The U.S. Defense Advanced Research Projects Agency tried again to test a hypersonic cruise missile. This time, the speedy missile didn’t just fall off the B-52 carrying it and tumble to the ground, as happened last year.
No, this time the Hypersonic Air-Breathing Weapon Concept, a co-development of DARPA and the U.S. Air Force, successfully separated from the launching plane—presumably a B-52—and, a few seconds later, fired its scramjet engine and accelerated to a cruising speed faster than Mach 5.
“The HAWC free flight test was a successful demonstration of the capabilities that will make hypersonic cruise missiles a highly effective tool for our warfighters,” said Andrew Knoedler, the DARPA program manager. “This brings us one step closer to transitioning HAWC to a program of record that offers next generation capability to the U.S. military.”
An operational missile based on HAWC, the Hypersonic Attack Cruise Missile, is one of a pair of hypersonic weapons the Air Force has been spending half a billion dollars on annually, in the hope of fielding at least one of them over the next couple of years.
The other super-fast missile candidate is a totally different kind of weapon. Whereas HAWC/HACM is an air-breathing cruise missile, the Air-Launched Rapid-Response Weapon is a so-called “boost-glide” system. In essence, a glider that gets its initial speed boost from a rocket motor.
HAWC, and presumably HACM, tops out slightly past five times the speed of sound. ARRW is a lot faster—up to Mach 8.
But HAWC/HACM’s slower speed actually is an advantage, from a certain point of view. “It’s easier to integrate a seeker on a cruise missile,” Mike White, the Pentagon’s assistant director for hypersonics, said last year. “And so, the ability to use a cruise missile for attack of targets that require seekers is a value.”
It’s not impossible to put a seeker on a hypersonic glider, but the glider does climb to the edge of the atmosphere during its boost phase. That’s a tough environment for any seeker. A hypersonic glider without a seeker might be less accurate than is a hypersonic cruise missile with a seeker.
Both weapons in theory could range a thousand miles or so, if not farther. Both could arm B-52s as the Air Force totally rebuilds the 1960s-vintage bombers for high-tech warfare with, say, China. Both have suffered embarrassing developmental problems.
An April test of the ARRW was a bust after the missile failed to separate from the B-52. Three months later another ARRW test missile separated but didn’t fire—it plummeted into the sea. That misfire was similar to the HAWC’s own botched test back in June 2020.
It turns out, developing hypersonic missiles is hard. But the Pentagon slowly is making progress, as the recent HAWC test indicates.