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LoFlyte (Low Observable Flight Test Experiment) [1] is a supersonic / hypersonic unmanned technology demonstrator stealth aircraft, [2] designed in a joint effort between the US Air Force and NASA [3] [4] to test the characteristics of hypersonic vehicles at low speeds and low altitudes. [5] It first flew in 1996. [3] Built by Accurate Automation. [6]
Wind tunnels are machines where an object is held stationary inside a tube, and air is blown around it to study the interaction between the object and the moving air. They are used to test the aerodynamic effects of aircraft, rockets, cars, and buildings. Different wind tunnels range in size from less than a foot across, to over 100 feet (30 m), and can have air that moves at speeds from a light breeze to hypersonic velocities.
The Ames Research Center (ARC), also known as NASA Ames, is a major NASA research center at Moffett Federal Airfield in California's Silicon Valley. It was founded in 1939 as the second National Advisory Committee for Aeronautics (NACA) laboratory. That agency was dissolved and its assets and personnel transferred to the newly created National Aeronautics and Space Administration (NASA) on October 1, 1958. NASA Ames is named in honor of Joseph Sweetman Ames, a physicist and one of the founding members of NACA. At last estimate NASA Ames had over US$3 billion in capital equipment, 2,300 research personnel and a US$860 million annual budget.
In aerodynamics, a hypersonic speed is one that exceeds five times the speed of sound, often stated as starting at speeds of Mach 5 and above.
A waverider is a hypersonic aircraft design that improves its supersonic lift-to-drag ratio by using the shock waves being generated by its own flight as a lifting surface, a phenomenon known as compression lift.
A scramjet is a variant of a ramjet airbreathing jet engine in which combustion takes place in supersonic airflow. As in ramjets, a scramjet relies on high vehicle speed to compress the incoming air forcefully before combustion, but whereas a ramjet decelerates the air to subsonic velocities before combustion using shock cones, a scramjet has no shock cone and slows the airflow using shockwaves produced by its ignition source in place of a shock cone. This allows the scramjet to operate efficiently at extremely high speeds.
The NASA Neil A. Armstrong Flight Research Center (AFRC) is an aeronautical research center operated by NASA. Its primary campus is located inside Edwards Air Force Base in California and is considered NASA's premier site for aeronautical research. AFRC operates some of the most advanced aircraft in the world and is known for many aviation firsts, including supporting the first crewed airplane to exceed the speed of sound in level flight, highest speed by a crewed, powered aircraft, the first pure digital fly-by-wire aircraft, and many others. AFRC operates a second site next to Air Force Plant 42 in Palmdale, California, known as Building 703, once the former Rockwell International/North American Aviation production facility. There, AFRC houses and operates several of NASA's Science Mission Directorate aircraft including SOFIA, a DC-8 Flying Laboratory, a Gulfstream C-20A UAVSAR and ER-2 High Altitude Platform. As of 2023, Bradley Flick is the center's director.
The Langley Research Center, located in Hampton, Virginia near the Chesapeake Bay front of Langley Air Force Base, is the oldest of NASA's field centers. LaRC has focused primarily on aeronautical research but has also tested space hardware such as the Apollo Lunar Module. In addition, many of the earliest high-profile space missions were planned and designed on-site. Langley was also considered a potential site for NASA's Manned Spacecraft Center prior to the eventual selection of Houston, Texas.
The Boeing X-48 is an American experimental unmanned aerial vehicle (UAV) built to investigate the characteristics of blended wing body (BWB) aircraft. Boeing designed the X-48 and two examples were built by Cranfield Aerospace in the UK. Boeing began flight testing the X-48B version for NASA in 2007. The X-48B was later modified into the X-48C version, which was flight tested from August 2012 to April 2013. Boeing and NASA plan to develop a larger BWB demonstrator.
The Rockwell X-30 was an advanced technology demonstrator project for the National Aero-Space Plane (NASP), part of a United States project to create a single-stage-to-orbit (SSTO) spacecraft and passenger spaceliner. Started in 1986, it was cancelled in the early 1990s before a prototype was completed, although much development work in advanced materials and aerospace design was completed. While a goal of a future NASP was a passenger liner capable of two-hour flights from Washington to Tokyo, the X-30 was planned for a crew of two and oriented towards testing.
A hypersonic wind tunnel is designed to generate a hypersonic flow field in the working section, thus simulating the typical flow features of this flow regime - including compression shocks and pronounced boundary layer effects, entropy layer and viscous interaction zones and most importantly high total temperatures of the flow. The speed of these tunnels vary from Mach 5 to 15. The power requirement of a wind tunnel increases linearly with its cross section and flow density, but cubically with the test velocity required. Hence installation of a continuous, closed circuit wind tunnel remains a costly affair. The first continuous Mach 7-10 wind tunnel with 1x1 m test section was planned at Kochel am See, Germany during WW II and finally put into operation as 'Tunnel A' in the late 1950s at AEDC Tullahoma, TN, USA for an installed power of 57 MW. In view of these high facility demands, also intermittently operated experimental facilities like blow-down wind tunnels are designed and installed to simulate the hypersonic flow. A hypersonic wind tunnel comprises in flow direction the main components: heater/cooler arrangements, dryer, convergent/divergent nozzle, test section, second throat and diffuser. A blow-down wind tunnel has a low vacuum reservoir at the back end, while a continuously operated, closed circuit wind tunnel has a high power compressor installation instead. Since the temperature drops with the expanding flow, the air inside the test section has the chance of becoming liquefied. For that reason, preheating is particularly critical.
The Boeing X-51 Waverider is an unmanned research scramjet experimental aircraft for hypersonic flight at Mach 5 and an altitude of 70,000 feet (21,000 m). The aircraft was designated X-51 in 2005. It completed its first powered hypersonic flight on 26 May 2010. After two unsuccessful test flights, the X-51 completed a flight of over six minutes and reached speeds of over Mach 5 for 210 seconds on 1 May 2013 for the longest duration powered hypersonic flight.
Scramjet programs refers to research and testing programs for the development of supersonic combustion ramjets, known as scramjets. This list provides a short overview of national and international collaborations, and civilian and military programs. The USA, Russia, India, and China (2014), have succeeded at developing scramjet technologies.
Lockheed L-301 was an experimental air-breathing hypersonic aircraft project. It was developed by the NASA and United States Air Force (USAF) organization National Hypersonic Flight Research Facility, with Skunk Works as the prime contractor. In January 1977, the program was "tentatively scheduled to operate two vehicles for eight years and to conduct 100 flights per vehicle." NASA discontinued work on L-301 and NHRF in September 1977 due to budget constraints and lack of need.
The University of Texas at Arlington Aerodynamics Research Center (ARC) is a facility located in the southeast portion of the campus operated under the Department of Mechanical and Aerospace Engineering. It was established in 1986 as part of an expansion of UTA's College of Engineering. The ARC contributes to the vision of UTA and the University of Texas System to transform the university into a full-fledged research institution. It showcases the aerodynamics research activities at UTA and, in its history, has established itself as a unique facility at a university level. The wind tunnels and equipment in the facility were mainly built by scouting for and upgrading decommissioned equipment from the government and industry. Currently, Masters and Ph.D. students perform research in the fields of high-speed gas dynamics, propulsion, and Computational fluid dynamics among other projects related to aerodynamics.
Hypersonic flight is flight through the atmosphere below altitudes of about 90 km at speeds greater than Mach 5, a speed where dissociation of air begins to become significant and high heat loads exist. Speeds over Mach 25 have been achieved below the thermosphere as of 2020.
In aeronautics, expansion and shock tunnels are aerodynamic testing facilities with a specific interest in high speeds and high temperature testing. Shock tunnels use steady flow nozzle expansion whereas expansion tunnels use unsteady expansion with higher enthalpy, or thermal energy. In both cases the gases are compressed and heated until the gases are released, expanding rapidly down the expansion chamber. The tunnels reach speeds from Mach 3 to Mach 30 to create testing conditions that simulate hypersonic to re-entry flight. These tunnels are used by military and government agencies to test hypersonic vehicles that undergo a variety of natural phenomenon that occur during hypersonic flight.
The Aeronautical/Astronautical Research Laboratory (AARL) is an aerospace engineering research facility operated by Ohio State University. It is the principal research facility of the College of Engineering's Department of Aerospace and Astronautical Engineering. It is located on the grounds of Ohio State University Airport, in Columbus, Ohio.
The 14-X is a Brazilian scramjet engine in development by the Aerothermodynamics and Hypersonics Laboratory Henry T. Nagamatsu of the Institute of Advanced Studies (IEAv) of the Department of Aerospace Science and Technology as part of the PropHiper. The name is a reference to the 14-bis, of the Brazilian inventor and aviation pioneer Alberto Santos-Dumont.
The HSTDV is an unmanned scramjet demonstration aircraft for hypersonic flight. It is being developed as a carrier vehicle for hypersonic and long-range cruise missiles, and will have multiple civilian applications including the launching of small satellites at low cost. The HSTDV program is being run by the Defence Research and Development Organisation (DRDO).
The Lockheed Martin X-59 Quesst, sometimes styled QueSST, is an American experimental supersonic aircraft being developed at Skunk Works for NASA's Low-Boom Flight Demonstrator project. Preliminary design started in February 2016, with the X-59 planned to begin flight testing in 2021. After delays, as of January 2024, it is planned to be delivered to NASA for flight testing in 2024. It is expected to cruise at Mach 1.42 at an altitude of 55,000 ft (16,800 m), creating a low 75 effective perceived noise level (EPNdB) thump to evaluate supersonic transport acceptability.
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