FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1937
1937 - 0081.PDF
JANUARY 14, 1937. FLIGHT. 3i Seeking Stability THE formation of the upper and lewei wings of a biplane, described in Patent No. 450076, is claimed to increase stability in roll at and beyond the stall and also to give some increase in the maximum lift coefficient. The span of the wings is approximately the same, but the vertical distance between them decreases very greatly as the wing tips art approached, this effect being obtained by giving the lower wing a large positive dihedral angle. Secondly, the upper wing is more highly tapered than the lower one and, at the tips, the trailing edge of the upper one is in advance of the leading edge of the lower one.—Patent No. 450676: H. B. Irving. Silencing IN" order to reduce the noise of the exhaust, the exhaust gases are led to a fixed expan sion chamber and from there they are led to the airscrew, in which suitable channels are provided, and ultimately they emerge at a series of points on the blades. The size of the expansion chamber must be appreciable compared with the channels leading the gases into it or away from it. As the airscrew rotates a suction effect is produced, and this will be greater when the gases emerge near the tip of the blades. The novel feature is the introduction of the fixed expansion chamber in such a silencing sys tem— Patent No. 449187: B. Jablonsky. Mounting of Airscrew Blades THE method often used for the mounting of airscrew blades on a hub by means ol threading a thrust washer on to the root of the blade and upsetting the base of the latter to form a mushroom head with a shoulder of a small radius of curvature has disadvantages, since the mechanical strength of the root may be seriously im paired. This is particularly the case when the blades are made of light metal alloys. In this patent i s described a method of at tachment whic h eliminates this m echanical weakness and thus makes the blades better able to with stand the large centrifugal forces to which they are subjected. The root of the blade X has a reduced shank w«i< li is bored out and which merges into the body of the blade by a curve of large radius. A steel collar A is threaded over this shank, the end of which is then spread open by a punch so as to occupy the conical rarity of the collar. This causes only a slight curvature to the fibres of the root and produces no sharp curves to cause weak- ness.-/We„( #0. 452403: Soeicte d'Inven tions Acronautiques cl Mt'chaniques. The TREND ro An improved method of mounting metal airscrew blades. Airliner Chairs P ATENT No. 447327 specifies a, chair which is particularly suitable for use in passenger-carrying aircraft, whereby tne user can, without rising, make adjust- m»+1 S0 t-hat he may sit ^ an approxi mately upright position or in a full reclining desired'1' °r "* a"y iutermediat« Position vJhti incJination of the back can be attnri' ^'further, the box can be rigidly chai t0.the floor- ^en not in use the SMCP mDV.be folded t0 °«upv very little "",1S- l-td.. and H. Burchall. INVENTION Recent Aeronautical Patents Reviewed Servo Braking T HE type of brake marketed by the Ben- dix Company falls into the class re ferred to as the self-wrapping or servo type, since an increased braking torque is developed, due to the fact that the primary shoe acts on the secondary shoe with a force which is augmented by the drag of the drum on. the primary shoe, which is capable of a limited amount of circumferen tial movement. In this way a very power ful action is obtained. In view of the fact that, in aircraft, brak ing is required in only one direction of travel, a simplified design of brake has been evolved, and this is described in the present patent. The shoes are carried by a spider, one arm of which carries the pin to which the secondary shoe is anchored. The same arm also carries the wheel cylinder for the hydraulic actuation of the primary shoe, while other arms are provided for carrying stops to locate the shoes. The spider forms the sole support for the stops, the pin and the actuating means, and by this means is obtained a brake which is not only light in weight, but which is easy to assemble.— Patent No. 454330: BeiCdix Aviation Cor poration. Rotor Drives T , IE drive for the rotor of a rotative-wing aircraft through a clutch in which the maximum torque that can be trans mitted automatically decreases as the speed falls. A clutch of this type is a centrifugal fluid flywheel. By this provision overload ing of the rotor during starting is avoided. An arrangement is also shown whereby the clutch operating pedal, the wheel brake pedal, and the rotor brake pedal are so interconnected that the clutch can only be engaged when the wheel brakes are on and the rotor brake off, while the wheel brakes can be operated independently at all times.— Patent No. 447066: A. G. Coats and P. llajner. The Direct-start Autogiro M OST types of rotative-wing aircraft have, in addition to the engine and the airscrew, for lorward propulsion, means for connecting and disconnecting the engine with the rotor and also means for varying the pitch angle of the rotor blades. The last-mentioned operation is made in conjunction with the operation of the clutch between the engine and the rotor, the general sequence of events being as follows: The starting effort is applied to the rotor when the blade angle is very small, approximately zero, in order to obtain a high speed of rotation, which is also assisted by suitable gearing. The speed of the rotor is then higher than its normal autorotation speed. In this way kinetic energy is stored in the rotor. As the clutch is disengaged, means are provided whereby the pitch angle of the rotor blade is automatically increased, and the kinetic energy thus stored is capable of giving a direct lift to the aeroplane until sufficient forward speed has been obtained to give the normal autorotative effect. If the blade angles are altered too quickly there results a" violent upward acceleration of the machine, and the stored energy is utilised before the forward speed is suffi cient to give the desired autorotative effect, and as a consequence the aircraft will tend to fall again. The present patent provides a means of preventing this by the auto matic provision of a time lag in the pitch- changing operation. This is done by the introduction of a dash-pot arrangement and it is equally applicable to all types of pitch- changing devices whether these are mechani cal or automatic in operation. The dash-pot acts on the pitch-changing gear, but not on the clutch release.—Patent No. 452364: Juan de la Cierva. Metal Airscrews I N one form of airscrew the backbone of the blade is formed by a hollow central tubular member, to which sheet metal fairings are either riveted or welded. In order to give increased rigidity, light ness and freedom from panting to blades of this type, it is proposed to form the back bone by the use of laminated tubes or chan nel sections which have a knife-edge taper to give a gradual change of section. For example, three tapered tubes, of circular cross-section, terminate together at the root of the blade, the length of each tube being different. The shorter tubes fit inside the larger ones. The fairing is built up of sheet steel members which are riveted or welded to the backbone and the root of the blade is riveted between steel collars. The method of construction, in addition to giving the advantages outlined above, is very simple in manufacture.—Patent No. 45.2611: C. R Fairey Retractable Tail Wheels MEANS Of retracting a tail wheel are described in a Dowty patent whereby the whole unit, including the shock- absorbing strut and the castering gear, can be raised and lowered by hydraulic pressure. In the illustration the wheel A is carried by a forked member B which is attached to the inner member C of the shock-ab sorber unit. The outer member D of the shock-absorber unit is anchored to the air craft and is capable of rotating about a horizontal axis E. This rotation is effected by the movement of the piston rod F, which is connected through a link mechan ism to,the lever G, which is integral with the fixed spindle. Fluid under pressure is admitted to one side of the piston or the other, depending on whether it is required to raise or lower the wheel. A device for locking the wheel in the verti cal position is provided, the pin H entering a hole in a locking plate which has an inclined ramp. The pin is spring-loaded and is re leased by hydraulic pressure when pressure ' is admitted to the main operating cylinder in such a direction as to raise the tail wheel unit. The areas of the t w o pistons are so arranged that the lock ing pin is first with drawn before retraction takes place. — Patent No. 4542/9- G. H. Dowty. The Dowty hydraulically retracted tail wheel. [Latest specifications are listed on page 46.]
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
