TURBINE 33

HISTORIC EUROPE

AIRCRAFT VINTAGE • CLASSIC • WARBIRDS +44 208 255 4000 www.AvBuyer.com MARCH 2022

The P-51 Mustang

Alongside the British Spitfire and the German ME109; the American P-51 Mustang is one of the most iconic aircraft to come out of WWII. As you well know, every plane has its story, but they aren’t always what you might expect — and the same can be said for the origin of the mighty Mustang…I bet you didn’t know, for example, that one of its finest attributes (its wing) came from the organisation that put man on the Moon!

With the Help of NASA…

The P-51’s origin can be traced right back to the rejection of one idea, that was replaced with another. The British Aircraft Purchasing Commission had established talks with North American in 1940 to ask them if they could build P40s under licence from Curtiss. However, in response, North American proposed something different instead: they wanted to produce a completely ground-up design, an entirely new aircraft — The P-51 (nicknamed the Mustang!)

North American set about its task in swift time and, using experimental data obtained from the US National Advisory Committee on Aeronautics or ‘NACA’ (which in 1958 became NASA), they achieved a giant leap in performance from the P40 by using a newly designed laminar wing profile. This moved the maximum thickness of the wing further aft from the leading edge and used nearly as much camber on the bottom of the wing as on the top. This feature reduced turbulent air flow across the wing, resulting in reduced drag thereby increasing speed and range.

The Mustang’s aft-mounted radiator design was also something to behold for not only did it decrease fuselage drag, it also utilised the heated air exiting the radiator as a form of jet propulsion to give it an extra bit of thrust called the ‘Meredith Effect’ (named after British engineer F.W. Meredith, who worked at the Defence Research Establishment at Farnborough, during the 1930s).

Less than 120 days after the British accepted North American’s proposal, North American flew the Mustang prototype. This was on the 26th of October 1940. The P-51 (‘P’ for Pursuit) entered service in Britain in early 1942, but reports were raised about the declining performance above 15,000 ft. The aircraft was initially powered by the same Alison single stage supercharged engine found in the P40. So the British, never being shy of putting their own mark on things, experimented with fitting their powerful RollsRoyce Merlin 61 engine (the same as found in the Mk. IX Spitfire). To their delight, they discovered that the Merlin’s two-stage supercharger gave the Mustang outstanding high-altitude performance.

North American quickly followed the Brits’ lead and by the summer of 1943, the Packard Merlin (licence-built Merlins) powered all P-51s coming off North American’s assembly line.