Design and Development
Design work on the DHA-3 began in 1946 after DHA identified a need to replace the de Havilland Dragon biplane then in widespread use in Australia. Although the British parent company's Dove was being produced at the same time, DHA saw that the Dove was not entirely suitable for Australian conditions. Using the Dove as a starting point, DHA designed an aircraft with three four-cylinder Gipsy Major engines instead of the Dove's two Gipsy Queen six-cylinder engines and a fixed tailwheel undercarriage instead of the Dove's retractable tricycle undercarriage. Like the Dove the DHA-3 was sized to carry 8 to 9 passengers with a single pilot.
The result was an aircraft with the same wingspan as the Dove and a slightly shorter fuselage. The name 'Drover' was selected by Sir Geoffrey de Havilland after suggestions for a name were invited from DHA employees. Mr Thomas King from the Drawing Office came up with the winning name. The first DHA-3 Mk. 1 Drover took to the air at Bankstown Airport on 23 January 1948 piloted by Brian (Black Jack) Walker, DHA's chief test pilot. The second aircraft did not fly until December 1949, while the first aircraft was delivered in October that year.
After entering service, by 1952 the type's shortcomings were becoming apparent. These included the aircraft's lack of power, especially in hot weather, and an unfortunate tendency for propellers to fail in-flight, resulting in the loss of two aircraft. The propeller problem was overcome by replacing the de Havilland variable-pitch propellers with Fairey Reed fixed-pitch propellers, modified aircraft being re-designated the DHA-3 Mk. 1F. All but the three aircraft that had crashed by that time were brought to this standard. The propeller change however did nothing to improve the type's performance. In a bid to improve lift all Mk. 1F aircraft were further modified with double slotted flaps in place of plain flaps, and were once again re-designated, this time as the DHA-3 Mk. 2.
Sixteen aircraft had been delivered by the end of 1952, but the problems suffered by the type stalled further sales for several years. The last four of the twenty Drovers built were produced in 1953 but were not sold until 1955 and 1956. In another bid to rectify the type's poor performance DHA re-engined seven Mk. 2 aircraft with Lycoming O-360 horizontally-opposed engines driving Hartzell feathering constant-speed propellers. Changes were also made to the flap control system and the tail wheel assembly. The first modified aircraft, re-designated as a DHA-3 Mk. 3, was returned to its owner the Royal Flying Doctor Service of Australia (RFDS) on 4 June 1960. Three Mk. 3s were later further modified; two aircraft operated by the NSW Section of the RFDS were modified in 1962 as the Mk. 3a with the tailplane altered to have seven degrees of dihedral (14° according to one source) and the span increased by 2 ft (61 cm). The third was modified as a Mk. 3b with an increase in MTOW of 300 lb (137 kg) to 6,800 lb (3,087 kg).
Read more about this topic: De Havilland Australia DHA-3 Drover
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