A Theory for VTOL Propeller Operation in a Static Condition

Résumé du livre

A general theory for performance calculations was formulated based on a continuous vortex representation along the lines of the classical lifting-line model. As opposed to forward flight, the deformation of the wake is appreciable just behind the propeller, and its determination constitutes the heart of the static problem. A computer program has been developed to calculate both the inflow at the propeller and the induced velocity at any field point for an arbitrary description of the trailing vortex sheets. To approximate the force- free condition imposed on the wake, an initial wake hypothesis derived from the theory of the Generalized Actuator Disk was first used. The resulting comparisons with both detailed and gross measurements were unsatisfactory and a refined hypothesis was derived. The refined wake hypothesis provides a more reasonable representation of the 'pitch' of the elements of the deformed trailing vortex sheets as well as the envelope of their trajectories.