Author Topic: (CONT): CLV - ONE J-2X Engine (not two J-2S)  (Read 58860 times)

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.  :)

Online 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

Online 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

Offline BogoMIPS

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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.

Offline Jim

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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.
"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 #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.
"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 #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

Offline gladiator1332

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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.

Online 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

Offline Jim

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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.

Offline Jim

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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.

Online 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

Online edkyle99

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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

Offline kraisee

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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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Offline Jim

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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


Online 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

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