When it comes to military aircraft technology, there’s fast and then there’s fast. The Air Force has lately been trying hard to redefine notions of speed and distance with its new hypersonic experimental aircraft, the X-51A Waverider. On Tuesday, a B-52 bomber will take off from Edwards Air Force Base in California with the X-51A strapped to its wing. When the plane hits an altitude of 50,000 feet, the unmanned, platypus-shaped Waverider will drop off and accelerate to speeds in excess of 4,500 miles per hour, also known as Mach 6. That’s twice the speed of the world’s fastest jet, the Lockheed SR-71 Blackbird. If all goes well, the X-51A Waverider will roar over the Pacific Ocean at that speed for 300 seconds, then burn out and fall into the ocean. The military has no plans to recover the aircraft.
So what’s the Air Force doing sending hundreds of millions of dollars of research zooming out into the middle of the ocean? Well, it’s not the X-51A itself that they’re interested in. It’s the hypersonic engine technology. Tuesday’s test will supply them with key data that can be used to build the next iteration of the unmanned aircraft and, eventually, missiles and even passenger planes. Powered by scramjet technology, the X-51A engine has virtually no moving parts. It uses oxygen from the atmosphere to mix with jet fuel and ignite to create thrust. And what a lot of thrust it creates. At its cruising speed, the WaveRider could travel from Los Angeles to New York City in about 45 minutes.
The military isn’t building a passenger plane, though. As exciting and impressive as the X-51A is, its real purpose is rather less pedestrian. The Defense Advanced Research Projects Agency (DARPA) helped develop the X-51A as part of a larger objective to build aircraft that can go Mach 20 and allow us to get anywhere in the world within an hour. They’re calling the next phase of the project the “High Speed Strike Weapon,” and it involves strapping a bunch of warheads to the X-51A to help defend us — or launch the first strike — in the event of World War III. Also in the program is the awesome but problematic HTV-2, a missile that can travel even faster than the X-51A. It’s awesome because it gets launched into space and screams back towards Earth at about 13,000 miles per hour. It’s problematic because both of the test flights disappeared in the upper regions of the atmosphere.
The X-51A’s track record is slightly more promising so far. Its first test flight in 2010 (above) started off strong as the aircraft accelerated to Mach 5, but a seal broke cutting the flight short. The next test didn’t go so well, after unexpected shockwaves sent the X-51A off course in a matter of seconds. But if the third time is the charm, the Air Force will move forward with their plan to weaponize the X-51A. They hope to have it battle ready by 2016. Or whenever the first strike of the inevitable apocalyptic global war. Whichever comes first.
Update (8.15.2012): Sadly, the X-51A Waverider failed to complete its test flight. Just before the its scramjet engine kicked in, the aircraft’s fin fell off sending it on an out of control trajectory. The X-51A fell apart 15 seconds after it separated from its rocket booster and fell to a watery, expensive grave. Over the course of the last few years, the Air Force had invested about $300 million in the project. It’s unclear if they’ll try again.