The “X” series consists of more than 60 experimental aircraft produced by US government agencies, including the Air Force and NASA, since the end of World War II. They were often extreme ...

The X-1 series aircraft were air-launched from a modified Boeing B-29 or a B-50 Superfortress bombers. Lasting from 1946 to 1958, the project’s goal was breaking the sound barrier, which was ...

Among manned, powered aircraft, the North American X-15 still holds records for highest altitude (67 miles) and greatest speed (Mach 6.7) — and that was all the way back in the 1960s.

NASA unveiled the experimental X-59 aircraft this month with plans to launch gauge the noise of the jet's sonic boom through a series of test flights.

The United States has seen the development of several so-called “X-planes,” the series of aircraft that have been used to test and evaluate new technologies and aerodynamic concepts.

If all goes according to plan, the new X-plane—which likely will be the largest purpose-built experimental aircraft in the seven-decade-old X series—is expected to begin flight tests in late ...

NASA's new experimental aircraft will go thump in the night – that's the plan, anyway. The X-59, set to be unveiled in Palmdale, California, on Friday, is designed to turn the volume down on ...

The “X” series consists of more than 60 experimental aircraft produced by US government agencies, including the Air Force and NASA, since the end of World War II. They were often extreme ...