The fastest air-breathing vehicle ever built was the NASA X-43. Only three of these aircraft were built, with one being destroyed and two operating successfully. The X-43 testbed aircraft measured 12 ...

NASA’s X-59 quiet supersonic aircraft conducted its historic first-ever flight. See the flight highlights here. Credit: NASA ...

The Rotor Systems Research Aircraft/X-Wing, a vehicle that was used to demonstrate an advanced rotor/fixed wing concept called X-Wing, is shown here on Nov. 4, 1986. The vehicle was rolled out in 1986 ...

Add Yahoo as a preferred source to see more of our stories on Google. A NASA aircraft had to make a "gear-up landing" in Houston on Tuesday due to a mechanical problem, NASA spokesperson Bethany ...

The X-31 Enhanced Fighter Maneuverability Demonstrator was used to test the newest technology in highly maneuverable fighters. The X-31 program logged an X-plane record of 580 flights during the ...