The 500 uses 6 oz./min. at WOT. Taking into account that fuel consumption is GENERALLY linear with thrust output, half throttle (6lbs.) would be 3 oz./min. Remember that RPM and thrust are not linnear. Half throttle is probably 130-140k. It all really depends on your flying style. I personally like long flights also. So safely, 70-80 ounces would give a 10 minute safe approx. flight time. Put it wherever it fits!!! Happy landings,