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Posted for "George Braly" <gwbraly@gami.com>:
Rob,
Nice analysis.
But there is a lot more to it. I’m in the middle of teaching an APS weekend
class and have the FAA coming by for a visit, so I am not going to try to
re-run the numbers.
But you might try to go back and re-do the numbers and consider some of the
following.
1) The centrifugal compressor efficiency will not likely be anywhere
near 80%. Many are as poor as 55 to 65% unless you happen to be at just the
right mass flow and the right RPM.
2) The belt drive has a significant penalty in lost horsepower.
3) The gear drive in the compressor has another significant drop in
efficiency.
4) To get the air temperature back down to tolerable (detonation
margins) ranges requires an intercooler
5) The losses across the intercooler and through the induction plumbing
to accommodate the twists and turns to make the intercooler fit in the system
extract a substantial further penalty requiring still more boost - - but at
the penalty of all of the efficiencies noted in 1-3, above.
And consider the engine I was referring to was a 400 hp engine, not a 300 hp.
Regards, George
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