Author Topic: Upper Stage for SLS  (Read 54386 times)

Offline marsavian

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Re: Upper Stage for SLS
« Reply #20 on: 10/08/2010 04:50 am »
What is the big deal with the upper stage, it's mentioned in the Bill and the 130mt figure can't be reached without it so it's not going to be forgotten. The Ares I upper stage could be finished and used now if it's such a big deal but I suspect time will be taken to get some commonality with ULA especially in light of any future propellant depots. Using SSMEs will allow that commonality. The SLS's first task is also clear, to fully support ISS, and it doesn't need an upper stage for that. To think that MSFC/Shelby will stop at a <100mT no upper stage vehicle is just silly especially with such a clear Bill mandate on the issue, you will have to try and stop them building a 3 stage version instead and then you go back to complaining about lack of payloads.
« Last Edit: 10/08/2010 04:55 am by marsavian »

Offline FinalFrontier

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Re: Upper Stage for SLS
« Reply #21 on: 10/08/2010 04:54 am »
What is the big deal with the upper stage, it's mentioned in the Bill and the 130mt figure can't be reached without it so it's not going to be forgotten. The Ares I upper stage could be finished and used now if it's such a big deal but I suspect time will be taken to get some commonality with ULA especially in light of any future propellant depots. Using SSMEs will allow that commonality. The SLS's first task is also clear, to fully support ISS, and it doesn't need an upper stage for that. To think that MSFC/Shelby will stop at a <100mT vehicle is just silly especially with such a clear Bill mandate on the issue, you will have to try and stop them building a 3 stage version instead and then you go back to complaining about lack of payloads.
To be honest: If they don't "stop" at 100mt or less and the budgetary situation really does degenerate further, as some think it will, then they may cause another Ares debacle. That ties in with the entire "mismanage it and no matter how good it is, it still fails" dilemma.

We will just have to see.
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Offline marsavian

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Re: Upper Stage for SLS
« Reply #22 on: 10/08/2010 05:05 am »
What is the big deal with the upper stage, it's mentioned in the Bill and the 130mt figure can't be reached without it so it's not going to be forgotten. The Ares I upper stage could be finished and used now if it's such a big deal but I suspect time will be taken to get some commonality with ULA especially in light of any future propellant depots. Using SSMEs will allow that commonality. The SLS's first task is also clear, to fully support ISS, and it doesn't need an upper stage for that. To think that MSFC/Shelby will stop at a <100mT vehicle is just silly especially with such a clear Bill mandate on the issue, you will have to try and stop them building a 3 stage version instead and then you go back to complaining about lack of payloads.
To be honest: If they don't "stop" at 100mt or less and the budgetary situation really does degenerate further, as some think it will, then they may cause another Ares debacle. That ties in with the entire "mismanage it and no matter how good it is, it still fails" dilemma.

We will just have to see.

They have to go up to 130mt. <100mt is for the upper stage less version. Ares I was always hard to justify because it is just EELV Heavy class and asking for tens of billions more for a theoretically higher safety factor is not an easy decision to sell. The SLS is different, it will offer unique lift capability way higher than any commercial vehicle and just as important HLV is seen as essential by all political sides. Any justification for canceling it is just not as clear as it was for Ares I regardless of how big it is.
« Last Edit: 10/08/2010 05:07 am by marsavian »

Offline Proponent

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Re: Upper Stage for SLS
« Reply #23 on: 10/08/2010 05:16 am »
I have no such argument. Jorge is right. Set a goal out to far, and it's meaningless, including an advanced upper stage. Proponent, you're right that that means no BLEO exploration.

If we are so uncertain of the future as to be unable to discuss an arrival date for a useful upper stage,  how can it make sense to bet the farm on the arrival of such stage?

Quote
The only answer (to allow BLEO exploration) is to use a cheap upper stage, which basically means one we already have. That's what I think OV-106 has been hinting at. Is that correct?

If there is an upper stage that one can be confident NASA will be able to afford and that can do something useful, why can't such a stage and it's target arrival date be discussed now?

My suspicion is that 1) even fitting a Delta IV upper stage to SLS has a cost in the (low) billions, and 2) doesn't enable much more than an Apollo 8 mission.  Maybe this is even worth a separate thread.  (Or maybe these things have already been nailed down in another thread; if so, please let me know where.)
« Last Edit: 10/08/2010 05:17 am by Proponent »

Offline Proponent

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Re: Upper Stage for SLS
« Reply #24 on: 10/08/2010 05:22 am »
We will just have to see.

You're OK with betting the farm on this?

Offline sdsds

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Re: Upper Stage for SLS
« Reply #25 on: 10/08/2010 05:23 am »
Thats not to say though, that with budgets limited DIVUS, centaur, or even Raptor are not viable options

Between the existing stages, there's really no question about the best choice for Earth departure.  We want 27 tons of propellant, not 21.  Unless we want to strap two Centaurs side-by-side?
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Offline pathfinder_01

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Re: Upper Stage for SLS
« Reply #26 on: 10/08/2010 05:26 am »
They have to go up to 130mt. <100mt is for the upper stage less version. Ares I was always hard to justify because it is just EELV Heavy class and asking for tens of billions more for a theoretically higher safety factor is not an easy decision to sell. The SLS is different, it will offer unique lift capability way higher than any commercial vehicle and just as important HLV is seen as essential by all political sides. Any justification for canceling it is just not as clear as it was for Ares I regardless of how big it is.

The problem here isn't how much it lifts but where it lifts it to. It can put 70 tons to LEO. It is about as useful as a 2 stage saturn V(i.e. Useless for BEO missions). That is the upper stage problem.  You need an upperstage that can push Orion somewhere besides LEO. 
« Last Edit: 10/08/2010 05:41 am by pathfinder_01 »

Offline Proponent

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Re: Upper Stage for SLS
« Reply #27 on: 10/08/2010 05:28 am »
What is the big deal with the upper stage, it's mentioned in the Bill and the 130mt figure can't be reached without it so it's not going to be forgotten.

If it's not a big deal, then why is it, according to Jorge and kraisee, such a big deal that the future is so uncertain as to prevent us from setting a target date for it?

Quote
The SLS's first task is also clear, to fully support ISS, and it doesn't need an upper stage for that.

If SLS is built, I want to be sure it's used for BEO exploration.  The fact that there is an official requirement for it to back up commercial services to and from ISS means, rather worryingly, that an LEO-only SLS can be justified as long as ISS is around.  This reduces the pressure to ever develop an upper stage; the political factions benefiting from SLS do so even if all it ever does is sit on the ground without an upper stage in case it's needed for a flight to ISS someday.

Offline Warren Platts

Re: Upper Stage for SLS
« Reply #28 on: 10/08/2010 05:47 am »
Quote from: Jon Goff
Quote
.  Use what is available until flight rates and proposed payloads require/mandate the development of something more optimal.
Heh.  The irony of this is delicious.

Yeah, no kidding.... I couldn't stop giggling when I first read that.

My view: when life gives you lemons, make lemonade. In order to rescue some semblance of efficiency out of the current situation, the SLS should launch one thing and one thing only: maximum numbers of fully loaded ACES-71 space tankers. That way, they can get the launch rate up into the 6-12 launches per year, there's a decent chance of getting per kg launch costs to less than $5K (we'll just write the development costs off the books).

The surfeit of propellant this would provide would obviate the need for Orion, and it could be scrapped now to save a little money, since fully propulsive reinjection to LEO would be possible. Humans can go up and down on Dragon, Boeing or Soyuz.

The expensive BLEO spacecraft can be limited to a single ACES-derived lander/shuttle. These can be launched on reliable EELV's. To get to the Moon, people can ride in the DTAL ascender module--it's more roomy that Orion was anyways.

To go to Mars, use a Bigelow Sundancer mated to an ACES-121. Such a craft would be a simple, yet fully reusable space craft capable of fully propulsive reentry back into the Earth-Moon system. Martian lander can be made by stretching the tanks on the DTAL lunar lander into an ACES-71 version.

This is really the only way to leverage current designs and thus minimize BLEO payload development costs and thus squeeze in a fairly aggressive BLEO exploration program on about 7 or 8 billion USD per year....
"When once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return."--Leonardo Da Vinci

Offline A_M_Swallow

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Re: Upper Stage for SLS
« Reply #29 on: 10/08/2010 08:21 pm »
What is the big deal with the upper stage, it's mentioned in the Bill and the 130mt figure can't be reached without it so it's not going to be forgotten.

If it's not a big deal, then why is it, according to Jorge and kraisee, such a big deal that the future is so uncertain as to prevent us from setting a target date for it?

If you want a date for the upper stage I will give you one 2060.

Until then NASA can get on with going to the Moon and Mars.

LEO to EML1 manned:  Orion with stretched propellant tanks.
EML1 to Moon surface: Lunar lander.
EML1 to Phobos manned: Mars Transfer Vehicle.
Phobos to Mars: Mars lander.

LEO to EML1 cargo: SEP tug.
EML1 to Phobos cargo: SEP tug.

LEO to Moon surface cargo: SEP tug to low lunar orbit with a chemical decent stage.  (Optional)

Offline alexw

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Re: Upper Stage for SLS
« Reply #30 on: 10/08/2010 11:07 pm »
If you want a date for the upper stage I will give you one 2060.
Until then NASA can get on with going to the Moon and Mars.
LEO to EML1 manned:  Orion with stretched propellant tanks.
EML1 to Moon surface: Lunar lander.
EML1 to Phobos manned: Mars Transfer Vehicle.
Phobos to Mars: Mars lander.
LEO to EML1 cargo: SEP tug.
EML1 to Phobos cargo: SEP tug.
LEO to Moon surface cargo: SEP tug to low lunar orbit with a chemical decent stage.  (Optional)
     That is a possibly valid architectural option: forgo the very large, capable JUS, and use EML rendezvous with SEP for all mass except Orion. But that probably takes even longer -- HEFT, for example, figured about $7 billion for ~300kW-class SEP, availability in the latter 2020s. We could do a big upper stage before then, or possibly smaller stages refueling at propellant depots.
   The disadvantage to this approach is that it's not great for lunar. That advantage is that it leaves you well positioned for Mars and main belt missions.
   -Alex

Offline sdsds

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Re: Upper Stage for SLS
« Reply #31 on: 10/09/2010 01:40 am »
What are the principle objections to an 8.5 m upper stage built using the same tooling as the SLS core, but wrapped in MLI rather than sprayed with foam and launched entirely inside a 10 m fairing?  Even with only two or three RL10 engines this would seem to make a fine Earth-departure stage.  I guess it doesn't do so well as a second ascent stage, though?

EDIT:  Hmm, and the geometry is all wrong.  If hypothetically the tanks were going to carry 36 t of propellant and were 8.5 m in diameter, they might be only 2.5 m tall....

EDIT again:  Assuming SLS in its initial form can launch 70 t to LEO, what would be the ideal propellant capacity for a Earth-departure stage that was part of that 70 t?  If the engine has an Isp of 460, the answer seems to be 36 t of propellant to propel 34 t of dry mass through TLI.  Given that the 5 m DIVUS carries 27 t of propellant, a 1.33x expansion of that design would be "just right."
« Last Edit: 10/09/2010 10:30 pm by sdsds »
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Offline Patchouli

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Re: Upper Stage for SLS
« Reply #32 on: 10/09/2010 08:47 pm »

     That is a possibly valid architectural option: forgo the very large, capable JUS, and use EML rendezvous with SEP for all mass except Orion. But that probably takes even longer -- HEFT, for example, figured about $7 billion for ~300kW-class SEP, availability in the latter 2020s. We could do a big upper stage before then, or possibly smaller stages refueling at propellant depots.
   The disadvantage to this approach is that it's not great for lunar. That advantage is that it leaves you well positioned for Mars and main belt missions.
   -Alex


I thought the same thing when I first saw CxP why not send everything but Orion via SEP/NEP?
The need to be able to use the lander as a lifeboat in case of an Apollo 13 type failure may not be necessary for lunar operations with modern spacecraft.
Has the shuttle recently experienced a failure like Apollo 13?
There has been failures where they cut the mission short in 90s but nothing close to Apollo 13.
Orion should be even more reliable on orbit then the shuttle assuming it has the same level of redundancy simply because it has newer systems.

An upper stage of some sort still would be nice though as it can increase the LEO payload as well as allow sending things to EML quickly.
« Last Edit: 10/09/2010 08:50 pm by Patchouli »

Offline sdsds

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Re: Upper Stage for SLS
« Reply #33 on: 10/10/2010 08:46 pm »
Attached is a drawing of my entry in the "Affordable Upper Stage for SLS" competition.  Inside an 8.5 meter fairing are shown:

- The top of the core LOX tank.
- An RL10B-2 engine with the nozzle pre-extended.
- Upper stage LOX and LH2 tanks sized such that:
  - Their diameters are 5.5m, matching Ares I and Ariane 5.
  - The combined mass of the propellants is 36 metric tons.

This is about 1.33x larger than the DIVHUS.

Assuming the basic SLS launcher can place 70 metric tons into orbit, the 36 metric tons of propellant should be able to take 34 metric tons of dry mass through TLI.  The burn-out mass of the stage itself should be about 5 metric tons, leaving 29 metric tons for the payload adapter and payload.  This is sufficient to send an Orion with a small mission module to a Lagrange point with enough propellant to both enter and leave orbit there.
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Offline alexw

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Re: Upper Stage for SLS
« Reply #34 on: 10/10/2010 09:19 pm »
Attached is a drawing of my entry in the "Affordable Upper Stage for SLS" competition.  Inside an 8.5 meter fairing are shown:
    It's probably just cheaper to have the DIVHUS stretched; 40mT of prop proposed. Little reason to duplicate what you already have.
    -Alex

Offline sdsds

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Re: Upper Stage for SLS
« Reply #35 on: 10/10/2010 10:34 pm »
    It's probably just cheaper to have the DIVHUS stretched; 40mT of prop proposed. Little reason to duplicate what you already have.

From a technical perspective you are probably correct that a stretched DIVHUS would do the job just as well, if not better.  Here are the problems with that:

- Congress wants SLS to be government owned.  The components of the Delta IV launch system are not owned by the government.

- Instead, ULA owns DIVHUS.  ULA is a launch service provider jointly owned by Boeing and LM.  ULA cannot simply choose to sell a stretched DIVHUS to NASA, and there is no evidence Boeing and LM would agree to develop and sell a stretched upper stage to NASA through ULA, without mating it to a ULA first stage booster.

Finally there are reasons to use AIUS 5.5 meter tanks.

- They can be stretched to hold (at least) 138 tons of propellant, as that was the intended capacity for AIUS.  In particular a 2x stretch of the proposed stage (to 72 tons of propellant) could be lifted by the basic SLS for an EOR with a payload prior to Earth-orbit departure.  (Yes, ULA propose stretching the 5 meter ACES tanks to this size too, but see above about ownership.  And ACES isn't an existing stage.)

- Congress asks NASA to use CxP contracts for SLS to the extent practicable.  Under CxP there was some totally cool work done on spun-formed, friction-stir welded 5.5 meter tank domes.  Why waste that effort?  ;)
« Last Edit: 10/10/2010 10:45 pm by sdsds »
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Offline alexw

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Re: Upper Stage for SLS
« Reply #36 on: 10/10/2010 10:50 pm »
     Hey, I'm not really a fan of DIVHUS (JUS is, after all, the triumph of DIRECT), but articles on NSF pointed towards the possibility of using Centaur, DIVHUS, or a stretched DIVHUS on SDHLV. OV-106 is, IIRC, particularly an advocate of this as an interim approach. There might be Boeing/LockMart/ULA/NASA contracting issues, but I assume that if these speakers are looking at the idea, such issues can be worked around.

     You certainly can build a stage from the AIUS tooling, but if you want to do payload EOR with it, you'll either have to do rapid double-SLS LC-39 A/B launch and immediate rendezvous, or essentially develop ACES independently.
     -Alex

Offline Proponent

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Re: Upper Stage for SLS
« Reply #37 on: 10/11/2010 02:06 am »
I thank both Jorge and kraisee for allowing their statements in an L2 thread to be quoted here.  I also apologize for having placed such quotes here after not having asked their permission but rather merely announced that I had done so.
« Last Edit: 10/11/2010 05:44 am by Proponent »

Offline sdsds

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Re: Upper Stage for SLS
« Reply #38 on: 10/11/2010 06:54 pm »
articles on NSF pointed towards the possibility of using Centaur, DIVHUS, or a stretched DIVHUS on SDHLV. [...] There might be [..] contracting issues, but I assume [they] can be worked around.

That looks like a well substantiated conjecture, at least for using unmodified (or only slightly modified) DIVHUS for some small number of SLS flights.  On the other hand I would very much like to see any credible discussion of using a 1.33x stretched DIVHUS for this!  It seems unlikely, unless ULA would have another customer for that stage?  (If only the DoD needed lift greater than DIVH with RS-68A!)

Quote
You certainly can build a stage from the AIUS tooling

Note that by doing so, NASA retains another piece of what would be needed to fly a vehicle like Ares I.  While it might be making a deal with the devil, this adds political support for the concept.

Quote
but if you want to do payload EOR with it, you'll either have to do rapid double-SLS LC-39 A/B launch and immediate rendezvous, or essentially develop ACES independently.

For the proposed 36 t ("ultra-short") 5.5 m stage, no rendezvous is needed because the 34 t payload rides to orbit on the same SLS vehicle.  For the 72 t ("short") 5.5 m stage, EOR rendezvous would be required.  But just because the Earth-departure stage is launched on SLS doesn't mean the BEO payload mass was.  If that mass were storable propellant it could have been incrementally delivered to orbit by e.g. many launches of a much smaller re-usable launch vehicle.

The "standard" 138 t AIUS might not fit well with SLS, but a "long" 172 t version certainly would!
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Offline Ben the Space Brit

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Re: Upper Stage for SLS
« Reply #39 on: 10/11/2010 07:02 pm »
The "standard" 138 t AIUS might not fit well with SLS, but a "long" 172 t version certainly would!

I presume this is because the 172t version has sufficient propellent to act as a second stage during ascent as well as retaining sufficient propellent for TOI?
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