GB488820A - Improvements relating to anti-icing devices for aircraft - Google Patents

Abstract

488,820. Electric heating of aircraft wings. PIDEAU, J. R., and DUCRET, A. M. Nov. 5, 1937, Nos. 30433, 30434, and 30435. Convention dates, Nov. 6, 1936, April 30, 1937, and Oct. 21, 1937. [Class 4] [Also in Group XI] Ice formation on parts of aircraft, such as the leading edge of the wings, is prevented by mounting thereupon a superficial electrically conductive covering from which heat is evolved by the passage of an electric current therethrough, in contact with the parts concerned or with a sheet of heat or electrical insulation thereon, the covering being exposed to the air. The electrically-conducting covering 1 may comprise a layer of a carbon or metal suspension in a suitable liquid, to which a small proportion of gum arabic or sodium silicate may be added, or a fine mesh wire cloth such as 100-250 mesh per sq. cm., or a very thin metal sheet such as produced by spraying metal, e.g. aluminium, nickel-chromium alloy, constantin, or tin, on the part to be protected. Suitable metal particles for the suspension comprise constantin, nickel, silver, nickel-chromium alloy, copper-manganese alloy, bismuth, &c., and suitable metal if wire cloth is used comprises nickel, " Monel Metal " (Registered Trade Mark), nickel-silver or nickel-chromium alloys. The layer of carbon suspension may vary in thickness, the thinnest part being preferably at the edge of the wing, and the thickest in the vicinity of the current leads 4. The de-icer may be constructed as a unit by mounting on detachable panels of metal, moulded materials &c. The parts to be protected are primarily heat insulated by means of a covering 5 of cork, felt, rubber, asbestos, fabric, cardboard, fibre &c., which may also serve as electrical insulation. For the latter, varnish, paint, paper &c., may additionally be used. Asbestos paper is preferred. Current is supplied to the conducting layer from a lead 4, constructed of braided metal strip, by means of strips 3 connected to a longitudinal strip 2 which contacts with the conducting layer ; the edge of the latter is preferably sandwiched between a pair of strips 2. The strips 2 and 3 may be composed of metallized paper such as asbestos paper strip sprayed with copper. In the use of wire cloth as the conducting layer, current is supplied from a lead 4 to flat conductors or braided strips welded on to the transverse ends of the cloth. The resistivity of the latter may vary according to variation in the profile of the wings. Specifications 471,175 and 471,244, [both in Group XI], are referred to.