A low-cost aero-propulsive analysis of distributed electric propulsion aircraft

Despite the complex aero-propulsive interactions inherent in propeller-driven aircraft, low-cost methods for the analysis of distributed electric propulsion (DEP) aircraft are highly desirable to enable rapid aircraft design at the conceptual level. In this paper, a computationally-inexpensive method for analyzing the effect of a wing wake on the performance of pusher propellers is demonstrated using a vortex lattice method (VLM) augmented with boundary layer corrections and coupled with a blade element model (BEM). This approach captures important features in blade loading unattainable by inviscid methods, and at computational costs far below those of high-fidelity methods. The analysis for tractor-configured aircraft uses a vortex ring model to analyze the slipstream interaction of the propellers over the wing. These aero-propulsive analyses are subsequently used to compare performance of comparable pusher-and tractor-configured aircraft. Results show increased propulsive efficiency for individual pusher propellers of up to 16.2%, depending on propeller location and thrust level. At the vehicle level, the DEP aircraft in a pusher configuration benefited from increased aero-propulsive efficiency of 5.5%. An equivalent DEP tractor configuration showed a comparable improvement of 5.3%. The simplicity of this approach allows for fast design iteration of DEP aircraft at a fraction of the cost of current high-fidelity methods.