X Planes

The X-planes are a series of experimental United States aircraft (and some rockets) used for testing of new technologies and usually kept highly secret during development.

 

As of 2006, new X-plane projects are still underway. The designation X-52 was skipped to avoid potential confusion with the operational B-52 Stratofortress strategic bomber.

X-44

Nasa X-43A

X-50

X-33

X-38

X-29

X-50A 

Virgin Galactic

The Bird of Prey

X-43 (Hyper-X: Greased Lightning)

http://www.nasa.gov/audience/forstudents/9-12/features/F_HyperX_Greased_Lightning9-12.html

X-35

X-47A

X-48B

http://www.fas.org/programs/ssp/man/uswpns/air/xplanes/xplanes.html

http://www.nasa.gov/centers/dryden/history/HistoricAircraft/X-Planes/1940/index.html

http://en.wikipedia.org/wiki/X-plane