Abstract: Helicopter wake effects on stratus and stratocumulus clouds are described. Holes and troughs were created in such clouds with dimensions several hundred feet across. The velocities and penetration distances of the downwash ...

Abstract: Results of helicopter clearing experiments conducted at the Greenbrier Valley Airport, Lewisburg, W. Va., during the period 7?29 September 1969, are presented and discussed. Thirty-five hover experiments and 18 runway-clearing ...

Abstract: Values of diffusion coefficients determined from the observed closing times of nine conical-shaped clearings in fog produced by hovering helicopters at Lewisburg, WV, in September 1969 are presented. The values were ...