The Bell P-39 Airacobra presents one of the most striking paradoxes of air combat in World War II: a disappointment in the hands of American pilots, it was the favourite aircraft of several Soviet air aces, including two of the three highest scorers, Aleksandr Ivanovich Pokryshkin and Grigori Andreevich Rechkalov. (1) The brief career of the Airacobra in Britain's Royal Air Force(RAF), with which the type first saw action months before its combat debut with the USAAF and Soviet VVS, may not explain the difference in U.S. and Soviet estimates of the aircraft's capabilities but provides a sidelight into how it came about.
Perhaps the most innovative design of its time for a single-engined warplane with its engine behind the pilot and nose-wheel undercarriage, the Airacobra first flew in April 1939, and was ordered for the U.S. Army Air Corps later in the same year. (2) On April 10, 1940 the Anglo-French purchasing board ordered 165 Airacobras for the French Armee de l'Air, this being only one item in a stack of contracts, for a total of 4,600 aircraft of different types, that was signed in Washington that day. (3) After the fall of France, the British took over the contract for the Airacobra, which was initially amended to 170 machines and subsequently supplemented by orders for 505 more. (4) It was at first intended to commence deliveries on the original order in November 1940, and to complete the handover in April 1941, but by December 1940, it was evident that deliveries were going to be a couple of months behind schedule, mainly owing to shortfalls in the delivery of engines and propellers to the Bell Aircraft Corporation. (5) Nevertheless the Royal Air Force was pleased with its acquisition: Air Commodore J.C Slessor, formerly the RAF's Director of Plans but currently in Washington for staff talks, reported on December 14, 1940: 'as far as I know --there is no other U.S. fighter which could be in quantity production by 1942 likely to exceed the Airacobra in performance and fire power.' (6)
Trials carried out by the RAF with the Airacobra flying against the Spitfire VB and a captured German Messerschmitt Bf 109E in September 1941 found that the Airacobra was faster than the Spitfire VB up to 15,000 feet but 'was out-climbed and just out-turned' by the Spitfire. As for the German aircraft:
The Me. 109 cannot compete with the Airacobra in a turn and even if the Me.109 is behind the Airacobra at the start, the latter should be able to shake him off and get in a burst before two complete turns have been carried out.
The Me. 109 then tried diving on the Airacobra from above and continuing the dive down to ground level after a very short burst of fire. It was found, however, that the Airacobra could catch up on the Me. 109 in dive of over 4, 000 feet. (7)
By this stage of course the Bf 109E had been superseded by the more aerodynamic Bf 109F, which in turn would be in the process of being superseded by the more powerful Bf 109G by the time American P-39 Airacobras went into action against the Luftwaffe in North Africa; but as it happened the Airacobra remained faster than these later marks of Bf 109 below 10,000 feet, and its superiority in turning became even more noticeable. Initially the RAF's main problem with the Airacobra was what to do with it. There was no question of using it to re-equip squadrons already flying the Spitfire, which was on balance as good below 15,000 feet and markedly superior at altitudes above that, and an even faster and more heavily armed type, the Hawker Typhoon, was beginning to come off the assembly lines in greater numbers. The main use for the Airacobra was envisaged as the 'the possible equipment of the Army Co-operation Squadrons', i.e. as a ground-attack aircraft; but even in this role the Airacobra had a competitor in the North American Mustang-A-36 in U.S. service-which was also being manufactured in the United States for a British contract. (8)
No. 601 Squadron RAF, previously flying Hawker Hurricanes, had begun re-equipping with Airacobras during the second half of August 1941. On October 9, 1941, two of 601 Squadron's Airacobras flew to Dunkirk 'where they shot up a number of bodies on the pier, and severely hurt the feelings of a trawler.' Next day a single Airacobra flew to France and shot up several barges behind Dunkirk. On November 11, 1941, three Airacobras set out on a shipping strike but found no targets. (9) That was the last combat mission flown by British Airacobras. It had been found that firing the guns mounted in the Airacobra's nose affected the compass, causing deviations from seven degrees to 150 degrees on various headings. (10) Inquiries in the U.S. elicited the response that the problem was due to British technicians' failure to demagnetize the guns, but the Ministry of Aircraft Production in London pointed out that the problem arose from the magnetic field of the guns changing in the process of firing. (11) Staff at RAF Fighter Command and the Admiralty Compass Observatory tried to find a solution and suggested that the distant-reading Pioneer compass should be installed in the Airacobra's wing, but these needed to be sent from the U.S., and Air Chief Marshal Sir William Sholto Douglas, Air Officer Commanding-in-Chief RAF Fighter Command, informed the Air Ministry on November 7, 1941, that till this "depressing situation" was...