Author Topic: RS-68 CLV First Stage  (Read 79655 times)

Offline zinfab

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Re: RS-68 CLV First Stage
« Reply #20 on: 07/13/2006 05:20 pm »
Would this group agree that the ATK solid rocket boosters are the most reliable rockets currently available?

If we switch to EELV, will they cut the size/mass of the CEV EVEN MORE, or redesign them to carry more (MORE development costs)?

Offline Jim

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RE: RS-68 CLV First Stage
« Reply #21 on: 07/13/2006 05:24 pm »
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edkyle99 - 13/7/2006  12:56 PM

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Jim - 13/7/2006  10:28 AM

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edkyle99 - 13/7/2006  11:04 AM

I don't breath until wheels stop on the runway.  Fair to mention, by the way, that liquid boosters fail more often than solids.  Just look at the recent GSLV failure from India, for one example.  GSLV has a powerful solid booster core with four strap-on liquid boosters.  The solid worked fine.  One of the liquids failed.  

There have been three launch failures this year so far, in 31 attempts.  All of the failures involved liquid propulsion systems.  Last year there were three failures in 55 attempts.  All of the failures were liquids.  Three of the four failures in 2004 were liquids.  The solid rocket failure (Shavit) involved a failed stage separation.  Etc.

 - Ed Kyle

the liquied failures are surivable.  The rest of the world is not a good database.  Spacex and India are not in the same population as the US and Russia wrt spacelaunch

If we only look at US launch vehicles since 1980 (including all shuttle launches), there have been 605 by my count with 36 launch vehicle failures.  Of these, I can only identify four that were clearly solid rocket motor failures:  STS-51L, Delta 241, Titan 4 K-11, and Titan 34D-9.  I count at least nine that were clearly liquid propulsion system failures:  AC-62, AC-70, AC-71, AC-74, Atlas 19F, Delta 178, Delta 269, Titan 34D-7, and Titan 34D-3.  There may have been others, as a few of the DoD launches are listed cryptically as "failed to orbit" on my list.

 - Ed Kyle

Altas 76E,  liquid, loss of thrust

Delta 228 hanging solid,

D259 was a solid tvc issue.

3 of the solid failures would have been not survivable but all of the liquids were.

There are no failed DOD launches that aren't acknowldged



Offline Jim

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Re: RS-68 CLV First Stage
« Reply #22 on: 07/13/2006 05:25 pm »
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zinfab - 13/7/2006  1:07 PM

Would this group agree that the ATK solid rocket boosters are the most reliable rockets currently available?

If we switch to EELV, will they cut the size/mass of the CEV EVEN MORE, or redesign them to carry more (MORE development costs)?

NO

And no, EELV development would be cheaper than for the Stick

Offline edkyle99

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Re: RS-68 CLV First Stage
« Reply #23 on: 07/13/2006 05:28 pm »
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Jim - 13/7/2006  12:01 PM

It was a successful launch and the mission was completed as far as a launch vehicle. And that is the official ruling.


Official ruling?  There are officials?  :-)

Whatever it was "ruled", it didn't look like a good launch to me.  

 - Ed Kyle

Offline bad_astra

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Re: RS-68 CLV First Stage
« Reply #24 on: 07/13/2006 05:44 pm »
Ed, if the columbia stack had been a sidemounted cargo pod a-la Polyus, the payload would have survived, therefore it was a good launch.
"Contact Light" -Buzz Aldrin

Offline rumble

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Re: RS-68 CLV First Stage
« Reply #25 on: 07/13/2006 06:18 pm »
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rumble - 13/7/2006  10:11 AM

How serious is this "chatter?"  Based on what I understand (which could be incorrect), I would assume a kerosene 1st stage (RD-180) for the core stage would need a beefy second stage.  The current plan for the 2nd stage/EDS doesn't seem to be this.

Could an RD-180 based 1st stage truly be a replacement for the capability of the RS-68 CaLV core stage, or would other vehicle changes be necessary to accompany this?

Dang...didn't put all of my thought here.  It would have made more sense if I had done that??

I mentioned a beefy second stage, because I'm not sure an RD-180 based 1st stage is appropriate for taking a payload nearly as close to orbit as the currently spec'd RS-68 stage with its substantially higher vacuum isp.  What I was assuming is that we might want an RP-1 stage to "pass the baton" to a higher isp stage earlier in the flight than we would with an LH2 1st stage.

Am I thinking correctly on this?

Offline Jim

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Re: RS-68 CLV First Stage
« Reply #26 on: 07/13/2006 06:31 pm »
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edkyle99 - 13/7/2006  1:15 PM

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Jim - 13/7/2006  12:01 PM

It was a successful launch and the mission was completed as far as a launch vehicle. And that is the official ruling.


Official ruling?  There are officials?  :-)

Whatever it was "ruled", it didn't look like a good launch to me.  

 - Ed Kyle

Stuff comes off every launch vehicle.

Offline edkyle99

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Re: RS-68 CLV First Stage
« Reply #27 on: 07/13/2006 06:58 pm »
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Jim - 13/7/2006  1:18 PM

Quote
edkyle99 - 13/7/2006  1:15 PM

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Jim - 13/7/2006  12:01 PM

It was a successful launch and the mission was completed as far as a launch vehicle. And that is the official ruling.


Official ruling?  There are officials?  :-)

Whatever it was "ruled", it didn't look like a good launch to me.  

 - Ed Kyle

Stuff comes off every launch vehicle.


I look at the issue from an insurance adjustor's point of view.  A successful launch is one that delivers a payload, *unscathed*, to the contracted orbit.  The shuttle launch stack successfully delivered its orbiter "payload" to the proper orbit, but it was most certainly not unscathed.  STS-107 delivered damaged goods (the orbiter Columbia with a fatal hole in its wing's leading edge) to orbit.  If this were a commerical type launch, with one company owning the launch vehicle and another owning the orbiter (as payload), an adjustor would ascribe the failure to the launch vehicle, and a claim would be promptly filed.

 - Ed Kyle

Offline edkyle99

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Re: RS-68 CLV First Stage
« Reply #28 on: 07/13/2006 07:03 pm »
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bad_astra - 13/7/2006  12:31 PM

Ed, if the columbia stack had been a sidemounted cargo pod a-la Polyus, the payload would have survived, therefore it was a good launch.


STS-107/Columbia was not Energia/Polyus.  Two different animals.  The orbiter has to be delivered undamaged into orbit.  It is not OK for the launch system to deliver it with a hole in its wing.

See my thoughts on this in message #48987.

 - Ed Kyle  


Offline Jim

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Re: RS-68 CLV First Stage
« Reply #29 on: 07/13/2006 07:26 pm »
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edkyle99 - 13/7/2006  2:45 PM

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Jim - 13/7/2006  1:18 PM

Quote
edkyle99 - 13/7/2006  1:15 PM

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Jim - 13/7/2006  12:01 PM

It was a successful launch and the mission was completed as far as a launch vehicle. And that is the official ruling.


Official ruling?  There are officials?  :-)

Whatever it was "ruled", it didn't look like a good launch to me.  

 - Ed Kyle

Stuff comes off every launch vehicle.

The orbiter is the part fo the LV and it performed its part of launch (SSME's, avionics) .  Any payload that would have deployed form the shuttle, would have done so and with success.  The orbiter failed as a reentry vehicle because it's TPS wasn't robust enough (a design flaw).  Foam coming off the ET is not flaw, it is happens with all vehicle that use foam.

NASA and the USAF classify it as a entry failure


I look at the issue from an insurance adjustor's point of view.  A successful launch is one that delivers a payload, *unscathed*, to the contracted orbit.  The shuttle launch stack successfully delivered its orbiter "payload" to the proper orbit, but it was most certainly not unscathed.  STS-107 delivered damaged goods (the orbiter Columbia with a fatal hole in its wing's leading edge) to orbit.  If this were a commerical type launch, with one company owning the launch vehicle and another owning the orbiter (as payload), an adjustor would ascribe the failure to the launch vehicle, and a claim would be promptly filed.

 - Ed Kyle

The orbiter is the part fo the LV and it performed its part of launch (SSME's, avionics). It isn't the payload.  Any payload that would have deployed form the shuttle, would have done so and with success.  The orbiter failed as a reentry vehicle because it's TPS wasn't robust enough (a design flaw).  Foam coming off the ET is not flaw, it is happens with all vehicle that use foam, trying to fix it is a crutch (that's why there will always be post flight inspections).  the orbiter wasn't properly designed for the flight environment    Harsh as it sounds this was a reuse issue.

NASA and the USAF classify it as a entry failure

Offline Jim

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Re: RS-68 CLV First Stage
« Reply #30 on: 07/13/2006 07:31 pm »
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edkyle99 - 13/7/2006  2:50 PM

Quote
bad_astra - 13/7/2006  12:31 PM

Ed, if the columbia stack had been a sidemounted cargo pod a-la Polyus, the payload would have survived, therefore it was a good launch.


STS-107/Columbia was not Energia/Polyus.  Two different animals.  

 - Ed Kyle  


wrong.  the Energia/Polyus was not an LV failure but a spacecraft failure, which was the same as OV-102

Offline pierogoletto

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Re: RS-68 CLV First Stage
« Reply #31 on: 07/13/2006 07:39 pm »
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hyper_snyper - 13/7/2006  3:35 AM

I think the SRBs were one of the main drivers to the architecture we have today.  Whether thats a good thing or bad thing I don't know.  If you're going to have a RS-68 first stage you might as well just mod a Delta IV to do the job, IMO.

I agree; more, it seems to me that the first concern is to have a man-rated architecture, which the SRBs grant since they are used for the Space Shuttle. I don't know, really, if the RS-68 engine has been man-rated.
Piero Giuseppe Goletto

Offline pierogoletto

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Re: RS-68 CLV First Stage
« Reply #32 on: 07/13/2006 07:44 pm »
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Jim - 13/7/2006  9:13 PM


The orbiter is the part fo the LV and it performed its part of launch (SSME's, avionics). It isn't the payload.  Any payload that would have deployed form the shuttle, would have done so and with success.  The orbiter failed as a reentry vehicle because it's TPS wasn't robust enough (a design flaw).  Foam coming off the ET is not flaw, it is happens with all vehicle that use foam, trying to fix it is a crutch (that's why there will always be post flight inspections).  the orbiter wasn't properly designed for the flight environment    Harsh as it sounds this was a reuse issue.

NASA and the USAF classify it as a entry failure

Jim, I agree.
The Orbiter is a part of the launch vehicle since during the ascent phase the SSME's are used (and all the avionics which controls the ascent and reentry phase is in the General Purpose Computers.
In my very humble opinion, the Orbiter design flaw is to have put the Orbiter on the ET instead of on the top of it.
Piero Giuseppe Goletto

Offline edkyle99

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Re: RS-68 CLV First Stage
« Reply #33 on: 07/13/2006 08:26 pm »
Quote
Jim - 13/7/2006  2:13 PM

Quote
edkyle99 - 13/7/2006  2:45 PM

I look at the issue from an insurance adjustor's point of view.  A successful launch is one that delivers a payload, *unscathed*, to the contracted orbit.  The shuttle launch stack successfully delivered its orbiter "payload" to the proper orbit, but it was most certainly not unscathed.  STS-107 delivered damaged goods (the orbiter Columbia with a fatal hole in its wing's leading edge) to orbit.  If this were a commerical type launch, with one company owning the launch vehicle and another owning the orbiter (as payload), an adjustor would ascribe the failure to the launch vehicle, and a claim would be promptly filed.

 - Ed Kyle

The orbiter is the part fo the LV and it performed its part of launch (SSME's, avionics). It isn't the payload.  Any payload that would have deployed form the shuttle, would have done so and with success.  The orbiter failed as a reentry vehicle because it's TPS wasn't robust enough (a design flaw).  Foam coming off the ET is not flaw, it is happens with all vehicle that use foam, trying to fix it is a crutch (that's why there will always be post flight inspections).  the orbiter wasn't properly designed for the flight environment    Harsh as it sounds this was a reuse issue.

NASA and the USAF classify it as a entry failure


Interesting points.  

Regardless of where the design flaw was (ET or orbiter), stuff (the relatively heavy bipod ramp) still came off the ET that wasn't supposed to come off.  That's different than the usual popcorning or smaller particle shedding.  

NASA has always defined payload as stuff carried in the orbiter's payload bay.  The truth is that space shuttle orbiters themselves are really part launch vehicle and part "payload".  The traditional description of "payload" is  orbited, separated mass that continues to function after the launch vehicle completes its job.  The delivered "payload" portion of the orbiter should, in my opinion, include the TPS and the wings (among other parts), because they are functional hardware delivered to orbit for later use.  They are similar, in my opinion, to the aeroshells and parachute systems delivered to orbit as part of the MER or Viking "payloads", etc.  

 - Ed Kyle

Offline Jim

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Re: RS-68 CLV First Stage
« Reply #34 on: 07/13/2006 09:36 pm »
Landing of an orbiter has nothing to do with the delivery of a satellite.  I am going to harsh again, but it is the same as the failure of the SRB parachutes on STS-4.  The SRB's were not recovered.  Is this a mission failure.

"The traditional description of "payload" is orbited, separated mass" is wrong.  Payload adapters, spintables, dual payload adapter assemblies are payload mass and not separated.  The cradles of the spacecraft that used to fly on the shuttle were not separated.   If the cradle was a damaged........  aeroshells and parachute are part of the spacecraft and not equivilent to the shuttle orbiter.

Offline R&R

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Re: RS-68 CLV First Stage
« Reply #35 on: 07/13/2006 10:04 pm »
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yinzer - 13/7/2006  10:03 PM

The lack of graceful emergency thrust termination can give higher LOC numbers with very detailed modeling - it makes aborts much more dynamic events.  The numbers are small enough that it's hard to make any sort of statistical judgement, and the probabilistic risk assessments made to date for the shuttle have all been wildly optimistic.

In any case, according to NASA Watch, MSFC is considering going to the RD-180 for the CaLV core stage.  And as long as they're doing that, they might as well go to a 2 RD-180 core stage for the CLV.  If they call it Atlas Phase 2 there's already a bunch of paperwork and promotional material available.  NASA Watch also says that there's consideration of dumping the CLV for an EELV because the CLV is having trouble lifting the CEV and is costing way more than was expected.

Did you find something more than the "hallway chatter" that I see described on NASA Watch?

I have a hard time believing NASA would make another significant design change like they did going from Revised Shuttle to RS68 engines, especially going to RD180's.  Since PW&Rocketdyne are very far from building them in the US if ever I wonder if NASA can avoid the political backlash of once again relying on the Russians as significantly as they have been with Soyuz flights to ISS.

Offline general

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Re: RS-68 CLV First Stage
« Reply #36 on: 07/13/2006 10:40 pm »
Seems that if the RD-180 provides better performance than RS68, thus allowing fewer engines, it should be considered.  Fewer engines means fewer chances for failure.  The reduced tank diameter is a bonus, too.  

And it seems that NASA hasn't been adverse to changing ESAS.

Offline hop

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RE: RS-68 CLV First Stage
« Reply #37 on: 07/13/2006 11:01 pm »
Arguing about whether Columbia was an LV failure seems like pointless pedantry to me. The actual failure mechanism isn't in doubt, and what column you want to put it in depends on your choice of criteria. Just because NASA classifies it one way doesn't make it the only valid classification. There is no doubt that Columbia broke up on re-entry, and there is also no doubt that an off-nominal event during launch was the cause of this. Trying to stuff it in one tidy category doesn't really gain you anything.

The real question to me is, is it significant in the debate over CLV booster ? The answer seems to be an emphatic NO since the failure mechanism isn't possible for a top mounted payload. Of course, that reasoning applies to any number of the other failures you might want to use in this kind of statistical guesstimate. Every failure is unique, and only has limited applicability to other LVs. Combine that with the small sample size, and it's clear you can only get a very general trend from them.

Accepting these limits, it still seems that mature solid systems fail less often than mature liquid systems. How much this relates to the reliability of any particular system isn't nearly as a clear. The shuttle SRM is different from most other solid systems, and the actual failure rates of individual systems are all over the map.

Offline Avron

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Re: RS-68 CLV First Stage
« Reply #38 on: 07/14/2006 04:34 am »
Solids vs "mature liquid systems" ( LOX driven systems - assumption)... lets up the statistical numbers... if x is the number of STS flights, then 2x is the number of SRB's used in the real world, but in the same time there are 3X SSME in these flights, with one failure to one SRB failure... based on this for US based manrated LV's in the last quarter century..

Clearly the "mature liquid systems" are ahead of the game.. and if you add in the time of operation, under flight load conditions... SRB just don't come close in that numbers game...its all MTFB.. reliability numbers are as a WAG an order of magnitude higher...

Offline edkyle99

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Re: RS-68 CLV First Stage
« Reply #39 on: 07/14/2006 02:31 pm »
Quote
Avron - 13/7/2006  11:21 PM

Solids vs "mature liquid systems" ( LOX driven systems - assumption)... lets up the statistical numbers... if x is the number of STS flights, then 2x is the number of SRB's used in the real world, but in the same time there are 3X SSME in these flights, with one failure to one SRB failure... based on this for US based manrated LV's in the last quarter century..

Clearly the "mature liquid systems" are ahead of the game.. and if you add in the time of operation, under flight load conditions... SRB just don't come close in that numbers game...its all MTFB.. reliability numbers are as a WAG an order of magnitude higher...


An engine is not a liquid propulsion system, it is only an engine.  The fair comparison against a solid rocket motor is to look at an entire equivalent liquid propulsion stage, which includes not only the engines but also the pressurization systems, etc.  To be even more fair, the entire comparison should be normalized to total impulse or some such.  

 - Ed Kyle

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