Westland Wapiti

Выпущенные требования 26/27 на самолет общего назначения стали сигналом к началу процесса перевооружения британских ВВС после окончания Первой мировой войны. Поскольку средств не хватало, предполагалось, что будет максимально использоваться значительная часть компонентов самолета de Havilland D.H.9A. Прототип был облетан в марте 1927 года, и после интенсивных испытаний была заказана партия из 25 Wapiti Mk I, которые прошли опытную эксплуатацию на Среднем Востоке, после чего самолет поступил на вооружение 84-й эскадрильи, дислоцированной в Ираке. Самолеты Wapiti Mk II стали основой для эскадрилий, дислоцированных в метрополии.
   Всего для британских ВВС до августа 1932 года было построено 517 самолетов различных модификаций. Самолеты стояли на вооружении девяти дислоцированных в метрополии эскадрилий британских Вспомогательных ВВС до 1937 года, а также находились на вооружении 11 эскадрилий, дислоцированных за рубежом. В начале Второй мировой войны около 80 таких самолетов эксплуатировались в Индии.


Варианты

   Wapiti Mk I: первый серийный вариант со звездообразным двигателем Bristol Jupiter VI мощностью 420 л. с.
   Wapiti Mk IA: усовершенствованный вариант с двигателем Jupiter VIIIF мощностью 480 л.с. и предкрылками типа Хэндли Пейдж; кроме самолетов для британских ВВС еще 38 были построены для австралийских ВВС
   Wapiti Mk IB: аналогичен Wapiti Mk IA, но с раздельными основными опорами шасси; оснащался сначала двигателем Jupiter VIIIF, затем - Armstrong Siddeley Panther мощностью 550 л.с.; четыре самолета поставлены в Южную Африку
   Wapiti Mk II: усовершенствованный цельнометаллический вариант
   Wapiti Mk IIA: основной серийный вариант с измененной конструкцией крыльев и возможностью применения колесного или поплавкового шасси
   Wapiti Mk III: 27 самолетов, построенных по лицензии в Южной Африке, в целом идентичных Wapiti Mk IIA и оснащенных двигателем Armstrong Siddeley Jaguar VI мощностью 490 л.с.
   Wapiti Mk V: разработан на основе проектировавшегося варианта Wapiti Mk IV с удлиненным фюзеляжем и некоторыми усовершенствованиями; двигатель Jupiter VIIIF мощностью 550 л.с.
   Wapiti Mk VI: учебно-тренировочный вариант с двойным управлением (16 самолетов)
   Wapiti Mk VII: самолет, первоначально построенный как Wapiti Mk V, но затем получивший обозначение Houston-Wallace, или P.V.6, а позже переоборудованный в экспериментальный Wapiti Mk VII
   Wapiti Mk VIII: разработан на базе проектировавшегося Wapiti Mk IV, оснащался двигателем Jaguar VI мощностью 512 л.с.; построены четыре самолета для центрального правительства Китая


ТАКТИКО-ТЕХНИЧЕСКИЕ ХАРАКТЕРИСТИКИ

   Westland Wapiti Mk IIA

   Тип: многоцелевой самолет военного назначения
   Силовая установка: один звездообразный ПД Bristol Jupiter VIII или VIIIF мощностью 480 л. с. (358 кВт)
   Летные характеристики: максимальная скорость на высоте 1525 м - 225 км/ч; практический потолок 6280 м; дальность 853 км
   Масса: пустого 1728 кг; максимальная взлетная 2449 кг
   Размеры: размах крыльев 14,15 м; длина 9,65 м; высота 3,61 м; площадь крыльев бипланной коробки 43,48 м2
   Вооружение: один 7,7-мм синхронизированный пулемет Vickers и один 7,7-мм пулемет Lewis в задней стрелковой установке Scarff, плюс до 263 кг бомб

Flight, June 1928

THE WESTLAND "WAPITI
Bristol "Jupiter VI" Engine

   THE "Wapiti," designed and constructed by the Westland Aircraft Works of Yeovil, is of the type known as a "General Purpose" machine, i.e., suitable for bombing, reconnaissance, photography, wireless and advanced training. It can be supplied either in composite timber and metal construction or as an all-metal machine. In both cases the wing covering, and that of control surfaces, fuselage rear portion, etc., is fabric.
   In its general design the "Wapiti" is a normal two-bay wire-braced biplane, and in view of the ample stowage accommodation which its function as a general purpose machine requires, it is of remarkably small dimensions and "clean" design, with a very good performance. The amount of gear that has to be carried in a machine of this type is prodigious, and it is to the credit of the Westland designers that they have managed to provide all the space required while still retaining such a good performance.
   In the lay-out of the "Wapiti" a great deal of attention has been paid to the subject of view. Thus it will be seen that the deck of the fuselage is raised considerably, bringing the pilot's head up to a level where he can look either over or under the top centre-section, the cockpit being so far aft that the small cut-out in the trailing edge provides an unobstructed view upwards. The gunner, being placed relatively far aft, has an excellent view in all directions. Features such as these, coupled with the good performance, ample stowage space and general simplicity of construction and reduction in maintenance cost, were doubtless instrumental in securing the order for "Wapitis" which the Air Ministry has placed with the Westland firm. At the moment it is rumoured that one of these machines is to be placed at the disposal of His Royal Highness the Prince of Wales, and it would probably be difficult to find a machine better suited to the carrying of a passenger whose life is so valuable to the Empire.

Constructional Features

   The fuselage of the Westland "Wapiti" is built up of three units, comprising the engine plate and first bay, the portion from the first bay to aft of the pilot's cockpit, and thence to the stern post. In the composite machine the first two units are of metal construction, the rear section having wood members and being braced by tie rods and, in places, by the plywood covering. In the all-metal machine the rear portion is also of metal construction.
   The first two fuselage units are built up of square-section drawn Duralumin and steel tubes, steel being employed for the most highly stressed members. The assembly of struts and longerons is by means of flitch plates, so that repairs are a relatively simple matter and require no very careful fitting by hand. At the joints the stresses are not taken on the butt ends but on the rivets, which are designed with sufficient bearing area to take the loads.
   As already mentioned, the rear portion of the fuselage is, in the composite machine, a wooden structure braced by tie rods. The top and bottom portions are covered with plywood, thus forming rigid members. The front portion of the fuselage is covered with aluminium sheet, with longitudinal corrugations to give stiffness. Where it is necessary to gain access to the interior of the fuselage or to the engine components, cowling panels are arranged to be detached by means of special flush-fitting clips.
   The wings of the composite type of machine are of normal construction, with spars spindled out to an I section and built-up wooden ribs of normal type. The interplane struts are of spruce, and streamline in section. If desired, the "Wapiti" can be supplied fitted with the new Handley Page automatic wing tip slots, which enable lateral control to be maintained in the stalled condition.
   The ailerons are of the Bristol-Frise type, in which the balance is obtained by locating the hinges some distance back from the leading edge of the aileron. This type of aileron is becoming very popular indeed, and is to be seen nowadays on a large number of British aircraft. In the "Wapiti" the ailerons are balanced statically as well as aerodynamically. In the all-metal type of machine, the wings and ailerons are of metal construction, but no details are available concerning the forms of construction employed.
   The tail units of the composite and all-metal types are interchangeable, and in both the front spar forms the hinge while the rear spar is actuated by the trimming gear, which gives a range of angular movement of 7 degrees. The rudder is of large area, and has a horn balance making it very light in operation.
   The undercarriage is of V-type, with the front legs acting as radius members and the rear legs telescopic. The front legs are circular section steel tubes with wood fairings, while the oleo legs are faired in by ribbed aluminium casings. Of the patented Westland oleo-pneumatic type, the telescopic legs are capable of having their capacity for absorbing shock varied according to the weight of the machine. Owing to the relatively low air pressures employed; this type of oleo leg has proved very satisfactory in use. There is no difficulty in keeping the legs airtight, and little attention is needed.
   The engine mounting in the "Wapiti" has been so designed that either the "Jupiter VI," the "Jupiter VIII," or the "Jupiter X" can be accommodated. The engine mounting is a flanged steel plate, to which is riveted a machined Duralumin face to form the engine bed. This bed is rigidly braced by a structure of square-section tubes which needs no attention after rigging. The installation is very accessible, and the mounting is simple, robust and free from vibration. All engine fittings are very accessible, as the cowling can be removed in less than two minutes. The fireproof bulkhead is located well behind the engine and allows plenty of room for working on the engine components.
   The engine can be started in three ways: Either by Hucks starter, by Bristol gas starter, or by sucking in by swinging the propeller and using the hand starter magneto. Alternatively, the Viet hand compressor starting system can be fitted.
   Under normal conditions of flying, the fuel supply is contained in two tanks, both located inside the fuselage ahead of the pilot's cockpit. The gravity tank has a capacity of 40 gallons and the main tank holds 68 gallons. The tanks are of welded aluminium, and the main tank is cylindrical and slung in straps anchoring it to curved aluminium brackets. To remove the tank it is only necessary to uncouple the pipes, take out two bracing wires, and after slackening the straps the tank can be slipped through the bottom of the fuselage. The gravity tank can be taken out of the machine through the top of the fuselage after the cowling is removed. The main tank feeds petrol to the gravity tank by means of a windmill-driven pump. In case of failure of this, the fuel is transferred to the gravity tank by a hand pump. For special long-distance flying a third tank of 23 gallons capacity is fitted. The oil tank is placed over the first bay of the fuselage, and the top surface is left exposed to the air for cooling and a five-element Vickers-Potts cooler is used. Normally, 11 gallons of oil are carried, but for long-distance flying the tank is filled up with 15 gallons.
  
Armament

   Armament for both defensive and offensive operations is carried. The former consists of a Vickers 0-303-inch air-cooled gun carried on an adjustable exterior mounting on the port side, and of a Lewis gun on a Scarff ring.
   The offensive equipment comprises bombs and bomb gear, with a course-setting bomb sight used by the observer in the prone position. The release of the bombs can be controlled from either cockpit. A total load of 580 lb. of bombs can be carried, the number and size of bombs within this limit being arranged as desired. The ammunition box for the Vickers gun holds 600 rounds in a belt, and for the Lewis gun, in the rear cockpit there are six magazines of 97 rounds each.
   For photographic duties an aircraft camera is carried in the bay behind the observer's cockpit. It operates through a rectangular hole in the floor of the fuselage.
   A supply of oxygen is available for pilot and observer, fittings being placed in both cockpits and the gunner having two points of supply, one for use when standing and the other for the prone position. The master control is in the hands of the pilot.
   The machine is equipped for wireless transmission and reception, the instruments being fitted inside the deck fairing aft of the observer's cockpit. The wireless compartment is open to the observer, and the folding seat is so arranged that it is usable when the observer faces aft. In this position a tapping key is within reach of his right hand. The generator is fitted on the starboard side and is therefore free from risk of damage by spent cartridges from the Vickers gun.

Long-Distance Equipment

   When the machine is required to undertake long flights over desert routes, for instance, additional fuel and oil with an increased complement of equipment are carried. Special provision has been made to carry the additional equipment, spares and rations entirely stowed inside the fuselage, the machine then carrying an extra 600 lb. above its normal load.
   The internal stowage of the equipment is a great point in favour of the "Wapiti," as no articles are carried outside where they would offer extra head resistance, and detract from the performance. The success of the design in this respect is brought out in the performance figures for normal and special load, from which it will be seen that the difference in speed at 10,000 ft. is only 3 miles per hour.
   The additional equipment consists of the auxiliary petrol tank and its fuel, a spare wheel, a spare tail skid, a fitter's tool box, engine spares, emergency rations, normal rations, water, personal equipment, bedding, etc. The whole of this equipment and the necessary structure for carrying it is easily removable, so that no extra weight is involved when the equipment is not required.

   Main Dimensions: Wing span, 46 ft. 5 in.; chord, 5 ft. 9 in.; wing area, 488 sq. ft.; gap, 5 ft. 10 3/8 in.; stagger, 1 ft. 4 in.; incidence, 3 degrees; dihedral, 3 degrees; length o.a., 31 ft. 8 in.; height, 11 ft. 10 in.; wheel track, 6 ft.
   Fuel and Oil Capacity: Petrol (normal), 108 gallons; oil (normal), 11 gallons; petrol (long-distance), 131 gallons oil (long-distance), 15 gallons.
   Weights and Loading: Weight of machine, empty, 2,644 lb.; fuel weight, 696 lb.; disposable load, 900 lb. Total loaded weight (with normal load), 4,240 lb. Total loaded weight (with long-distance equipment), 4,838 lb. Wing loading (normal), 8-7 lb./sq. ft. Wing loading (long-distance), 9-9 lb. /sq. ft.

Performance
   Normal weight. Long-distance.
   Altitude Rate of Climb Speed Rate of Climb Speed
   Ft. Ft./min. m.p.h. Ft./min. m.p.h.
   2,000 1,055 129 730 -
   5,000 1,050 133 760 130
   10,000 750 129 510 126
   15,000 480 123 270 118
   Service ceiling (i.e., height at which rate of climb is 100 ft./min.), 22,700 ft. The engine cannot be opened out fully below a height of 5,000 ft. Minimum take-off run, 95 yards; minimum distance to clear a screen 50 ft. high, 200 yards. Landing run, 126 yards. Landing speed, 50 m.p.h.
   Service ceiling, 18,800 ft. Take-off run, 166 yards. Minimum distance to clear screen 50 ft. high, 250 yards. Landing run, 169 yards. Landing speed, 53-3 m.p.h.

Flight, July 1928

THE WESTLAND "WAPITI”
One "Jupiter VI" Engine

   THE Westland Wapiti designed and built by the Westland Aircraft Works (branch of Fetters, Ltd.), Yeovil, can be supplied either as a composite wood and metal machine, or as an all-metal machine.
   It is suitable for bombing, reconnaissance, desert patrol work, photography, Army co-operation and advanced training.
   The armament consists of a fixed Vickers' type gun firing forward for use by the pilot, and a Lewis gun or twin guns carried on the scarff ring mounting over the observer's cockpit.
   Fuselage. - In the case of the composite machine the front portion of the fuselage is built up of square steel and duralumin tubes, while the rear portion is of wood, but in the all-metal machine the whole fuselage is constructed of square tube.
   Wings. - In the composite machine the wings are constructed of wood, and in the all-metal type they are built of steel strip. In both cases the wing covering is fabric.
   The ailerons are fitted with the Frise balance on all four wings.
   The tail units are constructed of wood in the case of the composite machine and duralumin in the all-metal type.
   Engine Installation. - The petrol is carried in the fuselage in a large cylindrical main tank fed to the engine by means of a Vickers' wind driven pump, and also in a tank feeding by gravity situated above the longerons. Provision is made for an additional tank, which can be very quickly fitted for long distance work.
   The engine mounting is built up of steel tube, and is so arranged that all parts of the engine are readily accessible.
   Undercarriage. - The undercarriage is of the Westland Oleo pneumatic type and has very good shock absorbing qualities. This type of undercarriage has been in use on many Westland machines and has proved very satisfactory.

Flight, July 1929

BRITISH AIRCRAFT AT OLYMPIA

WESTLAND AIRCRAFT WORKS

   THE Westland Aircraft Works, which are a branch of Petters, Ltd., will be represented at Olympia by three complete aircraft and one "Wapiti" fuselage, shown in skeleton. The three machines will be: One "Wapiti" General Purpose two-seater, with Bristol Series VIII engine, one "Westland IV" three-engined limousine, with three "Hermes" engines, and one "Widgeon" Mark IIIA light monoplane with "Cirrus" Mark III engine.

   The Westland "Wapiti" has now been in use with the Royal Air Force for some years, and has proved itself an unusually effective type of aircraft. Designed as a general purpose machine, the "Wapiti" has to carry a great deal of equipment, which not only means that its useful load has to be great, but also that the internal accommodation of the fuselage must be roomy, in order to enable all the various gear to be stowed away, and yet be readily accessible. Add to these requirements the fact that the performance must be good, and it will be seen that in the design of the "Wapiti" a good many problems had to be overcome. That the Westland designers have solved the various problems is proved by the fact that, in addition to large numbers now in service with the Royal Air Force, the "Wapiti" has been ordered in considerable quantities by the Royal Australian Air Force and the South African Air Force, as well as others.
   Originally, the "Wapiti" was designed as a mixed construction machine, but is now supplied as an all-metal aircraft, in which form it will be exhibited at Olympia. The fuselage construction makes use of square-section duralumin tubes, and in this connection, reference should be made to the skeleton fuselage which will be exhibited. This will be fitted with an Armstrong Siddeley "Jaguar" engine, and visitors to Olympia will have an opportunity to examine the typical Westland construction in detail on the skeleton fuselage. We gather that a "Jaguar"-engined "Wapiti" will be stationed at Heston aerodrome for demonstration purposes, so that potential purchasers may see and judge for themselves the capabilities of the machine.
   In the front portion of the "Wapiti" fuselage strut bracing is employed, the struts being, like the longerons, duralumin tubes of square section, and the joints between longerons and struts being made by means of flat flitch plates and tubular rivets. The strut ends do not bear upon the sides of the longerons, all bearing loads being taken by the tubular rivets. In the aft portion of the fuselage tierod bracing is used. The fuselage covering is fabric on the rear portion, but aluminium in front, the metal sheets being fluted at intervals of some 6 in. to give stiffness to the covering.
   It is perhaps indicative of the versatility of the Westland "Wapiti" that no less than three types of wings can be supplied with it. Some users still prefer the older type of wings of mixed construction, with wooden spars and ribs, mainly on account of the greater facility with which repairs can be carried out in service where the necessary plant for metal work does not exist. Then there is what may be termed the standard wing, which is of all-steel construction. This type of wing has been built, and is being built in large quantities for the "Wapiti" by the Gloster Aircraft Co., who had the plant and facilities already available when the orders for "Wapitis" became more numerous than could well be tackled by the Westland firm itself, at least at short notice. Extensions of the Yeovil works are now nearing completion, and when these are in working order doubtless all "Wapiti" wings will be made here. These will, in all probability, be of the third type of wing to which we have referred. This is a form of wing construction developed independently by the Westland technical staff, and uses duralumin as the chief constructional material. Finally, the "Wapiti" can be supplied fitted with Handley Page automatic wing-tip slots.
   Apart from the choice of wings which the purchaser of "Wapitis" now has, there is also quite a wide choice of undercarriages. The standard undercarriage is of the normal Vee type with cross axle. An alternative type with divided undercarriage and oleo legs is also available if this type is preferred, it being often argued that the "split" undercarriage is less likely to trip a machine up if it has to operate from aerodromes with long grass, etc. Then there is available for anyone who wishes to use the "Wapiti" as a seaplane a twin-float undercarriage with duralumin floats. And finally a ski type of undercarriage has been fitted for use on snow and ice. It will thus be seen that the Westland "Wapiti" has amply justified its title of General Purpose aircraft. Incidentally, while the complete machine at Olympia will have the cross-axle undercarriage, the skeleton fuselage will be fitted with the split type.
   As regards accommodation the "Wapiti" shows the usual seating arrangement, with pilot in the front cockpit, armed with machine gun with interrupter gear, and gunner-observer in the rear cockpit, which carries Scarff gun ring, etc. We cannot here go into details concerning the equipment normally carried by the "Wapiti," but it may be pointed out that the military load is high, no less than 1,108 lbs. This figure does not include fuel and oil, but does include the weight of the crew.
   Normally the tankage is for 600 lbs. of petrol and 100 lbs. of oil, but for desert work this can be increased to 996 lbs. and 150 lbs. respectively. The tare weight is 3,048 lbs., and the normal load 1,808 lbs. inclusive of fuel and oil. For desert work the military load can be increased to 1,436 lbs. giving, with the fuel and oil weight indicated above, a gross weight of 5,630 lbs. The normal gross weight is 4,856 lbs.
   The main dimensions of the Westland "Wapiti" are: Length o.a., 32 ft. 6 in.; ,wing span, 46 ft. 5 in.; height, 11 ft. 10 in.; wing chord, 5 ft. 9 in. Total wing area, 488 sq. ft. The wing loading at "normal" load is 9-95 lbs./sq. ft. and the power loading (at normal r.p.m.) 10-7 lbs./sq. ft. The maximum speed at 5,000 ft. is 142 m.p.h., and the cruising speed at the same height is 120 m.p.h. The climb is also particularly good. To 6,500 ft. in 6-4 mins.; to 10,000 ft. in 11 mins.; to 15,000 ft. in 15-2 mins. Service ceiling, 24,200 ft. Absolute ceiling, 25,700 ft.
   With "normal" fuel the duration is 1/2 hr. at ground level and 3 3/4 hrs. at 15,000 ft. With "desert" fuel these figures become 1/2 hr. at ground level and 4 3/4 hrs. at 15,000 ft.
<...>