Pat Flannery wrote:

Henry Spencer wrote:
Addendum: And there have been several rediscoveries of the fact that if
you put six or seven SSMEs underneath an ET, even with generous
allowances
for things like thrust structure, it makes orbit with about the same
payload as the shuttle.

What about RS-68s?

You would be hard pressed to get an RS-68 to go single stage.

The T/W ratio is twice the SSME, and the Isp is lower.

Plus it's a ... ahem ... hard starter.

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