Though technology is constantly changing, and new and improved models of aircraft are developed, the world currently has two types of planes that can be considered the fastest aircraft ever made. These types include unmanned aircraft, meaning controlled remotely, and manned aircraft, in which at least one pilot flies in the plane. These aircraft are made and flown for scientific purposes only.
The fastest aircraft that was controlled in-cabin by a pilot and crew was the North American X-15. The X-15 was developed to help scientists explore hypersonic flight, and it was flown between 1959 and 1968. Hypersonic speed is considered to be anything that exceeds Mach 5, or five times the speed of sound. The X-15 reached a speed of Mach 6.7. To accomplish speeds great enough to be considered the fastest aircraft in the world, the X-15 had to be launched from another plane that was already in flight.
A few X-15s remain intact and can be viewed on display at the U.S. Air Force Museum in Ohio, as well as in Washington D.C. at the National Air and Space Museum. Neil Armstrong was one of the pilots who flew the North American X-15, helping make history yet again, this time as a pilot of one of the fastest aircraft in the world. The X-15 made 199 total flights during its years of operation.
Though some very fast aircraft are unmanned, they are still of great importance and utility to the scientific community, as well as aircraft enthusiasts. In 2004, NASA launched the X-43A, which was an experimental unmanned aircraft. This plane reached a speed of 6,600 miles per hour (10,621.7 kilometers an hour), or Mach 10.
The X-43A is different from other aircraft because of its engine. NASA installed a scramjet engine, which helped reduce the overall weight of the aircraft by getting rid of the need for oxygen in flight. While in flight, the plane gathers oxygen, which helps it travel faster because of its lighter weight, easily propelling it to the title of the world's fastest aircraft.
Though it does not quite compare to airplanes in speed, the world's fastest helicopter does fall under the category of aircraft and deserves mention. Helicopters not only serve an important purpose for such entities as the military and rescue missions, they are also developed for demonstrations and test purposes. The U.S. Army Air Corps, in cooperation with the government of Qatar, developed the Lynx AH Mk.1. This helicopter was used for demonstration flights until 1986 when it officially set the world record at 249 mph (400.7 kilometers an hour).