<div class="section abstract"><div class="htmlview paragraph">Gas-heated hollow propeller blades have been investigated both analytically and experimentally to determine heat requirements for the prevention of icing on the blade surfaces during flight.</div><div class="htmlview paragraph">An analysis was made of a typical hollow propeller blade to determine the internal gas flow and temperature required to maintain the external surface temperature above 32 F.</div><div class="htmlview paragraph">The basic wet-air equation is given and curves are presented to illustrate the blade heating and temperature distributions which were obtained for one set of conditions. Full-scale gas-heated propellers have also been investigated experimentally in an icing wind tunnel and typical results are presented.</div><div class="htmlview paragraph">The rates of heating required to prevent icing are discussed and a modification of propeller blade interiors by using fins and partitions is shown by comparative experiments to permit large reductions in the required heat-source input.</div></div>