Lockheed SR-71 Blackbird
SR-71 Blackbird used a special fuel called JP-7. Before the flight, the fuel tanks used to leak. This is because at ground altitude the tolerances (distance between parts of the fuel tank) were larger than at the plane's cruising altitude. Once in the air, because of the speed and air resistance, the parts became very hot. Because of this heat, the distance between the parts shrank stopping the loss of fuel.