NACA 20-Foot Free-Spinning Wind Tunnel, NASA Langley
The large structure shown to the left of the photograph is the free-spinning wind tunnel in which dynamic scale models of modern airplanes are tested to determine their spinning characteristics and ability to recover from spins from movement of the control surfaces. From the information obtained in this manner the spin recovery characteristics of the full-scale airplane may be predicted.
The large sphere on the right is 60 feet in diameter and houses the NACA 12-foot free-flight wind tunnel in which dynamic scale models of airplanes are flown in actual controlled flight to provide information from which the stability characteristics of the full-scale airplane may be predicted.
Image credit: NASA