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Old May 12th 17, 12:15 PM posted to sci.space.policy
Jeff Findley[_6_]
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Posts: 2,307
Default RD-180 relplacement

In article ,
says...
Why would you test fire an expendable engine before you fly it? You'll
either test fire it and tear it down or you won't test fire it and
you'll fly it. They're doing test firings now because of nozzle
changes and a new engine controller and will later fly those engines,
but those engines are RS-25D reusable engines.


This is the "performance uber alles" mindset Henry Spencer used to
always fight against. That will never lower costs because it leads to
expendable, razor thin margin, designs that are limited in reliability.
They're limited in reliability due to the "infant mortality" problem
that every single launch is both a "test flight" and the "operational
flight". Doing double duty like that means your operational flights are
always somewhat risky in that any defect in manufacturing could doom the
flight.

The "performance uber alles" mindset is great for designing and building
ICBMs, but it's terrible if your goal is low cost, reliable, access to
space.

The real problem is that SLS is expenable and always will be.
Expendable is a stupid thing for a launch vehicle to be in the 2020s.

Jeff
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