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Aviation History
1931
1931 - 0695.PDF
FLIGHT. JULY 3, 1931 MOTH TRAINER The alterations to the normal metal-fuselage " Gipsy-Moth " which have been made in producing the new " Moth Trainer " consist mainly in shifting the rear liftwire attachment to the forward wing root, in order to give free exit from the front cockpit, in increasing thecockpit areas, in fitting four doors, and in taking the exhaust pipe away from the side and pointing it down-ward under the nose A CONOMY in flying training equipment is the key-^ note upon which the design of the new Moth LJ Trainer, recently produced by the De HavillandAircraft Co., Ltd., is based. The normal metal- fuselage Gipsy Moth was already fairly suitable for train-ing purposes, and the modifications necessary to make it entirely suitable for modern training requirements were notof a far-reaching nature from the constructional point of view. Consequently the De Havilland Company has beenable to put on the market, at really low cost, a new train- ing type suitable for modern conditions. That this is noidle claim is proved by the fact that the new Moth Trainer is available at prices below £1,000, the actual price vary-ing according to the additional equipment which it is desired to fit, and which is optional. As a variant of its normal form as a landplane train-ing machine, the Moth Trainer can also be supplied as a twin-float seaplane, and used for seaplane training (atextra cost, of course), or with skis instead of wheels for winter training in countries where snow-covered aerodromesor frozen lakes are the rule rather than the exception. Moreover, the three types of undercarriage are interchange-able, so that the machine can always be fitted up to suit the season of the year, using the wheel undercarriage inthe summer and the ski undercarriage in the winter. It is, of course, well known that De Havilland serviceexists in nearly every civilised country in the world, and, owing to the fact that so many of the components of theMoth Trainer are identical with those of the standard Gipsy Moth, purchasers of the Moth Trainer can beassured that spares are always readily obtainable, and at low cost. Thus, not only first cost, but upkeep and main-tenance costs, should be low for schools using the new school machine. Although flying training is the function which the MothTrainer has primarily been designed to fulfil, it has been specially designed also to carry out many other duties bymeans of additional equipment, which can be readily fitted without modification to the main structure. These dutiesinclude Advanced Training, Fighting Training, Bombing Training, Wireless Training, and Training in Photography.The machine has been considerably strengthened, and as a result the permissible Certificate of Airworthiness weightfor aerobatics has been raised from 1,550 lb. (704 kg.) to 1,640 lb. (746 kg.), and for normal flying the permissibleall-up weight has been increased from 1,750 lb. (796 kg.) to 1,820 lb. (827 kg.). These increases in the permissible all-up weight not onlyenable the extra equipment to be carried, but the Moth Trainer is made nicer to handle, even at the extra weight,by fitting wings of a completely new section, so designed that, although speed and climb are not adversely affectedin any way, the stall is less abrupt and the resultant spin is slower. Special Features Among the more important modifications made in pro-ducing the Moth Trainer, mention may be made of the arrangement of the lift wires. It will be recollected thatin the normal Gipsy-Moth the rear lift wire is in the plane of the rear spars. This means that the wire rather getsin the way if, in an emergency, the occupant of the front cockpit is obliged to leave hurriedly, as, for instance, injumping with his parachute. There is always a risk that some loose portion of clothing or equipment may catch onthis lift wire and cause a delay at a time when every second is likely to count. To avoid this possibility, therear lift wire in the Moth Trainer has been brought for- ward to the front spar wing root, where the lower portionof the wire is in front of the front cockpit, and thus right out of the way. Further to facilitate exit from the front cockpit, adeeper type of door has been fitted, so that the occupant can now very easily step straight out on to the lowerwing. These deep doors are fitted on both sides, enabling a rapid exit to be made from either side. This point is ofgreat importance, since it is easy to visualise conditions under which it would be relatively easy to get out on oneside of the machine, but impossible on the other. Thus, the addition of the second door may be regarded as a veryreal safety measure. The fitting of doors in both sides of the fuselage broughtup another problem. The exhaust pipe in the normal Gipsy-Moth runs along the port side of the fuselage. Thiswould obviously interfere with the use of the door on that side, and so in the Moth Trainer the exhaust pipe has beenshortened, and is bent down under the nose of the machine. In this position the exhaust pipe is not in the way, and,although the noise is possibly slightly greater when heard from a point outside the machine, in the cockpits there isno noticeable difference in noise. In a training aircraft, as, indeed, in all aircraft, viewis an important consideration, and as the number of air- craft increases, the subject of view will assume greaterand greater importance. By careful experiment and the application of experience, it has been found possible, inthe Moth Trainer, to make certain detail alterations which have resulted in a much improved view from both seats.The view from the back seat has been greatly improved in an upward direction by cutting away the trailing edge ofboth" top wings at the root end fittings. Biplane construc- tion normally restricts the upward view from the front 649
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