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Aviation History
1928
1928 - 0503.PDF
JUNE 21, 192s The engine mounting in the " Wapiti " has been so designedthat either the " Jupiter VI," the " Jupiter VIII," or the " Jupiter X " can be accommodated. The engine mountingis a flanged steel plate, to which is riveted a machined Duralumin face to form the engine bed. This bed is rigidlybraced by a structure of square-section tubes which needs no attention after rigging. The installation is very acces-sible, and the mounting is simple, robust and free from vibra- tion. All engine fittings are very accessible, as the cowlingcan be removed in less than two minutes. The fireproof bulkhead is located well behind the engine and allows plentyof room for working on the engine components. The engine can be started in three ways : Either byHucks 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 con-tained in two tanks, both located inside the fuselage ahead of the pilot's cockpit. The gravity tank has a capacity of40 gallons and the main tank holds 68 gallons. The tanks are of welded aluminium, and the main tank is cylindricaland slung in straps anchoring it to curved aluminium brackets. To remove the tank it is only necessary to un-couple the pipes, take out two bracing wires, and after slacken- ing the straps the tank can be slipped through the bottomof the fuselage. The gravity tank can be taken out of the machine through the top of the fuselage after the cowling isremoved. The main tank feeds petrol to the gravity tank ing aft of the observer's cockpit. The wireless compart-ment is open to the observer, and the folding seat is so arranged that it is usable when the observer faces aft. Inthis position a tapping key is within reach of his right hand. The generator is fitted on the starboard side and is thereforefree from risk of damage by spent cartridges from the Vickers gun. Long-Distance Equipment When the machine is required to undertake long flightsover 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 thefuselage, the machine then carrying an extra 600 lb. above its normal load. The internal stowage of the equipment is a great pointin favour of the " Wapiti," as no articles are carried outside where they would offer extra head resistance, and detractfrom the performance. The success of the design in this respect is brought out in the performance figures for normaland 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 petroltank 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 iseasily removable, so that no extra weight is involved when the equipment is not required. THE WESTLAND " WAPITI Three-quarter rear view. The particular machine illustrated is fittedwith Handley-Page slots. by means of a windmill-driven pump. In case of failureof this, the fuel is transferred to the gravity tank by a hand pump. For special long-distance flying a third tank of 23gallons capacity is fitted. The oil tank is placed over the first bay of the fuselage, and the top surface is -left exposedto 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 iscarried. The former consists of a Vickers 0-303-inch air- cooled gun carried on an adjustable exterior mounting on theport 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 controlledfrom either cockpit. A total load of 580 lb. of bombs can be carried, the number and size of bombs within this limitbeing arranged as desired. The ammunition box for the Vickers gun holds 600 rounds in a belt, and for the Lewisgun, in the rear cockpit there are six magazines of 97 rounds each. For photographic duties an aircraft camera is carried inthe 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 theother for the prone position. The master control is in the hands of the pilot. The machine is equipped for wireless transmission andreception, the instruments being fitted inside the deck fair- Maiv Dimensions : Wing span, 46 ft. 5 in. ; chord, 5 ft.9 in. ; wing area, 488 sq. ft. ; gap, 5 ft. lOf in. ; stagger, 1 ft. 4 in. ; incidence, 3 degrees ; dihedral, 3 degrees ; lengtho.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 1b.; fuel weight, 696 lb. ; disposable load, 900 lb. Total loadedweight (with normal load), 4,2401b. 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. Altitude. Ft. 2,0005,000 10,000 15,000 Performance Normal Rate of Climb. Ft./min.1,055 1,050 750 480 weight. Speed. m.p.h. I129 133 129 123 Long-distance. Kate of Climb. •t./min.730 760 510 270 Speed m.p.li— 130 126 118 Service ceiling (i.e., height at which rate of climb is100 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. Mini-mum distance to clear screen 50 ft. high, 250 yards. Landing run, 169 yards. Landing speed, 53-3 m.p.h. 459
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