ORIGINAL: Lutzifer
8.5 lbs, 775 sq/in wing area, 25 oz/sq.ft. wing loading are the specs listed witht the plane. It isn't really a matter of my plane, just in basic performance, what gives faster speeds? ex. Say a 14x8 spinning 10,000 rpm makes a plane go 50 mph. Then say a 12x10 spins about 10,000 rpm also Which is faster? Kind of weird question I know. It may not have a simple anwser. Is the 12x10 faster because of the greater pitch even though it is the same rpm?
It is more than just that.
How fast the engine will come up to speed also comes into play. Yes you may be able to clock a prop on the ground with a tach but in the air is a different matter all together. Some combos will not be able to hit top speed before the airplane is already too far away and you need to turn.
All that said there is a simple rule that has proven true time after time.
Higher diameter and lower pitch results in slower flying speed but better climbing ability, good for aerobatics.
Smaller diameter and higher pitch is for speed, good for stuff like pylon racing.
Any specific size for what you want to do depends on the specific engine and airplane combo but engine maufacturers recommendations are a good place to start.