This actually favors piston engines. The cooling load is spread around and
the chamber gets to rest between combustion events. Whether or not the
mechanical complexity and additional weight/volume is worth this advantage
is something we all have obviously made a decision on.


Monty

With very few exceptions, rotary engines have been difficult to cool in aircraft use.

 

If the premise is 7,000 RPM, then somebody is at or very close to wide open throttle. Some have observed that there is adequate power with the 2.8 gearbox to stall the prop on takeoff and over-speed the engine. Power must then be reduced until enough speed is attained to un stall the prop and carry on.

 

 If the prop is limiting the RPM at full throttle, that situation is at 100% of available power is it not? And maintained in that condition for some amount of time so as to stabilize the temps and so on can be nothing else but a 100% duty cycle. The plane being too fat for the power available has nothing to do with the 7,000 RPM of the premise.

 

If you choose to throttle back and run lean of peak, that situation becomes the 100% duty cycle. That becomes the normal maximum use of the equipment, not some special case.

 

In the Bonanza, throttle is reduced to stay below the red arc, or maximum structural cruise.

Running well lean of peak EGT and at reduced throttle, and still sitting at the start of the red arc. So, since there is a risk of airframe failure, the 100% duty cycle for this aircraft is 90% throttle and 50 degrees lean of peak at 6,500 feet.

 

Throttling back is you reducing power. Leaning to some reduced power setting is the same as reducing throttle. Best power is just rich of peak EGT.

 

Reducing power to cure a cooling problem does not count. Leaning to save fuel (and go slower) does not count. Closing throttle to descend to landing does not count. Closing the throttle on the race car to brake from 140 MPH does not count.

 

100% of the power available is 100%.

 

It is almost never the rated or demonstrated power of the engine in some controlled situation, like a dyno room on the ground.

 

Lynn E. Hanover