de Havilland DH.86
The de Havilland DH.86 Express was a four-engined biplane airliner designed and built in four months in 1933 for the Empire Air Mail Service between Singapore and Australia, and first flown in January 1934. It launched Qantas's overseas operations and served Imperial Airways and other Empire operators, but a series of fatal accidents in Australia and Europe exposed stability flaws that investigations traced to its rushed design, and Australia briefly suspended its certificate of airworthiness. Sixty-two were built before production ended in 1937, and impressed aircraft served the RAAF, the RNZAF and British forces during the Second World War. The last was written off in 1958, and only wreckage remains survive, at the Qantas Founders Museum at Longreach.
Why It Mattered
The DH.86 Express was designed for one job: flying the Singapore-Australia legs of the Empire Air Mail Service, the route agreed between Britain, India and Australia in 1933. Qantas had ordered the aircraft before the design existed, asking de Havilland for a prototype that would fly by the end of January 1934. It was the aircraft that launched Qantas's overseas operations, and Qantas's first normal service carrying passengers, freight and mail left Archerfield on 17 April 1935. The type was also de Havilland's first four-engined aircraft, yet investigations eventually uncovered a design with flaws, and its years of airline service were interrupted by seemingly inexplicable accidents. Sixty-two aircraft were built in all.
Design Notes
De Havilland designed and built the DH.86 in just four months. The design was basically a larger DH.84 Dragon: a four-engined enlargement of that successful type with tapered wings, built in the traditional "plywood and canvas" manner. Its four engines were 200 hp Gipsy Sixes, the most powerful engine de Havilland then made. The long-range version was laid out for ten passengers behind a single pilot in a streamlined nose, with a wireless operator behind him. Qantas's representative Lester Brain rejected the single-pilot layout at once, fearing pilot fatigue on the long stretches, and the fuselage was redesigned around a two-pilot nose, as Australia required; only four single-pilot aircraft were built. Investigations during 1936, after a series of fatal crashes, led to auxiliary endplate fins, the "Zulu Shield" extensions, being fitted to the tailplanes of late production aircraft to improve lateral stability; these aircraft were designated DH.86B.
Operational History
The prototype first flew on 14 January 1934, and the first production aircraft, entering service that October, was the fastest British passenger aircraft in the world. Imperial Airways flew its two-pilot Diana class on European and Empire air routes; Railway Air Services operated seven Expresses between 1934 and 1946; and DH.86s were also built for New Zealand's Union Airways. Its Australian career opened with two losses in four weeks: Holyman's Miss Hobart crashed in the Bass Strait on 19 October 1934, killing all 11 on board, and Qantas's VH-USG was lost near Longreach on its delivery flight on 15 November 1934. Investigations found faulty fin bias mechanisms on the crashed aircraft and at least one other, and a centre of gravity too far aft, so that control was lost at low altitude; the type seriously lacked directional stability. Holyman's VH-URT Loina was also lost in Bass Strait in October 1935, and after Lepena's forced landing on 13 December 1935 the Australian Government temporarily suspended the type's Certificate of Airworthiness. Official British testing of the DH.86A in 1936, following three fatal crashes in Europe, found poor control response in certain speed ranges and a vertical tail surface of inadequate area; the report went unpublished for forty years, and its results do not appear to have been communicated to Australia. In 1936 Australia rescinded its ban on importing American aircraft; large airliners in Australia were mostly American-built from then on. Production ended in 1937, with 62 aircraft built. During the Second World War the RAAF impressed eight surviving DH.86s from the Australian airlines for training and air ambulance duties; New Zealand's aircraft hunted German raiders and Japanese shipping for the RNZAF; and most European survivors were taken into military service for communications and radio navigational training.
Afterlife
New Zealand's three aircraft, worn by war service, were built into one survivor at the war's end; it returned to Union Airways before being finally retired in early 1947. A few Expresses came through the war and flew on with British charter companies, but the last surviving DH.86, G-ACZP, was written off after its undercarriage collapsed at Madrid in Spain in 1958. No complete DH.86 survives: the remains of Qantas DH.86 VH-USG are displayed in the Qantas Founders Museum, Longreach (Qld.), and they are all that survives of the sixty-two aircraft built.