Hay madmorgan:

One thing you will find out here is that if you are given poor direction, many of the other guys will jump all over whom ever. Not a bad thing unless you have thin skin.

Props are not expensive, try a 12X4 and note the difference. Go ahead and buy the gear system, you will chuck it if the plane lives long enough. A correct motor and prop is the best way to go, period. Usually the motor, prop, controller and battery is a decent setup that you can live with. Flying electrics is a acquired skill. I can get 15 minutes of good flight with the same equipment the guys can only get 10. I am not necessarily a better pilot, I have learned to apply just enough throttle to do what I want, anything more is a waste of energy.

You need to quit electrics or learn how to size motors, controllers and batteries. The first tool you need is that watt meeter. Yes, the motor or controller will let you know if you are over propping your setup. How? Its going to burn out and force you to keep trying something that will stay alive with normal use.

There are lots of ways to size a motor for the weight of your airframe. I am lazy and do not want to go through all those calculations and motor charts. I want to know what I have is going to put out the power I need before we go flying. How? Lazy remember? Ok, I have a little test stand where the motor fixture is on free running ball bearing wheels (shower door rollers from Low's) kept in line with runners on each side. A eye at the end of the cart takes a 50 lb fish leader that attaches to a good digital fish scale. If setting up a 8 pound airplane, I am looking for around 16 pounds of thrust out of my choice of systems. I know what that sucker is going to give, or not. Yep, a watt meeter sets between the battery and system so I can see what things are actually drawing. A 500 watt motor that is pulling 600 watts gets a smaller pitch prop and or length until its pulling 450 or so without getting hot. If everything is within specks and things get hot, I will go with a slightly higher system even if things are withing their ratings. Manufacturers frequently over rate their products, motors, controllers, batteries etc.

There a great how-to information on the net, you need to learn whats what or pay a nasty price for not doing it. Going to shut up now!! Enjoy