Three Articles for McGraw-Hill Encyclopedia of Science and Technology

Articles treating aerothermodynamics, hypersonic flight, and thermal stress. Aerothermodynamics refers to the flow of gases when significantly affected by heat exchanges. It concerns problems of hypersonic flight and combustion, in which dissociation and ionization may occur. Important practical applications are the improvement of internal flow in propulsion units and turbines and the application of knowledge about external flow to the structural design, guidance and control of supersonic vehicles. In hypersonic flight (Mach 5 and above), the characteristics of the flow field about a vehicle are sensibly unchanged at further increased speeds. One of the important problems in hypersonic flight is to design reentry vehicles to be lightweight, able to withstand large heat loads from adjacent hot-gas layers during reentry, and yet able to carry useful payloads. For flight ranges of the order of the earth's radius or greater, hypersonic vehicles perform favorably compared with supersonic airplanes. Study of thermal stress touches on all phases of aerospace vehicle design, and concerns temperature distribution, elastic and inelastic deformation, and the behavior of materials at elevated temperatures.