Propulsion technology for National Aero-Space Plane
America's entrée in the world of hypersonics is spearheaded by the National Aero-Space Plane program. Although the concept of hypersonic flight at speeds above Mach 6 has been investigated before in many countries, the efforts begun in the 1960's in the United States did not result in a major new capability. Many valid principles were examined, a good data base was developed, but a demonstration was not pursued with the priorities assigned to the space program at that time. During the 1970's, our hypersonic effort dwindled to a few dedicated research efforts which refined propulsion, aerodynamics, and computational fluid dynamics principles. To make real progress in the 1980's, and beyond, a focus and a rekindled effort was needed. The National Aero-Space Plane program provides that focus of activities. Through the demonstration of single-stage-to-orbit (SSTO) capabilities in a manned vehicle capable of normal aircraft-like operations, the United States seeks to revitalize our advanced hypersonics research, spearhead the rapid development of technology, and conclusively demonstrate through flight testing that the age of hypersonics has arrived. This paper briefly describes the growth of the National Aero-Space Plane program, its objectives, its National team organization, and the schedule now envisioned for the remainder of the program. The primary emphasis of the paper is National Aero-Space Plane propulsion technology. Key technical challenges are noted and a discussion of progress relative to those challenges associated with propulsion is presented.