On the other hand, staged combustion, if done right, could be a tough competitor in the long run, because it will take 28 Merlins to compete with only two BE-4s and an RL10.
I find this about as convincing as dismissing PCs because you only need one mainframe.
But which one is cheaper. The 28 Merlins or the 2 BE-4 plus the RL-10C?
Hmm. Ed is comparing the Vulcan 501 to a Falcon Heavy! Which is the equivalent with the Vulcan 561 with 6 strapped-on solid rocket boosters.
IMO, the Vulcan 501 is about equivalent to the Delta IV medium+ (5,2) not the Delta IV Heavy.
Given SpaceX isn't intending to use dual-launch, isn't Falcon Heavy their equivalent to all Vulcan variants?
So technically the BE-4 seems to be the better choice. But then again, I wouldnt trust anything that comes out of BO at this point, simply because of their secrecy. Someone acts like that if he has something to hide and I cant really trust someone who is not open. The BE-3 apparently works quite well, but unless there is some heritage, I would not give it much trust either.
Probably the people who are buying the engine (ULA) have a little more insight into what BO is doing than we do.
;-)
I think it’s fair for ULA to thump their chest at this point in time. Going forward however; with their level of uncertainty, it “may” be their “last” time...
This debate about the phrase "America's Premier Launch Services Provider" all reminds me of two things:
1) Robert Heinlein's "I met a lizard the other day who proudly told me he was a brontosaurus on his mother's side"
2) Someone I worked with who would retreat behind the litany "I am the former president of NEDCO, Northern Electric's Canadian operation" whenever he couldn't get what he wanted from a supplier, contractor, government employee.
Big difference between gas generator and staged combustion development effort. Also, Merlin produces 3.5 times less thrust than BE-4, which further scales the effort. It does show how smart SpaceX has been in its propulsion decisions (so much fan focus on reusability, etc., but that darn engine is the crux of the entire matter - the real key to Falcon 9 competitiveness). On the other hand, staged combustion, if done right, could be a tough competitor in the long run, because it will take 28 Merlins to compete with only two BE-4s and an RL10.
- Ed Kyle
Spacex was very smart to go with a conservative gas generator engine as it allowed them to get something flying without going into materials development.
Their only mistake was as Musk admitted himself was that Falcon 1 might have been a bit too small and he wished they started with a rocket about twice it's size.
Now Falcon and Saturn both have shown they can handle an in flight failure and still complete the mission so maybe have 5 to 9 engines in the first stage is not a bad thing.
From a failure stand point two engines is probably the worst possible number to have in the first stage as you doubled the change of failure but do not even have enough margin to handle a one at any point in first stage burn.
BTW gas generator engine can be made just as high thrust as a staged combustion engine.
A single F-1 sized GG engine would generally outperform two BE-4s by a good margin despite having a lower ISP.
Though it might be more expensive then even two BE-4s despite being easier to develop.
With the negative comparison of small engines over large followed by discussion of three possible new large engines...
I was amused to see one possible very large engine NOT mentioned.
An engine that is a constant thread generator on these forums.
So does anybody have any clue when SpaceX will have a large enough piece of one of their Raptors on a test bed that even SpaceX critics or Capitol Hill can call it a large engine under development?
But which one is cheaper. The 28 Merlins or the 2 BE-4 plus the RL-10C?
Well, from that hearing it sounds like a bit less than $20m for the BE-4 pair. My understanding is RL-10 also costs a bit less than $20m. So call it ~$35m for engines on a Vulcan 401.
I would be astonished if the unit cost of Merlin were even $1m, otherwise the price delta between Falcon 9 and Falcon Heavy would be bigger.
Hmm. Ed is comparing the Vulcan 501 to a Falcon Heavy! Which is the equivalent with the Vulcan 561 with 6 strapped-on solid rocket boosters.
No, what he's doing is surveying the entire range of payloads and selecting for the purpose of discussion the narrow window between where a Falcon 9 wouldn't be enough but a Vulcan would not yet need solids. Anything outside that window is quite a lot more favorable to SpaceX, but it's worth discussing because it's good to allow charitable assumptions in a discussion and I don't think Vulcan's costs look that good there. Merely less bad.
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