Welcom back. All models seem destine to crash, at least we can walk away from the crashes. Do check you connections, a lot of glitches are really bad connections.

I would think a 11 X 6 would be the standard for that engine, so 11 X 5 or 11 X 7 would work. Go to www.masterairscrew.com, they have an excellent technical page on props sizes and prop speeds, etc. Good reading on how to do it.

Good luck with the JR.

Cheers,

Chip