 The national aero space plane will launch horizontally, fly directly into space, complete its mission, and land horizontally like the space shuttle. Advanced, air-breathing, ramjet-scramjet engines being developed by a national team led by NASA and the Air Force will allow NASP to fly at up to 25 times the speed of sound. The significant heat will be generated by the NASP's tremendous speeds, advanced engine, and engine seal designs are necessary. Unlike rocket engines that carry large, heavy oxygen tanks, the air-breathing engines under development for the NASP extract oxygen from the air. These engines will efficiently scoop and compress air to burn with the hydrogen fuel. Temperatures in the engine reach over 5,000 degrees Fahrenheit, with pressures exceeding 100 pounds per square inch. To operate at speeds up to 25 times the speed of a bullet, the NASP engine must meter the combustion flow going through the engine duct. Much like your car's fuel valves, the articulating nozzle panels in the NASP engine will tailor the flow for maximum performance. To prevent the hot, potentially explosive combustion gases from escaping past the panels, high-temperature seals are required around the panels perimeters. These seals must withstand extreme temperatures, seal highly distorted sidewalls, and resist abrasion over the life of the engine. Advanced seal concepts are being developed at NASA's Lewis Research Center. These seals are made of high-temperature ceramic materials able to operate at temperatures up to 2,300 degrees Fahrenheit. Above this, some form of active cooling must be employed to stay within the operational limits of the material. One leading concept under development is the ceramic wafer seal, which consists of multiple ceramic wafers mounted in a channel of the articulating engine panel. The seal accommodates and seals the large sidewall distortions through relative sliding of adjacent elements, much like the behavior of a deck of cards. Another approach is the ceramic rope seal, which is braided out of high temperature ceramic fibers that maintain flexibility at temperature. Both seals are preloaded against the adjacent walls by a series of spring-like bellows. The hot performance of the two seals were measured at NASA Lewis using the specially designed test fixture. Though one cannot see the seals in this picture, the seals are mounted behind the front wall of the hot test rig. Tests have shown that the ceramic wafer seal has very low leakage, even at temperatures exceeding 1400 degrees Fahrenheit. It seals both flat and distorted walls equally well. Tests of the braided ceramic rope seal identified key construction variables that can be optimized to meet the target flow goal. High-temperature seal technology developed under NASP is immediately beneficial to numerous aeronautical, space and industrial applications. High-temperature seals will be required on advanced high-temperature combustors and nozzles being designed for future commercial and military supersonic aircraft. NASP high-temperature seal technology can provide an extra margin of safety over the low-temperature O-ring seals of the shuttle's solid rocket motors and improve gap seals for the shuttle's main engines. The innovative seal work performed by NASA Lewis under the NASP program has earned four U.S. patents over the last two years. While R&D Magazine recognized the ceramic wafer seal as one of the most significant new technical products of 1990, NASP, the National Aerospace Plane, is serving as a national focus for advancing the state of the art in access to space and numerous supporting technologies.