Please try to read at least the recent forum topics before posting questions like this. You'll find the answer there.
(Hint: There is a bug in a gaming engine supplied by one of Dogfight's partners, and until that partner fixes it, you should avoid pressing on two spots of the touchscreen at once. So don't manage throttle while shooting. And use the motion controller instead of the joystick if possible.)
(Ok, that was a lot more than a hint!)
Manfred