X-planes are what happens when the Air Force gets a huge pile of money to try something nutty. Or, okay, that may not be entirely true, but that big fat "X" stands for "eXperimental," and X-planes do have a noble lineage, from the Bell X-1 to the X-37 robotic space plane. The latest addition to the family is the X-56A, also known as "the MUTT."
NASA, of course, has a penchant for strained acronyms, and MUTT can hang with the best of 'em, standing for "Multi-Use Technology Testbed." The reason we need the X-56A is that when you design a plane like (say) the U-2, you give it very long and very skinny wings to enable extreme efficiency, especially at high altitudes. However, if you go too far, you run the risk of something called flutter, where a wing can flex such that its changing shape increases the aerodynamic load on it, amplifying the amount that it flexes. This can cause what's called a self-exciting oscillation, and the wing can start flexing back and forth so much that it snaps right off, a phenomenon that was the cause of two airline crashes in 1959 and 1960.
The X-56A will be testing several different sets of wings to explore the point at which flutter starts to occur. This is sort of like trying to figure out whether your brakes are any good by driving at high speed towards a brick wall, but in anticipation of a catastrophic wing failure, the MUTT will come with a ballistic parachute equipped as standard equipment. Needless to say, the X-56A will be unmanned, and it'll be constructed at about 15% scale at eight feet long and with a wingspan of 28 feet.
Built by Lockheed Martin's famous Skunk Works, the X-56A will help NASA design the next generation of cargo and passenger aircraft, some of which we might have already gotten a peek at. Final assembly should be completed in late April, with flight tests starting at Edwards Air Force Base this July.
Via Aviation Week