De Havilland Tiger Moth

Details
The ubiquitous Tiger Moth owed its origins to the famous de Havilland Moth, the first successful British private light aircraft. lt was destined to remain in service for over 15 years, and to provide initial flying experience for most wartime RAF and Commonwealth pilots, who regarded it with great affection. Many machines are still flying in private hands, the number. happily increasing yearly.

By the late 19205 it was becoming apparent that a replacement would have to be found for the Avro 504N, but there were several possible options. Contemporary thinking centred round a metal-framed aircraft, since the number of woodworking tradesmen in the RAF was on the decline, and it was proposed that power be provided by an Armstrong-Siddeley Mongoose engine‘ Orders were consequently placed on this basis for a number of Hawker Tomtits and also Avro 621s, the latter being later re-engined with the more powerful Armstrong-Siddeley Lynx IVC and named the Tutor.

Although not powered by a Mongoose, the Moth had already been tried in RAF service with some success, and therefore had to be regarded as a serious contender. Initially powered by a 60 hp ADC Cirrus I engine when it first appeared in 1926, several hundred were eventually built with later Cirrus and Cirrus-Hermes engines and also the de Havilland Gipsy. The RAF received over 160 of these machines, the final deliveries consisting of the metal-framed Gipsy-engined version, designated the DH.60M or Metal Moth.

Developed from the latter was the DH,60T or Moth Trainer, of which a number were supplied to overseas air forces. The RAF showed an interest, and prototype E-3 was test ﬂown at the Aeroplane and Armament Experimental Establishment at Martlesham Heath, being followed in August l93l by a later machine, E-5 (afterwards G-ABN]). Some modifications were made to the latter, including staggering the wings to make it easier to exit from the front cockpit with a parachute. This modification moved the C of G too far forward, which was rectified by giving the wings sweepback, The resulting report was particularly favourable as regards the ease of maintenance of the machine by service personnel. The only significant snag was that the wings were still not entirely satisfactory, the wingtips being likely to come too near the ground especially whilst landing in a crossewind or if the tyres were not fully inﬂated. However, this was soon cured by increasing dihedral on the lower mainplane.

Comparison of the results of the trials of these three main contenders led to orders being placed for the Tutor and Moth Trainer, The Tomtit was dropped at this stage, and in the event only limited orders were placed for the Tutor, whose makers became preoccupied with production of the Anson and later the Manchester and Lancaster bombers, By this time the de Havilland machine had been modified to such an extent that it was redesignated DH.82 by the makers, and the RAF gave it the name Tiger Moth. lnitial deliveries were 35 of the Mark l variant, powered by a Gipsy lll, but this proved prone to overheating, especially when climbing with insufficient airspeed, and replacement with the slightly more powerful Gipsy Major produced the DH,82a or Mark ll version, which was to become standard on the production lines. Another change on this version was the replacement of the doped fabric cover rear fuselage decking by a plywood decking.

Initial reaction to the Tiger Moth when it entered service in late l93l and early l932 was rather divided. It was not easy to fly, but this was no bad thing for a trainer. Problems of operating in a wind, the lack of brakes and fitment of a skid instead of a tailwheel caused unfavourable comment, but on the other hand it was easy and inexpensive to operate, and it soon wormed its way into the affections of the instructors and their pupils.

One of the first modifications to be carried out was the trial fitment of a mass balance to the ailerons, This had no effect on the handling characteristics, but reduced the risk of aileron flutter in a dive, a problem which had led to the loss of an Avro Cadet during trials. No maior alterations were subsequently made, but some trouble was later experienced in recovering from spins, especially in Tiger Moths which had been fitted with bomb racks. Tests were carried out at Boscombe Down, and the trouble was found to be due to a number of reasons, including the effect of the bomb racks on the airflow over the tail surfaces, and added weight due to accumulated repainting and other factors. A cure was effected by removing the aileron mass balances, and fitting anti~spin strakes along the top rear fuselage, extending forward from the line of the tailplane, this becoming a standard modification.

De Havillands were fully engaged in Mosquito production by 1941, but Tiger Moths were still badly needed. The solution was to transfer production to Cowley, near Oxford, where Morris Motors soon brought to bear their great experience in assembly-line production, achieving a rate of nearly 40 machines a week at a peak. Eventual UK production of Tiger Moths totalled well over 4,000, nearly 3,500 of them by Morris Motors. Small numbers were also built of a radio-controlled pilotless target version, named the Queen Bee.

In addition nearly 3,000 machines were built in Australia, Canada and New Zealand for use under the Commonwealth Air Training Plan. Those made in Canada required some modification to suit local conditions. These included moving the undercarriage forward, fitting brakes and a tailwheel, and replacing the normal wooden interplane struts by steel ones. The harsh winter climate required the fitting of a perspex canopy and cockpit heating, and the unreliability of supplies of Gipsy Majors due to shipping losses led to the fitting of 125 hp Menasco Pirate engine, which had already been fitted in a trial installation. In this guise they were known as Menasco Moths, but suffered from having not only less power, but an engine which was also heavier,

The main users of the Tiger Moth were civilian~operated Elementary and Reserve Flying Training Schools. and later their wartime counterparts at home and overseas‘ the Elementary Flying Training Schools. Tiger Moths were also used to train instructors at Flying Instructors Schools, and after the war they also formed the main equipment of Reserve Flying Schools. When they were eventually replaced by Chipmunks and Prentices, they found a ready sale for civilian use, many being refurbished and sold in the mid-fifties by Rollasons, who at one stage had over 100 parked at Croydon.