Influence of Meteorological Factors on the Vortex Wake of a Light Twin-Engine Aircraft

The smoke-marked trailing vortex wake generated by a light, twin-engine aircraft (AeroCommander 560F) was probed by another instrumented aircraft and the velocity and temperature fields in the wake were measured. Ground-based cameras recorded overall wake motion and decay due to instabilities. It was determined that wakes descending in a stably stratified atmosphere acquire buoyancy and then subsequently begin to lose it before they break up. The speed of descent of the wakes decreases with time, and the vortex spacing and the size of the buoyant oval both increase very slightly as the wake descends. A clear correlation between wake tilting and wind shear has been established, and it was determined that shear is one factor which causes the sometimes-observed single persistent vortex. (Modified author abstract)