I have been flying a Pico cub as a trainer and am using a 9x5 prop on a 5.1 geared 400. I use a 9.6v 600mh and like the performance but only get about 8 min out of it. I also use a 7.2v/600mah and it is more flight time. Will bringing down the prop size and pitch to say about a 8.4 give me more flight time?