Cranked-Arrow Wing Aerodynamics Project (CAWAP)
NASA's single-seat F-16XL (ship #1), tail number 849, is stationed at Dryden Flight Research Center, Edwards, CA. It arrived at Dryden on March 10, 1989, from General Dynamics in Fort Worth, TX.
Previously, the aircraft was used in the Cranked-Arrow Wing Aerodynamics Project (CAWAP) to test boundary layer pressures and distribution. The modified airplane featured a delta "cranked-arrow" wing with strips of tubing along the leading edge to the trailing edge to sense static on the wing and obtain pressure distribution data. The right wing received data on pressure distribution and the left wing had three types of instrumentation - preston tubes to measure local skin friction, boundary layer rakes to measure boundary layer profiles (the layer where the air interacts with the surfaces of a moving aircraft), and hot films to determine boundary layer transition locations.
The XL-1 aircraft provided aerodynamic data for NASA's High Speed Civil Transport (HSCT) research program. The unique cranked-arrow wing shape provided better low-speed lift and handling characteristics than the modified "double-delta" wing used on the Concorde supersonic transport (SST).
The first flight of CAWAP occurred in November 1995, and the test program ended in April 1996.
Sonic Boom Studies
The F-16XL Ship #1 was used to investigate the characteristics of sonic booms for NASA's High Speed Research Program. During the series of sonic boom research flights, the F-16XL flew 200 feet behind a NASA SR-71 to probe the boundary of the SR-71's supersonic shock wave, recording their shape and intensity. Data from the program could be used in the development of a high-speed civilian transport (HSCT). The studies helped HSCT engineers to better understand supersonic shock waves to reduce sonic boom intensity near populated areas.
Supersonic Laminar Flow Studies
The F-16XL aircraft was flown in a NASA-wide program to improve laminar airflow on aircraft flying at sustained supersonic speeds. It was the first program to look at laminar flow on swept wings at speeds faster than sound. Technological data from the program could assist in the development of future high-speed aircraft, including commercial transports.
The XL-1 aircraft was upgraded with a new Digital Flight Control System (DFCS) in 1997. The DFCS upgrade allowed NASA's F-16XL-1 the flexibility needed to perform experiments which required major new flight control functions or capabilities. The initial flight test objectives for the modified aircraft verified that the DFCS functioned properly and that the performance and handling qualities were acceptable throughout the flight envelope.
The digital flight control system was compatible with a Research Flight Control System (RFCS) that could be installed when necessary. RFCS capability provided a flexible, reliable, and safe means to modify the aircraft control system. The RFCS computer significantly increased computational speed and computer memory.
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