As far as DARPA is concerned, aircraft with vertical takeoff and landing (VTOL) capabilities are the future of versatile, efficient flight. The V-22 Osprey took a crack at it, but over the next decade, we'll need something better. Concept after concept has come across DARPA's desks, but none have measured up. The problem, as DARPA sees it, is that nobody has yet been able to create a faster-than-ever VTOL aircraft without significantly sacrificing the aircraft's usefulness and range.
To find a solution, DARPA put out an open call to designers, birthing the VTOL X-Plane project. Out of the pool of concepts that came their way, DARPA has rounded up a veritable A-team of aviation companies: Boeing, Sikorsky Aircraft, Aurora Flight Sciences, and Karem Aircraft. These four, awarded with prime contracts for Phase 1 of the VTOL X-Plane's development, still have a huge amount of work to do.
The VTOL X-Plane's final design will need to meet some impressive criteria. The plane will have to sustain speeds of 345-460 MPH, have a carrying capacity of at least 40 percent of its own weight, and increase hover efficiency while also reducing drag. Basically, in every way possible, the VTOL X-Plane needs to blow current tech out of the water.
As for the designs, all four companies chose to draw up plans for unmanned UAVs, but manned vehicles could be in the works as well. Since this is still the first phase of the aircraft's development, all DARPA has to show off are artists' concepts, and Aurora Flight Sciences hasn't even provided that much. Whatever the VTOL X-Plane eventually looks like, you can rest assured, it's still got a long way to go (several years, at least) before we see it take flight.