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Aviation History
1929
1929 - 0594.PDF
FLIGHT, MARCH 21, 1929 THE "HELICOGYRE" The Inventor explains his Machine to the R.Ae.S. ON March 18, Signor V. Isacco read before the Royal Aero- nautical Society a paper dealing with his invention, the " Helicogyre," which is being taken up by the Air Ministry, and of which one specimen is now nearing completion at the Cowes works of S. E. Saunders. With the greater portion of Mr. Isacco's paper we have not the space to deal here. A large section of it dealt with the history of rotating wing flight, and the lecturer gave his views of the reasons for the failure or comparative failure of the various types that have been built from time to time. The lecturer explained that he had called his machine the " Helicogyre " because the rotation of the wings is* caused, not by the air forces on them as in the Cierva " Autogiro," but by propellers driven by engines mounted on the main wings. In the " Helicogyre," the lecturer stated, sustentation is by two or more wings, individually articulated in all directions to a common hub, turning freely around a practically vertical axle. At the ends of each of these wings are mounted small engines with their airscrews to cause the rotation of the wings in all normal conditions of flight. The petrol tanks for the small wing engines are fitted inside the wings, each engine having its own tanks and feed. The sustaining wings have ailerons forming part of their trailing edges, these ailerons acting as elevators on an aeroplane by changing the incidence of the wings. (Actually they alter also the camber.—ED.) The lecturer stated that articulation not only in the direction of lift but also in the direction of drag was necessary to prevent the breaking off of the wings at the point where they join the central hub, and where there are changes of load due to periodic variationr; in the drag force. The claim was advanced that the efficiency of the " Heli- cogyre " is greater than that of other rotating wing machines because, owing to the fact that the axis of rotation is vertical, the component perpendicular to the plane of rotation is avoided, and this component, he claimed, was the cause of the low efficiency of the rotating wing with inclined axis. Calculations (not given in detail) showed that in the " Helico- gyre " the ratio of lift to drag was not greatly different (about 5 per cent.) from that of the orthodox aeroplane with the same profile and angle of incidence. Accepting as one of the essential conditions for a vertically- flying aircraft that it should have (a) inherent stability, and (b) controlled stability, the lecturer claimed that, thanks to the articulated wings, the " Helicogyre " possesses (a), while (fc) was achieved, when hovering, by small surfaces fitted between the main wings and firmly attached to the machine. The reason for the placing of the small engines on the wing tips instead of half-way was explained to be due to the better propeller efficiency of the engines where. their path was longest, i.e., where the translational speed was greatest. It was, Mr. Isacco said, possible to use wing engines running at 4,000 to 5,000 r.p.m. Also by placing them at the tips, the engines would, by their weight, serve to damp out to some extent the vertical oscillations of the wings caused by variations in pressure (i.e., according to whether their velocity is added to or subtracted from the horizontal velocity.—ED.•> Weight Lifted per Horse-Power Giving figures of machines of the " Helicogyre " type already built, the lecturer stated that machine No. 1 (French Governmenti lifted 1,875 lbs. with 100 h.p. of wing engines in spite of the fact that the 50 h.p. Anzani engines were in the middle of the wings, and that therefore the efficiency of their propellers was not more than 60 per cent. Machine No. 2, with two wings, each carrying a Bristol " Cherub " of 32 h.p. weighed 1,320 lbs., and rose into the air several times using only 50 h.p. The lecturer estimated that with four wings and four engines a weight of 30 Ibs./h.p. could easily be lifted, and with improved wing design he thought that an even greater load could easily be lifted. THE " HELICOGYRE " : Fig. 1 shows, diagrammatically, the general ^arrangement. In 2 are shown the small control surfaces, s, by means of which the machine is controlled when there is no translational speed, i.e., when the machine is hovering. 3 shows Signor Isacco's idea of the jet-propelled "Helicogyre" of the future. ; • •"-• •- .: ' 244 - , • '.-.. -. • •
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