Wikipedia has a list of the X planes, and quite a bit of information on
many of them. These are the airplanes that took bold leaps forward in
the state of the art of aviation....



But a few might take you by surprise...

Like the Air Force X-25,
http://en.wikipedia.org/wiki/Bensen_X-25

and the Navy's X-28 Sea Skimmer.
http://en.wikipedia.org/wiki/X-28_Sea_Skimmer





http://en.wikipedia.org/wiki/List_of...ental_aircraft