fighters and larger aircraft such as the Avro Lancaster heavy bomber. The Henderson Safety Tank Company provided crash-proof self-sealing fuel and oil tanks which were fitted "as standard" to the Miles Master trainer. German aircraft designers used layers of rubber laid over leather hide with a treated fiber inner surface for the self-sealing tanks on the Junkers Ju 88 early in the war. In the United States, Ernst Eger of United States Rubber Company (later Uniroyal) patented a self-sealing fuel tank design in 1941, one of many companies involved in developing this technology during the war. Elmo E. Hanson, lead chemist for Firestone Tire and Rubber Company filed a patent for self sealing tanks on January 21, 1941, Patent 2,404,766. Goodyear chemist James Merrill filed a patent in 1941 (published in 1947) for refining and successfully testing his method for manufacturing self-sealing tanks using a two-layer system of rubber compounds encased in a metal outer shell or the wing lining of the aircraft. In 1942, he received a War Production Board citation and the Goodyear tanks were subsequently placed in service in Goodyear-produced Vought F4U Corsair fighters, as well as other aircraft. By 1942 Fireproof Tanks had developed the first flexible fuel bladders as range extender tanks for the Spitfire Mk IX. These tanks were flexible containers, made of a laminated self-sealing material like vulcanized rubber and with as few seams as possible to minimize leak paths. As early tests showed that impact could over-pressurize a fuel tank, the self-sealing fuel cell is suspended, allowing it to absorb shocks without rupture. U.S. Navy fuel tanks during the war were able to withstand bullets and, on occasion, autocannon shells. Not all fighters were fitted with the relatively new invention. Self-sealing tanks tended to have lower capacity than non-sealed tanks. Nonetheless, aircraft that were fitted with self-sealing tanks managed to withstand much more damage than those with conventional fuel tanks. Combat experience in the Pacific War showed that the self-sealing fuel tank-equipped American aircraft could sustain far more damage than the lightly armored Japanese designs without self-sealing fuel tanks, such as the Mitsubishi A6M Zero. The same principles were applied to give self-sealing fuel lines in aircraft (MIL-PRF-7061C). Modern use Most jet fighters and all U.S. military rotary wing aircraft use some type of self-sealing tanks. Military rotary wing fuel tanks have the additional feature of being crashworthy. High altitudes require the