The Influence of Vertical Wind Gradients on the Longitudinal Motion of Airplanes
The Influence of Vertical Wind Gradients on the Longitudinal Motion of Airplanes

Author: Joseph Gera

Publisher:

Published: 1971

Total Pages: 28

ISBN-13:

DOWNLOAD EBOOK

The present study is an attempt to make an assessment of the influence of wind shear on the longitudinal motion of airplanes. It was assumed that the wind is completely horizontal and its speed varies linearly with altitude. It is shown quantitatively that both glide and climb performance are influenced by wind shear and that trimmed flight at constant airspeed, attitude, and with fixed controls is along a parabolic path relative to the ground. The problem of the landing approach in a wind shear is examined in some detail. Small disturbance theory indicates no wind-shear effect on the short-period motion and the time for the phugoid to damp to half amplitude but the phugoid frequency and damping ratio vary considerably with wind shear. A nondimensional quantity which depends on the wind shear and airspeed is shown to be a fundamental parameter influencing the longitudinal dynamic behavior of the airplane.

Analytical Investigation of the Effects of Vertical Wind Gradients on High Performance Aircraft
Analytical Investigation of the Effects of Vertical Wind Gradients on High Performance Aircraft

Author: Vincent A. Grosso

Publisher:

Published: 1961

Total Pages: 50

ISBN-13:

DOWNLOAD EBOOK

The equations representing the motion of an aircraft's center of gravity in three-dimensional space are derived and analyzed in cartesian and polar coordinates. The importance of variable, rotating winds on an aircraft's performance is determined from an analytical investigationof the derived equations. The equations are reduced to two dimensional space to allow a simplified investigation on an IBM 704 digital computer. Performance parameters for a hypothetical Mach Two aircraft climbing under the influence of vertical wind gradients are computedl. It is illustrated from the computations that flying reciprocal heading or attempting to fly crosswind when climbing with the hope of eliminating gradient effects is of no practical value. A method of correcting the rate of change of specific energy for the effects of gradients induced by winds changing in magnitude and direction as a function of altitude is developed. The correction equations are applied to computed climbs to illustrate their effectiveness. An outline for using the correction equations on flight test data is also included.