Anybody run a game test to see if feathering the prop increases gliding range after an engine failure on single engine fighters?
Single engine planes do not feather the prop, AFAIK. In twins this is much more critical because the off engine creates a lot of drag that yaws the plane towards the dead engine. This is very dangerous when flying at a slow speed (rudder ineffective) and applying full power on the good engine - like when losing an engine immediately after take-off.
Feathering the windmilling prop reduces the total drag of course. Twins are supposed to keep on flying on one engine, sometimes to quite long distances. Single engine planes were not supposed to fly 400 miles back home with no engine. If you were flying a single engine plane and lost the engine, the extra drag from the milling prop is the least of your worries...
In the twins, the yaw is the bigger issue than the total drag, and this is irrelevant in single engine planes.