de Havilland DH.85 Leopard Moth

Самолет DH.85 Leopard Moth появился в 1933 году как наследник модели DH.83 Puss Moth. При внешнем сходстве с предшественником он обладал рядом отличий, в том числе новой конструкцией фюзеляжа. Силовой набор из стальных труб заменили деревянным из ели и фанеры ДальшеMore>>> с кабиной для пилота и двух пассажиров, сидевших плечом к плечу на заднем сиденье. Прототип впервые взлетел 27 мая 1933 года в Стэг-Лэйне. Всего через две недели он выиграл ежегодные авиагонки на Королевский кубок в Хэтфилде. Еще два таких же самолета заняли третье и шестое места. Это хорошее начало гарантировало коммерческий успех. За три года построили, сначала в Стэг-Лэйн, а затем в Хэтфилде, 132 таких аэроплана.


Вариант

   DH.85A Leopard Moth: обозначение прототипа после переделки под установку мотора de Havilland Gipsy Six R мощностью 230 л.с. (172 кВт) с винтом изменяемого шага для испытаний


ТАКТИКО-ТЕХНИЧЕСКИЕ ХАРАКТЕРИСТИКИ

   de Havilland DH.85 Leopard Moth

   Тип: трехместный спортивно-туристический самолет
   Силовая установка: рядный поршневой мотор de Havilland Gipsy Major мощностью 130 л.с. (97 кВт)
   Летные характеристики: максимальная скорость 220 км/ч на оптимальной высоте; крейсерская скорость 192 км/ч на оптимальной высоте; начальная скороподъемность 168 м/мин; практический потолок 6555 м; дальность полета 1151 км
   Масса: пустого самолета 637 кг; максимальная взлетная масса 1009 кг
   Размеры: размах крыла 11,43 м; длина 7,47 м; высота 2,67 м; площадь крыла 19,14м2

Flight, November 1933

DE HAVILLAND "LEOPARD MOTH"

   WHEN the de Havilland Aircraft Co., Ltd., produced the first batch of six "Leopard Moths," three of which took part in the King's Cup Race and one of which won the race, piloted by its designer, Capt. Geoffrey de Havilland, it was known that these six machines were the forerunners of a new standard de Havilland model. The six machines have been flown fairly hard between last July and the present time, and so the experience accumulated before the final details of the production model were settled has been fairly extensive. This should mean that the production machines should be without those minor "snags" which can be so irritating to customers, and which may in exceptional cases be serious enough to mar the future of a new type. The first production "Leopard Moth" was finished a short time ago, but as the purchaser has not yet made up his mind about the colour scheme, the second production model was actually the first to go into the air, which it did early this week. The following notes and sketches, etc., were prepared from the production machines, but time did not permit us to include photographs of the actual production machine, and the two photographs published herewith show the winner and third respectively in the King's Cup Race. The changes made in the production model are not great, and would not be noticeable except by very careful inspection of the machines themselves.
   Although resembling the famous "Puss Moth" a good deal in outward appearance, the "Leopard Moth" differs from the earlier machine both in structural features and in the layout of the seating accommodation. Whereas the "Puss Moth" was primarily a two-seater, with provision for an occasional third seat, the "Leopard Moth" is fundamentally a three-seater, with pilot in front and the two passengers side by side behind him. The cabin furnishings are extremely comfortable and of attractive appearance, and the view is, thanks to the generous window area and the inverted "Gipsy Major" engine, very good indeed. In the matter of external appearance the "Leopard Moth" differs from the "Puss Moth" mainly in that its monoplane wing is strongly tapered in plan view, while the undercarriage struts do not run to the top longerons, but to points down the sides of the cabin.
   Structurally, the main difference is that the "Leopard Moth" has an all-wood fuselage, while that of the "Puss Moth" was of welded steel tube construction. The wing construction also differs in details, but not greatly in the general principles adopted.
   After some years' experience of metal construction, the de Havilland Aircraft Co., Ltd., came to the conclusion that there was, after all, much to be said for the old wood construction. Generally speaking, it was found that whenever a machine was produced in metal, it proved heavier than the corresponding wooden machine, and also in most cases a good deal dearer. When the firm produced the “Fox Moth” there were those who regarded this machine as a retrograde step, because it was made entirely of wood except for a few highly stressed steel fittings. But the answer to the critics was that the "Fox Moth" had an amazing ratio of gross to tare weight, and that it could be sold at a competitive price, neither of which could have been realised had the machine been of metal construction. In the "Leopard Moth" similar structural principles have been employed, although the fact that the machine is a strut-braced monoplane has necessarily led to certain detail changes.
   The fuselage of the "Leopard Moth" has a light skeleton of spruce, with a covering of plywood. The sides are flat, but the deck and bottom are cambered. The bottom of the primary fuselage structure is fiat, but under it run lengthwise two floor bearers or stringers, which project below the level of the longerons. The outer covering of the bottom is fabric, and here and there in the fuselage bottom are large inspection holes. The fabric is laced on in the vicinity of these holes, so that a portion of it can be turned back and the fuselage structure inspected through the holes in the plywood bottom. The space between the longitudinal bottom stringers is made use of for housing the controls, which are thus readily accessible for inspection and adjustment, but protected by the inner plywood bottom and the outer fabric covering.
   The fuselage is built in two sections, which meet on a solid bulkhead behind the cabin, and are joined together by bolts through the longerons. Cupped steel washers are used under the bolt heads and nuts, so that the wood can shrink quite an appreciable amount without slackness developing.
   In the wing construction also spruce and plywood are the chief structural materials. The two spars are of box type, with spruce flanges and plywood walls. The leading edge is covered with plywood, and the inner half of the wing is covered with plywood on the lower surface, from the wing root to the wing strut attachments. The wing ribs in the inner portion have spruce flanges and solid plywood webs. The drag member is in the form of a stout spruce beam, some 2 in. square, which runs from the inner end of the rear spar to the wing strut attachment on the front spar. This strut lies at the bottom of the wing section and is glued to the under surface plywood covering. The petrol tanks are placed in this part of the wing.
   Bracing of the wing is by streamline-section steel-tube struts, hinged at their lower ends to the fuselage and attached to the wing by steel fittings. In order to "bury" the joint of the struts to the wing, plywood "boxes" are taped on after the wing fittings are in place, and "gaiters" with curved upper ends fair the struts into these "boxes." The wings are designed to fold, and the locking device on the front spar is illustrated by two photographs. When the locking catch has been turned, the locking pin is withdrawn by means of a cable lying inside the wing and terminating at its outer end in a ring which projects from the lower wing covering where the wing struts join the wing. From this position the pilot is well placed for folding the wing when the catch is released. To permit the folded wings to clear the top of the fuselage, the inner portions of the trailing edge are hinged upwards.
   The undercarriage of the "Leopard Moth" is of the divided type, the vee struts being hinged at their upper ends to fittings on a stout wooden member on the bottom centreline of the fuselage. The telescopic legs are hinged to the sides of the fuselage, and are used as air brakes by being turned "broadside on." This is done by a transverse shaft which ends, like the upper ends of the telescopic legs, in toothed quadrants. The operating handle is on the right-hand side of the cabin. Dunlop wheels and brakes are fitted, and under the tail is a fully-castering tail wheel.
   A steel-tube framework of square-section tubes supports the "Gipsy Major" engine, which is neatly cowled in. The wing tanks give, gravity feed to the carburetter. An oil tank is placed transversely across the fuselage, behind the engine bulkhead.
   In the matter of performance, the "Leopard Moth" appears to be remarkably "clean." For example, the Everling "High-speed Figure" has a value of 30.5, which is far and away above the average. This figure relates speed to power and wing area, and a high value means that for the particular wing area the power used to attain the speed is low. The fuselage must obviously be of good shape, and the amount of interference between wings and fuselage must be very small indeed.
   The cleanness of the machine is also reflected in the other performance figures, and it is interesting to record that the gliding angle is 1 in 12. When the air brakes are "on," this is lowered to a gliding angle of 1 in 9. The length of run to take off is 140 yd. at normal weight and 215 yd. at maximum gross weight. The take-off times are 12 sec. and 17 sec. respectively. By using the wheel brakes the landing run is reduced to 105 yd. and 140 yd, for the two loadings. The stalling speed is 45-50 m.p.h.
   From the point of view of structural efficiency, the "Leopard Moth" appears to be of average "goodness." When the machine is fully equipped, the tare weight is 1,341 lb. As the maximum permissible gross weight for "Normal" C. of A. is 2,225 lb., the ratio of gross to tare weight is 1.66, so that the machine carries 66 per cent, of its own weight as disposable load. In view of the fact that the machine is a monoplane, this must be regarded as a satisfactory figure.

Flight, April 1936

MODERN LIGHT AIRCRAFT REVIEWED

D.H.

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   For those who want a rather higher speed and a longer range than those provided by the Hornet, there is still the Leopard Moth, which can be considered to be the descendant of the ever-popular Puss Moth and has many of the same pleasant characteristics. With a Gipsy Major engine the Leopard Moth carries three people at a cruising speed or 117 m.p.h.
   Although the Moth as we knew it is dead, the Tiger Moth is very much alive, and is used as a primary trainer all over the world. Since it is an excellent aerobatic performer, the word "primary" does not imply that its value as a trainer ends after a pupil's first solo.
   The specification of the Leopard Moth is as follows: Span, folded, 12ft, 10in.; length, 26ft. 6in.; weight empty, 1,405 lb.; disposable load, 820 lb.; maximum speed, 138 m.p.h.; cruising speed a at 1,000 ft. 117 m.p.h.; stalling speed, 50 m.p.h.; initial climb, 625 ft./min.; range, 695 miles. Makers: De Havilland Aircraft Co., Ltd., Flat field, Herts.