YF-12 inlet airframe interaction test in Ames 8X7ft supersonic wind tunnel

Robert Cubbison examines a model of the Lockheed YF-12 Blackbird in the test section of the 10- by 10-Foot Supersonic Wind Tunnel at the National Aeronautics and Space Administration (NASA) Lewis Research Center. The YF-12 was an experimental fighter version of Lockheed’s A-12 reconnaissance aircraft which had been developed into the renowned SR-71 Blackbird. NASA possessed two YF-12s at its Dryden Flight Research Center which could be used by researchers at all the NASA centers. During its nine-year life, the Dryden’s YF-12 research program logged 297 flights with approximately 450 flight hours. Lewis researchers were studying the YF-12’s inlet airflow in the 10- by 10-foot wind tunnel in late 1977. The advanced supersonic cruise aircraft of the time used mixed-compression inlets. These types of inlets were prone to flameout during atmospheric disturbances. Researchers at Lewis and Dryden developed a program to study these flameouts by artificially introducing flow disturbances. Testing at Dryden with a specially-equipped YF-12 aircraft yielded limited results. Lewis’ tests in the 10- by 10 were unsuccessful at inducing upstream disturbances. The researchers used two methods—a falling plate and a servo-driven wing.

A model of the General Dynamics YF-16 Fighting Falcon in the test section of the 8- by 6-Foot Supersonic Wind Tunnel at the National Aeronautics and Space Administration (NASA) Lewis Research Center. The YF-16 was General Dynamics response to the military’s 1972 request for proposals to design a new 20,000-pound fighter jet with exceptional acceleration, turn rate, and range. The aircraft included innovative design elements to help pilots survive turns up to 9Gs, a new frameless bubble canopy, and a Pratt and Whitney 24,000-pound thrust F-100 engine. The YF-16 made its initial flight in February 1974, just six weeks before this photograph, at Edwards Air Force Base. Less than a year later, the Air Force ordered 650 of the aircraft, designated as F-16 Fighting Falcons. The March and April 1974 tests in the 8- by 6-foot tunnel analyzed the aircraft’s fixed-shroud ejector nozzle. The fixed-nozzle area limited drag, but also limited the nozzle’s internal performance. NASA researchers identified and assessed aerodynamic and aerodynamic-propulsion interaction uncertainties associated the prototype concept. YF-16 models were also tested extensively in the 11- by 11-Foot Transonic Wind Tunnel and 9- by 7-Foot Supersonic Wind Tunnel at Ames Research Center and the 12-Foot Pressure Wind Tunnel at Langley Research Center.

This photo shows a head-on view of NASA's SR-71B, used for pilot proficiency and training, on the ramp at the Air Force's Plant 42 in Palmdale, California, shortly before delivery to the Ames-Dryden Flight Research Facility (later, Dryden Flight Research Center) at Edwards, California. NASA operated two of these unique aircraft, an SR-71A, for high-speed, high altitude research, and this SR- 71B pilot trainer for most of the decade of the 1990s. The "B" model is special because of its raised rear cockpit, which provided a second pilot position so a trainer and an experienced pilot could both see what was going on during flights. The SR-71 was designed and built by the Lockheed Skunk Works, now the Lockheed Martin Skunk Works. Studies have shown that less than 20 percent of the total thrust used to fly at Mach 3 is produced by the basic engine itself. The balance of the total thrust is produced by the unique design of the engine inlet and "moveable spike" system at the front of the engine nacelles, and by the ejector nozzles at the exhaust which burn air compressed in the engine bypass system. Data from the SR-71 high speed research program will be used to aid designers of future supersonic/hypersonic aircraft and propulsion systems, including a high speed civil transport.