[AR] engine life (was Re: Nozzles for Amateur Solids)
- From: Henry Spencer <hspencer@xxxxxxxxxxxxx>
- To: Arocket List <arocket@xxxxxxxxxxxxx>
- Date: Thu, 8 Mar 2018 09:47:20 -0500 (EST)
Robert Clark wrote:
But suppose we had a ceramic that had a melting point even higher than
the combustion temperatures? Then regenerative cooling would not be
needed and then like jet engines, rocket engines could operate for
thousands of hours, giving rockets reusability comparable to jet aircraft.
Modern jet engines use regenerative cooling *extensively*; in particular,
their turbine inlet temperatures routinely exceed the melting point (never
mind the maximum service temperature) of the turbine-blade materials. So
the idea that avoiding regenerative cooling is the magic that will confer
long operating life seems questionable.
By the way, conservatively-built rocket engines like the RL10A and the
XCOR engines already have reusability comparable to many jet engines
(allowing for the fact that one mission is hours of run time for a jet and
minutes for a rocket). The short useful lives of most large rocket
engines have more to do with their design philosophy (performance uber
alles!) than with anything inherent in rockets; jet engines designed the
same way -- e.g. for cruise missiles -- similarly have short lives and
poor reliability.
Henry
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