why dont glow engines for planes have a centrifical clutch? wouldnt it be nice to have the motor idle without the prop spinning!

Just unnecessary weight. Idle slowly enough, you don't need the extra mechanism.

I agree. Also just one more thing to go wrong. Full scale airplanes don;t have any sort of clutch either; at least none of the ones I've had experience with.

Cooling!

I vote for the weigh issue. Plus it wouldn't be scale.

And I also agree that the one on my Husqvarna gets pretty hot, but we're sawing air not wood.

The short answer is you don't need it. The plane will sit still with the engine idling and the prop spinning. Cars use a clutch because they can't sit still with the engine running without one.

Besides all the above, you would need something else than the propeller to start the engine with.

The bottom line is our engines cannot run without a propellor. The propellor provides the flywheel effect required.

If we disengaged the prop then a heavy flywheel would be required for the engine to run properly.

John

John, you are so dadgum technical.....

Hmm oh man did I leave my Geritol lying around here somewhere