NASA Hypersonic X-Plane Flight Development of Technologies and Capabilities for the 21st Century Access to Space

A new family of NASA experimental aircraft (X-planes) is being developed to uniquely, yet synergistically tackle a wide class of technologies to advance low-cost, efficient access to space for a range of payload classes. This family includes two non-air-breathing rocket-powered concepts, the X-33 and the X-34 aircraft, and two air-breathing vehicle concepts, the scramjet-powered Hyper-X and the rocket-based combinedcycle flight vehicle. This report describes the NASA vision for reliable, reusable, fly-to-orbit spacecraft in relation to the current space shuttle capability. These hypersonic X-plane programs, their objectives, and their status are discussed. The respective technology sets and flight program approaches are compared and contrasted. Additionally, the synergy between these programs to advance the entire technology front in a uniform way is discussed. NASA’s view of the value of in-flight hypersonic experimentation and technology development to act as the ultimate crucible for proving and accelerating technology readiness is provided. Finally, an opinion on end technology products and space access capabilities for the 21st century is offered. 1. NOMENCLATURE ALT approach and landing test ATD advanced technology demonstrator CAN Cooperative Agreement Notice CFD computational fluid dynamics DoD Department of Defense DFRC Dryden Flight Research Center, Edwards, California ELV expendable launch vehicle FADS flush airdata system GPS/DGPS differential global positioning satellite system HTT high-temperature tunnel INS inertial navigation system JSC Johnson Space Center, Houston, Texas KSC Kennedy Space Center, Cape Canaveral, Florida LaRC Langley Research Center, Hampton, Virginia LOX a propellant mixture composed of liquid hydrogen and oxygen MSFC Marshall Space Flight Center, Huntsville, Alabama NASP National Aerospace Plane NRA NASA Research Announcement OSC Orbital Sciences Corporation, Dulles, Virginia PTO Participating Test Organization RBCC rocket-based combined-cycle RTO Responsible Test Organization RLV reusable launch vehicle SCA Shuttle Carrier Aircraft SSTO single stage to orbit STS Space Transportation System TPS thermal protection system TSTO two stage to orbit WSMR White Sands Missile Range, New Mexico 2. INTRODUCTION Through its Department of Defense (DoD) and National Aeronautics and Space Administration* (NASA) joint experimental aircraft programs, the United States has striven to develop advanced aircraft technologies and push the frontiers of flight through the use of unique, experimental aircraft. Since the X-1 beginning in 1945, these aircraft have been designated “X.” These nonproduction, nonmission-oriented flight vehicles were designed to be one-of-a-kind flying laboratories that focused on solving special flight problems or developing specific technologies that might or might not find their way onto future applications. High risk and tailored to the special aeronautics problem at hand, these X-planes tackled aeronautics firsts, such as breaking the sound barrier, achieving supersonic and even hypersonic manned flight to better than Mach 6.0, and reaching altitudes in excess of 100,000 to 300,000 ft (ref 1). Technology firsts included variable-sweep wings, forward-swept wings to supersonic speeds, advanced metallic alloys for primary structure, gimbaled jet and rocket engines, and numerous other never-before-flown technologies. 3. NASA SHUTTLE AND THE QUEST During the 1950’s and 1960’s, the U.S. relied heavily on expendable launch vehicles (ELV) to launch a variety of payloads and humans into Earth orbit. This expensive launch mode limited payload size and weight because of rocket payload bay sizes and, most importantly, payload weight * NASA was known as the National Advisory Committee for Aeronautics (NACA) in the 1940’s and 1950’s.