A pair of successful launches of three advanced hypersonic rocket vehicles Thursday marked a milestone in the U.S. military’s efforts to develop hypersonic aircraft capable of traveling hundreds of miles per hour.
The rocket launches were launched from Vandenberg Air Force Base in California and would have been the first ground-based tests of such technology, according to a statement from Air Force Space Command, which oversees ground-based testing at Vandenberg.
The rocket launches, which brought the devices into a trajectory that could potentially carry them through space, were a “significant advancement,” said Col. Colton D. Boley, project manager for the Air Force Research Laboratory’s hypersonic research and development branch.
“This is a tremendous achievement for an Air Force team of researchers and engineers,” he said in the statement. “The rockets’ flawless launch configuration is an impressive accomplishment.”
The three vehicles tested are being dubbed the TL-4, TL-5 and TL-6, according to news reports. TL-4 and TL-5, which used solid propellant and took off from the Ground-Based Missile Defense site at Vandenberg, successfully ignited and orbited as planned. The last rocket, which used liquid propellant, failed after it was launched on its third attempt, according to a statement from the Department of Defense.
The Air Force plans to use a large aircraft or a piloted vehicle to conduct such flight tests in the future, according to news reports. The aircraft would be required to be able to deliver sophisticated equipment that would be capable of engaging high-speed targets at nearly hypersonic speeds.
The test was aimed at testing “the high-energy payload transition from a solid to liquid propellant for the hypersonic weapon,” in order to “determine if the test vehicle can perform fuel and oxidizer transitions smoothly, which will validate the smooth assimilation of the boosted flight stage into the upper stage,” the statement said.
The Air Force tested propulsion systems on the rocket on Dec. 11, 2013, and again in 2016, but this week’s flight marked the first time the three rocket stages successfully combined.
The first launch happened about 4 a.m. PST, and the second about 2:30 p.m. PST, CNN reported.
The X-51A Extrodunar test vehicle is based on a two-stage spaceplane that is the subject of a pending NASA contract to return samples from an asteroid.
The vehicles are about 37 feet long and weigh about 600 pounds when fully fueled. One of the rockets weighs about 5,000 pounds. The warheads atop the two vehicles — 40 to 50 percent larger than what’s currently available for deployment — are composed of non-nuclear explosives.
The Air Force’s current plan calls for testing and deploying tactical hypersonic aircraft by 2023.