I'm sticking a ryobi 31 in a 71" sukhoi. What would be your opinions on what would be the best prop for sport flying and mild 3d. I dont need it to be a speed demon because its already hard enough to get slowed down for landing on our runway,so I generally dont get high pitch props,but I do want it to have good thrust. What do you guys suggest?

An 18 x 6 is commonly used, and works well. If your Ryobi is modified, it might turn the 18 x 6 too fast. (7500 rpms max static is what is recommended for the Ryobi.) In that case, you could go to a 20 x 6 if you have the clearance for one. If not, you will have to use an 18 x 8, but an 8 pitch won't slow the plane down like you want...

AV8TOR

Do what av8tor suggests or you might find a 19x6 but i doubt it.zoar and a few others might have it.Or take a 20x6 and cu it down to a 19x6.Ive cut down some props and rebalanced with no problems.Shape your tip like an APC or Power Point.