On 16 December 2008, Northrop Grumman rolled out the prototype of the U.S. Navy's Unmanned Combat Air System Demonstrator (UCAS-D, also known as the X-47B). As a proposed carrier aircraft, its two critical tests are deck operations (including takeoffs and controlled hooked landings) and air-to-air refueling. The X-47B is about the size of an F/A-18E, with broadly similar performance and capabilities.
Unlike the current fighter, it is intended to be stealthy, so in theory all its weapons must be carried internally in its two bays. Visually, the X-47B differs radically from existing fighters, with an all-wing shape and without any vertical tail surface to reflect radar signals. Part of the demonstration is to show that such a shape can be controlled precisely enough to land safely on board a rolling, pitching carrier.