I build and fly electric powered gliders, trainers and warplanes. I suggest you get a computer program called "electricalc" or "Motocalc" Either of these will give you TONS of information on cell counts, types and sizes. Motor and prop selection. Stall and top speeds and expected flight times. These programs are not super accurate but do show which item ( motor, prop,battery) will change performance and aprox how much. I use electricalc but motocalc is as good. You can download motocalc to try for free. These programs are well worth the $40 they cost.