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Aviation History
1944
1944 - 2107.PDF
OCTOBER 12TH, 1944 FLIGHT 403 Helicopter News American Firms and Indi* viduals Challenge Sikorsky*s Lead : Superimposed and . Side * by - side Rotor Systems Represented FROM time to time we have recorded the almost feverish efforts being made by American designers to bring to a practical stage of development the direct-lift type of aircraft. Igor Sikorsky has a long start over his competitors, and although his many years of association with the numerous problems must have given him an accumulation of ex perience hardly likely to be shared by the more recent venturers into this difficult field, the newcomers are ^ undaunted and obviously determined to challenge the virtual monopoly which Sikorsky's long-standing develop ment work has created. The'result of so much activity can hardly fail to hasten progress and to bring nearer the day when the helicopter can be handed over to pilots of medium skill. At the moment that is not so. Line of Least Resistance It will be remembered that when Mr. Pullin started experiments with the Weir helicopters in Scotland, he chose the side-by-side rotor arrangement as lending^ itself more ea'sily to rotor research by avoiding the torque-reaction problems of the single-rotor type. In America the same arrangement has been used in the Platt-le Page helicopter which has been undergoing trials at Wright Field. The most obvious external difference between the Weir and the Platt-le Page helicopters seems to be that the outriggers of the latter are well streamlined. That would be explained by the fact that the Weir was simply a flying test bed for the rotors, while the American machine is obviously intended to be something more. The outriggers appear to be of wing section and probably :ontribute a certain amount of lift at forward speeds. We have no information on the point, but it would appear that the Piatt of the Platt-le Page combination is the same designer who some years ago produced a helicopter in which *T paddles were used instead of rotor blades. This was about the time when Rohrbach in Germany designed a some what similar lifting system. The Californian helicopter, designed and built by a The Hiller helicopter has two-bladed, superimposed, contra- rotating rotors of 25ft. diameter. The Platt-le Page side-by-side rotors are carried on streamlined outriggers, almost of wing shape. A Sikorsky R-S fitted with stretchers on the sides for carry ing wounded from inaccessible battle areas. 19-year-old engineer, Stanley Hiller, employs two-bladed superimposed contra-rotating rotors. This arrangement re duces or eliminates the torque- reaction problem, but is-said to reduce the rotor efficiency. Also it is to be expected that special precautions must be taken to ensure that the flap ping blades of * upper and lower rotors do not strike one another. Rotor diameter of the Hiller helicopter is 25ft., and the maximum speed is re ported to be in the neigh bourhood of 100 m.p.h., while the machine cruises at about 75-80 m.p.h. The duration is i£ hours.
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