AVIATION ENTHUSIASTS attending the Experimental Aircraft Assn. show in Oshkosh, Wis., earlier this month got a special treat: NASA and the Air Force rolled out a model of the futuristic LoFlyte Mach 5 Waverider. This is the first plane designed to go five times the speed of sound and survive the extreme stress of a hypersonic shock wave--by actually riding on top of the wave. By comparison, the current speed champ--the Lockheed SR-71 Blackbird--tops out at just over Mach 3, or 2,194 mph.
The current Waverider is only an eight-foot-long, remote-controlled model, and it won't even attempt to set any new records. Instead, it will be used to determine whether an aircraft designed to skip along atop a hypersonic shock wave is also stable enough at low speeds to take off and land safely. NASA will begin the testing in a couple of weeks. If all goes well, a 23-foot piloted prototype will be next.
Because the Waverider will be tricky to fly, the pilot will need the help of a "smart" control system, and Accurate Automation Corp. in Chattanooga, Tenn., has developed one that uses neural networks. By emulating primitive brain circuits, neural networks learn from experience. The system will handle "upsets" that require instant correction--things no human could react to quickly enough. Mississippi State University's Raspet Flight Research Laboratory built the airframe, and SWB Turbines in Appleton, Wis., supplied the jet engine.