n3cal, the 11x7 would be OK for break-in and flight, I'd run an APC 12.25x3.75 or 13x4W after break-in... you almost always want less pitch and more Dia for funfly type planes. have you ever broke in a ringed engine before? if not please go over to the engine forum and read up on break-in for RINGED engines, and carefully read your manual. if you break in/run your 50SX like an ABC engine it won't last more than a few flights


John