For a closer look at the exotic aircraft the Air Force might be cooking up at Area 51, launch the photo gallery.

For years, the U.S. military has wanted a plane that could loiter just outside enemy territory for more than a dozen hours and, on command, hurtle toward a target faster than the speed of sound. And then level it. But aircraft that excel at subsonic flight are inefficient at Mach speeds, and vice versa. The answer is Switchblade, an unmanned, shape-changing plane concept under development by Northrop Grumman.

After decades of upgrades to a fleet of notoriously cramped Sikorsky VH-3 Sea Kings, the White House has tasked Lockheed Martin with a dramatic, $6.1-billion makeover of Marine One, the presidential helicopter, starting this summer. The goal: to fit a mobile Oval Office into the tight quarters of a chopper. The new fleet will consist of 23 VH-71 aircraft, each of which will have 200 square feet of cabin space, nearly double the Sea King´s 116.

Aside from the legroom, the copter will incorporate major upgrades to the old defense and communications