As it rises through the atmosphere, a launch vehicle becomes heated, especially at high supersonic speed. This phenomenon can be observed, for instance, on the nose of the Ariane 5 launch vehicle solid propellant boosters.

Wind tunnel testing is conducted on scale models to determine the critical regions. In effect, during a test as in a real flight, the air flow around the model heats its surface. The model is covered with thermosensitive paint which changes colour as its temperature increases, thereby allowing heating maps of the model to be drawn.

These experimental results are used to predict real heating during climb of the launch vehicle.