X Planes

X Planes, a family of aircraft built for flight research
and never intended for production.
The X is for eXperimental, and originally the designation
was XS for eXperimental Supersonic.
To really find out about the X Planes programme, click here:
Dryden Flight Research Center
Designation Thumbnail Flights Description




The first aircraft to break the sound barrier on 14/10/1947. Rocket powered and launched from under the wing of a NB-29 "mother ship".

Research continued with the X-1A, X-1B and X-1E, providing flight data for the designs of later high-performance aircraft.










The first aircraft to reach Mach 3, achieving Mach 3.2 on its last flight which destroyed the aircraft and sadly killed the pilot.

The X-2 was the first aircraft to fly higher than 100,000 feet, achieving a high point of 126,200 feet.



26 Jet-powered and made of new aircraft materials such as titanium, the X-3 failed to achieve the hoped for speeds, but pioneered in the use of these new structural materials.



90 Powered by twin turbojet engines and featuring swept wings with no horizontal stabiliser, the X-4 helped demonstrate that a semi-tailless aircraft would fly and provided valuable data on airflow anomalies.



133 The X-5 had variable sweep wings, from 20 to 60 degrees. The aircraft verified wind-tunnel predictions of reduced drag and improved performance as the wing angle changed over the speed range up to Mach 1.




The X-15 is built internally of titanium with a skin of a chrome-nickel alloy known as Inconel X, and is rocket powered.

The X-15 first set speed and altitude records:
Mach 4.43 on Mar. 7, 1961
Mach 5.27 on June 23, 1961
Mach 6.04 on Nov. 9, 1961
Mach 6.7 on Oct. 3, 1967.
354,200 feet (67 miles) on Aug. 22, 1963




Wingless vehicles designed to fly back to Earth from space and be landed like an aircraft.

The data gathered by the lifting body program contributed to the design of today's space shuttle program.






The X-29 became the first forward-swept-wing aircraft in the world to exceed Mach 1.

It demonstrated that a highly unstable aircraft with forward-swept wings could be flown safely at high G-loads using a digital flight-control system.



555 The X-31 Enhanced Fighter Manoeuvrability demonstrator uses thrust vectoring by means of carbon-carbon paddles, and an advanced flight control system. This gives it high manoeuvrability and controlled flight at high angles of attack.
X-33 0 The X-33 Advanced Technology Demonstrator was a half-scale vehicle, with an "aerospike" rocket engine. An unpiloted vehicle, it was to be launched vertically and land horizontally and was expected to be capable of an altitude of 50 miles and speeds of more than Mach 11. However in 2001 NASA funding ceased.



3 The X-34 was a single-engine rocket that was to be launched from an Orbital Sciences L-1011 aircraft. The X-34 was intended to fly at Mach 8 and to reach an altitude of 250,000 feet, but in 2001 NASA funding ceased.


  First flew October 24, 2000. Designed to provide the U.S. Air Force, Navy and Marine Corps, and the United Kingdom’s Royal Navy and Royal Air Force with an affordable and stealthy tactical aircraft for the 21st century. Won the JSF competition and will be the F-35.



33 The X-36 Tailless Fighter Agility Research Aircraft demonstrated that tailless fighters could achieve superior levels of agility to today's best military fighter aircraft. The X-36 was 28% scale, and remotely piloted.
X-37 0 The X-37 is to be an Orbital Experimental Vehicle, lifted into orbit by the Space Shuttle and returned to Earth under its own power. It will be half the length of the Shuttle payload bay and is expected to weigh about six tons.



15 The X-38 Advanced Technology Demonstrator was designed to prove the concept of a Crew Return Vehicle for the International Space Station. It is expected to be developed for a fraction of the costs of previous human space vehicles.
X-40A   The X-40A is shaped like the X-37 but lacks its advanced thermal protection materials, and is 20% smaller. It is to be drop tested from helicopters to ensure that the X-37 flight-testing is less risky.