You start to consider whether pump packs with multiple chambers make more sense
in some of these scenarios, both because of better length for packaging the
engines compartment and because unless ignition is a problem smaller chambers
are generally pretty reliable and more instability proof and easier to
manufacture. Turbopump sets may scale differently.
Is RD-170 one or four engines? Is RD-180 one or two?
-george
Sent from my iPhone
On Apr 20, 2023, at 5:16 PM, Henry Spencer <hspencer@xxxxxxxxxxxxx> wrote:
On Fri, 21 Apr 2023, John Dom wrote:
N1 had too many relatively tiny engines bundled imo and maybe so has Musk's
Starship. Detonation altitude anybody?
Consider a 747 upgrade with 20 engines, go figure :-(.
How about a Falcon Heavy with 27? Five flights so far, if I've kept count
correctly, and all successful.
There's nothing particularly wrong with using big engine clusters, if they're
reliable engines. It looks like SpaceX hasn't got all the bugs out of the
Raptors yet, and one might suspect that they haven't done enough testing of
their big clusters.
That last was the N1's problem: the full first stage had *no* ground tests
-- none, zero -- because Korolev had wanted to avoid the costs and
bureaucratic complications of building a big new test stand for it. (The
Soviet lunar program was *not* a mirror-image of Apollo, and never had
Apollo's blank-check budget or national-crisis priority.) Unless I've missed
something, SpaceX has done only one or two full first-stage firings, which is
better than none but hardly a systematic test effort.
What about designing/building a bigger "F6"= 6*F1 engine ?
A number of the 1960s proposals for "post-Saturn" launchers used the
hypothetical "F-5" engine, equal to about five F-1s. No serious work was
ever done on it, though, and combustion stability might have been a major
problem (like the F-1, but worse).
Henry