Small UAV Motor and Propeller Methods - A Parametric System Engineering Model- Based Approach

摘要

Design, analysis and modeling of small unmanned air system (sUAS) propulsion subsystems (engines/motor-batteries and propellers) is not as straight-forward as one might assume. The assumption is probably valid for internal combustion engines which are relatively easy to model and, with the exception of small-engine unique fuel and mixture ratio issues, are well characterized. Traditional electric motors are also well characterized but modern brushless motors with digital electronic speed controllers are more complicated to model, especially for students. Full-scale aircraft propeller analysis methods are also well developed but they are rooted in non-dimensional analysis of full scale data that have questionable applicability to sUAS due to Reynolds number and other scale related effects. And from an education perspective traditional propeller methods are non-intuitive for students to understand much less apply to projects. Traditional propeller methods can also mask test data issues that become evident if propellers are analyzed as simple rotating wings. So what was originally intended as a straightforward model-based design paper has broadened and (1) starts by questioning why we continue to use traditional non-dimensional methods for small propeller performance analysis when simple rotating wing aerodynamic methods provide more physical insight, particularly for students, (2) develops a small test data-based brushless DC motor subsystem model and (3) develops a simple propeller thrust-to-torque ratio based approach to propeller sizing and motor matching applicable to systems engineering model based design.