Drag Reduction Through Distributed Electric Propulsion

TLDR

Electric propulsion advances enable a blown‑wing design using multiple tractor propellers along the wing. The authors modeled a four‑seat general‑aviation aircraft, derived momentum‑theory trade‑offs, and ran Navier‑Stokes aeropropulsive simulations of various wing‑propeller configurations at takeoff, landing, and cruise to assess lift and drag. The distributed‑propeller blown wing markedly raises low‑speed lift, permits a smaller wing with cruise drag and ride‑quality benefits, and overall promises substantial efficiency gains for small aircraft.

Abstract

One promising application of recent advances in electric aircraft propulsion technologies is a blown wing realized through the placement of a number of electric motors driving individual tractor propellers spaced along each wing. This configuration increases the maximum lift coefficient by providing substantially increased dynamic pressure across the wing at low speeds. This allows for a wing sized near the ideal area for maximum range at cruise conditions, imparting the cruise drag and ride quality benefits of this smaller wing size without decreasing takeoff and landing performance. A reference four-seat general aviation aircraft was chosen as an exemplary application case. Idealized momentum theory relations were derived to investigate tradeoffs in various design variables. Navier-Stokes aeropropulsive simulations were performed with various wing and propeller configurations at takeoff and landing conditions to provide insight into the effect of different wing and propeller designs on the realizable effective maximum lift coefficient. Similar analyses were performed at the cruise condition to ensure that drag targets are attainable. Results indicate that this configuration shows great promise to drastically improve the efficiency of small aircraft.