Hypersonic Weapon Explodes- Extreme Tech

US military’s experimental hypersonic weapon explodes seconds after launch

• By Sebastian Anthony on August 26, 2014 at 11:01 am
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It must be the season for exploding rockets: The US Army’s experimental Advanced Hypersonic Weapon, which will eventually be able to bomb anywhere in the world within an hour, exploded just four seconds after launch in Alaska. Similar to last week’s self-detonating SpaceX rocket, the US Department of Defense detected an error within the system shortly after launch, and thus decided to detonate the entire thing rather than risk any extra collateral damage. No one was injured by the incident, though falling debris did damage the rocket’s Kodiak Launch Complex.

The Advanced Hypersonic Weapon (AHW) is part of the USA’s Prompt Global Strike program, which is investigating various ways of delivering a conventional weapon strike (i.e. not nuclear) anywhere in the world within an hour. In recent years, the US armed forces have lamented that, unless you use ICBMs, deployment time is generally measured in days or weeks — and you can’t use ICBMs, because both Russia and China have launch-detection systems that would trigger an all-out nuclear war (yay for mutually assured destruction). Basically, the US needs a weapon/missile that has the speed and range of an ICBM — but which also follows a different trajectory (so it can’t be mistaken for an ICBM) and with a strictly non-nuclear warhead.

How a modern ICBM missile defense system works

Which brings us neatly onto hypersonic weapons. Hypersonic is generally considered to be Mach 5 (~3,800 mph, 1,700 meters per second) or above. While ICBMs themselves are hypersonic (on the order of 15,000 mph), in this case we’re more referring to cruise missiles, gliders, and (perhaps) reusable strike aircraft that are capable of hypersonic speeds. The Advanced Hypersonic Weapon is actually a glider: a fairly normal missile gets it up to hypersonic speeds, and then it glides to the target. The gliding phase makes it a lot more maneuverable — and it’s also a lot harder to intercept than a ballistic missile (which always approach from a predictable angle).

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So far, most of these hypersonic weapons consist of a rocket that launches them into the air and gets them up to speed — and then either a glider, or a missile or aircraft propelled by a scramjet to speeds in excess of Mach 5 (scramjets don’t work at low altitude or speed). In the case of the Advanced Hypersonic Weapon, it appears that its launcher rocket developed a fault and had to be detonated. We don’t believe that the AHW itself developed a fault. (Its first test flight, way back in 2011, was a success.)

The Advanced Hypersonic Weapon, exploding in Alaska

According to one witness, who was about 12 miles from the launch site, the explosion was loud and frightening, with a bright fireball afterward. KMXT radio reported that the rocket lifted off, and then very quickly turned nose-down and exploded. “We had to terminate,” a US DoD spokesperson said. “The weapon exploded during takeoff and fell back down in the range complex.”

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As we reported earlier in the week following SpaceX’s launch mishap, it’s much safer to initiate a controlled detonation in the air, than to let the rocket explode on the ground, or at some random point farther down range. There’s no word of when the next test flight will take place. Presumably it’ll be a while, though, if the DoD has to build another prototype.

SR-72 concept from Lockheed Martin

SR-72, hybrid turbine/scramjet engine operation

The Advanced Hypersonic Weapon, Boeing X-51 (pictured top), and Lockheed SR-72 are all being developed as part of the Prompt Global Strike program. The eventual goal is to produce the US military’s High Speed Strike Weapon (HSSW), which will be launched from submarines or aircraft carriers, with the ability to strike anywhere in the world in around 30 minutes. The hypersonic Lockheed SR-72 is probably the most exciting design of the bunch, using hybrid engine design that allows for turbojet at low speed/altitude, and then switching to scramjet once it reaches cruise speed/altitude.