Aerodynamic performance of aircraft wings with stationary vertical lift propellers

Abstract

Improvements in battery and motor technology are facilitating innovative aircraft configurations capable of vertical take-off and landing. Of these configurations, lift+cruise is popular for its inherent redundancy and the option to tailor separate propulsion systems for each flight regime. During cruise, the vertical flight propellers of a lift+cruise design are inactive and often exposed. Increasing the projected area of a body is understood to increase the drag, but the aerodynamic performance of an edgewise, stationary propeller and its influence on neighboring bodies is less clear. This study aimed to quantify the impact of two, tandem, edgewise and stationary propellers on the aerodynamic performance of a wing using wind tunnel measurements. The stationary position of the front and rear propellers were varied in 30∘ increments between 0-150∘, at angles of attack between -4∘ and 10∘. Results at Re = 4.3×105 showed the propellers and supporting systems had negligible influence on the lift. However, a drag increase of up to 30% was recorded when propeller positions were aligned perpendicular to the wing chord instead of parallel. Variations in the stationary position of the propeller altered the lift to drag ratio by up to 36% in a typical cruise configuration.