Production. Airplane manufacture, general. This stretching machine in the hydraulic press department of North American Aviation, Incorporated at Inglewood, California, forms sheet metal parts by stretching metal over a die. The sheet is stretched almost to its elastic limit so it will retain its form. This plant produces the battle-tested B-25 ("Billy Mitchell") bomber, used in General Doolittle's raid on Tokyo, and the P-51 ("Mustang") fighter plane, which was first brought into prominence by the British raid on Dieppe