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"Engines are incredibly expensive to manufacture" Well, the Shuttle engines were, on the order of $50M or something like that. But the Merlin-1D, according to

by jakub_h 10y ago

"Engines are incredibly expensive to manufacture" Well, the Shuttle engines were, on the order of $50M or something like that. But the Merlin-1D, according to a former SpaceX employee on Reddit, is in the ballpark of $1M per unit. They've really streamlined the design for mass production, so even if thrown away after a single use, the Merlins are actually much cheaper than the Shuttle engines even if you take RS-25 reuse into consideration (9 launches per one RS-25 unit in average - so about $5-6M per engine-launch in just amortized manufacturing costs?). They're also much simpler and sturdier, much like the F-1 engines - despite not being designed for it, it turned out that those could have been used for about twenty-thirty times without major problems and without major component replacements. The RS-25s pretty much required general overhaul after every flight.

mikeash 10y ago
Note that the SSME puts out about 3x the thrust and has a substantially better specific impulse, so you should probably be comparing one RS-25 to 3-5 Merlins. On the other hand, that SSME cost figure is probably in 1970s-era dollars....
InclinedPlane 10y ago
And the Falcon 9 first stage has nine engines, so that's about 9-14 million dollars worth of engines for the stage. That's in the ballpark of a quarter of the total hardware cost of the booster, and that almost certainly doesn't include the testing overhead for each engine. Anyway, my point is, even if all that SpaceX had to work with for reuse was the main rocket body and a pile of the majority of the engines in working order, that would easily add up to tens of millions of dollars worth of equipment, and thus tens of millions of dollars of cost savings on reflight. There's practically no way that reflight could be more expensive than a new rocket, there's just not enough complexity in the vehicle for that to realistically be possible.
- jakub_h 10y ago
  True. I've long held the view that low costs of launches basically require two things: the equipment should be cheap to manufacture and cheap to service. Shuttle violated the former big time and in all likelihood also the latter. F9 certainly satisfies the former already and there's no reason to think that it won't eventually satisfy the latter, too.

by jakub_h 10y ago

mikeash 10y ago

Note that the SSME puts out about 3x the thrust and has a substantially better specific impulse, so you should probably be comparing one RS-25 to 3-5 Merlins. On the other hand, that SSME cost figure is probably in 1970s-era dollars....

InclinedPlane 10y ago

And the Falcon 9 first stage has nine engines, so that's about 9-14 million dollars worth of engines for the stage. That's in the ballpark of a quarter of the total hardware cost of the booster, and that almost certainly doesn't include the testing overhead for each engine. Anyway, my point is, even if all that SpaceX had to work with for reuse was the main rocket body and a pile of the majority of the engines in working order, that would easily add up to tens of millions of dollars worth of equipment, and thus tens of millions of dollars of cost savings on reflight. There's practically no way that reflight could be more expensive than a new rocket, there's just not enough complexity in the vehicle for that to realistically be possible.

jakub_h 10y ago
True. I've long held the view that low costs of launches basically require two things: the equipment should be cheap to manufacture and cheap to service. Shuttle violated the former big time and in all likelihood also the latter. F9 certainly satisfies the former already and there's no reason to think that it won't eventually satisfy the latter, too.