Radical Wings & Wind Tunnels; Advanced Concepts Tested at NASA Langley
A fascinating history of the development of the NACA/NASA wind tunnels at the Langley Research Center in Hampton, Va. The authors not only provide insight behind the design and development of these wind tunnels, but take the reader through their use to study cutting-edge and radical aircraft designs over the last 77 years. Three unique wind tunnels are highlighted in this work: the Full Scale Tunnel, the 20-foot Vertical Spin Tunnel and the Free-Flight Tunnel.
The Full Scale Tunnel was dedicated in May 1931. The tunnel is a closed-circuit, open-throat tunnel characterized by an open quasi-elliptical test section 60 feet across, 30 feet high and 56 feet in length. This tunnel was capable of test speeds up to 100 mph and was used extensively during WWII in drag reduction studies of full-scale fighters, scout planes and torpedo bombers.
The 20-foot Vertical Spin Tunnel was built in 1941, replacing a late 1920s five-foot design and a 15-foot freespinning tunnel of 1935. This tunnel has a vertically oriented test section where the airflow allows the simulation of the downward velocity of an aircraft during spins. Models are hand-launched into the vertically rising airstream to evaluate spinning and spin-recovery behavior, tumbling resistance and recovery from out-of-control situations.
The Free-Flight Tunnel allows the study of the dynamic stability and control characteristics of an aircraft model in a free-flying condition. Airspeed and tunnel tilt angles are adjusted to maintain the unpowered model to remain stationary in the center of the tunnel. While the tunnel operator controls the airspeed and tunnel tilt, a “pilot” flies the plane during the test by feeding inputs to the model’s controls via thin wires that are kept slack during the flight.
The authors illustrate how these wind tunnels have been used over the years by focusing on the testing of more than 60 radical aerospace vehicles that did not or have not yet entered production. Starting in the 1920s with early monoplane designs, they take the reader through WWII and postwar innovations and continue to current research on hypersonic vehicles, lifting bodies and modern advanced fighters.
The book is an insightful read into the development and evolution of the American aerospace industry, and is amply illustrated with photographs of the vehicles discussed as they are being tested in the Langley wind tunnels. This book is a recommended read for anyone interested in this aspect of aviation history.