If any of you guys want a real-world, feel it in the seat of your pants demonstration, go to your local airport, and have them take you up in a light twin aircraft, and have them pull one engine back to idle. The propeller will still be turning at the normal rpm, but the engine will be producing very little power (the windmilling prop is actually feeding more hp into the engine than the engine is feeding into the prop. Next, have the instructor shut the engine down (pull the mixture control to idle-cutoff. Now the engine will still be windmilling, even though the engine is now producing zero power... you won't notice much, if any at all of a change in the drag from the windmilling propeller. Now have the instructor feather the propeller. You'll notice that the airplane will literally "leap" forward as the prop feathers because of the reduction in the drag from the windmilling propeller. It truly is an eye-opener! If you don't believe before, you certainly will after. Ask any multi-engine rated pilot...

There is a power setting used in multi-engine training for setting the "failed" engine so that it simulates having the propeller feathered, called "zero thrust"... it's the power setting where the power being fed from the engine into the propeller is approximately equal to the power that the windmilling propeller is feeding back into the engine.

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