EVALUATION OF THE WAKE OF AN S-58 HELICOPTER.
Abstract
A brief exploratory study of air movements near the ground within the wake generated by a 12,000 pound Sikorsky S-58 helicopter was conducted under conditions of light and moderate winds. Windspeed instrumentation was used to measure wake speeds in a plane approximately perpendicu lar to the test site surface wind. The smoke patterns induced by the wake were photographed in color and were used as the basis for correlation of wake speed data. The highest wake velocities occurred during hovering flight. The wake generated by the hovering helicopter contacted the ground quickly, expanded outward from the hover center upon ground contact and exhibited rapid growth - hence rapid wake speed deteriora tion - and the spreading portions were contained within 20 feet of the ground. Although the wake speeds produced during forward flight were not as high as those produced in hover flight, they persisted in the air mass for a much greater time. Also, the speed of travel of the wake sys tem toward the ground decreases as the helicopter forward speed increases. These wakes with their vortices drifted downwind approximately at wind speed. The maximum propagation of wake veloci ties upwind was approximately 85 feet. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1963
- Accession Number
- AD0417257
Entities
People
- Robert H. Ahlers
- William A. Hiering