It took six months, but the Defense Advanced Research Projects Agency finally has a handle on what caused its hypersonic weapon prototype to "terminate" itself over the Pacific Ocean back in April. The findings have paved the way for a fresh round of tests for the Mach-20 flier, potentially leading to a new class of superfast weapons.

The Hypersonic Test Vehicle 2 – a 12-foot, 2,000-pound wedge packing a three-stage Minotaur booster – launched without incident from California on April 22. It climbed to the edge of space for a planned 30-minute, 4,000-mile jaunt toward Kwajalein in the middle of the Pacific.

But nine minutes into the flight, controllers on the ground lost contact with the HTV-2. The culprit, according to Darpa's Engineering Review Board? "Higher-than-predicted yaw, which coupled into roll, thus exceeding the available control capability at the time of the anomaly."

In other words, the HTV wobbled too much. Rather than risking an out-of-control flight, the bot self-destructed. On the bright side, according to a chipper Darpa release, the failed test "demonstrated successfully the first-ever use of an autonomous flight-termination system."

Lockheed built two HTV-2 test vehicles, but Darpa held off on further flights until engineers could say for sure what killed the first HTV. Now the agency is ready to try again, with a few tweaks. "Engineers will adjust the vehicle’s center of gravity, decrease the angle of attack flown, and use the on-board reaction-control system to augment the vehicle flaps when HTV-2 flies next summer."

Time was, Pentagon planners anticipated adapting HTV into a weapon capable of striking any target in the world within minutes of launch from a base in the United States. With that ambition running afoul of (very sensible) diplomatic concerns, planners instead envisioned using hypersonic technology in a new, superfast bomber.

Now it's clear the Pentagon wants a less-ambitious bomber similar to models already in service. So instead, HTV-2 and its ilk are likely to lead to a new generation of missiles that can be carried by today's manned planes.

But first, HTV needs to fly a full test circuit without wobbling – and self-terminating.

Photo: Air Force

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