Ok, here is a new question :-)

What will be the consequences if I use a 10x7 prop like the hobby shop owner suggested? I hear ya about the 11x4 and 11-5 but what about 10x7?!?!?

Will I be able to take off and fly properly with a 10x7?? I bought 2 already and would like to use them if it doesn't mean hurting my engine or crashing my plane because I have to wrong prop!

Thanks!