I am gonna have some ground clearance problems with a 28" prop. I can do it but a 27" would be better. Have you tried any 27" props? I am flying a 26lb h9 sukhoi and right now I am using an air models 26x12 3blade. I am looking for something a little more efficient. Maybe a little more rpm and quicker spool up. The 26x12 3blade is giving me 5950 rpm warm running lawnboy ashless 32:1 for break in. Thanks.