Wittman tailwind

"Peter Dohm" wrote in message
...
It seems that I did not think the implications all the way through before
I
pressed the "send" button.

Running the C85 at 3200 RPM should result in around 125% power, so that a
cruise setting of 85% power would be around 65% of the "available" power.
Therefore, a clean little airplane like the Tailwind would actually have
a greater (rather than less) surplus thrust for take off and initial
climb.

The note of caution would be that full throttle would be take off only,
and not maximum continuous; so the pilot would have to understand the
limitations and treat it like a high performance engine rather than like
a trainer engine.

Peter


Most of the faster homebuilts with fixed pitch props don't generate maximum
power at takeoff simply because the props have so much pitch the engine
can't spin 'em to peak rpm.

The EZ crowd discovered this years ago. If I wanted to spend a couple of
hours reading old issues of "Canard Pusher" or whatever the appropriate
newsletter was, I could find a cite by the Rutan Aircraft Factory where they
recommend a slightly underpitched prop which would allow more than the
*certified* max RPM. This was primarily done to allow the engine to
generate more RPM and power at takeoff.

In my 0-320 RV-6, the engine only turns 2100 rpm on takeoff. As the
airplane accelerates, the rpm's increase as does my climb rate. The airplane
climbs better at 125 knots than 100, simply because the engine is generating
quite a few more horsepower.

KB