NASA's X-43D was designed to fly at speeds approaching Mach 15 — roughly 11,000 miles per hour — using a hydrogen-fueled scramjet to sustain just 30 seconds of powered flight before gliding to ...

To grasp in full the marvel that was the SST, let’s start with Ernst Mach, whose eponymous name plus associated integer number comprise a measure of speed versus the velocity of sound — more precisely ...