I just fitted new bearings to my HP VT21 four-stroke.

This engine is in a parasol-winged bird that putters around quite nicely on the limited power that the VT21 makes.

Just for fun I thought I'd try a whole heap of different props while giving the new bearings a chance to bed in.

I tried a whole range of props from 8x4 through to 11.5x7 -- and the damned thing turned them all with ease.

Okay, it did start to overheat a little with the 11.5x7 but it handled an 11x4 without any problems at all.

What's more, it was damned hard to tell the difference between any of the props when flying the plane (except that the ones that were bigger than 10 inches required a hand-launch because they wouldn't clear the ground.)

I find it quite incredible that such a small glow engine could turn a 11x4, 10x6, 9x7 and other big props just as well as the little 8x4 and 8x6 ones that I also tried.