Mounted a new 2 oz. clunk tank because i did not like the air bubbles from my hard tank and did not get good runs with it . Was doing the in hand testing thing like holding the plane and doing inverted and side to side and noticed if i went nose down there would be no fuel to pick up in the end of the tank. Am i missing something here or is the little time it takes to complete a wing over or some other stunts does the fuel flow just catch up or is there a little engine pause sometimes? Just can't get the correct thought "pattern" going here. Have never really pondered this while flying before. Muffler pressure on an OS 15. Thanks for any thoughts on this, Ray