ORIGINAL: cmircman
I hope this plane is a multi engine aircraft. At 30 to 35 pounds i highly doubt this plane would fly with that engine(i could be wrong). If you need more static thrust go with a larger diameter prop with lower pitch. If you need higher speed go smaller diameter with higher pitch. Props that have more than 2 blades tend to produce less static thrust. Usually if you take a prop that the pitch is half of the diameter, will work more efficient and give you best overal performance than high or low pitch props. It all really depends on several factors like weight, drag, wingloading and much more. The only true way to find the right prop is to grab one and try it.
Lol, I guess my memory from class was a little wrong. That's probably why I'm having troubles now. I guess I should go back and check my notes.
EDIT: I was correct. More blades will give you more static thrust; however, the engine will turn at a lower RPM and the propeller is not as efficient.
Btw, the plane did fly at 25 lbs, but we didn't have enough elevator control power to rotate at 30 lbs. That issue is being resolved by someone else. At 30 lbs our take-off distance signficantly increased, which is why I'm trying to get more power out of the engine, since we will ultimately be flying at 35 lbs.