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Aviation History
1947
1947 - 0812.PDF
474 FLIGHT M*y 22ND, 1947 (Right) Details of the operation of the dual push-pull control wheels. PERCIVAL MERGANSER WLERONS (Left) This drawing of the long under- carriage compactly folded into its com- » partment behind \the engine may be compared with the main illustration with wheels down, seen from the same angle. The non-steerable nose wheel folds up under the cockpit floor. The sturdy nature of the com- poaents and the stiffening-up of the airframe to support them is apparent. controls on the Gipsy Queen 51s. The main machined forgings, to which are attached the engine mountings, are placed on the rear side of the bulkhead, and they carry, in addition, lugs for the undercarriage members. Complete accessibility is given to the tightly cowled engines by detachable panels, and the unit is designed for quick removal complete with its oil tank and cooler. Reversible-pitch constant-speed D.H. airscrews are fitted, and provision is made for blade de-icing. On high-wing machines the main undercarriage legs are apt to become unwieldy, but the Messier (Electro Hydraulic Ltd.) design for the Merganser tucks away very well and is very neat in the extended position. The three wheels are retracted pneumatically and the main pair are each carried on a single oleo-pneumatic leg. Of-the three air bottles in the roof of the luggage compart- ment, two are for normal service and one for emergency use. The nose wheel, non-steerable but free to swivel, folds rearwards, and the main wheels fold forwards then upwards. In both cases the doors are mechanically closed over the wheels. Undercarriage Fittings Fittings for the legs are .attached directly to the rear main spar, and when down, the legs are vertical. A drag, strut hinged a little below the folding point of the leg, extends forward to a cross member picking up on lugs on the lower ends of the engine mounting brackets. On the prototype, the main undercarriage legs are attached to large one-piece H-form castings, but on pro- duction machines some ingenious design development will enable a great deal of expense and time to be saved. Although all four uprights of the two H castings differ, one channel forging can be used as the basis of each, and a pair when machined can be built up with a front and a rear plate to replace the casting. This buirt-up unit is shown in the main drawing. The tail portions of the engine nacelles are small separate units while the centre sections, housing the wheels, are of good stiff construction based on channel and 2-section stringers and Z frames. A full complement of instruments, including a com- plete blind-flying panel, is fitted to the Merganser, and provision is made for an automatic pilot, Decca navigator, and radio equipment up to 100 1b in weight. Windscreen wipers may also be fitted. Other equipment worthy of special mention includes fluorescent cockpit lighting, a taxying light in the nose, cabin heating by combustion heater, and the provision of an A.S.I., altimeter and clock on the front cabin bulkhead for the benefit of passengers. The announcement of the delay in production of Mer- gansers because delivery of Gipsy Queen 51 engines has fallen behind schedule, is disappointing. However, this will mean that work can proceed faster with the larger capacity model P.50 which is similar in layout and is powered with Alvis Leonides engines. In the meantime the prototype Merganser will be thoroughly flight-tested, and upon resumption of work, production should proceed without interruption for modifications. In view of the simi- larity of the Merganser and P50 Prince, flight testing of the Merganser, which has now started, will supply a good deal of aerodynamic and constructional data for the slightly larger machine as well. The table of alternative loadings and ranges shows that from basic figures of 5 passengers + 300 lb luggage + 1 crew for 800 miles range, the addition of each passenger or crew member would reduce the range by 200 miles. With 8 passengers and 1 crew 300 miles range is still pos- sible with 200 lb of luggage, or 500 miles without luggage. A useful arrangement would be 7 passengers, pilot, 300 lb luggage and 400 miles range. Freight alone can be tarried up to 1,350 lb for 800 miles or 1,825 lb for 300 miles. PERCIVAL MERGANSER DATA (de Havilland 29* h.p. Gipsy Queen SI) r All-up weight 6.7001b Disposable load 2,1101b Wing loading ... 21 Ib/sq ftPower loading ll.3Slb/h.p. Speeds :Max. atS.L 180 m.p.h. Max. at 5,0OOft 193 m.p.h.Max. cont. cruising at 5,000ft ... 183 m.p.h. Max. econ. cruising at S.L 150 m.p.h.Max. econ. cruising at 5,000ft ... 160 m.p.h. Max. econ. cruising at 8,000ft 7 m.p.h. Stalling (flaps down) , S?^-,p-h' Climb at S.L •°!P£;min 5,000ft I.IOOft/min Service ceiling (approx.) 24,000ft Duration at 5,000ft -A1"*.1!1"8 Hange 800 miles Take-off run to clear 50ft, still air, S.L 560 yd
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