Flights have been made with an airplane in icing conditions in order to test the effect of exhaust heat applied to the wings as a means of preventing ice formations. Other ice-prevention equipment, including an exhaust gas-heated pitot-static head, hot-air-heated windshield, and an inflatable de-icer of recent design, were also tested.
Information obtained by the National Advisory Committee for Aeronautics in ice-prevention tests indicates that the most effective method preventing the formation of ice that of heating the surfaces to be protected. The use of waste heat in the exhaust gases as a source of heat energy and the dynamic head in flight as a pump to circulate heated air has been proven practical in a series of test flights. In recent flight tests the exhaust gases were passed through the leading edge of the wings and ejected at the wing tips. Circulated air was passed over the exhaust tube inside each leading edge, then into the aftef part of the wing, and out to the atmosphere through louvers which were located near the aileron and flap hinges. Effective ice protection in all kinds of icing weather was obtained. Objections have been raised to the use of an exhaust gas tube in the wing leading edge, particularly by the military surfaces.
