North American P - 51 Mustang The North American P - 51 Mustang is the result of the initiative of the North American , who designed and built in record time to meet an order from England ( who had prompted the construction , under license from Curtiss , the P - 40 fighter ) , P - 51 was another legendary plane War II . Initially with poor performance at higher elevations due to poor motor Allison , became after receiving the Merlin engine from Rolls - Royce and , with the addition of an extra fuel tank behind the cockpit , filed an unbeatable range , allowing you to escort the heavy bombers in attacks on Germany . History . Soon after the beginning of the war in 1939 The British government established a commission to purchase with the United States , led by Sir . Henry Self . One of the many tasks of self was organizing the production of U . S . aircraft to RAF . At that time , the choices were quite limited : no American planes had ever reached the European aviation standards , and only Curtiss P - 40 Tomahawk had come close , and the Curtiss plant already operating at capacity until the plane had a short supply . At this point , the Dutch president Kindleberger the " North American Aviation " ( NAA ) , approached Self with the vision to sell the new bomber British average of NAA ' s , B - 25 Mitchell . Instead , Self asked if the NAA could produce the Tomahawk on license from Curtiss . ( The NAA has provided its training center at Harvard such planes , but in any case were not used . ) Kindleberger ' s reply was that NAA could produce a better aircraft with the same engine in less time . From this unlikely beginning came into being one of the best fighters in history . The use of large - scale version of the C P - 51 Mustang by U . S . Air Force and British Royal was decisive for the success and continuity of long - range bombers over occupied Europe , Germany and its allies , as well as aircraft with an extra fuel tank could reach flight autonomy that allowed him to escort the going and coming Allied bombers , was superior to the German fighters into combat , except for the Me - 262 Schwalbe that only come later in the conflict and insufficient to cope the Anglo - Americans . Thus their ability to penetrate deep into enemy territory on missions to escort defensive or offensive directed against the German fighters into its territory , largely responsible for both success in undoing the damage the Luftwaffe and industrial power at the service of Germany . Equally crucial was the Pacific war , its use for the same purpose : to attack enemy fighters Mitsubishi in the territory since the second half of 1944 and mainly starting from February 1945 , as a fighter escort for American bombers based on the main airfield Iwojima . Note that the last Japanese counter - attack in this battle was just a night attack against the camp of the P - 51 pilots . Its main flaws , the weakness in the lower compared to anti - aircraft fire and instability flight to maneuver when armed with bombs or rocket attacks has led to land both the Western allies in Europe , and in east , focus on the use of other aircraft more efficient to do so , as the Republic P - 47 Thunderbolt , American - made or Hawker Tempest of British manufacturing .