Sylvia Else wrote:
It's all about the overall cost of putting payload into orbit. A TSTO
would presumably give a better payload ratio, but with extra complexity
(equals dollars) both in the vehicles themselves, and in handling the
vehicles when they're in use. So the net cost per kg in orbit may be
higher for a TSTO than for an SSTO despite the higher payload ratio.
An airliner style operation using a single vehicle per mission is very
attractive if it's achievable. After the vehicle lands, you just refuel
it, put in the next mission's payload and you're ready to launch again.
And I posit we must approach that SSTO RLV launch scenario
incrementally. The 100/10/1 puts the masses involved in perspective.
However, one can argue that the expendable SSTO approach puts almost an
order of magnitude more mass into orbit, which is what I am suggesting.
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