Thanks, Matt. I think you are right. My G/B is 4.4:1 and I think I was overproped originally. The 13X6.5 seemed to work better and I'm going to try a 12X8 next. I should be careful only on takeoff and not use full throttle. If this doesn't work, then I'm going to get a 3s3P LiPo pack made from 1500 mAH cells.