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Low velocities
The article says ""Aerodynamic heating is not a factor at subsonic speeds"", but it is present isn't it? As T_amb*(gamma-1)/2 * M^2 is continous, then heating is taking place at all speeds, and whether it is significant depends on what is being considered. For example, Mach 0.5 in air at 20 deg C gives a temperature rise of close to 15 deg C. 
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