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Inside the Archive: Mustang

The P-51 Mustang was developed by North American Aviation for the British Royal Air Force after it requested a single-seat fighter to replace the Curtiss P-40. Yet its original incarnation, fitted with an Allison engine, was something of a damp squib, performing poorly at high altitude. The eureka moment came when the British swapped in a new Rolls-Royce Merlin engine, which drastically improved its performance. So much so that it began to dominate Germany’s top fighters, the Me 109 and Fw109.

You could go as far as to argue that its upgrade was a turning point in the war. In October 1943, as many as 9 per cent of the US’ Eighth Air Force bomber sorties credited with attacking their targets failed to return home, while 45 per cent limped back damaged. In 1944, those numbers fell to 3.5 per cent and 29.9 per cent. Suddenly, the Germans lost the fight for aerial supremacy: the P-51 could go deeper into their airspace than any previous aircraft and consistently won dogfights. The RAF alone deployed 1,500 Merlin-powered Mustangs for daylight duties over Europe, while the US fleet ballooned to 13,300.

In truth, the Mustang arrived a touch too late for the RAAF, which built its variant from imported, semi-finished parts. The first production model, A68-1, flew on 29 April 1945 and was used for trials by No 1 Aircraft Performance Unit until October 1946, before being placed in storage. Despite missing WWII, the Mustangs of No 77 Squadron took part in the Korean War from June 1950 until April 1951, before being replaced by Meteors.


  • Bill Keech


    The P-51 was an engineering marvel. But why was the under powered allison not picked up on in the US, before it was shipped to the UK?



    I used to see this aircraft in its hangar in Western Queensland before Col Pay came and flew it to Scone!

  • Chris Woods


    Allison engined P51A could hardly be described as a damp sqib, at low level it was a rocketship, and gave invaluable service in the reconnaissance and tactical roles over Europe.

  • Glenn McMahon


    The sound of a Merlin at 55 inches give me goose bumps…

  • Cormac Sweeney-Meyer



  • Waliy James


    Major goosebumps. Absolutely nothing like the growl of a Merlin. Dad flew Lancaster’s in England during WW2 and what I wouldnt give to hear one of them with four Merlins at full power beggars belief.

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