hi do fly with a timer -never know were on the field you will run out of fuel go dead stick and risk the plane-i purchased a clear syringe from the hobby shop-that is calculated in ozsEX-if you have a 10oz tank and you use 5ozs in 5 minutesyou now draw out the fuel left in the tank with the syring- in this case it would be 5ozs so you know you can fly a total of 10 minutes max on this planes tank of fuel the syringe is very useful if you have a sudden abrupt landing as the clunk in the tank can be jammed foward in the fuel tank-if you draw fuel out with the syringeand get air not fuel- good chance the clunk has been jammed to the front of the tank-and needs to be relocated to the rear of the tank-(by shaking it loose )-the result of the clunk being to the front of the tank are short unexplained engine runs on take off