Electric multirotor design and optimization

Abstract

This work satisfies the need for more thorough method of propulsion component selection for electric VTOL (eVTOL) propulsion system design by bridging traditional aircraft sizing and electric multirotor design. Presented here is a framework for both analysis of an existing propulsion system, and also optimization of a propulsion system given a set of mission requirements for generic multirotor vehicles. The system of both the analyzer and optimizer is termed multirotor sizing tool (MST). The analyzer is capable of taking in and/or estimating a multitude of propulsion system parameters to predict the performance profile of the system including range, endurance, speed, power, sensitivities. The optimizer designs a propulsion system to satisfy goals such as desired endurance, range, maneuverability, and so forth. It designs the lightest possible vehicle within in a range of design variables set by the user. The modeling of electrical propulsion system components is described. MST is then used to design several vehicles which are built and flown, and predicted vs. measured data are presented. In addition to describing the MST, the study addresses the optimization of orientation of selected rotors in order to achieve rates in multiple axes. A study of configurations and effects on rate authority is also presented, including combinations of co-axial and pusher/tractor configurations, standard, non-standard coplanar and non-coplanar rotor layouts and different frames. Thrust stand, wind tunnel, and flight test results are included. Two novel configuration designs are presented, both an upgrade of existing configurations.