In 1948 the Bell X-1 made history by flying faster then the speed of sound which is 1200 km/h. Being power by a rocket engine the Bell X-1 achieved the speed of 1600 km/h. The aircraft was built by Bell Aircraft for the United States Air Force. Few other variants of this aircraft were built and one of them, the Bell X-1A has exceeded the speed of 2600 km/h in 1954. The Bell X-1 is now retired and only 7 aircrafts were built. Bell X-1 is to this day the blueprint for supersonic aircrafts.