Presented at American Society for Metals Conference on Heat Tolerant Materials for Aerodynamic Applications, Albuquerque, N. Mex. Jan. 1957. The need for heat-tolerant materials in aerodynamic applications is discussed on the basis of the temperatures attainable in high-speed flight, the effects of these temperatures upon structural materials, and the problems encountered by the airframe designer as a result of the changes in these structural properties. (auth)