Don,

I agree with you on just using the same per cent for all of them. I think it would be more fun. The .10 size is small enough to keep together in the car, but big enough that retracts are easily available (for those of us who like them) without a significant weight penalty. 40" is about right.

FWIW, those Speed 400's are only 100W motors - .049 tops. Best prop is 4.75x4.75, but they'll take up to about 6x3. The .10-.15 equivalent is the 2000 kv E-Flite inrunner I mentioned earlier, which will like a 6x3 to 7x6.

I can't wait to see them available.

Andy