North American Aviation P-51 Mustang

North American Aviation P-51D Mustang "Old Crow" - 414450

Unlike most of the famous aircraft of WWII, the P-51 Mustang had not even been thought of when the war started. It was developed quickly to meet a British order, and was at first of only passing interest to the US Army. Soon, however, its outstanding qualities brought it to the very forefront, and in the final 18 months of war it was the leading US fighter in the European theatre. Not least of its many attributes was its ability to escort bombers over long distances. Goering said, "When i saw the Mustangs over Berlin, i knew the war was lost".

Discussions between the British Air Purchasing Commission and North American Aviation began in late 1940. The British wanted NAA to build the Curtiss Hawk 87 (Kittyhawk) under licence, NAA said they could design a much better fighter and, after British counter-arguments, a contract was signed in April 1940 for a prototype NA.73. British hesitation was due to the fact NAA had never built a fighter (except for the P-64), but the NA.73X prototype was a masterpiece. Rolled out in just 117 days, and flown on 26th October 1940, it combined every modern aerodynamic, structural and systems advance, chief results of which were exceptional internal fuel capacity and low drag.

In April 1942 the Mustang I entered service with No.2 Squadron, RAF Army Co-operation Command, in the low-level reconnaissance role. It was obviously far better than any previous American fighter, but the low rated height of its engine resulted in poor performance above medium altitudes. Orders mounted, a September 1940 batch having specified four cannon armament. USSAF trials soon resulted in American orders, starting with the cannon-armed P-51 and following with 500 A-36A fighter bombers. Altogether 1579 Allison-engined models were built, called Mk I, IA and II by the RAF, the F-6A being a photo version.

By 1942 several observers had suggested overcoming the high-altitude limitation by fitting a 60-series Merlin engine, and the first 'Mustang X' flew on 13th October 1942. However, only a few weeks later NAA did a totally different conversion, and this was ordered in massive numbers (2200) before the first XP-51B flew in December 1942. Largely redesigned, the P-51B had an additional inter cooler radiator and augmented coolant and oil radiators, and a large area four blade propeller to absorb the power at high altitude, where it’s all round performance put the new variant in the very front rank.

By summer 1943 extremely large scale production of the P-51B was in hand at Inglewood and of the identical C at Dallas, and combat wings of the 8th Air Force in England received aircraft on 1st December 1943. The key to long-range escort, was a task expected to be met by a special design such as the unsuccessful XP-75 Eagle, which had extra fuel capacity. More fuel in the fuselage, at the expense of tricky stability until the extra tank had been emptied, was augmented by drop tanks of 75 and finally 108 US gallons (284 and 409 litre's) capacity under each wing, with which flights could be made to a target 850 miles away, covering every point in Western Europe. Once the tanks had been emptied and dropped the P-51 could out-perform any regular Bf 109 of Fw 190.

One of the features unchanged in the P-51B was the canopy, but it was soon realised the British Malcolm sliding hood was better and this was fitted as a field modification to RAF Mustang III's and to many USAAF P-51Bs and Cs. Later in 1944, NAA introduced the P-51D with a sliding 'bubble' canopy, cut-down rear fuselage, increased firepower and, later bigger bomb-load plus rocket attachments. By the end of 1944 an extended dorsal fin was standard. P-51s served with many Allied air forces. As well as the P-51K with a propeller of different make, NAA built prototypes of the P-51F and G lightweight Mustangs, from which emerged the final production model, the P-51H, a few of which saw action against Japan. The P-82 Twin Mustang, like the P-51J, was too late for the war.

The RAF was the first air force to operate the P-51, which was originally designed to meet RAF requirements. The first Mustang Mk I's (P-51A's) entered service in 1941, wearing the standard RAF fighter markings. Due to poor high-altitude performance, the Mustangs were soon transferred to Army co-operation and fighter reconnaissance duties. On 27th July 1942, 16 RAF Mustangs undertook their first long-range reconnaissance mission over Germany. During Operation Jubilee, the Dieppe Raid (19th August 1942), four British and Canadian Mustang squadrons, including No.26 Squadron saw action. By 1943/1944, British Mustangs were used extensively to seek out V-1 flying bomb sites. The final RAF Mustang Mk I and Mustang Mk II aircraft were struck off charge in 1945. The RAF operated several Mustang Mk III (P-51B/C) machines, the first units converting to the type in late 1943 and 1944. Mustang Mk III units were operational until the end of World War II, though many units had already converted to the Mustang Mk IV (P-51D/K). As the Mustang was a Lend-Lease type, all aircraft still on RAF charge at the end of the war were either returned to the USAAF "on paper" or retained by the RAF for scrapping. The final Mustangs were retired from RAF use in 1947.

After the war, the P-51 remained in US service with the Strategic Air Command until 1949, and with the Air National Guard and Reserves into the 1950s. It became one of the first fighters to see combat in the Korean War. In addition, over 50 air forces around the world acquired and used the Mustang for many more years, some as recently as the early 1980s. When the US Air Force realigned their aircraft designations in the 1950s, the Mustang became the F-51.