NASA test pilots are justly famed for their bravery, but before prototype planes are built, their response to the brutal physics of high-speed flight is modelled exhaustively at smaller scales.
In this image, taken in March 1962, shock waves can be seen breaking across a miniature X-15 hypersonic rocket-powered aircraft. The model was set up inside in the Supersonic Pressure Tunnel built at NASA’s Langley Research Centre in the US.
Full-size X-15s went on to set speed and altitude records. In October 1967, one piloted by William Knight reached 31,120 metres above the Earth and hit a top speed of 7274 kilometres per hour.