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.
does the legislation actually direct NASA to develop the upper stage or just to be able to use one to go BEO
Quote from: MickQ on 10/07/2010 05:48 amWould 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.
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?
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.
Quote from: alexw on 10/07/2010 08:57 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.
There are basically three options for the upper stage right now...
Quote from: Proponent on 10/06/2010 04:36 amif 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.
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.
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.
Quote from: Proponent on 10/06/2010 05:01 amAfter 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.
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.
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?
Quote from: Robotbeat on 10/08/2010 03:46 amI 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.
[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.
Quote from: MickQ on 10/08/2010 04:16 amQuote from: Robotbeat on 10/08/2010 03:46 amI 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
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.
Quote from: marsavian on 10/08/2010 04:50 amWhat 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.
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?
We will just have to see.
Thats not to say though, that with budgets limited DIVUS, centaur, or even Raptor are not viable options
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.
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 SLS's first task is also clear, to fully support ISS, and it doesn't need an upper stage for that.
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.
. Use what is available until flight rates and proposed payloads require/mandate the development of something more optimal.
Quote from: marsavian on 10/08/2010 04:50 amWhat 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)
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
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.
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.
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.
The "standard" 138 t AIUS might not fit well with SLS, but a "long" 172 t version certainly would!
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. Affordable2. Low boiloff/long duration3. DEPOTS DEPOTS DEPOTS4. ACES derived.
5. Maintain Strong Bipartisan Congressional SupportNote: ACES is nifty. However, what ACES has, many others will also eventually develop. Cheers!
What are the drawbacks, if any, of an 8.4m diameter stage of <some> length on either the Atlas-V or the Delta-IV?
What are the drawbacks, if any, of an 8.4m diameter stage of <some> length on either the Atlas-V or the Delta-IV?...
ULA would prefer 5/5.3m
Quote from: Jim on 10/12/2010 06:09 pmULA would prefer 5/5.3mWhat 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.
Quote from: Patchouli on 10/12/2010 07:20 pmQuote from: Jim on 10/12/2010 06:09 pmULA would prefer 5/5.3mWhat 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.
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?
Quote from: Patchouli on 10/12/2010 07:36 pmThe 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.
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.
J-2x is a waste, IMO.
Quote from: Robotbeat on 10/12/2010 09:38 pmJ-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...
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?
Quote from: simonbp on 10/13/2010 01:33 amQuote from: Robotbeat on 10/12/2010 09:38 pmJ-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.
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?
<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.
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.
ULA preference is based on their existing production line.
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.
"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.
Quote from: simonbp on 10/13/2010 01:33 amThere's no way a single J-2X will cost more than six RL-10s ...Quote from: alexw on 10/13/2010 01:58 amEntirely 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.
[...] 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.
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.
Hence the reason why j2x should be shelved as it has been.
Quote from: Proponent on 10/07/2010 05:05 am[...] 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!QuoteI'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 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 stagep32http://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.
What we probably will need for most architectures is a restartable, long-loitering EDS, not an S-II redux. -Alex
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.
Quote from: MP99 on 10/15/2010 07:41 amQuote from: Downix on 10/14/2010 07:47 pmThe 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.
Quote from: Downix on 10/14/2010 07:47 pmThe 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).
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?
Air Force is thinking of replacing the RL-10 with a new engine:http://www.spacenews.com/military/air-force-upper-stage.html
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.
Quote from: Lars_J on 10/19/2010 09:44 pmThe 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?
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.
Ed,how much of RS-68 was new at the time?cheers, Martin
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 [...] 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.
Quote from: clongton on 10/20/2010 04:11 pmThey 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?
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!
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.
Quote from: clongton on 10/20/2010 07:25 pmBuilding 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.
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.
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.
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 from: 93143 on 10/20/2010 09:02 pmAll 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
93143, did you mean specifically could JUS be made large enough, as opposed to some generic black box SLS US?
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).
Quote from: Ben the Space Brit on 10/20/2010 12:16 pmFWIW, 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.