Just finished up a 25 minute flight on the butterfly this morning. All I need now is a lawn chair and the help of some thermals and I will be able to stay up all day. This was the first flight on a new battery pack (2600 mAh NiMH). As the pack goes through a few cycles I think I can get a least 30 minute flights. My flights are at less than half throttle and with this new battery pack I have a lot more power than my old LiPo setup. My Butterfly is very heavy it weighs in at 70 oz and is a beast when I try to hand launch it, but with the new battery I have more than enough power to get this bird airborne from the ground. The reason my plane is so heavy is because the brushless motor I have up front is so light (2.2 oz) and to get the plane to balance I was putting 18 oz of weight up front. So I dumped the LiPo battery (7.4V 3000mAh) and 10 oz of weight and had an 18 oz 8 cell NiMH made to use as my power source. That is where some of my overweight issue comes from. I also put on some 4" tires which are 4.3 oz more than my original wheel choice. All in all I am happy with my results, and look forward to many more relaxed flights.