2006 05:05 AM »
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kraisee - 20/4/2006  11:37 PM

From that brief description, the 34D-9 failure sounds somewhat similar to the event which took Challenger.   Assuming it was in the same "family" of failure modes, am I right in thinking the boosters were redesigned to erradicate this problem in a similar way as the Shuttle SRB's were re-designed?

The STS-51L failure was at a field joint and was due to a less than perfect design.  The joint "flexed" more than expected during the ignition transient, allowing hot gasses to blow by the joint's O-ring seals.  The problem was worsened by cold temperatures, when the O-rings were stiffened by the cold.  The design problem was known before STS-51L, but the seriousness of the problem was not fully acknowledged or understood by all participants.  

I don't believe that the 34D-9 failure was at a joint.  The Titan SRM field joint design was believed to be better (more rigid, didn't allow water ingress, etc.) than the shuttle SRB joint design.  My recollection is that the initial 34D-9 burn-through was on a side-wall of the motor casing, due to failure of the insulation between the propellant and the steel casing.  It doesn't take long for solid rocket motor gases to melt steel!

The initial Titan SRM solution was improved inspection techniques.  Ultimately, the solution was to replace the 7-segment SRM with the completely new, more-powerful 3-segment SRMU that flew on Titan 4B.  The costly SRMU development effort, for a launch vehicle that only flew 17 times, was one reason that Titan 4 launch costs rose so much.  

 - Ed Kyle

Offline quark

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #123 on: 04/21/2006 05:37 AM »
The solids vs liquids debate is kind of like the "tastes great", "less filling" debate.  Unfortunately the direct reliability, failure history evidence is anecdotal.  the samples are small and there are way way too many variables.  However, I think some general conclusions can be drawn that are relevant to crew safety (the point of this discussion).

On the plus side, solids have very few moving parts and conceptually fewer failure modes.  However, the manufacturing process is very sensitive---lots of mixing chemicals and susceptible to material lot changes etc.  Also solids cannot be tested before use and cannot be shutdown after ignition.

Liquid engines are hot fired before use and can even be shutdown on the pad before launch commit (done on the shuttle and the Atlas).  However, they have lots of moving parts.

On both sides, reliability comes down to two factors, design reliability and process reliability.  ESAS focused on design reliability which tends to be a paper exercise.  Process reliability (how well the system is put together and flown by real people) is typically ignored.  Looking at real flight records is the only way to get a handle on both components working together.  I think it's safe to say that you could design a solid to be as reliable as any liquid and vise versa.  The same goes for the process.

On to some pragmatic considerations:  

1. The catastrophic fraction is generally agreed to be much smaller for liquids than for solids.  This is the fraction of failure modes that are catastrophic in their effects.  The reason for this is fairly straightforward:  the PV (pressure*volume) energy stored in a SRB is much higher than for a liquid.  PV energy can be released quickly by most failure modes.  Chemical energy stored in propellants is difficult to release in an accident.  Based on history, liquid failures tend to be leaks or failures to start (titan 34d-3, 34d-9, Atlas Ac 70, 71 and 74).  Either are vey easy to abort away from.

2. The key safety feature of the new CLV/CEV design (whether SDV or EELV derived) is for the CEV to abort off the stack in the event of an accident.  Liquid failure modes are easier to sense and liquids can be shutdown (the shutdown command can be sent) to allow the crew time to abort.  In fact, in configuration involving multiple liquid engines per stage, engine out capability can be designed in allowing abort to orbit scenarios or even mission success in the event of an engine failure.  This works very well for RL-10 based upper stages (like the evolved centaur with 4 engines) since the cat fraction of the RL-10 is extremely low due to its very low operating pressures.  By the way, the ESAS study mentioned engine-out as a possibility but gave no credit to configurations that included it.

3.  Engine out is not a possibility for solids.  Furthermore, it is very problamatic to abort off a malfunctioning SRB because of the fact that the rogue SRB might be chasing you.  The current requirement for the CEV abort system is that it has to deliver something like 12 g's because of the SRB underneath.

4.  A few non-safety related considerations:  liquids can be throttled alowing more flexibility in mission design that can be used to tailor black zones and performance.  Liquids generally have much higher ISP, also good for performance.

To me, liquids ought to win hands down for human spaceflight because of cat fraction, abort ability and engine out.  Reliability is not the issue.  I think it significant that the Shuttle, Delta and Atlas programs all use a combination of both liquids and solids.  (On the other hand, the Soyuz, the human launcher with the world's highest demonstrated relaibility, is all liquid).

Offline quark

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #124 on: 04/21/2006 05:47 AM »
Neither of the two titan failures was due to the joint design.  34d-9 was a failure of the liner to propellant bond line which allowed a rapid case burn through---not at a case joint.  Root cause was manufacturing defect.

K-11 was indirectly caused by the corrective action for 34d-9.  NDI put in place after 34d-9 detected a large debond between the propellant and rubber restrictor.  This led to a repair where the rubber was cut away and replaced.  The cutting procedure left an invisible slit in the propellant which allowed flame in that resulted in a case burn through mere seconds before planned SRB jettison.

I would classify both failures as process failures, related to errors in manufacturing, not design flaws.  Challenger I would classify as a design flaw in the joint that allowed hot gas on the o-ring.

Offline Jim

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #125 on: 04/21/2006 12:00 PM »
Just a note, I believe the tang of Titan and shuttle SRM's were reversed also.  (tang up vs tang down)

Offline edkyle99

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #126 on: 04/21/2006 05:51 PM »
Quote
quark - 21/4/2006  12:37 AM

The solids vs liquids debate is kind of like the "tastes great", "less filling" debate.  Unfortunately the direct reliability, failure history evidence is anecdotal.  the samples are small and there are way way too many variables.  However, I think some general conclusions can be drawn that are relevant to crew safety (the point of this discussion)....

To me, liquids ought to win hands down for human spaceflight because of cat fraction, abort ability and engine out.  Reliability is not the issue.  I think it significant that the Shuttle, Delta and Atlas programs all use a combination of both liquids and solids.  (On the other hand, the Soyuz, the human launcher with the world's highest demonstrated relaibility, is all liquid).

A nice summation of the question.  One additional consideration could be ground processing safety.  A liquid booster with empty propellant tanks is inherently safer to work around than a loaded solid motor.  There have been several nasty accidents over the years involving solid motors (an upper stage motor at the Cape during the '60s and more recent accidents at Alcantara and Sriharikota).  With loaded SRBs in the place, the VAB is a more hazardous work environment, which makes ground processing less efficient than it might otherwise be.  Saturn V personnel worked out of offices that were up in the towers right next to their stages.  The old Saturn offices had to be abandoned when shuttle came along.  STS personnel work out of offices that are not in the VAB at all.  

 - Ed Kyle

Offline kraisee

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #127 on: 04/21/2006 06:30 PM »
Quote
edkyle99 - 21/4/2006  1:51 PM
One additional consideration could be ground processing safety.  A liquid booster with empty propellant tanks is inherently safer to work around than a loaded solid motor.  There have been several nasty accidents over the years involving solid motors (an upper stage motor at the Cape during the '60s and more recent accidents at Alcantara and Sriharikota).  With loaded SRBs in the place, the VAB is a more hazardous work environment, which makes ground processing less efficient than it might otherwise be.

Very good point Ed.

That's a huge safety issue I hadn't given very much thought to, and yet would be one of those things that could cause the whole program to be called into question if it ever happened.

Ross.
"The meek shall inherit the Earth -- the rest of us will go to the stars"
-Robert A. Heinlein

Offline Jim

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #128 on: 04/21/2006 06:34 PM »
Quote
edkyle99 - 21/4/2006  1:51 PM
Quote
quark - 21/4/2006  12:37 AMThe solids vs liquids debate is kind of like the "tastes great", "less filling" debate.  Unfortunately the direct reliability, failure history evidence is anecdotal.  the samples are small and there are way way too many variables.  However, I think some general conclusions can be drawn that are relevant to crew safety (the point of this discussion)....To me, liquids ought to win hands down for human spaceflight because of cat fraction, abort ability and engine out.  Reliability is not the issue.  I think it significant that the Shuttle, Delta and Atlas programs all use a combination of both liquids and solids.  (On the other hand, the Soyuz, the human launcher with the world's highest demonstrated relaibility, is all liquid).
A nice summation of the question.  One additional consideration could be ground processing safety.  A liquid booster with empty propellant tanks is inherently safer to work around than a loaded solid motor.  There have been several nasty accidents over the years involving solid motors (an upper stage motor at the Cape during the '60s and more recent accidents at Alcantara and Sriharikota).  With loaded SRBs in the place, the VAB is a more hazardous work environment, which makes ground processing less efficient than it might otherwise be.  Saturn V personnel worked out of offices that were up in the towers right next to their stages.  The old Saturn offices had to be abandoned when shuttle came along.  STS personnel work out of offices that are not in the VAB at all.   - Ed Kyle

Forgot the SRMU segment that was dropped at EAFB and ignited

Offline edkyle99

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #129 on: 04/22/2006 10:18 PM »
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Jim - 21/4/2006  1:34 PMForgot the SRMU segment that was dropped at EAFB and ignited

Is that the event that was captured on video from a ridge some distance away, where you you see one or two astonishingly powerful  shock waves racing across the desert floor?  Or am I thinking of an accident that happened in Utah?

 - Ed Kyle

Offline hop

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #130 on: 04/23/2006 12:00 AM »
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On the plus side, solids have very few moving parts and conceptually fewer failure modes.
Is that really significant for things like the shuttle SRBs, which have their own avionics, thrust vectoring and APUs ?

Offline rsp1202

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #131 on: 04/23/2006 12:20 AM »
Ed, you're thinking of the Henderson, Nevada, explosion, circa 1988. See:

http://www.metacafe.com/watch/38716/marshmellow_factory_explosion/

http://www.chemaxx.com/expolode.html

Offline kraisee

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #132 on: 04/24/2006 01:21 AM »
Did they ever determine what the actual cause of that horrific accident was at Henderson?

Or was there nothing left to assess anything conclusively?

Ross.
"The meek shall inherit the Earth -- the rest of us will go to the stars"
-Robert A. Heinlein

Offline hop

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #133 on: 04/24/2006 01:35 AM »
http://en.wikipedia.org/wiki/PEPCON_disaster makes it sound like a long series of bad judgements.

Offline Jim

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #134 on: 04/24/2006 01:36 AM »
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kraisee - 23/4/2006  9:21 PMDid they ever determine what the actual cause of that horrific accident was at Henderson?Or was there nothing left to assess anything conclusively?Ross.

Bad storage practices

Offline edkyle99

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #135 on: 04/24/2006 02:33 AM »
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rsp1202 - 22/4/2006  7:20 PM

Ed, you're thinking of the Henderson, Nevada, explosion, circa 1988. See:

http://www.metacafe.com/watch/38716/marshmellow_factory_explosion/

http://www.chemaxx.com/expolode.html

Thanks!  That's the one I was mis-remembering as having been in Utah.  Those
shock waves, and that flattened factory building(!), make me wonder about CEV
escape-ability, even though I know that on paper it seems possible.  But this
accident shows that you have to be moving awfully fast to escape the worst of
the overpressure wave (or whatever it is properly called).

Now, the SRMU one at EAFB - That wasn't the blowup during a qualification test,
right?

 - Ed Kyle

Offline kraisee

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #136 on: 04/24/2006 03:36 AM »
According to the wikipedia site about the Henderson explosion, that amount of devastation was created by 8.5 million pounds of ammonium perchlorate in storage at the plant.

I know that's just one part of the mixture which makes up an SRB's propellant, but each Shuttle SRB has about 1.1 million pounds of the stuff when sitting on the pad, and a 5-segment will have about 1.4 million pounds of it.

That means a single CaLV and CLV being assembled in the VAB for just one moon mission will have about half the explosive we saw go off in that video.

That'd still be plenty enough to level most of the LC-39 industrial in the immediate viscinity of the VAB, wouldn't it?

Yikes.   That's a scary thought.   I hope everyone handling that stuff is very, very careful indeed.

Ross.
"The meek shall inherit the Earth -- the rest of us will go to the stars"
-Robert A. Heinlein

Offline simonbp

RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #137 on: 04/24/2006 03:43 AM »
Yes, but the part of the purpose of the binder is to act as a buffer for the explosive - just like the silica in dynamite makes the nitroglycerin safer to handle...

Simon ;)

Offline Jim

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #138 on: 04/24/2006 11:11 AM »
Quote
edkyle99 - 23/4/2006  10:33 PM
Quote
rsp1202 - 22/4/2006  7:20 PMEd, you're thinking of the Henderson, Nevada, explosion, circa 1988. See:http://www.metacafe.com/watch/38716/marshmellow_factory_explosion/http://www.chemaxx.com/expolode.html
Thanks!  That's the one I was mis-remembering as having been in Utah.  Those shock waves, and that flattened factory building(!), make me wonder about CEV escape-ability, even though I know that on paper it seems possible.  But this accident shows that you have to be moving awfully fast to escape the worst of the overpressure wave (or whatever it is properly called).Now, the SRMU one at EAFB - That wasn't the blowup during a qualification test, right? - Ed Kyle

Two SRMU explosions at EAFB. 

1.  Test firing - Chunk of propellant broke loose, choked the flow at the throat and the whole motor blew up.

2.  Assembly for a test - Crane collapsed and segment ignited during fall down hill

Offline newsartist

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #139 on: 04/25/2006 03:47 AM »
Jim:

...on 'item 2', were igniters installed at the time of the accident? With S+A device? or was it strictly propellant charge that shock detonated?

Offline Jim

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RE: (CONT): CLV - ONE J-2X Engine (not two J-2S)
« Reply #140 on: 04/25/2006 11:14 AM »
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newsartist - 24/4/2006  11:47 PMJim:...on 'item 2', were igniters installed at the time of the accident? With S+A device? or was it strictly propellant charge that shock detonated?

It was only a segment, not the whole motor.  Static electricity from sliding down an embankment set it off

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