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Old May 12th 17, 05:33 AM posted to sci.space.policy
Fred J. McCall[_3_]
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Default RD-180 relplacement

JF Mezei wrote:

On 2017-05-11 21:54, Fred J. McCall wrote:

They're not keeping the same materials. That's how they're making it
cheaper.


For critical parts like the turbo pump, is that wise? It means
essenstially building a new engine that will need to be tested and
validated.


They're going to have to do that anyway, since it will be a new
production line with modifications to the engine.


What materials can they substitute with which one when you consider the
very very cold and "a little hot" temperatures the engine needs to handle?

Would it be correct that for the 1970s, building the turbo pump was the
most expensive portion? Does it make sense to change materials in this
rather critical piece?


Pay me $1.16 billion and I'll work it all up for you. By the time
they get through all the modifications to manufacturing process and
materials (which won't be done for the first six engines under the
original contract) they think they can cut the price of the engine by
about a third (so just under $40 million per engine in current
dollars)



30 minutes is a preposterously long firing time for an expendable
engine.


8 minute flight and probabnly a few test firings before. Wouldn't that
bring it to 20-30 minute range?


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.


--
"The reasonable man adapts himself to the world; the unreasonable
man persists in trying to adapt the world to himself. Therefore,
all progress depends on the unreasonable man."
--George Bernard Shaw