Each plane will be a bit different, the 8 minutes is about right for the first few flights but I like to land then see how much fuel I used then set the timer. I fly with one fellow that has the OS .55 in a Pulse ARF, not sure of the tank size, it's the stock tank that came with the ARF, he is getting a half hour or three 10 minute flights before he has to tank up again. I have never seen a combo that gets that kind of mileage. I figure my own planes at about one minute per ounce of fuel so I buy my tanks with that in mind.