Author Topic: Upper Stage for SLS  (Read 54393 times)

Offline Proponent

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Upper Stage for SLS
« on: 10/07/2010 05:05 am »
[This is intended to be the continuation of a discussion that has been quite rightly booted out of an L2 forum for being OT.]

The Senate's FY2011 authorization bill specifies that SLS is to be flown into earth orbit by 2016.  It also specifies that an upper stage, enabling SLS to go beyond earth orbit, is to be developed but sets no timetable.  This wishiwashiness about building a beyond-earth-orbit-capable vehicle leaves me concerned about the following scenario.  Circa 2016, SLS does indeed fly to LEO.  The necessary trio of presidential will, Congressional sentiment and economic reality, however, fails to coalesce behind building an upper stage anytime soon.  Key SLS constituencies being well served by SLS's existence, regardless of whether it flies much or ever leaves LEO, SLS languishes without an upper stage for years, all the while consuming limited funds.  If this goes on too long, SLS's lack of accomplishment may ultimately even catch up with its political benefits, the result being termination.

That's my nightmare.  I'd be less worried if the Senate bill at least specified a date for an upper stage.  That not being the case, I'll be a happier space cadet if someone can convince me that my fears are unjustified.
« Last Edit: 10/07/2010 05:08 am by Proponent »

Offline pathfinder_01

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Re: Upper Stage for SLS
« Reply #1 on: 10/07/2010 05:10 am »
No date for an upper stage to my knowlege or specifications. 70 tons to LEO is useless. 30 tons to l1/l2 or the moon is another story.  All SLS needs to do is lift Orion, be able to lift 70 tons to LEO without upper stage, and be able to grow to 130 tons with upper stage.

Hopefully someone at NASA will straighten this out. It is part of the reason I am so anti SLS.

Offline MickQ

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Re: Upper Stage for SLS
« Reply #2 on: 10/07/2010 05:48 am »
Would the safest path be for NASA to concentrate solely on the LEO vehicle but make it able to accept a comercially available upper stage for the BEO role eg. ACES 41/71/181 as the mission requires ???  I mean, does the legislation actually direct NASA to develop the upper stage or just to be able to use one to go BEO ???

Mick.

Offline pathfinder_01

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Re: Upper Stage for SLS
« Reply #3 on: 10/07/2010 05:59 am »
Would the safest path be for NASA to concentrate solely on the LEO vehicle but make it able to accept a comercially available upper stage for the BEO role eg. ACES 41/71/181 as the mission requires ???  I mean, does the legislation actually direct NASA to develop the upper stage or just to be able to use one to go BEO ???

Mick.

The problem with the commercial route is I don't think any are available. ACES if I recall correctly wanted NASA to pay for it. ULA would then use ACES on all its boosters. The ACES 70 would fit in well with SLS, but not sure NASA has the funds and the clout to kick money over to that route.

Offline sdsds

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Re: Upper Stage for SLS
« Reply #4 on: 10/07/2010 06:14 am »
does the legislation actually direct NASA to develop the upper stage or just to be able to use one to go BEO ???

SLS must have "the capability to carry" an upper stage that would bring its LEO capability to 130 t. [302(c)(1)(B)].

In meeting that requirement NASA must "to the extent practicable" extend or modify existing contracts. [302(b)(2)]  So for example there is an existing contract with PWR to develop J-2X, an upper stage engine.

The act does not seem to preclude NASA from also using other upper stages on SLS, an approach that might make sense if early missions do not require the full capability described in 302(c)(1)(B).
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Offline Downix

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Re: Upper Stage for SLS
« Reply #5 on: 10/07/2010 06:19 am »
Would the safest path be for NASA to concentrate solely on the LEO vehicle but make it able to accept a comercially available upper stage for the BEO role eg. ACES 41/71/181 as the mission requires ???  I mean, does the legislation actually direct NASA to develop the upper stage or just to be able to use one to go BEO ???

Mick.

The problem with the commercial route is I don't think any are available. ACES if I recall correctly wanted NASA to pay for it. ULA would then use ACES on all its boosters. The ACES 70 would fit in well with SLS, but not sure NASA has the funds and the clout to kick money over to that route.
You mean, you don't think any are available, other than the upper stages we are already using, aka Delta IV US, and Centaur, correct?

I'd already done the math, it is more than possible to fit 3 Centaur under the Jupiters shroud, as either a mate-up upper stage, or to enable multiple payloads.  As SLS is similar to Jupiter, it would go without saying that, yes, we do have upper stages available, just not optimized ones.  (Heck, even a single DIVUS makes moon operations possible)
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Offline Ben the Space Brit

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Re: Upper Stage for SLS
« Reply #6 on: 10/07/2010 07:30 am »
The only significant BEO time-line that exists presently (AFAIK) is President Obama's proposal that BEO pathfinder missions begin in the early 2020s with the first NEO encounter in 2025 and the Phobos encounter/Mars orbiter in 2030 with a human landing on Mars "soon thereafter".  IMO, that means that the upper stage needs to get to hardware testing in space really no later than 2018/19.

There are basically three options for the upper stage right now:

* 5.4m Centaur-heritage with 2, 4 or 6 RL-10C engines (ACES family);

* 5.5m AIUS-heritage with 1 x J-2X or 4 x RL-10 (I suspect this is the Senate's choice, from the language in the authorisation bill);

* 8.4m with 6 x RL-10 (JUS).

As stated above, I suspect that the political winds are behind AIUS (I call it 'Ares-IA').  Nonetheless, the ACES family, including the stretched-length version for the Atlas-V Phase 3A, is probably the best choice from a programmatic standpoint and the JUS from a standpoint of capability.

With respect to the ACES family, does the stretched version used on the Atlas-V P3A have a specific designation?
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Offline alexw

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Re: Upper Stage for SLS
« Reply #7 on: 10/07/2010 08:57 am »
The only significant BEO time-line that exists presently (AFAIK) is President Obama's proposal that BEO pathfinder missions begin in the early 2020s with the first NEO encounter in 2025 and the Phobos encounter/Mars orbiter in 2030 with a human landing on Mars "soon thereafter".  IMO, that means that the upper stage needs to get to hardware testing in space really no later than 2018/19.

There are basically three options for the upper stage right now:

* 5.4m Centaur-heritage with 2, 4 or 6 RL-10C engines (ACES family);

* 5.5m AIUS-heritage with 1 x J-2X or 4 x RL-10 (I suspect this is the Senate's choice, from the language in the authorisation bill);

* 8.4m with 6 x RL-10 (JUS).

As stated above, I suspect that the political winds are behind AIUS (I call it 'Ares-IA').  Nonetheless, the ACES family, including the stretched-length version for the Atlas-V Phase 3A, is probably the best choice from a programmatic standpoint and the JUS from a standpoint of capability.

With respect to the ACES family, does the stretched version used on the Atlas-V P3A have a specific designation?

   The ACES tanks are probably now 5.1m, not 5.4m; the latter would have matched the Atlas V payload fairing (and would have required new tooling in San Diego, I assume), the former would be built with the Delta IV tooling in Decatur, and I guess would fit under the fairing.

    Barr and Kutter says explicitly that there are actually two competing ULA families of stages: "Common Centaur" or "Common Upper Stage" (I think these refer to the same thing), and the full-blown ACES.  The point of the Common stage is to consolidate Centaur and (4m) DCSS for cost savings and probably get rid of the 4m payload fairing versions of Atlas and Delta, with the performance bought back (and then some) by prop options from 21mt-41mt. SEC and DEC both possible; I presume that SEC would win out *unless* CST-100 or NASA emerged as wanting engine-out or the increased performance (something like +2mT right now for Atlas xx2 if DEC was flying). It seems like the Common stage might happen on its own from ULA for cost reasons; one would think that Commercial Crew will bring this forward rather than pay to do the work for conventional (3m) DEC.

    ACES is actually separate, and enormously capable (bigger fairings, tanker, depots, low-boiloff, modular family, etc.) and that's the upper stage that almost certainly wouldn't happen unless NASA paid for it to support exploration. Might not even use RL-10C -- ULA speaks of interest in 2,4,6, even 9-engine clusters of a newer 25klbs-class engine, or even bigger (by which they presumably mean RL-60 or MB-60 (I'm not sure these are the same thing), or possibly Vinci, or maybe even Raptor).

   JUS is conceived to be like ACES.

    I really don't know what the 5.5 AIUS-derived is supposed to be like; HEFT speaks of making it into something with RL-10 and very low boiloff, but after removing the orange foam I'm not sure what it retains in common with AIUS.

    See Barr & Kutter 2010 (the recent Atlas V Phase II paper), and also the rev10a and rev11 (2010) versions of the Atlas V User's Guide.
    -Alex


Offline Ben the Space Brit

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Re: Upper Stage for SLS
« Reply #8 on: 10/07/2010 10:20 am »
    I really don't know what the 5.5 AIUS-derived is supposed to be like; HEFT speaks of making it into something with RL-10 and very low boiloff, but after removing the orange foam I'm not sure what it retains in common with AIUS.

It would have the 5.5m barrel, the avionics ring and the common bulkhead propellent tanks in common.

Regarding ACES, I might be wrong, but it was my impression that the were to have a 5.4m diameter because that maches the OML of the Atlas-V 5m PLF.
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Offline A_M_Swallow

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Re: Upper Stage for SLS
« Reply #9 on: 10/07/2010 09:50 pm »
When a Solar Electric Propulsion (SEP) tug with changeable payload flies that can be used as an upper stage.  The first few SEP designs are likely to be too small for the SLS.  When the 100 metric ton (mT) VASIMR tug flies 70mT will provide quite a payload and propellant.  A reusable SEP could rendezvous with the 'package' left in LEO by the SLS.

Offline alexw

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Re: Upper Stage for SLS
« Reply #10 on: 10/07/2010 10:45 pm »
    I really don't know what the 5.5 AIUS-derived is supposed to be like; HEFT speaks of making it into something with RL-10 and very low boiloff, but after removing the orange foam I'm not sure what it retains in common with AIUS.
It would have the 5.5m barrel, the avionics ring and the common bulkhead propellent tanks in common.
     The bulkhead might well change in design if the thing is supposed to have essentially ZBO while spiraling up from LEO to EML1 over the course of a year.

Quote
Regarding ACES, I might be wrong, but it was my impression that the were to have a 5.4m diameter because that maches the OML of the Atlas-V 5m PLF.
   It looks like that was the old plan, possibly because if new tooling was required, might as well match the OML.

   However, look at the 2010 (rev11) revision of the Atlas V User's Guide -- it doesn't speak of ACES, but does say on p.8-1 under "Common Upper Stage": "Conceptually, the vehicle diameter is 5.1 m (17.2 ft) to accommodate current aluminum production capabilities at our Decatur, Alabama production facility." Barr and Kutter say only "5m", but that looks a like a 1-sig fig rounding that glosses over the change in build location. It seems doubtful that Common Centaur would be built 5.1m, but ACES would get all new tooling for 5.4m.

    If you're going to build new tooling for ACES, of course, it doesn't have to be 5.4m -- the EELVs have been investigated with 6 & 7 meter fairings. There might even be some argument for this in order to better use it on SLS. HEFT was looking at a ~7m CPS (??), which is neither the 5.5m AIUS tooling nor the 8.4m core tooling.
   -Alex

Offline jml

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Re: Upper Stage for SLS
« Reply #11 on: 10/07/2010 11:29 pm »

There are basically three options for the upper stage right now...

There are a few ways to make an 8.4m SLS upper stage.
One is the performance-optimized ACES-heritage JUS.

Another is to build the upper stage at MAF as essentially a shortened version of the 8.4m ET/Core using the existing tooling, but with the SRB attachment beam deleted from the inter-tank area, a thrust structure and propellant feed lines sized for the smaller upper stage engine(s), and the tank barrel walls milled somewhat thinner than the core.

Disadvantages: Heavier and lower performing than designs using a common inter-tank bulkhead like AIUS or Centuar or ACES. May require 5-seg SRBs and/or stretched-core and/or J-2X to meet, say, CxP's LOI mass requirements. Does not have inherent low-boiloff advantages of ACES design.

Advantages: Better suited to the "NASA should focus on designing and building `to cost' versus overall performance" philosophy of the Authorization Act (as stated in the Senate Committee's companion report). Requires less development effort than an all-new upper stage, and, at expected flight/production rates, does not require a separate production line, possibly saving a good $500 million or so per year of fixed costs over an ACES-style JUS.

Beyond this, of course, we could consider hybrid designs using, say, the core-stage LM-built barrel sections and core-stage tank domes on the top and bottom of the stage, but with the inter-tank completely replaced with an 8.4m diameter variant of the Boeing Ares I US composite common bulkhead.

Offline alexw

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Re: Upper Stage for SLS
« Reply #12 on: 10/07/2010 11:47 pm »
Interesting; thanks for pointing that out.

The problem with such a stage -- basically a latter-day SIVB? -- is that it probably eliminates EOR architectures, or use of propellant depots. That's leaves LOR for lunar surface. (Or, I suppose, MOR...)

You might be able to use it with staging out of EML, but you'll have to develop a completely different stage entirely to loiter to or tank at EML, probably obviating the cost benefits.

But maybe it's worth thinking about. Suppose you did an immediate burn from LEO to EML, not consuming all propellant, but pulling away from the Earthshine ASAP? What would the boiloff losses drop to during the T-EML-I orbit? Would a sunshield (like that proposed for Atlas V 4x1 unencapsulated Centaur) help?

Sounds ugly, but any option that could reduce costs is worth considering.
  -Alex

Offline Proponent

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Re: Upper Stage for SLS
« Reply #13 on: 10/08/2010 02:39 am »
Guys, this is all very interesting, but the issue raised in the OP is not which upper stage is best for SLS but rather is there much hope of ever getting an upper stage built in the first place.  I can't really say anybody's OT, since the thread's title is general (my fault; I was trying to make it emotionally neutral), but this is the topic in which I'm particularly interested.

The L2 thread whence this this thread came contained the following exchanges.  I've edited them for brevity; if either Jorge or kraisee believes I have misrepresented any of his statements, I hope he will correct me.

if the backers of SLS/Orion are seriously interested in going beyond LEO and they're setting deadlines, they ought at to set a deadline for a BEO-capable system (SLS with an upper stage), not for an LEO-only system.

The past is littered with bills that set deadlines so far in the future they became meaningless. CxP and Obama's FY11 proposal share that same flaw.

No more. It is time we focus on regaining base capability, setting realistic near-term deadlines, and not getting too far ahead of ourselves.

Jorge is spot-on regarding the point that anything in these bills referring to a time beyond a few years into the future is pretty meaningless.

During DIRECT, the term we use for anything beyond the current 4-year Presidential cycle, was "fantasyland".

At best, NASA will get a steady path until the next President is elected, or until both Congressional Houses change parties.

I don't know how Congress will look next year, so I can't even begin to predict what might happen there.

I do not expect Obama will win a second term, so I expect NASA has until no later than the middle of the next President's first year (mid-2013) to nail this new program down hard enough that it can't be uprooted.

This is the main reason why I simply do not believe that a 6-8 year Ares-V development effort can survive to operational flights, while a 3-4 year Jupiter-130 'foundational system' has a real chance of success.   IMHO, once you have that basic capability set in stone, an upgrade (Jupiter 24x) really becomes more a matter of 'when', not 'if' -- you may have to wait for a NASA-friendly President/Congress to get the J-24x upgrades, but they won't cancel the basic J-130 capability if it is already flying when they come into power.

After all, the Saturn V flew all up on its very first flight in 1967, and that was with all-new first and second stages.  This little change would make me feel a heck of a lot better about the Senate bill.

The Saturn V had several times the budget SLS will. The plain facts are that in this budgetary environment, the upper stage must be developed serially, *after* the core elements.  Therefore it is foolish to specify a deadline for it because it is too far in the future. This is not a "little" change.

It seems to me that the gist of what Jorge is saying, at least some of which kraisee agrees with, is that nobody knows what's going to happen several years down the road, and the development of an upper stage is further in the future than we can see clearly.

So far I pretty much agree.  But then Jorge seems to say that even setting a goal, a target date for an upper stage is counterproductive.  That I'm having trouble understanding.  But what's really worrying is that kraisee's post seems to say that, given budgetary reality, the viable strategy is to build an LEO-capable SLS and then hope, pray, cross your fingers and press your thumbs that the stars will align to permit the construction of an upper stage.  This scares me, and I think it's a terrible strategy.  If that's the best we do, if we can't even talk about a target date for a BEO-capable SLS, then I submit that the plan is incompatible with budgetary reality to begin with.  More precisely, the plan is compatible with budgetary reality if viewed as a plan to build a large HLV for getting to LEO; viewed as a plan for exploring beyond earth orbit it seems incompatible.

Anybody got a counterargument that will help me sleep?
« Last Edit: 10/08/2010 02:58 am by Proponent »

Offline Robotbeat

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Re: Upper Stage for SLS
« Reply #14 on: 10/08/2010 03:46 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.

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?
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Offline MickQ

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Re: Upper Stage for SLS
« Reply #15 on: 10/08/2010 04:16 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.

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?

I tend to agree with this.  Use what is available until flight rates and proposed payloads require/mandate the development of something more optimal.

Mick.

Offline jongoff

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Re: Upper Stage for SLS
« Reply #16 on: 10/08/2010 04:23 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.

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?

I tend to agree with this.  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.  It's also kind of amusing that Ross and the other DIRECT guys, who keep hammering on "build only one vehicle because its probably the only one you're going to get" are banking on effectively a second round of development to upgrade their vehicle.  It *is* a huge improvement over CxP, which had almost nothing in common between vehicles.  But, it's still a similar leap of faith--you're spending a huge amount of money right now building a vehicle that gets you half-way to enabling BEO exploration, in the hopes that you'll be given a new batch of money down the road to develop the actual BEO capable vehicle...

Maybe I'm just not getting it.

~Jon

Offline FinalFrontier

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Re: Upper Stage for SLS
« Reply #17 on: 10/08/2010 04:41 am »
[This is intended to be the continuation of a discussion that has been quite rightly booted out of an L2 forum for being OT.]

The Senate's FY2011 authorization bill specifies that SLS is to be flown into earth orbit by 2016.  It also specifies that an upper stage, enabling SLS to go beyond earth orbit, is to be developed but sets no timetable.  This wishiwashiness about building a beyond-earth-orbit-capable vehicle leaves me concerned about the following scenario.  Circa 2016, SLS does indeed fly to LEO.  The necessary trio of presidential will, Congressional sentiment and economic reality, however, fails to coalesce behind building an upper stage anytime soon.  Key SLS constituencies being well served by SLS's existence, regardless of whether it flies much or ever leaves LEO, SLS languishes without an upper stage for years, all the while consuming limited funds.  If this goes on too long, SLS's lack of accomplishment may ultimately even catch up with its political benefits, the result being termination.

That's my nightmare.  I'd be less worried if the Senate bill at least specified a date for an upper stage.  That not being the case, I'll be a happier space cadet if someone can convince me that my fears are unjustified.
Some time ago there was a thread discussing Jupiter upper stage options. ACES or Centaur or DIVUS were among the favorites short of building the full sized JUS. Glad to see we are picking up the discussion again :) 

The primary objective of not building the full size JUS (8.4 meter+ 6 rl 10 b2) would be to save money and time by using an existing one. Seem to recall DIVUS was the favorite here, but centaur is good as well. Also possibility for using Raptor after it completed.
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Offline 93143

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Re: Upper Stage for SLS
« Reply #18 on: 10/08/2010 04:43 am »
...well, once J-130 is flying, the cheapest way to get a significant BEO capability is to develop either ACES or JUS (the cost is similar).  Which one gives better performance?  Which one do you think Congress will go for?

[I'm hoping for both (you might be able to simultaneously develop both for substantially less than the sum of their individual costs), but I kinda doubt that will happen...  I just don't like to see a good idea go to waste.  The RL-60 is another example - it helps that it's a perfect match to sub in for the RL-10 on a multipurpose single-stage reusable lunar/Mars lander...]

We can't do everything at once.  It takes longer than four years (two years, now that Obama's halfway through what may be his last term) to go from STS and ISS to affordable commercial cislunar shuttle services and O'Neill cylinders.  It takes longer than that just to develop a bare-bones lunar lander, never mind a good one.  Heck, NASA will be lucky to get the SLS core flying halfway through the next Presidential term.  All we can do is try to take reasonably-sized steps, and make sure the current step sets us up so that the next step is as attractive as possible to whoever is in power...
« Last Edit: 10/08/2010 04:51 am by 93143 »

Offline FinalFrontier

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Re: Upper Stage for SLS
« Reply #19 on: 10/08/2010 04:48 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.

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?

I tend to agree with this.  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.  It's also kind of amusing that Ross and the other DIRECT guys, who keep hammering on "build only one vehicle because its probably the only one you're going to get" are banking on effectively a second round of development to upgrade their vehicle.  It *is* a huge improvement over CxP, which had almost nothing in common between vehicles.  But, it's still a similar leap of faith--you're spending a huge amount of money right now building a vehicle that gets you half-way to enabling BEO exploration, in the hopes that you'll be given a new batch of money down the road to develop the actual BEO capable vehicle...

Maybe I'm just not getting it.

~Jon

JUS is actually quite cheap. Its basically a larger diameter ACES, except without the advanced anti boil off features, long duration features ect. unless needed (also with 6 rl10b2 instead of 4) The reason for considering this is, that after many checks of the data and different configs it was found that JUS gave, by far, the best performance for the vehicle overall than any other conifg. Thats not to say though, that with budgets limited DIVUS, centaur, or even Raptor are not viable options, quite the opposite they may be the best options. Best part about that is you don't have to marry the design to one or the other, you could in fact fly one mission with J140+centaur and another with J140+DIVUS or even J130+ethier or.

« Last Edit: 10/08/2010 04:49 am by FinalFrontier »
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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 »

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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?

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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 »

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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....
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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)

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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 »

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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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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

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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 »

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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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Offline FinalFrontier

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Re: Upper Stage for SLS
« Reply #40 on: 10/12/2010 02:38 am »
Key words going forward IMO:

1. Affordable
2. Low boiloff/long duration
3. DEPOTS DEPOTS DEPOTS
4. ACES derived.
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Re: Upper Stage for SLS
« Reply #41 on: 10/12/2010 02:12 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


Key words going forward IMO:

1. Affordable
2. Low boiloff/long duration
3. DEPOTS DEPOTS DEPOTS
4. ACES derived.


5. Maintain Strong Bipartisan Congressional Support

Note: ACES is nifty. However, what ACES has, many others will also eventually develop. Technology isn't static. There usually are, or will be, many ways to do things that are useful. As Alex noted, one of NASA's potential options is to "essentially develop ACES independently"...

Cheers!
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Offline clongton

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Re: Upper Stage for SLS
« Reply #42 on: 10/12/2010 04:19 pm »
What are the drawbacks, if any, of an 8.4m diameter stage of <some> length on either the Atlas-V or the Delta-IV? If looking for commonality, why not use the SLS tooling at Michoud to build an 8.4m upper stage, like DIRECT had planned (JUS), but with the ability to provide different barrel lengths to accommodate Atlas (AUS), Delta (DUS) or SLS (JUS) geometries? That would also speak to proponent's original question in that if such 3-fold commonality were available the stage would be better positioned to be built in the foreseeable future.
« Last Edit: 10/12/2010 04:21 pm by clongton »
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Offline Warren Platts

Re: Upper Stage for SLS
« Reply #43 on: 10/12/2010 04:59 pm »
5. Maintain Strong Bipartisan Congressional Support

Note: ACES is nifty. However, what ACES has, many others will also eventually develop. Cheers!

What's that supposed to mean? That the key to maintaining support in Congress is to give ULA the shaft yet again?
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Offline Ben the Space Brit

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Re: Upper Stage for SLS
« Reply #44 on: 10/12/2010 05:45 pm »
@ clongton

I think that the dead weight issue is pretty significant for an 8.4m upper stage.  The core might get off the ground, but you'd then be into an Ares-V-style descending feedback loop of core under-performance leading to you having to load ever more weight onto the upper stage, which reduced the core's performance even further, etc.
« Last Edit: 10/12/2010 05:46 pm by Ben the Space Brit »
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Re: Upper Stage for SLS
« Reply #45 on: 10/12/2010 05:54 pm »
What are the drawbacks, if any, of an 8.4m diameter stage of <some> length on either the Atlas-V or the Delta-IV?

Hi Chuck

Just to check, you are taking about an 8.4m diameter stage on top of current EELV!?

The drawbacks, if any, of that? Beyond looking ugly  ;D

More seriously, I could think of quite a few, ranging from considerations related with integration, support and launch facilities, passing by considerations related with the maximum capability of that stage vs maximum lift capability of EELV configurations vs geometry aspects of such stage or when thinking about some things related with control and ascent environments, trajectory, etc...

On my humble opinion, if wishing to brainstorm about some kind of upper stage synergy between current EELV (or eventual upgraded / further conceptual phases of EELV) and some other launch vehicle (SLS?) that might use something like 8.4m diameter as main factor, then I think that would make a lot more sense to think about upper stages with 5.0m to 5.5m diameters (perhaps maximum around 6.5m or so...).

But I'm not sure if understood the original intention of the question,
António
« Last Edit: 10/12/2010 06:04 pm by simcosmos »
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Offline Robotbeat

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Re: Upper Stage for SLS
« Reply #46 on: 10/12/2010 06:08 pm »
What are the drawbacks, if any, of an 8.4m diameter stage of <some> length on either the Atlas-V or the Delta-IV?...
As far as using it as an actual EELV upper stage, I'm sure there are lots of draw-backs. As far as just getting the stage up there as a sort of payload, I'm sure it's possible. Once orbital refueling is demonstrated, this would be a viable backup to SDHLV in case that effort stalls.

That's why I support an "upper" stage (with RL-10!) for SLS as soon as possible, because a big EDS of some sort is going to be needed for BEO exploration.

The ability to "decouple constraints" is very important to ensuring the mission actually succeeds.
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Offline Jim

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Re: Upper Stage for SLS
« Reply #47 on: 10/12/2010 06:09 pm »
ULA would prefer 5/5.3m
« Last Edit: 10/12/2010 06:09 pm by Jim »

Offline Patchouli

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Re: Upper Stage for SLS
« Reply #48 on: 10/12/2010 07:20 pm »
ULA would prefer 5/5.3m

What about a compromise between 8.4M and 5M since one extreme is too big for ULA and the other is too small for exploration?
Maybe go with 6 to 6.6M or the diameter of the S-IVB which should still fit inside a 747 LCF or Airbus Beluga.

« Last Edit: 10/12/2010 07:20 pm by Patchouli »

Offline Jim

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Re: Upper Stage for SLS
« Reply #49 on: 10/12/2010 07:23 pm »
ULA would prefer 5/5.3m

What about a compromise between 8.4M and 5M since one extreme is too big for ULA and the other is too small for exploration?
Maybe go with 6 to 6.6M or the diameter of the S-IVB which should still fit inside a 747 LCF or Airbus Beluga.



ULA preference is based on their existing production line.

Offline Patchouli

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Re: Upper Stage for SLS
« Reply #50 on: 10/12/2010 07:36 pm »
The way it looks something based off the Ares I US might be the best option for an upper stage for SLS.

The next question finish the J2 or go with a cluster of RL-10s or RL-60s?

Offline Lars_J

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Re: Upper Stage for SLS
« Reply #51 on: 10/12/2010 07:43 pm »
ULA would prefer 5/5.3m

What about a compromise between 8.4M and 5M since one extreme is too big for ULA and the other is too small for exploration?
Maybe go with 6 to 6.6M or the diameter of the S-IVB which should still fit inside a 747 LCF or Airbus Beluga.

Why such a bizarre compromise? Without 8.4m you'll loose the PLF volume capability, and if you can't do that - you might as well go down to 5.3 to take advantage of existing assets/capabilities of ULA/Boeing/LM.

Nothing in between makes sense IMO.
« Last Edit: 10/12/2010 07:45 pm by Lars_J »

Offline Patchouli

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Re: Upper Stage for SLS
« Reply #52 on: 10/12/2010 07:51 pm »
ULA would prefer 5/5.3m

What about a compromise between 8.4M and 5M since one extreme is too big for ULA and the other is too small for exploration?
Maybe go with 6 to 6.6M or the diameter of the S-IVB which should still fit inside a 747 LCF or Airbus Beluga.

Why such a bizarre compromise? Without 8.4m you'll loose the PLF volume capability, and if you can't do that - you might as well go down to 5.3 to take advantage of existing assets/capabilities of ULA/Boeing/LM.

Nothing in between makes sense IMO.

Mostly because a lunar architecture did fit inside a 6.6M fairing but you still can use a hammerhead fairing for larger items.
The Titian IVB only had a 3M wide second stage but a 5.1M wide fairing.
My biggest worry with a 5.3M stage is propellant volume and bending loads on the stage.
Most BEO operations probably would involve send 30 to 50T into TLI or escape.
« Last Edit: 10/12/2010 07:57 pm by Patchouli »

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Re: Upper Stage for SLS
« Reply #53 on: 10/12/2010 07:58 pm »
What do you mean by "loose the PLF volume capability", Lars? You could still put a 5.1m (or 6m) common stage inside an 8.4m fairing. Do you mean the loss of volume because the stage itself would be longer (consume more linear distance) within the fairing?
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Offline Lars_J

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Re: Upper Stage for SLS
« Reply #54 on: 10/12/2010 08:09 pm »
Either way... Putting a 5.3m upper stage inside a fairing IMO makes more sense than putting a 6.6m stage inside a fairing. Thus, go for 8.4m or 5.3m upper stage.

I'm not advocating 5.3m as the ultimate solution. But it makes more sense as an intermediate solution than a 6.6m stage does.
« Last Edit: 10/12/2010 08:11 pm by Lars_J »

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Re: Upper Stage for SLS
« Reply #55 on: 10/12/2010 08:26 pm »
If the LH2 tank was an 8.4m sphere, and the LOX tank was a 5.5m cylinder, how tall would the LOX tank be?
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Offline Downix

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Re: Upper Stage for SLS
« Reply #56 on: 10/12/2010 08:45 pm »
One can have commonality without being identical.  Think for a second, you make a control system, and a thrust base consisting of two RL-10's.  For a ULA 5m US, you have two of these base, all using the same control system.  For the SLS 8.4m US, you have three of these bases, and again using the same control system.  The tank tooling and building is not the real cost saver, the engine and control systems are.  Having a common component which can be adapted to both designs would bring along mass production quantity without limiting either designs.
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Offline Robotbeat

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Re: Upper Stage for SLS
« Reply #57 on: 10/12/2010 09:38 pm »
The way it looks something based off the Ares I US might be the best option for an upper stage for SLS.

The next question finish the J2 or go with a cluster of RL-10s or RL-60s?
RL-10 (of some flavor) for sure. Excellent Isp, which is the most important thing for an EDS. And an EDS is what we want more than anything, right? To depart Earth?

J-2x is a waste, IMO.
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Offline FinalFrontier

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Re: Upper Stage for SLS
« Reply #58 on: 10/12/2010 09:45 pm »
The way it looks something based off the Ares I US might be the best option for an upper stage for SLS.

The next question finish the J2 or go with a cluster of RL-10s or RL-60s?
RL-10 (of some flavor) for sure. Excellent Isp, which is the most important thing for an EDS. And an EDS is what we want more than anything, right? To depart Earth?

J-2x is a waste, IMO.
Agreed
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Offline Patchouli

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Re: Upper Stage for SLS
« Reply #59 on: 10/12/2010 10:52 pm »
One can have commonality without being identical.  Think for a second, you make a control system, and a thrust base consisting of two RL-10's.  For a ULA 5m US, you have two of these base, all using the same control system.  For the SLS 8.4m US, you have three of these bases, and again using the same control system.  The tank tooling and building is not the real cost saver, the engine and control systems are.  Having a common component which can be adapted to both designs would bring along mass production quantity without limiting either designs.

Personally I'd feel a shortened Ares I US with six RL-10s aka the JUS would be the best upper stage for the money.

Since EDS gets released at something like 70 to 80% orbital velocity it no longer needs the high thrust of the J-2X.

Offline HappyMartian

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Re: Upper Stage for SLS
« Reply #60 on: 10/12/2010 11:33 pm »
The way it looks something based off the Ares I US might be the best option for an upper stage for SLS.

The next question finish the J2 or go with a cluster of RL-10s or RL-60s?


Well, if you are going to load up with propellant at L1 or L2, maybe your question is answered already because you are going to put some legs on the upper stage and land it on the Moon... don't get me wrong, I do like the J-2X, but engine out capability on the upper stage/lander means... I suppose you could use both... one J-2X and three RL-10s. ;)

Whatever you do, don't make the upper stage too tall.

Cheers! :)
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Offline HappyMartian

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Re: Upper Stage for SLS
« Reply #61 on: 10/12/2010 11:49 pm »
Oh, and you might want the engines in pods around and above the bottom of the upper stage... Is that doable? I guess so.

Cheers!
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Offline HappyMartian

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Re: Upper Stage for SLS
« Reply #62 on: 10/13/2010 01:20 am »
The upper stage with legs should be as fat and short as you can make it, given your other constraints...

Cheers! :)
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Offline simonbp

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Re: Upper Stage for SLS
« Reply #63 on: 10/13/2010 01:33 am »
J-2x is a waste, IMO.

If you are only igniting it after reaching orbit, maybe. But, if you ignite it during ascent, meaning on an escape trajectory, T/W is going to kill you.

There's no way a single J-2X will cost more than six RL-10s, and most of the R&D is already paid for. Indeed, J-2X is actually more ready fro flight than any hypothetical new  man-rated RL-10 variant...

Offline alexw

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Re: Upper Stage for SLS
« Reply #64 on: 10/13/2010 01:58 am »
J-2x is a waste, IMO.
If you are only igniting it after reaching orbit, maybe. But, if you ignite it during ascent, meaning on an escape trajectory, T/W is going to kill you.
   Depends on the core stage vehicle, doesn't it? Which vehicle did you have in mind? For DIRECT, the J-241 (J-2X) is only a few mT above the J-246 (which assumes 5 RL-10B-2 on ascent, doesn't it?), despite out-thrusting it more than 2:1, and the J-244 (using RL-60) betters the J-2X by a few mT despite lower thrust.
    Sure, on an RS-68 vehicle the T/W kills you, but that looks unlikely now.

Quote
There's no way a single J-2X will cost more than six RL-10s, and most of the R&D is already paid for. Indeed, J-2X is actually more ready fro flight than any hypothetical new  man-rated RL-10 variant...
    Entirely from memory -- please, someone with better data correct me here -- RL-10 is of order a few $million each, and J-2X was heading towards $50 million each.

   There are half a dozen ways of making a human-rated RL-10. Fly RL-10A-2 straight up at 75% thrust, take the B-2 and fix the full nozzle extension in position, fix the B-2 nozzle extension onto the A-2 motor, fix just the 'B' (&'A') shells of the B-2 extension onto either motor, etc. These pieces have all flown, many times. Best performance, of course, with qualifying the plumbing for "human-rating" margins at 100% thrust.

    -Alex

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Re: Upper Stage for SLS
« Reply #65 on: 10/13/2010 03:03 am »
If the LH2 tank was an 8.4m sphere, and the LOX tank was a 5.5m cylinder, how tall would the LOX tank be?

4.87m.  The resulting stage holds 153 t of propellant.

That's because the 8.41m sphere holds 311,724 liters of LH2 massing 22 t.  The matching LOX tank needs to hold 131 t of LOX, which requires a volume of 115,193 liters.  See attached diagram, again showing an RL10B-2 and an 8.41m fairing.
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Re: Upper Stage for SLS
« Reply #66 on: 10/13/2010 03:20 am »
J-2x is a waste, IMO.
If you are only igniting it after reaching orbit, maybe. But, if you ignite it during ascent, meaning on an escape trajectory, T/W is going to kill you.
   Depends on the core stage vehicle, doesn't it? Which vehicle did you have in mind? For DIRECT, the J-241 (J-2X) is only a few mT above the J-246 (which assumes 5 RL-10B-2 on ascent, doesn't it?), despite out-thrusting it more than 2:1, and the J-244 (using RL-60) betters the J-2X by a few mT despite lower thrust.

Comparing payload to LEO and payload to Earth-escape isn't easy.  Seeking confirmation/correction on the following:

1.  Stopping briefly in circular LEO on the way to Earth departure is a pretty standard approach, the performance loss is not great, and it adds flexibility in matching up launch and departure windows.

2.  T/W is an issue when a significant component of the thrust vector is directed against the gravitational field.  For an impulsive maneuver at perigee, gravity drag is zero; for a finite thrust maneuver near perigee the gravity drag is low.

3.  If the required burn duration is significant compared to the orbital period not all the burn can occur near perigee, and gravity losses would be high.  But what about breaking the burn up across several passes through perigee?  Does that keep gravity losses low?
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Offline Proponent

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Re: Upper Stage for SLS
« Reply #67 on: 10/13/2010 05:20 am »
Going back to the OP, which is about if and when SLS will become BEO-capable, let me propose a thought experiment in alternative history.

Suppose that in 1961 JFK had said "This nation should commit itself to achieving the capability of landing a man on the moon and returning him safely to the earth."  A capability rather than a mission, and that without a deadline.

Imagine then that Congress had authorized and funded the development of the Apollo CSM and the S-IC and S-IVB stages of the Saturn V, all to be operational by 1968.  A LM and and S-II stage would be developed as funding permitted, with no specific timetable.

The resulting launch vehicle (actually the Saturn INT-20*) could have lofted 65 tons to LEO or 79 tons if built for a 6-G maximum acceleration (do these numbers sound familiar?).  It could easily have put the Apollo CSM into LEO.  Maybe, with use of the SPS, it could even have sent the CSM on a circum-lunar mission.  But would NASA have ever landed on the moon, given the changes in the political climate as the 60s wore on?  I'm not so sure.  And back then the US government's fiscal position and the outlook for the American economy were much better than they are now.

EDIT:  If you're looking the INT-20 up on astronautix.com, note that the payloads listed for an acceleration limit of 4.68 G are actually in pounds, not kilograms as claimed.
« Last Edit: 10/13/2010 05:26 am by Proponent »

Offline Proponent

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Re: Upper Stage for SLS
« Reply #68 on: 10/13/2010 05:23 am »
If the required burn duration is significant compared to the orbital period not all the burn can occur near perigee, and gravity losses would be high.  But what about breaking the burn up across several passes through perigee?  Does that keep gravity losses low?

It certainly does reduce gravity losses.  It is possible and has been proposed, for example, for Mars missions with Apollo-Saturn hardware.  The drawbacks are multiple passes through the van Allen Belts, boil-off losses (the Mars missions mentioned were to be performed with hydrogen slush for this reason) and increased complexity.
« Last Edit: 10/13/2010 05:27 am by Proponent »

Offline MP99

Re: Upper Stage for SLS
« Reply #69 on: 10/13/2010 07:19 am »
     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

That's true for EOR.

If you're going to build an LOR/L1R/L2R architecture, then a stretched DIVHUS or Centaur is a pretty good fit.

<snip>

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.

Although J-130 is quoted as ~70mT to 130x130nmi, it's ~77mT to 30x130nmi. That requires a small circ burn, and everything scales by about another 10% to >30mT through TLI.

Note, that using an AIUS-type stage on top of a J-246 would achieve <35mT through TLI, and requires multiple RL-10's and a two-stage ascent.

For BEO missions, this still requires a new in-space propulsion stage.



Also, some payloads can take a "slow boat" trajectory to the Moon which would boost payload further.

cheers, Martin

Edit: BEO.
« Last Edit: 10/13/2010 07:20 am by MP99 »

Offline orbitjunkie

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Re: Upper Stage for SLS
« Reply #70 on: 10/13/2010 04:01 pm »
There are a few ways to make an 8.4m SLS upper stage.
One is the performance-optimized ACES-heritage JUS.

Another is to build the upper stage at MAF as essentially a shortened version of the 8.4m ET/Core using the existing tooling...
Advantages: Better suited to the "NASA should focus on designing and building `to cost' versus overall performance" philosophy of the Authorization Act (as stated in the Senate Committee's companion report). Requires less development effort than an all-new upper stage, and, at expected flight/production rates, does not require a separate production line, possibly saving a good $500 million or so per year of fixed costs over an ACES-style JUS.
Does the $500 million only include tanks, domes, and assembly/test, or also engines, avionics, etc...? I thought it wasn't that bad to just build tanks.


ULA preference is based on their existing production line.
Jim, does this assume ULA would be acutally producing it? I thought I saw somewhere on another thread that ULA couldn't bid or be directly integrated into an upper stage contract? Perhaps they'd be satisfied with the side-benefits of significant component commonality?


Key words going forward IMO:
1. Affordable
2. Low boiloff/long duration
3. DEPOTS DEPOTS DEPOTS
4. ACES derived.
5. Maintain Strong Bipartisan Congressional Support
[/quote]

Yes, I totally agree with all of this. Given #5, my hunch is that Congress will lean the same direction for the upper stage - meaning they will want a govt owned US for their govt owned LV. So that would rule out essentially funding ACES as such for use on SLS.

FWIW, I really like the DIRECT phase 3 option with depots. I think they should definitely push towards that. Which means an 8.4m diameter US. It would be something of a shame to not use the AIUS tooling that has just been ordered/built, but I say oh well. That was sized for AIUS/Orion and I think it would limit us too much. It's been said that the US is the critical piece of BEO exploration, more than the first stage, so despite my tendencies for cheapness I'd say don't skimp on it. Didn't HEFT specify a 7m CPS? IIRC, isn't that what would be compatible with Sidemount? I bet they just took numbers from an older Sidemount study and used those.

My vote:
- Design (but not build) as much of the US as you can get away with now, so that you can make sure to build the SLS core sufficient for using a fully loaded US. Redesigning the core later will be a costly distraction, but there are difficult time constraints to building the first one. That implies deciding on the US, or at least the upper limits for it, now. Although the new Authorization bill sets the 130mt upper limit, if I were NASA I would plan for that final goal to be distant, if ever, and require a significant new chunk of change. Meaning you could afford to do a core redesign whatever at that time. They just need something that seems plausible on paper and satisfies Congress, though my money is says they won't get funded past a J-24x type vehicle.
- Go with something very JUS-like. By that I mean significant low-boiloff design but without all the bells and whistles like active cryocoolers. This will really open up your architecture options. I would also plan to use the same manufacturing capability to build an 8.4m depot with all the bells and whistles.
- Carefully protect the option of easily adding refueling to the US. It won't be finalized and built for a few years, so that gives time to demonstrate cryo propellant transfer and depot technology. In other words, don't require depots to be on the critical path but assume they'll be available in about 10 years.
- Use existing stages until full US is developed for a few demonstration missions, but don't pay to adapt them unless it's necessary to test a new engine variant.
- Engine selection can be an open question. Personally I'd ramp down/table J-2X for now, and risk a few dollars and say 1-2 years to investigate and decide on RL-60 vs RL-10. I am assume this would give you high-confidence cost/performance numbers on all three engines about 8-9 years before you needed them. Perhaps by then your mission (e.g. lunar landings) will be clear and you can get the most commonality possible.

I really like the idea of SEP tugs, but I think a chemical stage will be necessary for the forseeable future. It can do the slow-boat WSB trajectories for cargo or to boost and SEP out of the deepest part of the gravity wells and radiation belts later. And it will be needed for crew anyway, so I don't think it can be omitted. So I'd say establish a long term SEP tech development and demo project, starting off on as little as it can manage. If we have a big chem US anyway, I don't see a big need for the intermediate class tug, go straight for the big kahuna as your primary interplanetary propulsion to Mars.

Offline clongton

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Re: Upper Stage for SLS
« Reply #71 on: 10/13/2010 04:15 pm »
There's no way a single J-2X will cost more than six RL-10s ...

Entirely from memory -- please, someone with better data correct me here -- RL-10 is of order a few $million each, and J-2X was heading towards $50 million each.

http://yarchive.net/space/rocket/rl10.html (05 Jul 2000)
Quote
"The price of an SSME has varied by a factor of two, purely on minor manufacturing changes; the RL10 has done the same from over $4 million in 1986 to half that today.

That would put the price of an RL-10 at $2m each. If the price of a single J-2X is indeed inching toward $50m each, then that means that you can get twenty-five (25) RL-10's for the price of just one (1) J-2X.
« Last Edit: 10/13/2010 04:20 pm by clongton »
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Offline FinalFrontier

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Re: Upper Stage for SLS
« Reply #72 on: 10/13/2010 05:29 pm »
There's no way a single J-2X will cost more than six RL-10s ...

Entirely from memory -- please, someone with better data correct me here -- RL-10 is of order a few $million each, and J-2X was heading towards $50 million each.

http://yarchive.net/space/rocket/rl10.html (05 Jul 2000)
Quote
"The price of an SSME has varied by a factor of two, purely on minor manufacturing changes; the RL10 has done the same from over $4 million in 1986 to half that today.

That would put the price of an RL-10 at $2m each. If the price of a single J-2X is indeed inching toward $50m each, then that means that you can get twenty-five (25) RL-10's for the price of just one (1) J-2X.

Hence the reason why j2x should be shelved as it has been.
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Re: Upper Stage for SLS
« Reply #73 on: 10/13/2010 07:19 pm »
[...] concerned about the following scenario.  Circa 2016, SLS does indeed fly to LEO.  The necessary trio of presidential will, Congressional sentiment and economic reality, however, fails to coalesce behind building an upper stage anytime soon.  [...] That's my nightmare. 

Your dreaded nightmare starts with SLS flying to LEO in 2016.  That's pretty close to my wished-for fantasy, if you added an Orion carrying crew on that flight!

Quote
I'd be less worried if the Senate bill at least specified a date for an upper stage.  That not being the case, I'll be a happier space cadet if someone can convince me that my fears are unjustified.

They are not unjustified, but they may be premature.  Between now and 2014 two different Congresses will have chances to provide amended authorization language.  My forecasting is based around the assumption that the next Congress will reaffirm the need for an upper stage, and will fund it as a minor modification to the AIUS contract (i.e. with no change to the stage diameter).  I also believe they will appropriate funds for the J-2X testing program to continue.

I see nothing leading to an upper stage engine decision much before 2016.  If SLS doesn't fly on schedule, pressure will come roaring back for a CLV using a single engine upper stage.  Until then certain constituencies will bide their time, exerting just enough influence to keep the J-2X option on the table.
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Offline sdsds

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Re: Upper Stage for SLS
« Reply #74 on: 10/13/2010 07:25 pm »
Hence the reason why j2x should be shelved as it has been.

Rephrased:  j2x has been shelved

Not by the continuing resolution it hasn't.  Do you know something more about how members of Congress (particularly Representatives on the House appropriations subcommittee) are seeing this?
« Last Edit: 10/13/2010 09:32 pm by sdsds »
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Offline MP99

Re: Upper Stage for SLS
« Reply #75 on: 10/13/2010 10:12 pm »
[...] concerned about the following scenario.  Circa 2016, SLS does indeed fly to LEO.  The necessary trio of presidential will, Congressional sentiment and economic reality, however, fails to coalesce behind building an upper stage anytime soon.  [...] That's my nightmare. 

Your dreaded nightmare starts with SLS flying to LEO in 2016.  That's pretty close to my wished-for fantasy, if you added an Orion carrying crew on that flight!
Quote
I'd be less worried if the Senate bill at least specified a date for an upper stage.  That not being the case, I'll be a happier space cadet if someone can convince me that my fears are unjustified.

They are not unjustified, but they may be premature.  Between now and 2014 two different Congresses will have chances to provide amended authorization language.  My forecasting is based around the assumption that the next Congress will reaffirm the need for an upper stage, and will fund it as a minor modification to the AIUS contract (i.e. with no change to the stage diameter).  I also believe they will appropriate funds for the J-2X testing program to continue.

I see nothing leading to an upper stage engine decision much before 2016.  If SLS doesn't fly on schedule, pressure will come roaring back for a CLV using a single engine upper stage.  Until then certain constituencies will bide their time, exerting just enough influence to keep the J-2X option on the table.

A "4/3" or J-130 system with a mildly-stretched ULA u/s gets very close to a "4/3" or "4/4" vehicle plus AIUS-derived upper stage in terms of mass pushed through TLI. For LOR Lunar missions or EML1/2 rendezvous BEO missions, that's possibly the cheapest way to assemble mass ready for descent or Injection. Of course, this would still require either a lander or Injection stage, and I'm still a fan of DIRECT-style EOR for Lunar missions.

cheers, Martin

Offline guru

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Re: Upper Stage for SLS
« Reply #76 on: 10/14/2010 07:01 pm »
A couple of unlikely (probably implausible) ideas just being thrown out for fun:

1. If the SLS uses a 5 engine core, then, for the second stage, shorten the core tanks and use one SSME on the same boattail.  (This would require a kick stage for LEO insertion.  Air lighting an SSME isn't too hard from what I hear, but starting one a second time while in micro-gravity like for a circularization burn apparently is.)  SpaceX uses this concept on the Falcon IX where the second stage uses shortened first stage tanks and both stages the same engine, though not the same boat tail.

2.  Buy an upper-stage commercially, perhaps even from overseas.  Maybe NPO-Energomash would be willing to redevelop and sell an Energia EUS.

http://www.astronautix.com/stages/eneiaeus.htm


Offline marsavian

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Re: Upper Stage for SLS
« Reply #77 on: 10/14/2010 07:30 pm »
HEFT is considering the RS-25E as the upper stage

p32
http://nasawatch.com/archives/2010/09/human-explorati.html


Offline Downix

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Re: Upper Stage for SLS
« Reply #78 on: 10/14/2010 07:47 pm »
The RS-25E is no good as an upper-stage engine.  Air-start, sure, but not for EDS work.  For EDS, RL-10 is still king.
chuck - Toilet paper has no real value? Try living with 5 other adults for 6 months in a can with no toilet paper. Man oh man. Toilet paper would be worth it's weight in gold!

Offline marsavian

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Re: Upper Stage for SLS
« Reply #79 on: 10/14/2010 08:26 pm »
Doesn't change the fact they are still considering it along with J-2X and NGE (RL10 replacement).

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Re: Upper Stage for SLS
« Reply #80 on: 10/15/2010 05:56 am »
I suspect -- entirely without much evidence -- that that was more political camouflage. A J-150SH-ish core alone still isn't big enough for the Griffin camp (or you, marsavian, if I've understood your preferences correctly), and mentioning that "well, we could add an SSME-based middle stage" gives them some cover to say "look! this design scales to 140mT when we're ready to use it!" Naturally, we need not build this SSME middle stage (or HPTB filament-cased SRBs) now, just at some indeterminate point in the future...
    Of course, at some indeterminate point in the future, we'll have demonstrated propellant depots, large SEP, or low-ish-boiloff + docking (or the program has already collapsed), any one of which will very likely negate any need for a bigger LEO lift vehicle.

   What we probably will need for most architectures is a restartable, long-loitering EDS, not an S-II redux.
     -Alex

Offline MP99

Re: Upper Stage for SLS
« Reply #81 on: 10/15/2010 07:41 am »
A couple of unlikely (probably implausible) ideas just being thrown out for fun:

1. If the SLS uses a 5 engine core, then, for the second stage, shorten the core tanks and use one SSME on the same boattail.  (This would require a kick stage for LEO insertion.  Air lighting an SSME isn't too hard from what I hear, but starting one a second time while in micro-gravity like for a circularization burn apparently is.)  SpaceX uses this concept on the Falcon IX where the second stage uses shortened first stage tanks and both stages the same engine, though not the same boat tail.

HEFT is considering the RS-25E as the upper stage

p32
http://nasawatch.com/archives/2010/09/human-explorati.html

The RS-25E is no good as an upper-stage engine.  Air-start, sure, but not for EDS work.  For EDS, RL-10 is still king.

HEFT2 gives 140mT for 5/5 with HTPB SRB's and an RS-25 upper stage.

The Boeing launcher gives 112mT with HTPB SRB's and 6x RL-10A-4-2 upper stage.

However, HEFT/RS-25 requires CPS to act as an EDS. I worked through the numbers at:- http://forum.nasaspaceflight.com/index.php?topic=22381.msg637680#msg637680.

In summary, HEFT/RS-25 with 10% margin/MR delivers CPS with 102mT of prop, and Boeing B-246SH delivers an EDS with 100mT of prop, despite a "headline" 28mT disadvantage in payload to LEO. RS-25 u/s is a very inefficient way to deliver prop/EDS to LEO (although the Boeing u/s would have a bit higher burnout mass than CPS).

Although RS-25 can be used in an upper stage role, it looks like it needs to be used in a second-stage-of-three config to get a worthwhile boost over the Ares V / J-24x mission mode, ie combined upper-stage-and-EDS.

cheers, Martin

PS J-130 delivers payloads to 130x130nmi with a single sustained RS-25 burn, ie no restart required. Although J-2/RL-10 could restart, J-24x doesn't use it either - again a single sustained burn until the payload is safely in it's delivery orbit.

An RS-25 upper stage could presumably do the same thing, but doesn't really change the results above (104mT instead of 102mT if HEFT's 140mT is to a circular orbit).



Edit: I've just realised an error in the link I provided above. I used B-246 u/s as an EDS, but the 112.2mT payload to 130x130nmi is with sufficient reserves to allow "upper stage de-orbited". B-246SH would perform somewhat better than I calculated in that post.

"Deorbit the upper stage via 30 x 130 nmi orbit; ΔV = 181 fps". Either requires RCS subsystem+burn+prop, or penalty for RL-10 engine restart.
« Last Edit: 10/15/2010 01:04 pm by MP99 »

Offline alexw

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Re: Upper Stage for SLS
« Reply #82 on: 10/15/2010 08:28 am »
And the Boeing comparison only has 4 SSME, not the HEFT-5, too.
  -Alex

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Re: Upper Stage for SLS
« Reply #83 on: 10/15/2010 10:40 am »
What we probably will need for most architectures is a restartable, long-loitering EDS, not an S-II redux.
     -Alex

RL-10 powered, likely the new RL-10C
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Offline Mark S

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Re: Upper Stage for SLS
« Reply #84 on: 10/15/2010 11:08 am »
Although J-2/RL-10 could restart, J-24x doesn't use it either - again a single sustained burn until the payload is safely in it's delivery orbit.

My understanding is that the J-24x core stages early enough for it to splash into the north Atlantic.  The staging velocity and altitude are much lower than orbital speed. The JUS must act as a true second stage in order for the payload to reach any kind of stable orbit.  So there are two burns involved in a J-24x launch, with a possible circularization burn if the launch profile warrants it.

Mark S.

Offline MP99

Re: Upper Stage for SLS
« Reply #85 on: 10/15/2010 01:45 pm »
The RS-25E is no good as an upper-stage engine.  Air-start, sure, but not for EDS work.  For EDS, RL-10 is still king.

J-130 delivers payloads to 130x130nmi with a single sustained RS-25 burn, ie no restart required. Although J-2/RL-10 could restart, J-24x doesn't use it either - again a single sustained burn until the payload is safely in it's delivery orbit.

An RS-25 upper stage could presumably do the same thing, but doesn't really change the results above (104mT instead of 102mT if HEFT's 140mT is to a circular orbit).

My understanding is that the J-24x core stages early enough for it to splash into the north Atlantic.  The staging velocity and altitude are much lower than orbital speed. The JUS must act as a true second stage in order for the payload to reach any kind of stable orbit.  So there are two burns involved in a J-24x launch, with a possible circularization burn if the launch profile warrants it.
(Quotes re-assembled and added to show additional context)

Mark,

Context is that we're talking of upper stage restarts. RS-25 is excluded from being an EDS engine because it can't re-start, but it could still be a purely upper stage engine, because HEFT uses a separate CPS stage (or a kick stage) instead of requiring a u/s restart.

Alternatively, my post above showed that both J-130 core (ie RS-25 all the way to orbit) and the upper stage of J-241/J-246 perform a single sustained burn, ie no engine restart. An RS-25-based upper stage might be able to do the same (although RS-25 would have a much higher rate of prop consumption, which might throw a spanner in the works).



However, RS-25 u/s + CPS fails to out-perform a combined upper-stage-and-EDS when EDS-type duties are required (and I'd even underestimated performance of the B-246Sh that I used for comparison - see above).

But, if you're using SLS to deliver prop to a depot, an RS-25 u/s would give you a bigger payload as prop (140mT+ if HEFT's quote is to a circular orbit - that would be 25mT more per launch than with a comparable B-246SH). Plenty of payback for using RS-25 if we need lots of prop for NEO or Mars missions.

This would still require an RL-10-based EDS.

Cheers, Martin

Offline orbitjunkie

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Re: Upper Stage for SLS
« Reply #86 on: 10/15/2010 08:37 pm »
I know the issue of air-start RS-25 has been discussed before... basically you have to keep it in the "start box" conditions until you light it at high altitude. Or something like that. I don't really know what all that entails.

So here's a question: could you use RS-25 on an EDS if you only burned it once? It might be on a 3rd stage or CPS type thing. Or put another way, is it crazy to think about keeping an SSME in the start box conditions all the way through ascent, and in your coasting orbit for ~90 min?

Offline clongton

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Re: Upper Stage for SLS
« Reply #87 on: 10/15/2010 08:53 pm »
I know the issue of air-start RS-25 has been discussed before... basically you have to keep it in the "start box" conditions until you light it at high altitude. Or something like that. I don't really know what all that entails.

So here's a question: could you use RS-25 on an EDS if you only burned it once? It might be on a 3rd stage or CPS type thing. Or put another way, is it crazy to think about keeping an SSME in the start box conditions all the way through ascent, and in your coasting orbit for ~90 min?

Could it be done? Sure, but I wouldn't recommend it.

The RS-25 is an extremely complex engine, and very, very fickle. It is a difficult engine to get a successful ignition out of. But you'd never know that watching all the Shuttle launches; they make it look easy.

The truth of the matter is that there are hundreds of checks going on during the countdown and every one of them must shoot the curl right down the middle or the engine won't light. The margin of deviation from the norm is very, very slim; almost nonexistant. The GSE for the RS-25 is incredibly good, but the flight version would of necessity not be as robust; there's just too much to it. IMO I would suggest that you take a real chance that you don't get the engine to light on the first shot and once that happens then the mission is over because there would not be sufficient consumables to attempt a second start.

I would suggest that it is a far wiser thing to go with a robust and easily started (and re-started) engine, such as the RL-10, than to go for the most complex system available, regardless of the performance increase. Strictly speaking, the RS-25 just was never intended for altitude starts, even though it is possible. The further away we get from home, the simpler and more robust our systems need to be in order to ensure mission viability. Our systems simply have to work reliably, every time and without exception. In my opinion, as good as the RS-25 is, I don't think it would make a good EDS engine for those reasons. It is far too complex.
Chuck - DIRECT co-founder
I started my career on the Saturn-V F-1A engine

Offline orbitjunkie

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Re: Upper Stage for SLS
« Reply #88 on: 10/17/2010 02:54 am »
Thanks for the detailed response, Chuck. I didn't realize RS-25 was such a fickle device, you're right that they do make it look easy. Personally, I think that having restart capability is extremely useful, if not an outright requirement, on an upper stage. My vote as of today is certainly on the RL-10 or a variant. I didn't suspect RS-25 would be a great idea, but you never know until you ask/look into it!

Offline alexw

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Re: Upper Stage for SLS
« Reply #89 on: 10/17/2010 03:35 am »
orbitjunkie, to add to Chuck's comments on the SSME itself, basically we're talking about two completely different kinds of upper stages. One is a "middle stage", what I referred to above as "SII-redux", which could employ airstart SSME in a single suborbital burn, and its purpose would be almost entirely to increase mass to LEO; thrust may be more important than isp. The other kind is an "EDS", which needs to be capable of restart and some loiter, preferably multiple restart and long loiter, and for which isp is usually more valuable than thrust.
   
    It is -- as you ask -- possible to use a non-restartable upper stage as a limited kind of EDS; Ariane V's HM7B hydrolox is not restartable, so Ariane V has to fly a single-burn ascent trajectory to delivery satellites into GTO. Most (?) vehicles can burn the upper stage during ascent, shut down and coast, then burn again. (IIRC, at least one of the EELVs can execute 3-burn trajectories?) -- the direct insertion approach is less efficient. The equivalent niche for this in a hypothetical SSME-based upper stage is that it could be used to sling payloads on a direct insertion to EML, where BEO payloads could rendezvous. The trouble is, we would still need a true "EDS" stage to go from EML to Mars, etc., (or a very large lunar lander), so this extra niche for such a stage doesn't seem very useful. It's also operationally questionable, since BEO mission architectures might prefer to orbit in LEO for a bit and check out the vehicles before beginning the burn sending people far from Earth. (Apollo did so for an orbit or two.)  Loitering also enlarges the space of BEO trajectories -- you don't necessarily have to start from a launch window on earth that only opens a few times a month, which direct-ascent trajectories are often limited by.

    So, for all these reasons, it is possible to see a role for an SSME upper stage, but it's a very limited one, and in many architectures would still require building a true EDS as well. That's hardly a cost savings. The better choice is just to build one upper stage -- almost certainly an RL-10 cluster, or RL-10 evolved (though there are other conceivable options: RL-60, Vinci, possibly Raptor or J-2X or Russian engines) -- and use it for all roles in one.

   That's an important idea behind both DIRECT and the ULA architecture. CxP didn't.
     -Alex

Offline orbitjunkie

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Re: Upper Stage for SLS
« Reply #90 on: 10/17/2010 04:33 am »
Alex, right on and thanks for articulating the architectural difficulties with an SSME-derived EDS. They had occurred to me but I didn't think though many details or mention them myself. I agree it would not make sense to use SSME for your primary EDS, because you'd still need to have ANOTHER stage for any kind of capture burn at your destination.

Although, supposing they had already developed a true, restartable EDS, and later they add that SSME second stage (perhaps in order to reach the 130mt upper goal) I do wonder if you could use that 2nd stage to your advantage in ways it wasn't intended. It would certainly be limited to missions that didn't require a restart or had little dV after the departure burn (like the libration orbit you mentioned, or some escape trajectories). But especially if the true EDS ends up using J-2X, the performance difference might be worthwhile. So then the relevant questions become:
 - Would in-orbit start of the SSME be that much harder than air-start? Probably so? and more costly to solve?
 - Could you get any useful loiter time out of it, even one orbit? This will surely be a function of the first question, and also how badly boiloff would eat your lunch on a stage designed as a second stage, not an EDS. Probably would have significant operational constraints.

FWIW, I hope they move toward the DIRECT phase 3 setup, with a JUS and depots. But if NASA goes a different route, maybe there are other ways to mix and match the hardware. My question has now morphed into "if they develop an SSME air-start 2nd stage, could you use it beneficially in a way it wasn't intended?". That may technically be on topic, but is probably not where we want this thread to go. :-)

Offline guru

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Re: Upper Stage for SLS
« Reply #91 on: 10/17/2010 05:31 am »
Hmm... maybe build a stage with one SSME and two RL-10s.  You lose maybe 2.5 tonnes to LEO (out of 130 tonnes) with the two extra RL-10s and plumbing, and then you lose about 5 tonnes through TLI/TMI (out of about 48 tonnes) with the SSME as dead weight. But overall, you come out ahead of an RL-10 only or SSME only stage by the time you actually reach TLI/TMI (because you can put more into LEO with the SSME thrust, and you can restart the RL-10s instead of having to do a one burn TMI/TLI injection).

Offline guru

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Re: Upper Stage for SLS
« Reply #92 on: 10/17/2010 05:44 am »
More on topic to proponents question of will the SLS's proper upper stage be built in a timely fashion... I don't think so.  For one thing, there isn't a deadline given for it, and probably no funds will be appropriated for its development any time soon.  However, I'm not sure that developing the really big upper stage offers much advantage over something like a Common Upper Stage.

The Saturn V could launch 45 tonnes towards the moon.  A J-130 type vehicle with a Common Upper Stage (CUS) could launch about 34 tonnes towards the moon, or 29 tonnes to Mars on a slow velocity free return trajectory minimally suitable for a human mission (3.7 km/s delta v).  If the CUS is to be developed anyway - and the military has recently sent out requests for proposals for it - then it would seem prudent to use that stage early on.  Two launch scenarios (edit: i.e. scenarios that use two launches instead of one) would then still offer a 50% payload increase over the one launch Saturn V moon missions, and could still allow for three crew member Mars Direct style missions to Mars. (Of course, you would still require four launches instead of two for the Mars missions because early NASA DRM plans severely overestimated the percentage of entry mass that could be safely landed using available technology, but that's more relevant to other threads.)
« Last Edit: 10/17/2010 05:46 am by guru »

Offline yg1968

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Re: Upper Stage for SLS
« Reply #93 on: 10/19/2010 02:48 pm »
Air Force is thinking of replacing the RL-10 with a new engine:
http://www.spacenews.com/military/air-force-upper-stage.html
« Last Edit: 10/19/2010 02:49 pm by yg1968 »

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Re: Upper Stage for SLS
« Reply #94 on: 10/19/2010 09:38 pm »
Air Force is thinking of replacing the RL-10 with a new engine:
http://www.spacenews.com/military/air-force-upper-stage.html

Nice find.

RL-60 anyone?

Offline Lars_J

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Re: Upper Stage for SLS
« Reply #95 on: 10/19/2010 09:44 pm »
The article seems to imply that only PwR and AeroJet are viable candidates in this potential contract. One would hope that bids from others are considered.

Offline clongton

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Re: Upper Stage for SLS
« Reply #96 on: 10/20/2010 12:03 pm »
The article seems to imply that only PwR and AeroJet are viable candidates in this potential contract. One would hope that bids from others are considered.

What other domestic companies have this capability *and* the capacity to deliver?
Chuck - DIRECT co-founder
I started my career on the Saturn-V F-1A engine

Offline Ben the Space Brit

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Re: Upper Stage for SLS
« Reply #97 on: 10/20/2010 12:16 pm »
FWIW, it should be remembered that SpaceX's Raptor is currently blueprints at most, and would be manufactured by a company with no prior hydrolox experience.  Naturally, no non-US engine would even be considered for a 'flagship' like SLS.

So, I'm afraid something PWR or Aerojet is pretty much the only game in town right now.
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Online edkyle99

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Re: Upper Stage for SLS
« Reply #98 on: 10/20/2010 02:14 pm »
The article seems to imply that only PwR and AeroJet are viable candidates in this potential contract. One would hope that bids from others are considered.

What other domestic companies have this capability *and* the capacity to deliver?

I'm not sure either of these companies can "deliver" - especially since the primary goal seems to be cost reduction.  I won't be surprised to see one or both propose designs based largely on existing non-U.S. engines or non-U.S. components.  Pratt's RL-60, for example, had a Russian LOX turbopump, a Japanese LH2 turbopump, main valves from Belgium, and a Swedish nozzle.  Aerojet seems largely in the business of slapping its logo on Russian-made engines.  It's been maybe decades since either of these companies developed an all-U.S. high thrust liquid rocket engine from scratch.

 - Ed Kyle
« Last Edit: 10/20/2010 02:27 pm by edkyle99 »

Offline yg1968

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Re: Upper Stage for SLS
« Reply #99 on: 10/20/2010 02:38 pm »
Air Force is thinking of replacing the RL-10 with a new engine:
http://www.spacenews.com/military/air-force-upper-stage.html

I didn't realize it but there is actually already a thread discussing the RL-10 replacement:
http://forum.nasaspaceflight.com/index.php?topic=23029.0
« Last Edit: 10/20/2010 03:05 pm by yg1968 »

Offline guru

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Re: Upper Stage for SLS
« Reply #100 on: 10/20/2010 03:01 pm »
Intended For Flight:

Fastrac (1998). 60k
XRS-2200 Aerospike (1999) 200k
RS-68 (2002).  650k
RS-68A (2008).  700k
J-2X Powerpack (2011).  290k

Not for flight:

Integrated Powerhead Demonstrator (2006) 250k
TR-106 (2000) 650k

Edit:  Though admittedly, only three of these could be called upper stage engines, and the TR-106 was from TRW (now Northrop Grumman), but it shows that the primary contractors have developed new, in some cases low cost, rocket engine technology recently.


« Last Edit: 10/20/2010 03:07 pm by guru »

Offline MP99

Re: Upper Stage for SLS
« Reply #101 on: 10/20/2010 03:03 pm »
Ed,

how much of RS-68 was new at the time?

cheers, Martin

Offline orbitjunkie

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Re: Upper Stage for SLS
« Reply #102 on: 10/20/2010 03:44 pm »
And what about SpaceX's Raptor? That would seem to be in the right class.

A bigger question in all this is going to be the timeline for the decision on the US. If they postpone any serious planning for it for a few years, the reasonable choices for what engine to use may be a bit different.

Today:
 - J-2X, despite poor Isp and high cost, may have some political favor and was meant to be "human rated" from the beginning. Is it safe to say its path to a flight engine is more well known?
 - RL-10 derivatives, lower cost, great heritage, better performance and lends itself to clusters and engine-out performance. Would need some mods for NASA to put people on top of it.
 - Lots of AIUS tooling and work is well underway. There will be pressure to utilize this.

In a few years:
 - J-2X, development probably shut down because of no early decision. This kind of engine restart is relatively difficult...
 - RL-10 is on its way out and the AF NGE is on its way in. NASA may not be willing to pay RL-10 sustainment costs all on its own. The AF may not want to let NASA impact it in any way by adding new requirements. Depending on the exact timeline, NGE could have been just awarded or well into development. Perhaps NASA could have their own variant of it for a relatively small premium?
 - SpaceX Raptor may have been given a green-light and be in design or development stages already
 - It seems likely that AIUS will be totally gone and probably not a likely template for the new US.

DIRECT was all about accomplishing Constellation's goals faster, better, and cheaper. There was at least a nominal plan with an advertised schedule. Building an RL-10 upper stage right away made lots of sense.

Now NASA is in a different situation where they need to develop the core version of SLS ASAP. There is no concrete plan or timetable and no definite date for an upper stage, much less money. It's a reasonable argument to put as little thought as you can get away with into the US, especially since you could do some limited missions in the interim with existing upper stages. In direct opposition to this argument is the one to build the core the first time such that it can support some unknown future US and maybe even theoretical evolution options.

Offline Lars_J

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Re: Upper Stage for SLS
« Reply #103 on: 10/20/2010 04:05 pm »
FWIW, it should be remembered that SpaceX's Raptor is currently blueprints at most, and would be manufactured by a company with no prior hydrolox experience.  Naturally, no non-US engine would even be considered for a 'flagship' like SLS.

So, I'm afraid something PWR or Aerojet is pretty much the only game in town right now.

All true... except that I believe SpaceX is actively developing Raptor, even if it may be a slow burn for now. Besides evolutionary Merlin upgradres (1D), their propulsion team is most likely concentrating on Raptor. It will be needed for the efforts to capture more of the satellite launch business.

So, yes, PwR and AeroJet can claim the only domestic hydrolox experience - but only for a while longer.

Online edkyle99

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Re: Upper Stage for SLS
« Reply #104 on: 10/20/2010 04:07 pm »
Ed,

how much of RS-68 was new at the time?

cheers, Martin

Rocketdyne, not Pratt, developed RS-68.  In addition, RS-68 uses components from Japan's Mitsubishi Heavy Industries, dropping it from the "all U.S." category. 

 - Ed Kyle

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Re: Upper Stage for SLS
« Reply #105 on: 10/20/2010 04:11 pm »
In direct opposition to this argument is the one to build the core the first time such that it can support some unknown future US and maybe even theoretical evolution options.

They should at a minimum develop the concept specs for the US based on ESAS mass requirements for lunar missions, and then build the SLS core to be capable of handling that much mass mounted on top of it. That way when they get around to the US they won't have to *also* redesign the core for the new loads. It won't cost any more to build a lunar-capable core than to build a non-lunar-capable core. The question is; do you want to design *and qualify* it once or twice? When we get around to going back to the moon, and even the Flexable Path Architecture says we will, then ESAS mass targets are appropriate to design to.
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Offline sdsds

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Re: Upper Stage for SLS
« Reply #106 on: 10/20/2010 04:32 pm »
They should at a minimum develop the concept specs for the US based on ESAS mass requirements for lunar missions [...] When we get around to going back to the moon, and even the Flexable Path Architecture says we will, then ESAS mass targets are appropriate to design to.

But what if the chosen mode for the lunar missions is EML Rendezvous rather that LEO Rendezvous?  Then mightn't different mass targets be appropriate?
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Offline clongton

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Re: Upper Stage for SLS
« Reply #107 on: 10/20/2010 06:00 pm »
They should at a minimum develop the concept specs for the US based on ESAS mass requirements for lunar missions [...] When we get around to going back to the moon, and even the Flexable Path Architecture says we will, then ESAS mass targets are appropriate to design to.

But what if the chosen mode for the lunar missions is EML Rendezvous rather that LEO Rendezvous?  Then mightn't different mass targets be appropriate?

Even with EML crew transfer stations I can't envision a lunar exploration program that won't require large logistic support launched directly from KSC. When I suggested ESAS mass requirements I was thinking specifically of cargo flights.
Chuck - DIRECT co-founder
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Offline orbitjunkie

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Re: Upper Stage for SLS
« Reply #108 on: 10/20/2010 06:19 pm »
Chuck, this is exactly the chicken and the egg problem I'm talking about and I think your approach is a good one. It's analagous to how the specs for the SLS are spelled out in the Authorization Act - build something that can hit this mass range, and optimize for cost.

It is definitely foreign thinking since NASA is used to designing for a particular mission, and here we have no specific mission. With no specific mission, who's to say the ESAS mass targets are relevant? This could be a challenging one to solve, mostly because it is a fairly different paradigm. If NASA can shift into this mode of thinking here, it will be a good sign.

Of course, constraining the current SLS design based on recommendations from "some old study" will no doubt hamstring the design of some future system. Much like the often quoted story of how you can trace the SRB diameter to two horses rear ends. Or, more accurately, how the ISS construction was defined by Shuttle payload capabilities. But, given what they have to work with now (lack of specific mission requirements and funding), there's no way to avoid it. And whatever future constraints SLS+US/EDS give us, it will be much better than what we have now!

Offline clongton

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Re: Upper Stage for SLS
« Reply #109 on: 10/20/2010 07:25 pm »
Chuck, this is exactly the chicken and the egg problem I'm talking about and I think your approach is a good one. It's analagous to how the specs for the SLS are spelled out in the Authorization Act - build something that can hit this mass range, and optimize for cost.

It is definitely foreign thinking since NASA is used to designing for a particular mission, and here we have no specific mission. With no specific mission, who's to say the ESAS mass targets are relevant? This could be a challenging one to solve, mostly because it is a fairly different paradigm. If NASA can shift into this mode of thinking here, it will be a good sign.

Of course, constraining the current SLS design based on recommendations from "some old study" will no doubt hamstring the design of some future system. Much like the often quoted story of how you can trace the SRB diameter to two horses rear ends. Or, more accurately, how the ISS construction was defined by Shuttle payload capabilities. But, given what they have to work with now (lack of specific mission requirements and funding), there's no way to avoid it. And whatever future constraints SLS+US/EDS give us, it will be much better than what we have now!

The SLS core will be roughly the equivalent of the Jupiter-130. When we designed the JUS we optimized it for that core because the analysis had shown that with the 2-launch lunar mission envisioned under ESAS, that the core-optimized JUS fit the ESAS mass requirements like a glove. Building an upper stage bigger than the Jupiter-246's JUS both degrades the core's performance and would not be economically sustainable, so a larger upper stage would be unwise. Building an upper stage smaller than the Jupiter-246's JUS would not allow efficient use of the HLV for lunar missions. So the Jupiter-246 turns out to actually be the Gold Standard for the foreseeable future in terms of heavy lift efficiency and economic sustainability. It is flexible, multi-mission adaptable, and economically sustainable, even at modest flight rates; hence my recommendation.
Chuck - DIRECT co-founder
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Offline 93143

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Re: Upper Stage for SLS
« Reply #110 on: 10/20/2010 08:00 pm »
Building an upper stage bigger than the Jupiter-246's JUS both degrades the core's performance and would not be economically sustainable, so a larger upper stage would be unwise.

A while back I asked if it was possible to meet the 130 short ton target with a non-SH vehicle simply by using a larger upper stage.  I got told by somebody or other that the JUS was optimized for propellant delivery, and that it couldn't be made significantly larger, certainly not enough to meet the 118 mT target.  Period.

Is this true?  'Cause it doesn't sound true; the payloads of the J-130 and the J-246 are awfully similar for designs separated only by the addition of an upper stage...

I'm not saying it would be a good idea; I'm just asking if it's possible.

Offline clongton

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Re: Upper Stage for SLS
« Reply #111 on: 10/20/2010 08:41 pm »
Building an upper stage bigger than the Jupiter-246's JUS both degrades the core's performance and would not be economically sustainable, so a larger upper stage would be unwise.

A while back I asked if it was possible to meet the 130 short ton target with a non-SH vehicle simply by using a larger upper stage.  I got told by somebody or other that the JUS was optimized for propellant delivery, and that it couldn't be made significantly larger, certainly not enough to meet the 118 mT target.  Period.

Is this true?  'Cause it doesn't sound true; the payloads of the J-130 and the J-246 are awfully similar for designs separated only by the addition of an upper stage...

I'm not saying it would be a good idea; I'm just asking if it's possible.

1. Your question about using a larger upper stage on the J-130 doesn't make any sense because the J-130 does not have an upper stage to enlarge. The "130" in the LV name means (1) 1 cryogenic stage to achieve orbit, (3) 3 main engines in the core stage, and (0) 0 [zero] engines in the upper stage (no upper stage). That's what the name "J-130" means. Perhaps you need to better phrase the question and I'll be happy to tell you what I can.

2. The JUS was not optimized for propellant delivery. It was optimized to efficiently use the core performance to execute a manned lunar mission as defined in the ESAS.
« Last Edit: 10/20/2010 08:44 pm by clongton »
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Offline alexterrell

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Re: Upper Stage for SLS
« Reply #112 on: 10/20/2010 08:50 pm »

2. The JUS was not optimized for propellant delivery. It was optimized to efficiently use the core performance to execute a manned lunar mission as defined in the ESAS.

Thought you can understand why some one would suggest such?

IIRC, the JUS can take 175 tons of fuel. But if the Jupiter 246 is to deliver its 70-100 of payload to orbit, the fuel tank would only take 75 tons of fuel (or was it 100t).

So for a single launch mission, the fuel tank is larger than it has to be. Could the fuel tank be reduced to save mass? If yes, then it is optimised for fuel delivery.

It's a question of terminology. Yes it was optimised for ESAS manned missions, and a way of achieving this was to optimise it for fuel delivery.

 

Offline 93143

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Re: Upper Stage for SLS
« Reply #113 on: 10/20/2010 09:02 pm »
1. Your question about using a larger upper stage on the J-130 doesn't make any sense because the J-130 does not have an upper stage to enlarge. The "130" in the LV name means (1) 1 cryogenic stage to achieve orbit, (3) 3 main engines in the core stage, and (0) 0 [zero] engines in the upper stage (no upper stage). That's what the name "J-130" means. Perhaps you need to better phrase the question and I'll be happy to tell you what I can.

...you've misread my post.  The only reference to J-130 is in the second paragraph, where I compare its payload to the J-246.  Perhaps you saw my reference to 130 short tons and misinterpreted it?

All right, here goes:  Could the SLS upper stage theoretically be made large enough that the version with upper stage could launch 118 mT (130 short tons)?

Quote
2. The JUS was not optimized for propellant delivery. It was optimized to efficiently use the core performance to execute a manned lunar mission as defined in the ESAS.

That's what I thought.

Offline clongton

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Re: Upper Stage for SLS
« Reply #114 on: 10/20/2010 09:13 pm »
All right, here goes:  Could the SLS upper stage theoretically be made large enough that the version with upper stage could launch 118 mT (130 short tons)?

Yes
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Offline 93143

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Re: Upper Stage for SLS
« Reply #115 on: 10/20/2010 09:36 pm »
Thanks.

Offline MP99

Re: Upper Stage for SLS
« Reply #116 on: 10/21/2010 08:16 am »
All right, here goes:  Could the SLS upper stage theoretically be made large enough that the version with upper stage could launch 118 mT (130 short tons)?

Yes



2. The JUS was not optimized for propellant delivery. It was optimized to efficiently use the core performance to execute a manned lunar mission as defined in the ESAS.

Interesting point here.

There are three obvious targets that an SLS upper stage could be designed for.

1) Maximise payload to LEO. HEFT suggests that an RS-25 u/s could maximise this. In this case, you're optimising the two stages of your rocket for 9-9.5Km/s gross delta-V.

2) Single-launch TLI (eg CxP cargo-only mission, LOR). In this case, the combined core and upper stage must also perform a 3Km/S+ TLI burn. Now you're optimising the rocket's two stages to perform ~12.5Km/S total gross delta-V.

3) DIRECT phase 2 EOR, which is a bit more complicated. Still needs to perform the 12.5Km/s from (2), but the final 3Km/S+ also needs to carry the TLI payload. This is what DIRECT is optimised for. This needs the largest remaing prop in LEO for the lowest EDS mass, so that after you've docked you maximise payload through TLI.

cheers, Martin

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Re: Upper Stage for SLS
« Reply #117 on: 10/21/2010 02:35 pm »
All right, here goes:  Could the SLS upper stage theoretically be made large enough that the version with upper stage could launch 118 mT (130 short tons)?

Yes

Hmm... that's a good question and an interesting response. 93143, did you mean specifically could JUS be made large enough, as opposed to some generic black box SLS US?

Assuming you and Chuck meant JUS, here's a follow-on question: How complicated would the JUS upgrade-to-130 tons be? As simple as a tank stretch and maybe strengthening?

I keep thinking about that 130 ton upper limit in the Authorization bill. It worries me because it seems like a dangerous open door to a rabbit hole which may be too constraining or too inviting to NASA (depending on your perspective). I am also not sure how Congress will exercise their oversight with regards to that requirement.

All said, it would seem wise from any perspective to find a way to meet that requirement with the least possible additional development effort.

Perhaps a path to stretch something like a JUS would be the cheapest and quickest option, if you had to exercise it?

Offline 93143

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Re: Upper Stage for SLS
« Reply #118 on: 10/21/2010 06:33 pm »
93143, did you mean specifically could JUS be made large enough, as opposed to some generic black box SLS US?

I just meant an upper stage of unconstrained design.  I'm not sure what Chuck meant; looking at my question, I realize it could be read both ways...

Even if the core were designed for JUS, it would be a relatively simple operation to redesign it for a heavier US at some indeterminate point in the future, even if you didn't actually plan to...  I'm not quite sure that meets the requirements of the law, but it's close...

Offline clongton

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Re: Upper Stage for SLS
« Reply #119 on: 10/21/2010 07:26 pm »
The goal is to design the core only once, qualify it and fly it until SLS itself is replaced 40 years from now. Follow the Soyuz model; build it once - fly it forever. Let all subsequent development be in the upper stage(s).
« Last Edit: 10/21/2010 07:28 pm by clongton »
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Offline Halidon

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Re: Upper Stage for SLS
« Reply #120 on: 10/21/2010 10:06 pm »
FWIW, it should be remembered that SpaceX's Raptor is currently blueprints at most, and would be manufactured by a company with no prior hydrolox experience.  Naturally, no non-US engine would even be considered for a 'flagship' like SLS.

So, I'm afraid something PWR or Aerojet is pretty much the only game in town right now.
They didn't have any RP-1 experience before 2002. If this upper stage is anything like 8 years away, like if we fly the HLV without an US for LEO work initially, Raptor may be right there waiting.

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Re: Upper Stage for SLS
« Reply #121 on: 11/05/2010 06:17 am »
A custom-sized J-2X stage would be great, but what can be done until it becomes available?

If the SLS vehicle performed like a Jupiter 130H (i.e. 85.603 metric tons to 51.5x130nm at 29deg), it could loft two of the smaller Delta IV upper stages plus a 30 metric ton payload.  The two stages, fired sequentially or in parallel, could send the payload to Earth-escape velocity, so it could easily be sent through a standard TLI, or on a ballistic trajectory to EML1 or EML2.
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Offline Patchouli

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Re: Upper Stage for SLS
« Reply #122 on: 11/05/2010 09:45 pm »
The goal is to design the core only once, qualify it and fly it until SLS itself is replaced 40 years from now. Follow the Soyuz model; build it once - fly it forever. Let all subsequent development be in the upper stage(s).

Or the Enegria /Starlifter model

The Energia family could produce a 35, 100 and 175T LV using the same parts.
http://www.buran-energia.com/energia/famille-desc.php


Starlifter on the other hand allows an incremental move to reusability.
http://www.starbooster.com/StarLifter_I.pdf

Spacex's Merlin 2 could be used as a replacement for the RD-170 a stretched F9 or Atlas CCB should work for the tanks.

For an upper stage the RL-60 and even the RL-10 beats any J-2 based solution hands down.

SDLVs with SSMEs tend to be stage and a half to orbit vehicles so they don't need a high thrust upper stage ISP is going to be far more important.

FWIW, it should be remembered that SpaceX's Raptor is currently blueprints at most, and would be manufactured by a company with no prior hydrolox experience.  Naturally, no non-US engine would even be considered for a 'flagship' like SLS.

So, I'm afraid something PWR or Aerojet is pretty much the only game in town right now.
They didn't have any RP-1 experience before 2002. If this upper stage is anything like 8 years away, like if we fly the HLV without an US for LEO work initially, Raptor may be right there waiting.

The most useful thing Spacex might have to contribute to SLS would be Merlin 2 vs Raptor.

The reason why is Merlin 2 would create another alternative to the RSRM for booster use even better then the RD-180.

Raptor would not really be much of an improvement over six RL-10s and in fact could have lower TLI performance if it's ISP turns out being much lower then the RL-10.

On the Jupiter vehicles which probably represent a good idea of what SLS will be the RL-10 does outperform the J-2X for lunar missions.


« Last Edit: 11/06/2010 03:47 am by Patchouli »

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