Curtiss Wright experimented with air cooled rotary engines specifically
targeted for aviation use. The RC-90 shared the same geometry with the RC-60,
except the housings were 50% wider (much like the 13B is 10mm wider than the
12A). The RC-90 displaced 90 cu inches per rotor. I believe two and four
rotor engines were built. Norbye's book may have some photos. I don't recall
the rating.

The air cooled rotor housings had a multitude of deep, thin, closely-spaced
fins. By my recollection, I'd say they were perhaps three inches deep by
.090" thick with .090" spacing. There was a very high speed blower used to
force cooling air through the fins. I am sure that passive cooling would be
inadequate.

I don't know why in particular C-W gave up on the concept. It is true that
the heat flux in a rotary (locally in the spark plug region) is far higher
than in a piston engine, and that cooling is one of the bigger challenges
even with liquid cooling. I'd have to assume that C-W concluded that the
liquid cooled engine was a better trade off all around, with more growth
potential.

Jon Lauter
Rotary Power Marine Corporation

 
The AirCraft Rotary Engine NewsLetter.              Powered by Linux.

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