The Bell X-1, piloted by Chuck Yeager, became the first manned aeroplane to break the sound barrier. The Mach 1 flight took place on 14 October 1947 with the aeroplane being drop launched by the B-29 bomber and reaching speeds of up to 1,100km/h.
There was some controversy between the American’s and the United Kingdom over the X-1 because the UK had already embarked on a top-secret project to achieve Mach 1. The Miles M.52 was close to finished when an agreement between the UK and the US allowed for an exchange of high-speed research data. The US didn’t hold up their end of the bargain, propelling the Bell project forward and leaving the UK empty-handed. The secret fix lay with using a variable-incidence tail which allowed for a manoeuvrable tail.
The designers went with a rocket engine because turbojet engines could not hold up at high altitude and a combination of the two was too weighty. The shape of a bullet was closely adopted due to its known stability at supersonic speeds. Swept-wings were foregone with the team opting instead for the tried and tested straight-wing design. Modern planes would adopt the swept-wing design, wings that angle from the body because they allowed for much higher speeds. I will leave out the detail on ‘aerodynamic drag rise’ and ‘fluid compressibility’ for another time…
The US Postal Service issued a commemorative stamp for the X-1 in 1997 and the research techniques used in the design of the X-1 would be employed until the 90s.