X-Mozilla-Keys:                                                                                 
Fredmoreno@aol.com wrote:

To David Carter:

Thanks for your kind comments.  I am happy to help out on cooling and cooling
drag.  I am not a rotary engine expert at all, experience limited to piston
engines.  But rotary engines have many, many virtues that make them good for
sport planes.  Among these is small size, light weight, and lots of power
pulses per rev which makes the problems of vibration and torque reversals in
gear boxes and props far smaller, and thus more forgiving of less than
perfect design.  

The Wankel two rotor has the same number of power pulses per revolution
as 
a four cylinder four stroke piston engine.

I agree with earlier comments; with modern materials for
seals, the original problem of seal life should be well under control. 

Seal life was well under control as far back as 1973. Plain rubber
water jacket O-rings gave a problem in those years when the engine
was overheated. I know. I had a 1973 RX2 and the water seals went out.

One
wonders about the combustion event always occurring at the same place without
cooling charge to cool the surface temperature, but this must be manageable
as lots of engines are doing very nicely.  What we need is a rotary engine
with a specific fuel consumption of about 0.4 pounds per hp hour and about
400 horsepower that we can package in a sleek, skinny airplane......  Maybe
someday.

Fred

There is no aircraft piston engine today that can be practically run at
a BSFC of 0.4! Most are running at 0.46 or higher to cool the exhaust
valves.
When I gave that talk yesterday I asked everybody if anyone was running
their aircraft engine lean of peak. I allways ask that question when I 
give a rotary engine talk. One person raised his hand. It is far
too expensive if you screw up while using the manufacturers 50 degrees
lean of peak recommendations. That setting is how the engine
manufacturers get the 0.42 to 0.43 BSFC numbers they mention in
the engine handbooks. At aircraft power levels water cooled
automotive engines are no better. Some like the big block Chevy were
much worse.
 
Paul Lamar
 
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