Two chase aircraft, a Learjet 23 (NASA 701) and a Cessna T-37 (NASA/USAF 00084), are shown in formation with a Boeing B-747 jetliner (NASA 905) in this 1974 NASA Flight Research Center (FRC) photograph. The two chase aircraft were used to probe the trailing wake vortices generated by the airflow around the wings of the B-747 aircraft. The vortex trails were made visible by smoke generators mounted under the wings of the B-747 aircraft.
NASA
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