RE: DL-50 engine
The scimitar from MA is at least a propeller... it will rev up pretty good, but thrust can be a little disappointing because it is so narrow on the outer 1/3 of the blade. It would definitely be a good "flying break-in" prop, no doubt, unless you have it on a high-drag airframe. I'd use it before the 22 x 10, simply because it will let the engine breathe easier.