Patent GB-449532-A (GB)
Title: Means for automatically preventing detrimental ice formation in aircraft
IPC: B64D15/16
Filed: 1934-12-21
Abstract: 449,532. Preventing ice formation on aircraft and in aircraft engines; induction systems; fluid-pressure servomotors. SWAN, A., GRIFFITH, A. A., and HELMORE, W., Royal Aircraft Establishment, South Farnborough, Hampshire. Dec. 21, 1934, No. 36607. [Class 4] [See also Groups XXVII and XXIX] Apparatus for automatically eliminating the formation of ice on aircraft comprises means for conducting a supply of anti-freezing agent to the affected part of the aircraft and control mechanism for said means embodying a device responsive to ice formation having a part on which ice forms when ice-forming conditions prevail, the physical presence of which ice is arranged to release the supply of anti-freezing fluid. In one form, Fig. 1, a carburetter 10 having a dual air inlet of which one branch 13 communicates with a source of hot air and the other with a source of cold air is provided with a flap valve 14 controlling the inlet air temperature which valve is automatically controlled by a device 15 responsive to ice formation. This device comprises passages 17, 18 formed in a plug projecting into the induction pipe, the mouth of passage 17 having a small aperture 19 whilst that of passage 18 has a comparatively large opening, so that the presence of ice will first cause blockage of aperture 19 before that of passage 18. Passage 18 contains a pressure equalizing plug 55 with a restricted aperture. Passages 17, 18 communicate by pipes 22, 23 with compartments formed in a casing 20 by a flexible diaphragm 21. Each compartment also communicates with the atmosphere by a bleed hole 24. Blockage of passage 17 disturbs the equilibrium of the diaphragm and causes actuation of a valve member 25 adapted to place one end of a cylinder 26 in communication with the pressure side of the lubricating system ; the other end of the cylinder is permanently connected to the low pressure side of the system. A piston 27 movable in cylinder 26 is coupled to flap valve 14 and is provided with spring return means, which operate when the diaphragm returns the valve 25 to its normal position, return movement of the piston being made possible by the provision of a bleed hole 37. In another form, Fig. 2, forwardly directed passages 46, 49 communicate with chambers above and below a flexible diaphragm 48, the position of which determines that of a valve 41 controlling supply of an anti-freezing liquid from a tank 38 to an absorbent covering 40 on the leading edge of a wing. In this form blockage of an aperture 47 causes a reduction of pressure in the chamber below the diaphragm. In place of a pressurecontrolled diaphragm a perforated member, e.g. a piece of gauze may be mounted in a position normal to the relative wind and is spring-biassed in such manner that movement only occurs under the action of the relative wind when the perforations in the member are obstructed by ice thus increasing its wind resistance. A number of devices such as described may be employed on different parts of an aircraft or a single device may control means for permitting flow of anti-freezing liquid to a number of spaced points. In place of a direct connection between diaphragm and valve, electric contact means may be used and the valve may be operated by electromagnetic means. Specification 423,510, [Group XXIX], is referred to.