1. 3 blade props will generally require less energy from the engine to turn it do to a smaller thinner blade, thus less fuel burn. Now the down side is that a 3 blade prop doesn't hold it's rpm very well in aerobatic manuevers, thus not allowing the airplane to retain energy through the manuever.
Problem with your theory; you forgot that it has an extra blade, so thinner or not, the three bladed will be heavier, so will require more energy to turn. (The 3 blades should also carry about the same amount of "flywheel" effect as two slightly larger blades, so I have to dispute that claim too.
2. A 3 blade prop is generally designed to run at a constant rpm for cruise flight. Do to aerodynamic energy, everytime you make a turn, the lighter weight prop will either bog down or speed up slightly. For most RC flight this is not that important, except for aerobatics.
"generally designed to run at constant speed and constant rpm for cruise flight." ?? Didn't know that RC prop manufacturers designed props specifically for anything other than plain flying.
"Aerodynamic energy" ??
3. 3 Blade props can generally be made to make an airplane run a little faster do to slightly less drag on the prop and slightly lighter weight.
Absolutely NOT true. It's been well proven that a single blade prop is more efficient (less drag) than a two bladed, so how could a three bladed prop have less drag than a two bladed? Again, three blades are heavier than two.
4. A 2 blade prop is generally thicker in blade size, longer in blade length, and heavier for the same engine size requirements. Therefore, if you plan on doing an aerobatics, a 2 blade prop will carry a more constant rpm giving you airplane more torque through manuvers. This extra torque generally pulls an airplane through a manuver with less energy loss.
Again I disagree about weight. You MIGHT get a bit more flywheel effect, but I'm not convinced.
I think you'll find that the only reason a two bladed prop is better for aerobatics is because a two bladed prop is just more efficient than a 3 bladed prop.
5. 2 blade props require more energy from the engine to maintain thus a higher fuel burn rate than a 3 Blade.
It might take a miniscule amount more energy to get a two bladed prop up to speed, but you just said that a two bladed prop holds more energy, therefore it will take LESS energy to keep it turning. So using your previous argument, it should burn less fuel.
The bottom line? A 3 bladed prop is less efficient due to the blades being closer together and "cavitating" in the disturbed airflow caused by the preceding blade. The ONLY reason to use a 3 bladed prop in RC is to gain ground clearance.
Dennis-