ORIGINAL: ghee-grose
You say your flight timer is set for 15 minutes.....are you running the stock tank? What size engine is on it? With my .46 I get about 23-25 minutes on a tank. (trust me, I had to fly it dry the other day because my throttle stuck open at about 3/4 throttle)
I'm running a OS 50SX and I'm running it pretty rich. I know that I can probably get 20+ out of the tank, but I very seldom fly a plane longer than 15 because I find my concentration starts waning, and that's asking for a crash!