Aircraft History

The Chipmunk was the responsibility of Wsiewolod J Jakimiuk, a Polish émigré who had escaped from his home country in 1940. He had gained his diploma in 1929, studying initially at Wilno University and then at the Ecole Supérieure d'Aéronautique in France. Prior to the Second World War, he had been responsible for the design of the PZL24 and PZL50 fighters. By the time he joined de Havilland at Downsview near Toronto, the factory was already fully involved in the production of the famous Mosquito fighter-bomber. The emergence of the Chipmunk marked the beginning of a new era of post war production.

A cursory glance at the Chipmunk reveals its origins. Its lines are reminiscent of the Tiger Moth and Puss Moth; the vertical fin is straight off a Mosquito; even the engine cowling is unmistakably de Havilland. Regardless of the aircraft's Canadian design, no one at Hatfield (the company's British home) could ever deny it was part of the family.

The Chipmunk was the first de Havilland aircraft in which no wood was used: its construction is almost all of metal, although control surfaces and the rear two-thirds of the wings are fabric-covered. Like its predecessor, the Tiger Moth, the two seats are in tandem configuration, however the Chipmunk is flown solo from the front cockpit. The aircraft was designed for a long hard military life, and closer inspection reveals the sturdiness of its undercarriage, riveted fuselage and wing panels. Ease of maintenance was a key requirement, so the design features many standard parts, a fixed-pitch metal propeller and de Havilland's well-proven Gipsy Major engine.

Jakimiuk's new aircraft was designated the DHC1 and flew for the first time on the 22nd May 1946. Flight testing revealed the Chipmunk's beautifully crisp and well-harmonised controls, however the second prototype was later to crash after entering an unrecoverable spin whilst being flown from the rear cockpit with an extreme aft centre of gravity. A modified tail design had previously been tested but had been abandoned before the crash and was never adopted in production, although most later aircraft featured spin-recovery strakes. A modified spin technique was also introduced, which involved applying opposite aileron at the point of entry to reduce the likelihood of entering a spiral dive instead of a spin. This was extensively investigated by de Havilland's chief test pilot, John Derry, who demonstrated it to most of the University Air Squadrons and Reserve Flying Schools using the Chipmunk in early 1950. The spin recovery technique remained unchanged.

Other modifications included moving the undercarriage forward by four inches to improve ground handling and fitting a broader-chord rudder, which was requested by the test and demonstration pilots in Canada in order to improve handling during the last part of the slow roll. The enlarged rudder was first flown on 5th May 1949, and was incorporated from the 63rd aircraft onward in Canada. However, it was not fitted to British-built aircraft until 1951, despite the fact that A&AEE Boscombe Down had called for improved rudder travel in late 1948 to improve aerobatic handling, reduce the amount of rudder required in a prolonged climb, and improve side slipping.

It is widely believed that the broad-chord rudder was introduced to aid spin recovery, although this is not the case. The second UK aircraft, WB550, was tested at Boscombe Down with an enlarged rudder in April 1950 at about the time of the first spinning accident, which resulted in the death of the son of a Member of Parliament. In order to satisfy the subsequent enquiry, it was stated that an enlarged rudder was being tested, which would help prevent such incidents. So the myth was born.

The British production versions were the T.10 for the RAF, T.20 for overseas air forces, and civilian T.21. Civilianised versions of RAF aircraft became available in large numbers from the late 1950s, the T.10 becoming the Mk.22 in civil service (the Mk.22A was a modification featuring a greater fuel capacity). Some aircraft were fitted with a crop-spraying tanks in place of the front cockpit and were designated Mk.23.

1,283 Chipmunks were built by the end of production: 217 in Canada, 1,000 in Britain and 66 under licence in Portugal. The last aircraft were retired from the RAF's air-experience flights in 1996, although two Chipmunks remain in the Battle of Britain Memorial Flight for converting fast jet pilots to the Spitfires and Hurricanes. The Royal Navy retains two aircraft for tailwheel training and currency, and the Army has an airworthy example in its historic flight. The Chipmunk remains a very popular aircraft and its exceptional flying qualities are seldom surpassed by more modern types. Many, like G-AORW, remain in excellent original condition and retain all of their character and period charm. Sadly a large number have been extensively modified with modern instrumentation and navigation aids, which in our opinion detract from the unique experience of flying a classic aircraft, and only add to the steady decline in traditional airmanship and "stick and rudder" flying skills.

The front fuselage of G-AORW carries a date of 11th August 1950 and it was ready for collection from the Broughton factory on 16th August. It initially entered service with No.5 Reserve Flying School RAF Castle Bromwich, Near Birmingham, but was one of the first Chipmunks to be civilianised when it was sold in 1953. It subsequently saw service with Derby Aviation.

Incidentally, Wsiewolod Jakimiuk continued a successful career in aeronautical engineering, eventually returning to Europe to play a key part in the development of Concorde in the 1960s and 70s.

Many thanks to Rod Brown for providing much of the information on this page. Further information can be found on his own website, www.chipmunkflyer.co.uk