Craig,

Short answer: The prop is probably the highest-drag item on your airplane if it's turning and in flat pitch (max RPM). You should test the descent rate/glide range for yourself... Pull the engine to idle, stabilize at best glide speed and look at your descent rate. Then pull the prop control all the way out. You'll be surprised if you've not done this before. It's an invaluable lesson.

Bob

> how much drag off the propeller disk can be modulated by using the
> prop rpm control ?

A lot as noted by Scott.

> but then again . . . if the engine is ceased . . . the spring in the
> prop hub makes the blades go flat pitch . . . maximum drag !

As long as the engine is turning, the oil pump is typically making normal oil pressure, so most engine failures give you the option of pulling the prop back to course pitch (greatly reducing drag).

If oil pressure is lost, you are correct, the prop will go to max rpm, but insufficient oil pressure may subsequently cause the engine to seize, which is fairly low drag:(

Craig



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