Comment by pfdietz
1 day ago
Why make an SSTO when you can make a TSTO? First stage recovery is a solved problem and will always greatly relax the engineering problems over making a SSTO.
1 day ago
Why make an SSTO when you can make a TSTO? First stage recovery is a solved problem and will always greatly relax the engineering problems over making a SSTO.
Because of course SSTO has benefits over TSTO, simplicity of operation being one example.
Against the cost of a lower payload fraction. Say you get 4% with TSTO, 2% with SSTO. And if you run into trouble with the design, the SSTO payload moves towards 0%. Your operational savings need to compensate for a doubling of cost per unit mass payload, possibly much more.
And even though full reusability is much easier with two stages, and has not been achieved yet.
The argument for SSTOs was that staging was too scary. But experience since then shows this argument was bogus. Staging can be made highly reliable.
Even a small amount of delta V provided by a first stage makes the job of the "almost SSTO" second stage much easier. And a low delta V first stage can be rugged, with high high safety factors, and is easy to recover at the launch site.
Put another way: if you have an SSTO, its payload increases dramatically if you stack it on a very low performance recoverable first stage.
I don't see any way SSTOs are going to be preferable to TSTOs, especially if the SSTO has to use hydrogen to get off the ground.
Everybody may have their own criteria of preferences, so the same solution with fail for one and succeed for another.
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