There are a few aircraft in the world that are used for a long period of time. Sometimes it is fame, sometimes it is just because it was built to last. Rarely, is it because it did the job well and that many pilots enjoyed using it. Sometimes, however, an aircraft meets all of these criteria, and then it may qualify as a legend. North American Aviation (NAA) produced a legend for a British contract in 1940, design number NA-73. The British gave it the name 'Mustang'.
The contract was the result of a boast by NAA that it could build a fighter better than the Curtiss P40 (Kittyhawk in RAF1 service). The contract gave them 120 days to finalise the design, so NAA designed and built it in 117 days. Unfortunately, they had to wait another six weeks until Allison delivered the engine.
The design utilised wind tunnel data for the Curtiss XP46, which resulted in a single-seat, low-wing monoplane with a single, in-line2 engine. It had a laminar-flow wing that combined high lift with low drag and a low-drag fuselage. The original design had a conventional cockpit hood faired into the rear fuselage. The results of flight testing showed its potential for high speed.
As a condition of the export licence - the USA was still neutral - NAA supplied two examples for military testing, designated XP513. There was only lukewarm interest, as fighter funds had been used up.
In RAF service the Mustang I was shown to have poor performance over 12,000 feet and so was issued to army co-operation units for close support of ground forces and ground attack units. The first combat mission was flown in May 1942. The original armament was four .303" and two .5" machine guns in the wings and a further two .5" guns in the lower nose. By this time, the US Army Air Force (USAAF) was also using the Mustang as a support fighter, giving it the designation A364 and calling it the Apache. This name soon changed back to Mustang.
The Mustang would have given good service but would not have been such an outstanding aircraft with the original Allison engine. Another successful in-line engine, the famous Rolls-Royce Merlin, was tried in the Mustang. Immediately, the operation ceiling was increased to 40,000 feet and the Mustang was set on the road to fame. Armament was standardised as six .5" machine guns in the wings. Here, at last, was a fighter of some use. It was not as good as the Spitfire, but it had the range to escort the USAAF's 8th Army bombers to Germany.
Escort to Berlin
Daylight bombing was the forté of the USAAF. The heavy defensive armament of the B17 Flying Fortress was expected to keep enemy fighters at bay, but it had limited success and the Luftwaffe made them pay with heavy losses over prestige targets. They had started without continuous fighter cover simply because the RAF had no long-range fighters. All were originally designed as home defence fighters, with limited fuel capacity. The Mustang changed all that. With the addition of external fuel tanks (drop tanks), it could escort bombers to Berlin and back.
The last big design change was to get rid of the old, faired-in cockpit with its visibility problems, cut down the rear fuselage and fit a bubble canopy. This was the P51D (Mustang IV in the RAF), one of the Second World War's great fighter aircraft. NAA were not slouching at production either, at peak times they made 857 P-51s in one month - that's about 29 per day! From early 1944, Mustangs were available in quantity and helped to achieve almost total air superiority above Western Europe by 1945.
With over 15,000 Mustangs produced, the end of the war saw dispersal of many to the USA's allies and friends. It remained in RAF service until 1947, but Canada retained it until 1960 as did Australia, where the Commonwealth Aircraft of Australia (CAA) made 200 licence-built Mustangs from 1945 to 1948. Other users, among many, were Sweden, Switzerland and Israel. A separate development, the F82 Twin Mustang (outwardly two P51 fuselages on one wing!), became the standard USAF two-seat radar night fighter.
More Combat - On...
In 1947, the USAAF became the US Air Force (USAF) and the following year, the 'P' designation was dropped in favour of 'F' for fighter. The F51 was again in the front line when the Korean War began on June 25, 1950. As jet fighters had taken over the role of escort and interceptor, the Mustang had, once again, been re-roled as close support/ground attack. Its ruggedness was ideal for the rough airfields of Korea. Its period of service lasted from 1950 to 1953, with Mustangs flying over 62,000 missions, losing 350 aircraft to anti-aircraft fire. The South African and Australian Air Forces also used the Mustang in Korea. The last USAF F51 was withdrawn from the West Virginia Air National Guard in 1957.
With any other World War II aircraft the story should have stopped there, but the old P51 design kept on going. In 1954, Trans-Florida Aviation bought the rights concerning the F-51 from NAA and marketed refurbished two-seaters - the Cavalier 2000 - for civil use. After changing its name to Cavalier Aircraft, the company produced various refurbished models called the Mustang Rider. In 1967, a military version - Mustang II - was acquired by the USAF to give to countries it supported under the Military Assistance Program (MAP) scheme. These were close support aircraft remanufactured from F51 airframes. A further version, the Turbo Mustang III was developed, which replaced the Packard-Merlin engine with a Rolls-Royce Dart turboprop, but further development was stopped.
In 1970, Cavalier sold the F51 project to Piper aircraft. The second and third prototypes of the Turbo Mustang III were fitted with a Lycoming turboprop. Each had ten underwing ordnance attachment points and wingtip fuel tanks. These were put forward as counter insurgency (COIN) aircraft for use in Vietnam. It was a complete redesign incorporating only 10% of the F51's airframe. The company designation was PA-38 Enforcer and, although tested by the USAF, it was not adopted.
Thus ended the military career of the Mustang P51 and F51. It soldiered on into the 1970s in Latin America but all are now withdrawn and sold, in storage or derelict. The P51 is still seen in the USA in air racing, modified for speed. Still more are reappearing as airworthy display aircraft, lovingly restored and flown at historic aircraft meets thought the USA and Europe. It may not be the greatest fighter aircraft of all time, but it certainly is the longest lived and deserves to be ranked with the greatest.