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Aviation History
1951
1951 - 0126.PDF
FLIGHT, 18 January 1951 THE HELICOPTER ... main blades in such a way that any extension of the auxiliary blades results in an increase in pitch of the main blades. By suitable choice of springs and linkage the designer has achieved a constant-speed rotor in which collective pitch is always properly co-ordinated with throttle opening. The pilot has an override collective pitch lever which controls the radial displacement of the blades. The control system is novel in that vertical and horizontal tail surfaces mounted within a ring cowl, and in the slip- stream from an ordinary fixed-pitch airscrew, provide torque compensation and directional and longitudinal con- trol. The torque compensation is automatic, since the de- flection of the vertical surfaces is controlled by a hydraulic torque-measuring device on the rotor mast. Lateral control is obtained by displacing the rotor head on a parallel linkage, and a similar movement in the fore-and-aft sense is used to trim for varying eg. position. The other point of interest is the blade construction. Each blade, which is of constant chord from root to tip, is built up of a solid duralumin spar and duralumin ribs, with a duralumin-sheet skin. These components are assembled by clamping together, and no bolts or rivets are used except at the hub attachment-fitting. This gives an exceedingly simple construction adapted to mass production by unskilled labour, and a blade which is good from the fatigue point of view. The S.N.C.A. Sud-Ouest have devoted their attention to the jet-propelled rotor, and have built two experimental two- seaters using the central-pressure method of providing the reaction jets at the blade tips. The second model weighs 2,475 lb with a useful load of 880 lb, and the engine that drives the compressor develops 200 h.p. A further three- seater model, intended as a general-purpose type, is under development. In this case the compressor is driven by a small 200 h.p. gas turbine, so increasing the useful load to the very high figure of 57 per cent. Helicopter development had started in this country before World War II. Substantially at the same time, and quite independently, the firm of G. and J. Weir had built and flown a small side-by-side twin rotor helicopter employing exactly the same principles as the Focke-Achgelis Type Fa 61, which is usually looked upon as being the world's first practical helicopter. Further development in a bigger size was proceeding but had to be abandoned early in the war. In 1945, when technical resources again became available, the Ministry of Supply sponsored a programme covering three sizes of helicopter: the Bristol 171, a four-five-seater of 5,220 lb gross weight with a 500 h.p. Leonides engine; the 173, a 12-14-seater weighing 10,000 lb and using two of the type 171 rotors and power units in a tandem configuration; and the Cierva three-rotored Air Horse, of 17,500 lb gross, of which 4,500 lb is payload when carrying fuel for a range of 140 miles. Artists' impressions of the Bristol 173 have appeared in recent issues of Flight (December 28th and January 4th) and the other two machines have been fully described and do not call for comment here. The significant point to note in this programme is that all three sizes were obtained without the need for going outside existing know- ledge by having to explore the problems of increasing rotor size. Thus, all the rotors were within the range of 48ft to 52ft diameter, thus catering for between 5,000 lb and 6,000 lb lift per rotor, and the basic unit weight was doubled or trebled by using two or three rotors. In addition to these three types, the Fairey Aviation Co. exploited the Gyrodyne principle as a private venture. Currently, the Bristol 171 is in small production, the Bristol 173 is reported to be in the final assembly stage and should shortly begin flight trials, and the Air Horse is continuing development trials. The Air Horse in its present form is only single-engined, but in conformity with the British view that the helicopter for civil operation between city centres must be multi-engined, various twin-engined development layouts are being studied. The jet-propelled helicopter is recognized as an important future development and, while no disclosure of activities in this direction has been made, it is understood that several constructors are engaged in developing more efficient jet devices for application to rotor blades. PLANING-TAIL HULL TNCREASED safety for amphibious aircraft while waterborne,•i and improved flight performance, are claimed as a charac- teristic of the newly developed N.A.C.A. " planing-tail" hull, asa result of water and flight tests conducted by Goodyear Aircraft Corporation. For the tests, the hull of one of Goodyear's GA-2 amphibianswas converted to incorporate the deep, pointed step and long afterbody characteristics of the planing-tail hull. The new-typehull is incorporated in the latest Goodyear- GA-22. „ VAMPIRE MK. 53 THE name Mistral has been conferred on the S.N.C.A.S.E.-built Vampire Mk. 53, developed from the Mk. 51 and similarly powered with the Hispano-Suiza-built Rolls-RoyceNene. In the development of the type collaboration of S.N.C.A.S.E. with de Havilland, Rolls-Royce and Boulton Paulhas been richly rewarded. Almost entirely French-equipped, the Mistral has an ejector seat, and should prove 46 m.p.h. fasterat sea-level than the Mk 51. Rate of climb should be improved by 35 per cent. THIRTY YEARS of GOODWILL MR. H. ("JERRY") SHAW, of the Shell Petroleum aviationdepartment, was recently presented with a memento "as a token of affectionate appreciation of over 30 years' unstintinghelp given to his fellow aviators." Some 200 of his friends in the aviation world—mainlyairline executives, pilots and ex-pilots—subscribed; they also signed their names in a book which, with the trophy, was handedto Mr. Shaw by Mr. J. W. S. Brancker of B.O.A.C, at a party given at the Royal Air Force Club3 with Sir Alan Cobham ashost. The idea originated with Maj. Woods Humphrey, ImperialAirways chief from 1924 to 1938, who referred to Jerry Shaw as "the most skilful aerial hitch-hiker of all timei" Thememento is in keeping with that sentiment; executed in bronze, it consists of a hand making the hitch-hiker's sign and bears theinscription "That's Jerry, that was." The rather modernistic hand, actually, is a doubleone, suggestive of the head in the famous Shell adver-tisements associated with the slogan. At the presentation to "Jeriy " Shaw, referred to above : (Left to right) The recipient, with \ memento; Mr. J.W.S.Branker, \ and Captain Gordon Store (B.O.A.C.); Major J. L. B. H. Corde$(G.A.P.A.N.), Copt.john Stocks (M.C.A.), Mrs. Cordet.
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