Am about to commence building of a Pusher Canard model (refer my post in the Scratch Building Forum). The power plant is pusher configuration & I have at least 2 different engines that can be made to run in reverse by rotating the front section thru 90 degrees. Alternatively, I can use the same engines in normal mode & use pusher props.

At this point, I'm favouring running the engine in reverse as I can use standard props simply by installing them on backwards. This will give me far greater variety in diameter & pitch sizes comapred to the rather rare pusher props.

Anyway, enough of the intro. My question is: do engines running in reverse have a tendancy to loosen the prop nut? I base this thought on the way the crankshaft threads are cut on our engines. With an engine running in the normal direction & apart from backfiring, the threads are such that the prop nut should remain tightened or even become tighter. But when running in the opposite direction & allowing for the RPM's varying from low to high, does the prop nut start to "undo"?

In theory yes but in practice no? I simply don't know, hence the question.