▁t anks ▁for ▁the ▁Mil es ▁Master ▁tra iner . ▁ ▁The ▁Germ ans ▁were ▁using ▁layers ▁of ▁rub ber ▁laid ▁over ▁le ather ▁hide ▁with ▁a ▁treated ▁fib re ▁inner ▁surface ▁for ▁the ▁self - se aling ▁t anks ▁on ▁their ▁J unk ers ▁Ju ▁ 8 8 ▁bom bers ▁early ▁in ▁the ▁war . ▁ ▁In ▁the ▁US , ▁Ernst ▁E ger ▁of ▁United ▁States ▁Rub ber ▁Company ▁( l ater ▁Un iro yal ) ▁pat ented ▁a ▁self - se aling ▁fuel ▁tank ▁design ▁in ▁ 1 9 4 1 ; ▁one ▁of ▁many ▁companies ▁involved ▁in ▁developing ▁this ▁technology ▁during ▁the ▁war . ▁El mo ▁E ▁Hans on , ▁lead ▁chem ist ▁for ▁Fir estone ▁T ire ▁and ▁Rub ber ▁Company ▁file d ▁a ▁pat ent ▁for ▁self ▁se aling ▁t anks ▁on ▁January ▁ 2 1 , ▁ 1 9 4 1 , ▁Pat ent ▁number ▁ 2 , 4 0 4 , 7 6 6 . ▁ ▁Go ody ear ▁chem ist ▁James ▁M err ill ▁file d ▁a ▁pat ent ▁in ▁ 1 9 4 1 ▁( pub lished ▁in ▁ 1 9 4 7 ) ▁for ▁ref ining ▁and ▁successfully ▁testing ▁his ▁method ▁for ▁manufact uring ▁self - se aling ▁t anks ▁using ▁a ▁two - layer ▁system ▁of ▁rub ber ▁comp ounds ▁enc ased ▁in ▁a ▁metal ▁outer ▁shell ▁or ▁the ▁wing ▁l ining ▁of ▁the ▁aircraft . ▁In ▁ 1 9 4 2 , ▁he ▁received ▁a ▁War ▁Production ▁Board ▁c itation ▁from