Unmatched Speed: 1967 Air Force-NASA X-15 Aircraft Hit Mach 6, Influenced Hypersonic Flight

What Made the X-15 Special? As militaries around the world track and analyze the fast-moving, multi-national race to develop and deploy hypersonic weapons, some are likely to overlook the decades-long and complex history informing the U.S. military’s’ effort to mature the technology.

After publicly calling itself number 3 in the global hypersonic arms race several years ago, the U.S. military has been quickly closing the gap with Russia and China with successful testing and development of its own land-air-and-surface launched hypersonic weapons.

The X-15 Is Born

Beneath the radar aperture of the intense current focus on hypersonics, there are highly impactful and lesser-recognized historical accomplishments, such as NASA’s X-15.

The North American X-15 is a U.S. Air Force-NASA hypersonic rocket-powered aircraft that set speed records as far back as the 1960s.

The aircraft reached speeds of Mach 6 and reached altitudes of 250,000 feet along the “edge of outer space,”as described by aerospaceweb.org

The aerospaceweb.org article says that in 1967, the X-15 reached what was at the time a world record speed of 4,520 miles per hour, making it the highest speed ever recorded by a crewed, powered aircraft.

“The basic X-15 was a single-seat, mid-wing monoplane designed to explore the areas of high aerodynamic heating rates, stability and control, physiological phenomena, and other problems relating to hypersonic flight (above Mach 5),” a 2014 NASA fact sheet on the X-15 states.

The aircraft was primarily a research and reconnaissance plane intended to explore the parameters, possibilities, and limitations of hypersonic flight and the mix of variables involved in making it possible.