I've completed a build of an F550 and was curious about the flight time. I'm running on 3S (11.1) volt 5000 maH Turnigy battery weighing 450 gms. With the stock F550 and one battery I flew for 8 minutes. I then added another battery in parallel and a little more weight (about 400 gms for my FPV camera,transmitter, Range Video OSD/GPS, and a 3S 1100 maH battery. All up weight was 2200 gms. My flight time is 13min 15 sec until the VU signals low battery. Batteries checked and voltage was 11.34 VDC.