F,20 • AERODYNAMIC HEATING OF HIGH SPEED VEHICLES 



CHAPTER 2. APPLICATION OF THEORY TO 

 ENGINEERING PROBLEMS AT HIGH SPEEDS 



F,20. Aerodynamic Heating of High Speed Vehicles. The rise in 

 temperature of the air in immediate contact with the surface of a vehicle 

 as a result of high speed causes transfer of heat into the vehicle, thus the 

 expression "aerodynamic heating." The temperature rise of the contact 

 air may be caused by direct compression, such as at the nose of a blunt 

 body, or friction in a boundary layer, or both. The glowing of meteorites 

 is a manifestation of the high temperatures associated with aerodynamic 

 heating. 



2.5 



800 1200 1600 



Temperature, °F 



Fig. F,20a. Effect of temperature on the weight ratio 

 for the same tensile load for various metals. 



At low speeds, aerodynamic heating is usually objectionable only to 

 the pilot. However, at high speeds, such heating actually dictates the 

 design of the vehicle, not only for structural reasons, but also because 

 of the problem of insulating vital compartments, such as for fuel and 

 guidance equipment. Indeed, the design of hypersonic missiles, such as 

 glide or ballistic rockets, awaits further research on boundary layer heat 

 transfer rates and high temperature insulating and structural materials. 



Fig. F,20a and F,20b show the effect of temperature on the strength 

 of aluminum alloy, stainless steel, and titanium using aluminum alloy at 

 room temperature as the base [59]. While the loss in tensile yield-strength 

 with temperature is indicated in Fig. F,20a, a more significant presen- 

 tation is given in Fig. F,20b, which gives the relative weights of metal 



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