The X-66A and other planes suggested as part of the Sustainable Flight National Partnership. (Image credit: NASA) X-plane status is granted by the Air Force to development programs such as that of ...

The mini space plane was built by Boeing and measures about 29 feet long. Like NASA’s space shuttles, the X-37B is designed to return to Earth and land on a runway.

The United States Space Force’s secretive X-37B space plane touched down to earth on Friday after spending 434 days in orbit conducting mysterious tests.

The X-37B space plane touched down at Vandenberg Space Force Base in California after 434 days in space. Space Force is in general quite secretive about the spacecraft and its missions, ...

Instead it’s likely the U.S. military’s X-37B space plane taking off for its latest mission. The uncrewed plane, operated by U.S. Space Force, is set to launch Thursday, Dec. 28 in the evening.

It’s now officially the X-66A, meaning that it’s an experimental research aircraft. NASA already has two ongoing X-plane programs, so the X-66A makes three of them.

Meet the X-66A, NASA's Sustainable Flight Demonstrator full-scale single-aisle research plane, featuring transonic truss-braced wings and designed to explore net-zero aviation emissions and more ...

DARPA's new X-plane concept will remove these moving external control surfaces to reduce aerodynamic drag and increase fuel efficiency, contradicting a century of standard aviation design practices.