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Aviation History
1947
1947 - 0308.PDF
2OO FLIGHT MARCH'6TH. Percival Programme New P.50 Medium Transport with Leonides Engines Announced CE most other companies in almostevery industry, Percival Aircrafthave had to reshuffle their produc- tion programme to suit the ever-changingposition regarding material supplies, dates for delivery of components and thelike. It was originally planned to get thePrentice and Merganser built, tested, and in the air as soon as possible. Production of the Prentice has now com-menced, and numbers will build up rapidly as the Luton factory gets into its stride, and as Blackburn productionof Prentices starts up at Brough in a few weeks' time. The Merganser should have flown before Christmas, but theParis Show caused some delay and the difficult period since then has further upset the schedule. However,although the completed prototype Merganser waits upon the weather to begin its trials, a further big blow has fallen inthe form of a serious delay in delivery of Gipsy Queen 51 engines. No alternative power units exist in this countryat present, so Merganser production*must be held up, pos- sibly for as much as ten months. In consequence of this delay, a new Percival mediumtransport, similar to but rather larger than the Merganser, has been announced. To be known as the P.50, this air-craft was originally to have been introduced in the autumn, but design work was well advanced and Alvis Leonidesengines can be made available for it; construction will, therefore, start immediately. To simplify production and keep costs down, Mergansercomponents will be used wherever possible, and the fuse- lage in particular will be very similar in construction anddimensions. The P.50 was planned for simultaneous pro- duction with the Merganser in 1948, and this intentionwill still, if possible, be fulfilled, but whereas the P.50 was to profit from experience of all kinds with its small relation,the process will now be reversed. New Wing Construction With the object of reducing the time taken for design—in particular for stressing—on the Merganser, the proto- type has been built with a straight-forward, two-spar,multi-rib wing. A rather different wing construction was to have been introduced on production machines as soonas possible. Now, the first example of the lighter, sim- plified, single-spar construction will be seen on the proto-type P.50. A rather heavier gauge skin will be used which, stiffened with spanwise stringers, will be made todo more of the work previously given to .a second spar and close-pitched ribs. Externally the P.50 will look very much like a Mer-ganser with greater wing span. The increase of ten feet results from a wider engine bay, and wider spacing ofengines to give sufficient clearance for the larger airscrews. Good features of the high-wing, nose-wheel Merganserlayout, such as the roomy cabin with level floor, and large doors and windows will, of course, be retained on the P.50. From the accompanying g.a. drawing "the square-cutwing tips and straight leading and trailing edges are apparent. The extension of the larger engine nacellesbehind the trailing edge may also be seen. The Leonides engines each develop 505 h.p. for take-off, and are fittedwith constant speed, feathering and braking airscrews with provision for blade de-icing. Four flexible bag tanks placedin the wings provide a fuel capacity of 140 gallons. For the size of the aircraft, the single main wheels nowappear rather small, but it will be noticed that twin nose wheels are fitted. In contrast to the Merganser fuselageof the same main dimensions, the windows are arranged rather differently, and the freight compartment on the P.50is located behind the cabin, therefore no front fuselage door is required. Estimated figures for performance suit the requirementsof an 8/10 passenger feeder-line or charter aircraft, and compared with the Merganser the top speed is improved byabout 25 m.p.h., and cruising speeds by 10 to 15 m.p.h. The take-off and initial climb figures are also rather better,and the all-up weight of 9,600 lb is 2,900 lb greater. Per- formance figures and dimensions are given in the tablebelow, and on the G.A. drawing. It is hoped that the P.50 will fly this summer. PERCIVAL P.50 DATA Two Alvis Leonides 505 h.p. engines All-up weight 9.600 1b Disposable load 3,260 1b Wing Area 365 sq ft Wing loading 26.3 Ib/sq ft Power loading 9.5 Ib/h.p. Cabin length 15ft ,, width ... ... ... ... ... ... ... 5ft 6in ,, height 6ft Luggage compartment 61.5 eu ft Maximum speed at sea level ... ... ... .... 206 m.p.h. „ 6.000ft 223 m.p.h. Cruising speed. 50 per cent power, S.L 164 m.p.h. 6,000ft 170 m.p.h. Cruising speed, 70 per cent power, S.L 183 m.p.h. 6,000ft 195 m.p.h. Stalling speed (flaps down) 74 m.p.h. Rate of climb, S.L l,l20ft;min ,, 6,000ft l,l60ft/min Service ceiling (approx) 25,000ft Take-off, still air, S.L., to clear 50ft 500 yd Duration at 6,000ft 4.8 hr Still-air Range 816 miles LATEST CYCLONE Over 1,500 h.p. from a Nine Cylinder Radial F. just over twenty years of development the power outputof the Curtiss Wright Cyclone 9 has been increased from 400 to 1,525 h.p. This new high figure for maximum poweris produced by the latest Cyclone gHE which is announced^* as the successor of the 9HD now found in military aircraft s''f»^^'as the Ryan Fireball and in particular in the DC4 transport. The new high power figure is attained through the use of waterinjection, or by using 122/145 grade fuel, and the power unit is to be fitted in the Curtiss Wright CW32 freight aircraft. The water injection system is particularly light and corn-pact and is brought into operation automatically by a manifold pressure regulator. A 50:50 water/alcohol mixture is injectedinto the induction system from two small nozzles positioned just past the carburettor. Like other late models of Cyclone, the 9HE has a forgedaluminium alloy cylinder head with very deep finning and W- type alloy cooling fins clasped tightly around the steel barrel.The 9HE must now be the most powerful 9-cylinder aircraft engine and have the highest power to weight ratio so farachieved for a radial engine. ;.:"
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