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Aviation History
1943
1943 - 2838.PDF
-618 FLIGHT Keeping Them DECEMBER 2ND, 1943 arm AntUicing System Uses Ensine Exhaust Heat By HARRY WILKIN FOR several months past the U.S. Navy has been flyingCatalina patrol bombers equipped witii a heatingsystem which removes the hazard of ice'f^wfertWrT on the wings, tail and control surfaces. This system differsfrom de-icers in that, instead of cracking up a formed layer of ice so that the fragments will be blown off by theair current, it prevents the freezing of moisture on the wings, ailerons, elevator and rudder. This difference is of the greatest importance to safety,as disaster from icing usually results, not from weight of the ice, but because of loss of lift and flying control. Iceaccumulation changes the cross section of wing and tail foils, particularly of the wing leading-edge, and destroysthe uniform, smooth contour of the surfaces, so'that aero- dynamic efficiency is lost or reduced to a dangerous extent.Also, ice frozen on the control mechanism of the ailerons and tail surfaces increases the hazard by rendering theminoperative. The new anti-icing system, which was brought to a stateof practical development during six years of research and experimenting, utilises waste heat fr.om the aircraft engineexhaust to maintain the temperature of the parts above ^ihe freezing point of water. In addition to use of thesystem in some of the Catalinas, it is being installed in the new Consolidated Vultee two-engined flying boatP4Y-1, which is in production for the Navy at New Orleans, and before next winter is to be provided in the CoronadoPB2Y-3 four-engined bombers now building for the Navy at San Diego, California. In theory, the use of engine beat to keep leading-edgesand surfaces warm was logical and apparently simple, but working out a practical method of applying the principleproved far otherwise. The result represents the combined -efforts of the National Advisory Committee for Aeronautics,which conceived and partly developed the idea, and of engineers of the Consolidated Vultee Aircraft Corp. PEI NOTE: ARROWS INDICATE GENERAL PATH OF CIRCULATING AIH STARBOARD SIDE WING ANTL-TCEF! INSTALLATION IDENTICAL TO PORT SIDE (AS SHOWN) iod consists essentially of heating air indirectly as of heat exchangers located in the engine exhaust "pipes and circulating the hot air in the wings and tail at controlled initial temperatures ranging up to a maximum of 350 deg. F. This hot air keeps the metal of leading- edges at 60 deg. F. even in atmospheric temperatures as low as -40 deg. F., and tests recently completed in high northern latitudes are stated to have shown that the system functioned perfectly. Final flight tests were conducted in a Liberator bomber and other aircraft at Minneapolis by Engineer Rodert, of the N.A.C.A. ; Harold F. Schmidt, Consolidated Vultee engineer; and a crew of Army engineers. System in Liberator By the system installed in the Liberator, heated airfrom the two outboard engines is supplied to the leadings-** edges of the two outer wing panels and flows back throughthe ulterior of the wing and over the surfaces of the ailerons to prevent icing of the controls. Similarly, heatedair from the inboard engines is directed to the leading- edges of the wing sections between inboard and outboard—engines, and ducts convey hot air from the inboard engines through the fuselage to the tail surfaces. Other ductscarry hot air to the cabin and flight deck to heat the former and prevent frosting of the pilots' windshield andthe bombardier's window. An additional feature in the Catalina and the Coronado is the installation of an auxiliaryheater in the tail to supply more heat for prevention of freezing of water sprayed on the surfaces during take-offsand landings. Arrangement of the elements of the system as installedin the Catalina patrol bomber is shown in the accompany- ing drawing showing the port engine, port wing, fuselage -—and tail. Outside air enters ram air scoops on the engine nacelle and passes through a heat exchanger surrounding the exhaust tail pipe, wherethe air is heated by convec- tion from the exhaust gps. The heated air $£&*travels chordwise of the wing panel through feederducts in the leading-edge, shown in enlarged detail"A" at the right. It also flows spanwise through aduct in front of the front spar and escapes through aseries of vents in the duct to warm the metal of the lead-ing-edge. The released air then circulates in the in-terior of the panel, heating the whole skin, and finallyis vented to>the atmosphere through qjf outlet back ofthe rear spar. The amount of heating isregulated by a wing gate and actuator inserted be-tween the heat exchanger and the wing leading-edgefeeder ducts (detail "A"). A movable cover on thewing-gate duct is operated through linkage by a ther-mostat unit which opens • and closes the duct. When ING GATE ACTUATOR UN'T -
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