Designed by the Bell Aircraft Corporation, the unusual, mid-engined P-39 Airacobra holds the record for the highest number of enemy aircraft victories attributed to any U.S.-built fighter in history. The lack of an efficient turbo-supercharger for its engine meant that the airplane did not perform well at high altitude. However, in the hands of Soviet pilots at low altitude over the Eastern Front, the P-39 made a massive contribution to the war effort.