Go to MotoCalc.com and download there 30 day deal. I just got back in this hobby and this program can help answer a lot of your motor-plane set up ?s. What I have learned is outrunners are the newest motor design and have more power then inrunners so they don't need high KVs (volts-RPM) like inrunners do. If I undrstand it correctly the lower the KVs the longer the flight times but may have a little less power then the same motor with a little higher KV rating(890-910) (flight time vs power and amp draw). Outrunners are good motors but I don't think there good for all set ups according to motocalc.