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Aviation History
1937
1937 - 0039.PDF
JANUARY 7, 1937. FLIGHT. 15 V.P. Airscrews WHEN variable-pitch airscrew blades are made of a light alloy it is usually found that the metal is too soft to accommodate the thrust and journal bearings between the root of the blade and the hub. It is therefore necessary for a sleeve of some harder metal, such as steel, to be fitted over the root of the blade, and this sleeve must be securely locked to the lighter metal of the blade. A form of construction by which this can be done is described in this patent. The sleeve has on its internal surface a coarse-pitch thread of rounded profile, and this is screwed on to the root of the blade. To the end of the blade a plate is attached by means of a number of screws, and around the edge of this plate are a series of serra tions which fit into corresponding serrations at the end of the metal sleeve. This system of construction provides a locking method in which the strain is dis tributed throughout a large mass of metal and in which high localised pressure in the soft metal is avoided. Further, although the sleeve is securely attached to the blade and any movement between it and the end of the blade is prevented during operation, nevertheless it can be easily detached and dismantled when this is required.—Patent No. 451518: A. G. Elliott, A. A. Rubbra and L. G. Farrhurst. Mixture Cooling MEANS for cooling the supercharged air or mixture of a radial engine, and so increasing its volumetric efficiency, are described in this patent. The illustra tion shows a portion of a nine-cylinder The Bristol mixture-cooling manifold. radial. Two of the cylinders are indicated at A and B, and surrounding them is an annular induction manifold which has an unobstructed bore and which communicates direct with the inlet ports as shown at C and D. At the rear of the crank case is the blower casing E, which contains a centri fugal compressor. Between each cylinder, connecting the blower casing with the annular induction manifold, are a bank of tubes F through which the supercharged air or mixture passes. The position of the tubes affords adequate cooling and, further, the arrange ment of the piping minimises the pressure drop between the compressor and the cylin ders.—Patent No. 450047: Bristol Aeroplane Company, Ltd., A. H. R. Fedden and T. B. Barrington. Boost Control T HE system cf controls described in Patent No. 447324 relates to systems in which a supercharger is driven through a two- speed gear and in which there is an auto matic control of the throttle opening that depends on the pressure generated by the supercharger. In such cases an over-riding control is provided whereby the pilot can, lor short periods, open the throttle irrespec tive of the boost pressure. Various forms are described in this patent to make this over-riding device inoperative during the time that the supercharger is driven at the higher speed. Several ways in which the various controls The TREND of INVENTION Recent Aeronautical Patents Revived can be interconnected are shown, in some of which the automatic control of the maxi mum throttle opening is cut out when de sired, provided the supercharger is beiny driven at the low speed.—Patent So. 447324: A. A. Rubbra. Automatic Steering AN improvement in automatic piloting apparatus is described in this patent, which relates to the system de scribed in an earlier patent No. 410813). In this scheme the rudder and other con trol surfaces are actuated by a hydraulic servo motor which is controlled by the rela tive movement between the aeroplane and a gyroscope. Arrangements are also pro vided whereby the controls can be manually operated, at will, without any interference from the servo-motors. Means are now provided to assist the pilot in obtaining manual control at any moment and to enable him to do so no matter what the setting of the automatic control may be, or even if the automatic control has ceased to function. Previously the pilot was able to cut out the automatic control by turning a by-pass valve and so by-passing the oil pressure. Should tins throw-out means fail or become inoperative, another valve is provided in the system which enables the pilot to assume control. This latter valve is a safety valve which operates at a pressure slightly in ex cess of the normal working pressure. If the pilot attempts to operate the controls manu ally, he will, by exerting sufficient force, cause this safety valve to open, so permit ting the operation of the desired control.— Patent No. 455673: Sperry Gyroscope Com pany, Inc. Retractable Undercarriage THE landing wheels of an aeroplane are in some cases carried by a leg which consists of two hinged members, one of which forms the shock-absorber unit, the other being a link of fixed length. A sys tem of retraction for this type of under carriage is described in patent No. 452324. The wheel is mounted to the lower end of the shock-absorber strut A. The upper end Vr-- of this strut is hinged to a short rigid strut B, which in turn is hinged to the aircraft. A link C also connects a point on the shock-absorber cylinder A to a fixed point on the aircraft. The lifting jack D is con nected to the aircraft at one end, while the other end is connected to the lower portion of the shock-absorber unit. Extension of the jack causes the under carriage linkage to pivot about the three points above referred to (and it is guided during its retraction by the directing bar C) until it assumes the position shown by the dotted lines. When the undercarriage is in the lowered position the jack helps to lock the system while allowing the shock absorber to func tion in its normal manner.—Patent No. 452324: Socie'td d'Inventions Aeronautigues et Mechaniqnes. Wing Structure FOR an improved form of wing structure the inventors claim increased rigidity with the minimum of weight, together with a method of attachment to the fuselage which is rigid and not deformable, and therefore capable of resisting torsional stresses. Many variations of the invention are de scribed in the specification, but a typical one is shown in the illustration. The main spar is shown at A and is located in line with the centre of main stresses and at a A French retractable undercarriage layout. Morane-Saulnier wing construction system. distance from the leading edge equivalent to one-third the width of the wing. A second spar B is fitted at the trailing edge and may form the hinge support for the aileron I. Between these two spars, trian gular bars C are fitted to form a trussed girder construction enclosing triangular cells. Points D, E and F represent points of attachment to the fuselage. This three-point method of attachment is an important feature of the invention, since the fact that they do not lie along a straight line ensures the rigidity of the whole of the aeroplane. The structure greatly facilitates the work during construction and also reduces the risk of beats or vibrations being set up in -the wing. — Patent No. 450729: Aeroplanes Morane-Sauhuer, Soeiete Anonyme de Con structions Aeronautiques. Bomb Traps I X the type of release gear for bombs in which a radius rod is used.to guide the bomb during its early movement, which system was described in Patent Nos. 416884 and 419563, there is in some cases a possi bility of the radius rod fouling the edges of the doors of the chamber containing the bomb and thus preventing the doors from closing again after the bomb has been released. In the present specification a mechanism is described whereby the doors are auto matically opened before there is any possi bility of the radius rod fouling them, and, further, they remain open until the rod has been withdrawn. These results are effected by a cam mechanism, and the radius rod is returned by a spring which is so arranged to act as a spring check if the rod tends to overshoot its normal position on the return stroke.—Pal cut No. 448736: Sir W. G. Armstrong-Wtiitwotth Aircraft, Ltd.. and 5. W, D. LorltK'ood. Tcont. overleaf
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