It was fourth time lucky for Boeing’s X-51A Waverider, as it blasted into the history books on Monday. The fourth test of the hypersonic drone achieved the longest scramjet-powered hypersonic flight yet, hitting a top speed of Mach 5.1 (which is 2,924 knots, 3,366 mph and 5,417 km/h using SI standard conversion). Dropped from a B-52H bomber out of Edwards Air Force Base in California, the unmanned craft flew at top speed for three and a half minutes before it made a controlled dive into the Pacific Ocean after six minutes of flight.

This successful test of the Waverider for the U.S. Air Force Research Laboratory comes eight months after another X-51A went out of control shortly after being released on a test flight due to the faulty deployment of a control fin. On Monday, the fourth Waverider was released from 50,000 feet (15,240 m) over Point Mugu Naval Air Warfare Center Sea Range at 10:55 AM PDT ( 17:55 GMT). Because the scramjet will only work at hypersonic speeds, a solid rocket booster was used to push Waverider to a speed of Mach 4.8 (2,752 knots, 3,168 mph, 5,098 km/h). After the spent booster was jettisoned, the scramjet was ignited and Waverider reached Mach 5.1, which it remained at until its JP-7 jet fuel was exhausted.

“This demonstration of a practical hypersonic scramjet engine is a historic achievement that has been years in the making,” said Darryl Davis, president, Boeing Phantom Works. “This test proves the technology has matured to the point that it opens the door to practical applications, such as advanced defense systems and more cost-effective access to space.”

The X-51A is designed to test the technology needed to build a hypersonic missile or aircraft. The 25-foot (7.62 m) long vehicle is a combination of of a wingless cruise vehicle powered by a SJY61 supersonic combustion ramjet or “scramjet” engine built by Pratt & Whitney, and a modified Army Tactical Missile. It’s called Waverider because it rides its own shockwave at hypersonic speeds in excess of Mach 5 (2,867 knots, 3,300 mph, 5,310 km/h). The new speed record breaks the previous one set by a previous Waverider vehicle in 2010.

The video below outlines the potential of the scramjet system.

Source: Boeing

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