NASA, and Orion, aren't going to the Moon. That's not the mission.
If 3 people could go to the moon in an Apollo sized capsule 40 years ago I'm not sure why things are different now.The laws of physics didn't change. The politics of NASA did.Who cares how big the SM is. The whole thing is bloated.The shape was fine and so was the SIZE. I still haven't seen any rationalisation for needing a capsule of Orion's diameter.
I do not think low-altitude abort with the SM would be practical: the mass to be accelerated would be huge. Dragon can do it, because the abort engines and propellant are contained within Dragon itself, not within something akin to an SM.
Dragon does not have an SM - the entire vehicle (except for the trunk) lands and, in later versions, will be reused.
Quote from: Proponent on 02/02/2013 10:08 AMI do not think low-altitude abort with the SM would be practical: the mass to be accelerated would be huge. Dragon can do it, because the abort engines and propellant are contained within Dragon itself, not within something akin to an SM.the mass would be more than CST-100. CST-100 CSM is about 10mt I believe, and Orion CSM is more like 22mt or so. so yea, about double. But the LAS tower is already doing it. I merely propose using storables in the SM as pusher LAS so that that mass does double duty. It's either aborting, or doing the TEI burn and acting as the OMS system. It is just scaled up accordingly. The SM gains some mass by having more engine power than it needs for non-abort operations, but it looses a lot more mass by not having the single-purpose LAS tower.If CST-100 can abort the command AND Service module with LOX and ethanol, and Dragon can abort the command module with hypergolics, and Dreamchaser can abort the whole lifting body with whatever the heck it will use....then I'd think that Orion can abort the whole CSM with the right engines and proper propellant sizing. And whatever is necessary for an abort will probably be more than adequate for TEI burn and OMS burns.
The Orion CSM has a much larger delta-V than Dragon, CST-100 or Dream Chaser. I don't have the exact numbers, but we're talking well over a kilometer per second rather than a few hundred meters per second. Therefore, it's going to be quite heavy. On top of that, because Orion rides on a rocket where most of the thrust comes from SRBs that can't be shut down in an abort, it needs higher abort abort acceleration than do the other craft. Add all of that up, and I think it's going to turn out that using SM propulsion for low-altitude aborts is very tough.I think the better approach would be to launch Orion without a crew and send the crew up commercially. Then the LAS isn't needed and Orion can be simplified and lightened. It would still need to be capable of re-entry, since aerobraking into LEO on return from a BEO mission is presently still a technology yet to be developed.
It did work.. 100% success.. Ares 1 was a great success, so much of a success that its been covered as an option years later when there is no assured access to space, other than via the Russian's and maybe the Chinese.. in fact its still been applauded, what else do you need?
I just had a odd thought.Things started to go bad for Ares 1 once they ran into problem with the air startable SSME, which then meant instead of Ares V using just a simple updated J2S, they needed the completely redesinged J2X and all of that cost. And they ran into performance problems with the lower thrust J2X, and problems snowballed from there for Ares 1 and Orion.But, what if, at that point, they just decided to make the Ares 1 5.5m upper stage longer, and make a booster stage out of it? They were plannning to design and build that element anyway, making it longer should have been a pretty minor thing, especially when all the problems of stacking the stage on a 4 and then 5 and then 5.5 seg SRB started to really get out of control.You make it about the length of a Delta IV core, put four RS-25E's on the bottom (which will be shared with Ares V) and a man-rated DCSS on top (iCPS), and I'd think you could get Orion to LEO.I think it'd have quite a bit better perfomrance than Delta IV, because I believe the A1US was to be made out of AL2195, and have a common bulkhead. Both of those same things would go into this, just the stage is longer, with an EELV upper stage. And it'd have the high performance RS-25's rather than the lower performning RS-68's. You don't have to develop the air-lit SSME, you can then develop just the more simple J2S for Ares V, you are using the same engine as Ares V and it's already man rated, and you remove solids from the equation completely for crews.Or you could make the core shorter, use maybe 2 RS-25's, and then a cluster of GEM-60's or Atlas SRB's to augment the performance to get it where NASA wanted it. That way more SRB's mean Orion could be fatter for BLEO missions later. The crew launcher would be adjustable to what it needed to be then, to account for Orion mass creep.You have SRB's then, but heh...Ares 1 was going to use a really big solid anyway.And if they didn't want to use an EELV upper stage, they could have still made the A1US, but it would be common with the Ares 1 liquid booster then. It could then use the J2S that Ares V would use for more commonality if they wanted to go that route instead of fostering EELV synergy.It's still far from ideal compared to just using EELV's directly, but it seems much more desirable than trying to make Ares 1 work for so long, and in effect, creating the gap by not having an LV in time to fly after STS was retired.THey were making a new liquid 5.5m core anyway to make an upper stage out of it...which was to have no synergy with anything else....so why not just make the LV out of that and don't worry about the big solid or the upper stage engine at all? And they could have still had "their" rocket, which seems to probably be the major reason the more obvious choices of using EELV's were discarded in the ESAS study.Could this have worked and been developed in time to establish ISS service after STS retired?
I just had a odd thought.Things started to go bad for Ares 1 once they ran into problem with the air startable SSME,
[...] they could have still made the A1US, but it would be common with the Ares 1 liquid booster then.
[...] don't worry about the big solid
My data recorder says different ! Things started to go bad for Ares I, and for the whole Constellation program, when NASA realized that the administration would not fund the program as promised. More, Shuttle return to flight and other contingencies further diminished the available funding.The solution was to reduce the number of program elements, to eliminate expensive elements, to enforce commonalities between CLV and CaLV, to find commonalities with external programs. From 3 liquid fuel engine elements (RS-25 air start, RS-25 ground start, J-2S) they went to 2 (RS-68, J-2X).
This is quite a stretch. An upper stage must be optimized or it would not reach orbit with a significant payload, or at all.
That would have been a bug, not a feature - wrt politics. The Constellation program was designed such that it would keep the "big solid" in the big picture. CLV was the funded project, not CaLV.
In theory, yes, but it would have failed in the ESAS guidelines they put down, namely "one engine per stage."Anything more than that, then the ESAS would have been shown to have been in error, and could have opened up the entire thing to lawsuits by the losers of the competition.
I'll take one last hail Mary pass at it though. Given that a big solid was required and an RS-25 couldn't feasible be made to air start.Maybe take a Delta IV core, modify it with a single RS-25 engine, and side mount it to an SRB with the RS-25 angled outwards like the Shuttle's were. The SRB's are designed to be side mounted anyway, although obviously it wouldn't quite be the same. But should be any harder than trying to inline mount it.Then you remove the air-startable RS-25, and the J2X. Ares 1 and Ares V both use RS-25 and SRB's. You remove the extra 5.5m upper stage development too. With one RS-25, the Delta IV core should burn to disposable orbit, and then on ISS support missions, Orion does it's own EOI burn to get to the ISS.For Lunar missions, maybe an EELV upper stage is used, or the Service Module is designed with enough prop to get itself to EOR, and then the TEI burn from LLO. Put Orion above the top of the SRB So that it's not next to it...which would be undesirable.Not that it would be a good LV...but perhaps more workable than Ares 1?
He he... great minds think alike LOL !Lobo, search this forum for "1 1/2 SD CLV" and you'll see the same crazy ideea explored 6 years ago.Or something much like that.I even toyed with moving the Lox tank out-of-axis wrt. the H2 tank so that the c-of-m would be as close as possible to the SRB axis; and that was because one of the critics said that if the RS-25 quits in the early stage, the rocket goes cartwheel.But the basic principle still haunts me occasionally !Yes, with such a stage-and-a-half-to-orbit CLV design,- you have the great RS-25, ground started and firing all the way to orbit;- you can adjust the sizing of liquid propellant tanks without growing to monster height, because the LH2 tank lies parallel to the SRB; - you have Orion on topSince this is a speculation thread, I will attach some of the graphics that I used to play with at the time, and no one needs to feel offended, OK ?Just having fun !