HYPERSONIC EXPERIMENTAL RESEARCH VEHICLE
Artist's Rendering of HYPER-X
Hyper-X, NASA's multi-year hypersonic flight research program, seeks to overcome one of the greatest aeronautical research challenges - air-breathing hypersonic flight. Far outpacing contemporary aircraft of supersonic capability, three X-43A vehicles will fly at speeds of Mach 7 and 10. Ultimately, the revolutionary technologies exposed by the Hyper-X Program promise to increase payload capacities and reduce costs for future air and space vehicles.
MicroCraft, Inc. of Tullahoma, Tenn., is the industry partner chosen by NASA to construct the X-43 vehicles. The contract award announcement occurred on March 24, 1997, with construction of the vehicles beginning soon thereafter. Orbital Sciences Corporation's Launch Vehicles Division in Chandler, Ariz. will construct the Hyper-X launch vehicles.
The Hyper-X Phase I program — an agency-wide effort to address one of the greatest aeronautical research challenges — is conducted jointly by Dryden and Langley. Program management hopes to demonstrate technology that could ultimately be applied in vehicle types from hypersonic aircraft to reusable space launchers. Each of three vehicles will be approximately 12 feet long with a wing span of about five feet.
One of the primary goals of NASA's Aeronautics Enterprise, as delineated in the NASA Strategic Plan, specifies the development and demonstration of technologies for air-breathing hypersonic flight. Since the cancellation of the National Aerospace Plane (NASP) program in November 1994, the United States has not had a cohesive hypersonic technology development program, so the time is right for a new "better, faster, cheaper" program. Hyper-X captures NASP technology, quickly moving it forward to the next step, which is demonstration of hypersonic airbreathing propulsion in flight.
The goal of the Hyper-X program is to flight validate key propulsion and related technologies for air-breathing hypersonic aircraft. The first X-43 is scheduled to fly at Mach 7 in 2000. This is far faster than any air-breathing aircraft have ever flown. The world's fastest air-breathing aircraft, the SR-71, cruises slightly above Mach 3. The highest speed attained by NASA's rocket-powered X-15 was Mach 6.7, back in 1967.
Computational Fluid Dynamic (CFD) Image of Hyper-X at Mach 7 Test Condition
Ramjets and Scramjets
Heading the technology wish-list for the Hyper-X program is demonstration of a ramjet/scramjet engine, followed by demonstration of design tools and methods for air-breathing hypersonic vehicles. The scramjet engine is the key enabling technology for this program. Without it, sustained hypersonic flight could prove impossible.
Ramjets operate by subsonic combustion of fuel in a stream of air compressed by the forward speed of the aircraft itself, as opposed to conventional turbojet engines, in which the compressor section (the fan blades) compresses the air. In comparison to turbojets, ramjets have no moving parts.
Scramjets (supersonic-combustion ramjets) are ramjet engines in which the airflow through the whole engine remains supersonic. Scramjet technology is challenging because only limited testing can be performed in ground facilities. Long duration, full-scale testing requires flight test speeds above Mach 8. Hyper-X will build knowledge, confidence and a technology bridge to very high Mach number flight.
The fuel for X-43 will be hydrogen. Rockets carry their own oxygen for combustion; an air-breathing scramjet engine burns oxygen scooped from the atmosphere. Scramjets, therefore, get their oxygen in the same manner as normal jet engines do. Utilizing conventional turbojet technology, air-breathing hypersonic vehicles should carry more cargo/payload than equivalent rocket-powered systems, due simply to having more weight and payload space available because of not having to carry oxidizer on-board.
Artist's Rendering of HYPER-X
NASA Langley is carrying out various wind-tunnel tests on the X-43A design in an effort to refine the vehicle's design. Later, an X-43 vehicle may be tested in Langley's 8-Foot High Temperature Wind Tunnel. The vehicle, with a fully operating ramjet/scramjet propulsion system, will be put through tests in the tunnel simulating many, but not all, Mach 7 flight conditions. Dryden is working very closely with Langley in this refinement process, as well as working out the flight test issues, such as flight profile, vehicle instrumentation, and Pegasus booster/Hyper-X adaptation and integration. Flight test logistics support issues are being worked out.
Three flights are planned -two at Mach 7 and one at Mach 10. The flight tests will be conducted within the Western Test Range off the coast of southern California. The current flight profile calls for launching the X-43 vehicles on a westerly heading. The flights will terminate in the Pacific Ocean and the vehicles will not be recovered. The ground track is completely over water and is nearly 400 miles in length.
Artist's Rendering of HYPER-X and Launch Vehicle Attached to B-52
Hyper-X will ride on the first stage of a Pegasus booster rocket, which will be launched by Dryden's B-52 at 17,000 and 43,000 feet. For each flight, the booster will accelerate the Hyper-X research vehicle to the test conditions (Mach 7 or 10) at approximately 100,000 feet, where it will separate from the booster and fly under its own power. Vehicle and engine ground tests and analyses will be performed prior to each flight in order to compare flight and ground test results.
The Hyper-X program is managed by a combined Langley-Dryden team. Langley's Vince Rausch is the overall Program Manager. Langley is the responsible NASA center for hypersonic technology development. Joel Sitz of Dryden is the Hyper-X Flight Research Project Manager, responsible for the research flight testing for the program. Dryden is involved in every aspect of the program. The Langley Hyper-X Technology Project Manager is Charles McClinton.
Hyper-X vs. NASP
One major difference between the Hyper-X program and the previous National Aerospace Plane (NASP) program is the technical approach taken. The NASP program sought to integrate many new, untried technologies into a full-scale test vehicle. The primary legacy of the NASP program was the realization that its multiple technologies, including large scale scramjets, were not mature enough to be flight tested in a single, highly integrated vehicle-system approach. Scramjets required separate flight testing and integration into an airframe, a crucial element in hypersonic vehicle construction. The Hyper-X program is taking the step-by-step incremental approach, starting naturally enough with the key scramjet engine technology. Also, rather than attempting to construct a large vehicle, Hyper-X will utilize the three small-scale vehicles which save millions of dollars and reduce the possibility of one enormous financial loss in the event of a crash during the flight test program.
Other hypersonic flight projects have been attempted, even dating back to the 1960's. Between the status of technology, funding, politics, and interest at the specific time of each project, none ever got very far. So, in effect, hypersonics is still a flight science in it's infancy.
Just about everything in the Hyper-X project logo means something. The "X" does indeed represent "experimental". However, it also is the Roman numeral "10," as Hyper-X will fly at speeds up to Mach 10. In addition, there are 10 white stars in the "X" representing this speed. Superimposed over the "X" in the center of the logo is a side-profile of the vehicle. The graduating background colors represent the extreme heating environment Hyper-X will encounter, with red at the nose representing the hottest portion of the vehicle. Red fades to yellow toward the rear of the vehicle, which still encounters temperatures up to 2000 degrees Fahrenheit.