Just over a decade ago, I started working on a two-volume series on the North American Aviation Mustang, chiefly aimed at modellers and warbird enthusiasts. The two volumes were respectively to cover the Allison-engined and Packard Merlin-engined versions of the famous fighter. That project never came to fruition, but while researching what would have been Volume 1, I came to some surprising conclusions. In essence most of what people think they know about the versions of the Mustang powered by the Allison V-1710 engine is probably incorrect.
There are probably more myths about the North American Aviation Mustang than any other aircraft of the Second World War, and possibly any aircraft in history. Many of these relate to the models powered by the V-1710, and indeed to the V-1710 itself. It came to the point where I felt there was no alternative but to write a history of the Allison-powered Mustangs, addressing both the significant neglect that these types have received in the overall history of the aircraft, and the numerous myths and misconceptions that have grown up.
It’s well known how the Mustang came into being, commissioned from the relatively inexperienced firm of North American Aviation (NAA) by the British government in the dark days of 1940. Famously, Chief Designer Edgar Schmued and President ‘Dutch’ Kindelberger offered their own design when asked to licence-build Curtiss fighters, and the British took a gamble that it would be better. NAA produced their own blueprints in double quick time. But here, as legend has it, the aircraft faltered. Saddled with the Allison V-1710, the Mustang that initially went into service with the RAF was restricted to low altitudes and supposedly less important roles, while even the Curtiss Kittyhawk got to stay in its primary air-to-air fighter role.
All Mustangs from the initial order delivered from 1941, were allocated to Army Co-operation Command (ACC) – a new organisation set up to oversee the squadrons of the RAF charged with direct support to the army. When the Westland Lysander proved incapable of surviving above the battlefields of France in 1940, the RAF quickly learned that it needed a totally different kind of aircraft for tactical reconnaissance – one with much better performance.
The allocation of Mustangs to ACC has often been seen as a downgrade in role from that of pure fighter. In fact, it says much for the Mustang’s capability as a fighter within the envelope ACC tended to operate. The reason is that ACC was at the time operating exclusively in northern Europe where the Luftwaffe’s best fighters were stationed. The RAF needed fighters that could not just do the job of low-level reconnaissance but go toe-to-toe with these mostly up-to-date Luftwaffe fighters. The Kittyhawks were indeed employed as pure fighters, but only in theatres where the quality of the opposition was less high. The Mustangs even proved fast enough to avoid interception in the majority of cases, allowing the pilots to bring home vital intelligence and photographs. They found that the Allison not only performed superbly at low level, but was reliable to the point of being almost literally bulletproof, and gave excellent fuel economy.
In fact, the Allison-powered Mustang Mk I was so good at its job that two years after its introduction, there was still nothing better to replace it. The RAF had to husband its stock of Allison Mustangs to see its tactical reconnaissance squadrons through the Allied landings at D-Day, and some of the by now three-year-old aircraft made it to the end of the war in Europe, while the RAF reluctantly replaced worn out machines and combat losses with aircraft it acknowledged were less suitable.
In fact, the RAF’s Allison Mustangs performed so well at low altitude that it persuaded both NAA and the US Army Air Force that the first bespoke American variant of the type should also be a low-level specialist. Much has been written about the fighter-bomber A-36 – a great deal of it wrong. The type never received the name Apache, for a start, that common misconception arising from a mistake in the 1970s. Another popular story about the A-36 is a conspiracy theory that it was ordered as a dive-bomber to get around the 1942 budget for fighters having been used up. Again, there is no evidence to support this whatsoever, while examining the wider context around the USAAF’s priorities, purchasing patterns and conversations behind closed doors indicate the startling truth that the Air Force ordered an attack version of the Mustang because that was exactly what it needed! The A-36 went on to perform magnificently in the Mediterranean theatre in 1943-44 and a little later in the Far East.
Even that well-worn claim that it took the Merlin to make the Mustang into a long-range bomber escort was challenged in the Far East. Over a month before the Merlin-powered Mustang undertook its first long-range escort to 8th Air Force bombers over Germany, Allison-engined P-51As were doing the same for raids on Rangoon by B-24s of the 10th Air Force.
Much has been – and indeed is still being – written, claiming that the USAAF had no interest in the Mustang, especially in the role in which it became best known, as a long-range escort fighter. Yet again, research into the primary sources revealed that the Air Force showed considerable interest in the Mustang right from the beginning, aware that its advanced aerodynamic features offered big potential performance gains. Cannily, the USAAF allowed the British to pay for the development of what was seen as an almost radically experimental type, and then to test it in combat.
The undoubted brilliance of the Merlin-powered Mustang has perhaps understandably led to most focus falling on that variant. It was only by re-focussing attention on the Allison-engined Mustangs in their own right that it was possible to establish a clearer understanding of their career. I hope that by doing so, the Allison Mustangs and their crews will regain the share of the limelight they have been missing for so many years.
Matthew Willis is an aviation historian, writer and novelist and author of Mustang: The Untold Story.
