Hypersonic Atmospheric Flight

Progress in aeronautics and astronautics within the past decades has been remarkable because people have learned to master the difficult feat of hypervelocity flight. A variety of manned and unmanned aircraft have been developed for faster transportation from one point on earth to another. Similarly, aerospace vehicles have been constructed for further exploration of the vast depths of space and the neighboring planets in the solar system. 

All bodies traveling in a fluid experience dynamic heating, the magnitude of which depends upon the body characteristics and the environmental parameters. Modern supersonic aircraft, for example, experience appreciable heating. This incident flux is accommodated by the use of an insulated metallic structure, which provides a near balance between the incident thermal pulse and the heat dissipated by surface radiation. Hence, only a small amount of heat has to be absorbed by mechanisms other than radiation. 

Major Property of Interest Type of Polymer Propulsion System Application 

Ablative Phenol-formaldehyde Charring resin for rocket nozzle 

Chemical resistance Fluorosilicone Seals, gaskets, hose linings for liquid fuels 

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Plastics have found numerous uses in specialty areas such as hypersonic atmospheric flight and chemical propulsion exhaust systems. The particular plastic employed in these applications is based on the inherent properties of the plastics or the ability to combine it with another component material to obtain a balance of properties uncommon to either component. Some of the compositions and important properties of plastics are given in Tables 2-9 and 2-10 that have been developed over the years for use in flight vehicles and propulsion systems that are dependent upon chemical, mechanical, electrical, nuclear, and solar means for accelerating the working fluid by high temperatures. 

Since 1950, plastics have been development for uses in very high temperature environments. By 1954, it was demonstrated that plastic materials were suitable for thermally protecting structures during intense propulsion heating. This discovery, at that time, became one of the greatest achievements of modern times, because it essentially initially eliminated the thermal barrier to hypersonic atmospheric flight as well as many of the internal heating problems associated with chemical propulsion systems. 

Thermal protection The design of vehicles for hypersonic atmospheric flight represents a compromise between the intended... 

The design of vehicles for hypersonic atmospheric flight represents a compromise between the intended mission, the thermo structural aspects of the environment, the rate and magnitude of vehicle deceleration permitted, and the amount of lift necessary for flight control and landing at a predetermined point on some planet. 

There are different entry simulation testing equipment to evaluate plastic materials. The utility of polymeric materials for hypersonic atmospheric flight applications is determined by a series of sequential evaluations. Initial screening of candidate materials is carried out in the laboratory, using the high temperature apparatuses. 

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