OK so my running an 11x5 at 13000rpm on the ground is just fine then... right? Some people, both here and at my field, think that's a little fast. It's all I know however. I used a 12x5 and didn't like it (well, liked the climb, didn't like the lower rpm/speed). Should I try a 12x6 for more speed? It would bog the engine down even more though. Sorry if this is dragging on, I feel like I"ve heard different things now and am confused.