[AR] Re: SpaceX Single Stage to Orbit
- From: Henry Spencer <hspencer@xxxxxxxxxxxxx>
- To: Arocket List <arocket@xxxxxxxxxxxxx>
- Date: Wed, 22 May 2019 22:33:56 -0400 (EDT)
On Wed, 22 May 2019, anthony@xxxxxxxxxxx wrote:
Wasn’t the former Titan capable of SSTO, assuming a practical “zero”
payload?
The Titan II first stage could even carry a token payload into orbit,
maybe 1t or so if you did things just right, *but* it would need new
engines to do SSTO at all: the stock engines have *too much* thrust to
fly an efficient trajectory, and their design doesn't lend itself to
substantial throttling. The new engines wouldn't have to be lighter, or
have higher Isp, but they'd need lower thrust and preferably throttling
capability as well. (In practice, while you were doing new ones, you'd
surely give them longer nozzles for a modest Isp gain -- even the Titan II
engines got an ablative nozzle extension for the Titan IIIB -- and they'd
probably end up lighter too...)
Max Hunter thought you could do the same with a classical Atlas (yes,
taking the booster-engine ring along to orbit), probably even with a Delta
core, if you tried hard.
And as Bill has already noted, the Falcon 9 first stage has the right
numbers to do it, probably without even needing engine mods since it's got
enough engines to shut some of them down for thrust reduction.
Henry
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