I did as John said and bought three packs and it's about perfect for me. I fly a stunt plane and I'm getting 15 minute flights from my 3 cell 2100mah packs. I start with all of them fully charged and as soon as I land I put the pack on the charger, by the time I land the next flight it is almost fully charged, it is ready to go again by the time I'm done with my third flight. Three packs are fine but I think four would be even better. There would be no down time. I have been getting my motors, ESCs and packs from Hobby King and the packs are about $10.00 a piece. Just finished a new plane and will be buying a few more packs. I'm not a big fan of Hobby King but the packs and a lot of other items are being shipped from there US warehouse so they aren't nailing you on shipping. I fly gas, glow and electric now and enjoy all three. There is usually a small electric in my van with me at all times so if I see a spot that looks like a good place to fly I just pull over and have some fun. I have ticked off a few golfers but what the heck, it gives them an excuse for there poor game at the end of the day. I can't do that with a gas or glow plane.