"Larry Dighera" wrote in message
...

Do you think that drag caused by an idling engine (and propeller) is
increased or decreased when it is producing zero power instead of idle
power?

It's an interesting question.

http://naca.larc.nasa.gov/reports/1934/naca-report-464/

includes comparison of a stopped prop, feathered prop, windmilling prop,
windmilling prop attached to a dead engine, and a prop driven by an idling
engine.

At low speeds, the idling engine produces thrust, while at higher speeds (75
mph in the case of the experiment) it is almost indistinguishable from the
prop driving a dead engine.

Julian Scarfe