Why write a whole page for something that can be simplified into 3 lines?Orion CM/SM Mass to LEO - 22 tonsDelta IV Heavy lift capacity to LEO - 22 tonsAres I lift capacity to LEO - 25 tonsNo margin on DIV for Orion
I am starting to believe that there never has been any justification for Orion under any scenario. It's designed for a Mars direct return trajectory. Dragon or a beefed up CST-100 could handle lunar return. I think hauling an Orion to Mars and back is too much mass. Have a DS hab at EL1/2. Ride to rendezvous in Dragon or CST-100. Transfer. Go to Mars and return to EM L1/2 in hab, transfer to a Dragon or Boeing capsule for reentry. Leave the hab parked for next mission. Or use an Aldrin cycler and rendezvous as it swings by. Orion only has a 21 day active use capacity, so its use as a lifeboat is very limited. I'd rather expend Delta V on decelerating the hab for reuse than sending Orion's great mass all the way to Mars and back when it really isn't necessary. A better CxP would not have included such a massive capsule. It would have used a less massive capsule that would go to LLO or EM L-1/2 and back, but not to Mars.A lighter capsule would have prevented Ares I performance from ever becoming an issue.
Interesting concept. As the SM's not designed yet, maybe the design could be changed to that? I don't think there's much to be done with the CM at this point.
Quote from: Lobo on 05/21/2013 12:33 amInteresting concept. As the SM's not designed yet, maybe the design could be changed to that? I don't think there's much to be done with the CM at this point.It's not?
I’m bumping this with a bit of an addition parameter.First, does anyone know in particular why McDonnel Douglas went with a hydrolox booster on Delta IV for the EELV competition? Especially when it needed a new engine developed? (I’m assuming Jim probably knows, :-) )I mean, hydrolox isn’t the best 1st stage booster. It required a much larger booster core than Atlas V or any similar performing kerolox booster. Delta II used the kerolox RS-27 engine. There wasn’t a US made kerolox engine other than RS-27 that I know of, but there wasn’t a US made hydrolox booster engine either. RS-25 is a sustainer engine, not really a booster engine.So, if MD was going to evolved Delta II for EELV, why didn’t they stick with the RS-27, and grow the core to 5m, and put maybe five of them on there? Or maybe four with GEM-60 SRB to get it off the pad? Four of them had more thrust than the first RS-68, and not much less than RD-180. What was the thought process to switch to a brand new engine development, and a propellant that isn’t the best booster propellant, not to mention being one of the most temperamental propellants. I see why the Russians and SpaceX use kerolox for the upper stage for commonality and because it’s a really easy propellant to handle and I think rockets that use kerolox are cheaper overall than hydrolox. LH2 is the most difficult and so they wanted to make the whole rocket use it?Hopefully someone can enlighten me on that. Especially when the Delta II already used a 200klbs kerolox engine that probably could have been upgraded to get to around 250klbs without much trouble.Ok, so I set this up for a bit of alternative history going back to the EELV program for this thread.So, MD wants to create new 5m wide rocket core tooling, and a new engine, and a new upper stage using RL-10 engine for Delta IV?What if instead, they went with a 5m wide kerolox booster, which either used 4-5 RS-27A’s (or upgraded versions with more thrust), or, instead of having PWR create the RS-68 new, have them dust off the F-1, and create maybe an “F-1S” version of the F-1A. I guess the F-1B is going to be like this, but like the J2S, make the F-1S with a specific eye for being simple and cheap. A big Merlin 1D in effect maybe? Maybe a larger upper stage (because the GG F-1 won’t be as efficient as a stage combustion kerolox engine like the RD-180) and maybe RL-60’s on it. They were 90% developed by 2003 anyway.So, you have something similar to an Atlas V-phase 2, but with probably less first stage burn and more 2nd stage burn. This LV should probably put somewhere between 20-25mt to LEO, which would fulfill the upper end of the EELV requirements I believe. No need for a tri-core heavy version. And while it would seem overpowered for the bulk of the EELV payloads that Atlas V and Delta IV Medium handle, would it be any more money than Delta IV? It might be more money than Atlas V, because the US-made F-1B would be more expensive each than the RD-180’s. But You have an LV that would be be shorter than a Delta IV medium, cost about the same, but put up D4H payloads. GEM-60’s should bump that up easily if ever needed. I mean, it’d basically be the same hardware as a Delta IV medium.So, let’s say MD developed that, and let’s say Boeing buys them. And even if Boeing is caught stealing info from LM and ULA is formed, This version of Delta IV would exist.So, during the ESAS evaluation, where NASA evaluated Atlas Phase 2, as well as an 8m wide Atlas X, they could evaluate this LV. The single stick version should get Orion to LEO. But it could be stretched, and have another F-1 added, and you basically have the Dynetics booster. Now you have a crew launcher with direct synergy with EELV, and a cargo launcher with much synergy with EELV, except NASA could launch it from their pads at KSC (as Boeing would have had no reason to build the ability to launch a tri-core heavy from LC-37, since the single-stick would handle up to Delta IV-heavy roughly).So the tri-core heavy would be only used by NASA. And they could build the larger upper stage/EDS for it. It only has two boosters, which was another requirement they seemed to fixate on in ESAS. This cargo launcher would have six F-1 engines, and with a larger EDS, it should throw easily what Ares V was supposed to, to LEO. NASA could have PWR develop the J2S (not the J2X) as was originally envisioned in ESAS on the cargo launchers. It was mostly developed already, and should have been a relatively cheap and easy development, rather than the J2X which I understand was a very different engine than J2S. And I don’t know if they could fit enough RL-60’s on it. But it should be able to fit a couple of J2S under there. So, putting aside for a moment the politics of the time probably made SDHLV inevitable, this EELV derivative seems like it would have met all of what seemed to be NASA’s ESAS criteria. No more than two boosters, 25mt crew launcher, 125mt cargo launcher, 1.5 architecture, etc. And with a famous US-built engine. NASA evaluated Atlas Phase 2 heavy, but seemed to reject it as you’d need two of them for their planned architecture, and they wanted 1.5 architecture. Atlas Phase 3A would have probably worked, but it had more than two boosters, and they said it wouldn’t even fit on any existing pad, which I think was because the four boosters were placed at 90 degrees to each other, making it just over 15m in depth as well as width, which I think is a problem to fit it on a ML with tower.Could this have been the better CxP? While having a lot of synergy with EELV’s? The only new developments over a Delta IV with single F-1 engine, would have been the stretched 5m core, making the tri-core heavy, man-rating it, and a new wide upper stage with J2S engines)Compare that with CxP in developing a new 8.4m core (using existing tooling) a new Ares V upper stage, a new Ares 1 upper stage, J2S for Ares V anyway, air-startable SSME for Ares 1, and 5-seg booster.
They danced around this a lot, and had no problem looking at a new diameter core in their concepts. KSC can't handle an 8 or 8.4m tri-core LV, but the 5-5.4m wide hydrolox LV is a little to small. And they didn't seem to like the 5-5.4m wide kerolox Atlas Phase 2 because it needed 2-launches of tri-core LV, or a 5-core AVP3a and NASA didn't like that many boosters and the depth dimension.But no one thought to look at maybe a 6-6.5m kerolox core with 3-4 RD-180's?It's over powered but workable for a crew launcher, and a tri-core version is as capabile as the LV 27.3 they chose.One new core, and one new upper stage (it would need J2S but so did LV27.3), and NASA has both a new crew launcher, and cargo launcher. And the crew launcher could probably use Delta's existing DCSS like I said, for a little more synergy with EELV.The cores could be produced at a reasonable clip at MAF, along with the new HLV upper stage (when needed, down the road). Seems like such an obvious option, what am I not seeing? Why wasn't it even looked at, even if they opted for Ares 1/5 anyway.
{snip}Saving a billion a year on the launcher, but losing 5 billion a year in NASA's overall budget, would be a very bad trade indeed as the losses would mostly be directed towards the Science directorate.Though I personally am not a fan of the current direction for SLS, it still represents the backbone of NASA's entire political support structure and without that, NASA could be in a much, much worse position.Ross.
A_M, Unfortunately it doesn't work that way.There is at least a decade's difference between when NASA's political support mechanism was destroyed, and when there could potentially be a moon base -- it just takes that long to develop all of the systems required.{snip}
SLS and Orion are development projects not a manufacturing operation.The Moon base would be a development project.The overlap is smaller, particularly since NASA can start development in s few months.
The thing most people here (me included) have a really hard time swallowing is that the politics is sadly 90% of the fight. Without it, the other 10% doesn't matter at all. Loathe this truth to your heart's content. But ignore it at your peril.