X-Planes
- Aerospace Technology - NASA X-43 (Hyper-X) Hypersonic Aircraft News and project information on the X-43A air vehicle, an experimental hypersonic flight research program managed by the NASA Langley Center.
- Boeing Phantom Works This advanced research and development unit of The Boeing Company pursues breakthrough improvements in the affordability, quality and performance of aerospace systems.
- Howstuffworks "How Hypersonic Planes Work" What sets the X-43A apart from other rocket-powered aircraft is that it is powered by a scramjet engine. Learn all about it.
- Invisible-Defenders.org Future strike aircraft. This site concerns itself completely with low observable aircraft whose existence has been acknowledged by the U.S. Department of Defense.
- NASA Aeronautics Enterprise Future aerospace technology programs, events, FAQs, library and newsletter. Also, aircraft graphics and photos collections, and an aircraft video selection. Peek into the future.
- Proteus A high-altitude, multi-mission aircraft now used for the Crystal-Face global warming study.
- Solar-Impulse About 50 scientists are working on psychiatrist Bernard Piccard's Euro 40-million Solar Impulse project to harness solar energy to fly a plane around the world. The concept exists in the computers of researchers at the Lausanne polytechnic in Switzerland. Trials are set for 2007.
- X-36 Tailless Agility Research Aircraft The Boeing Company and the National Aeronautics and Space Administration (NASA) are teamed to develop a prototype fighter aircraft designed for stealth and agility.  The subscale tailless aircraft is called the X-36.
- X-43 Hyper-X Program A hypersonic demonstrator aircraft powered by a scramjet engine.
- X-45 Unmanned Combat Air Vehicle A robotic plane built by Boeing's Phantom Works for the Pentagon's Defense Advanced Research Projects Agency and the Air Force and designed specifically for combat missions. DARPA press releases, photos and videos, fact sheet, operational animation.
- XCOR Aerospace Trying to become the first private enterprise to send a human into space, and developer of the EZ-Rocket (a modified Long-EZ homebuilt aircraft) flying rocket airplane.
- XB-70 Conceived for the SAC in the 1950's, the North American XB-70 Valkyrie was a Mach 3 high speed bomber.
- XB-70A Valkyrie Research Aircraft Information on the XB-70 Valkyrie from the Boeing Co. archives.
