POWERHOUSE COLLECTION

Notes

During the 1920s the De Havilland Aircraft Works developed a line of light aircraft for the civilian post World War I market intended to be affordable and easy to fly. These aircraft were called after various types of moths in recognition of Geoffrey De Havilland's fascination and renown as a lepidopterist. The first model introduced in 1925 was the DH 60 Cirrus Moth, a light civilian aircraft easy to fly, cheap to purchase and maintain, and small in size thereby minimising hanger space. In 1927 a variation was introduced, the Gipsy Moth, being more powerful and reliable. Many light plane records were broken in this aircraft around the world thereby advancing the cause of civil aviation. With its low purchase and maintenance costs, and manoeuvrability, the DH 60 Moth was the ideal plane for use by the British military in training new pilots with the addition of several modifications including moving the top section forward and sweeping the wings back to improve pilot access and escape. Also, by installing the engine upside down the pilot had an improved forward view, however one disadvantage of this was the loss of engine oil through leakage. These modifications consequently became a new aircraft, the DH 82 Tiger Moth. This model of a Tiger Moth was made by the Museum's model maker, Iain Scott-Stevenson for the 'Women with Wings' exhibition in 2001 but was not displayed. It took about two working weeks to complete and is made of cotton thread, plywood, piano wire and Jelutong, pattern maker's timber from Malaysia, which is soft and easy work. The model is finished in silver automotive spray paint in the livery of the Royal Aero Club of NSW, comprising an orange stripe on the fuselage and dark blue engine cowling. The lettering on the wing is computer-cut vinyl Full size aircraft construction requires more from the natural qualities of timber than any other industry that uses wood for structural purposes. Material of the highest quality was demanded and its selection and preparation were stringently inspected. Despite the expense and wastage, wooden planes such as the Tiger Moth, were cheaper to build, had lower plant requirements, needed little specialised tooling and had lower labour proficiency needs than metal aircraft. Wood provided a very stable flying structure and was resistant to a broad range of stress factors. Furthermore, the ease of repair, particularly in training planes, was a great advantage. The DH 82 Tiger Moths were built of Sitka Spruce (Picea sitchensis) a northern temperate conifer grown naturally on the Pacific coastal belt of Canada and the United States and in plantations in the United Kingdom, particularly Wales. It is a straight grained timber, with a fine even texture, non resinous, soft and light in weight, which dries rapidly under both air and kiln conditions. The first model Tiger Moth, the DH 82 was powered by a 120 Gipsy III inverted inline engine. It was sold to the air forces of Brazil, Denmark, Persia, Portugal and Sweden. An improved model, the DH 82A Tiger Moth II, was equipped with a Gipsy Major engine rated at 130 hp, as well as structural changes that included the replacement of fabric with plywood for the rear fuselage decking and the ability to shroud the rear cockpit for instrument flight training. Prior to the outbreak of World War II, Tiger Moths were manufactured by De Havilland Aircraft of Canada, and under license in Norway, Portugal and Sweden. During the war, Tiger Moths were manufactured by De Havilland affiliates in Australia and New Zealand while a "winterised" version the DH 82C was manufactured in Canada with a 145 h.p. Gipsy Major engine. Over 8,700 Tiger Moths were eventually manufactured, with approximately 4,200 going the Royal Air Force. On 10 October 1939 the Australian Government approved a submission from the Air Board for the purchase of 350 Tiger Moths and 500 engines from local producers. The aircraft were to be made by De Havilland Aircraft Pty Ltd at its works at Mascot Aerodrome, Sydney. Here the Australian-Tiger Moths were essentially similar to the their British counterparts however seventy local modifications were made to the airframe including the installation of plywood skinning on the wing leading edges and the use of plastic-coated bracing wires. The Gypsy Major engines were produced in record time in Australia by General Motors-Holden's Ltd at Fishermans Bend, Melbourne. They were built from incomplete drawings, in French, using metric measurements which required very precise conversion. Work commenced on aircraft construction at Mascot in November 1939 and it was predicted that when the factory was in full operation, production would be at the rate of one aircraft per day. On 17 December 1939 De Havilland leased additional hangar space at Mascot, and transferred its administrative offices to the nearby suburb of Alexandria, where the production of propellers had commenced in August 1939. In May 1940 the first entirely Australian-produced Tiger Moth emerged from the company's works, constructor's number 21. In August 1942 De Havilland completed the last of the 1,035 Tiger Moths authorised and turned its efforts to the production of the DH 84 Dragon and DH 98 Mosquito projects. Of the Tiger Moths produced in Australia 576 were consigned to the RAAF with a further 101 diverted to the Empire Air Training Scheme (EATS), 120 to the South African EATS and 94 to the Southern Rhodesia EATS. In 1944 the Mascot production line was re-opened and 35 additional Tiger Moths were delivered to the RAAF between September 1944 and February 1945, to offset wastage, and provide for post-war training. 2001