MEASUREMENT AND MODELLING OF MULTICOPTER UAS ROTOR BLADE DEFLECTION IN HOVER

Abstract: Package deliveries, surveillance and entertainment are all areas where unmanned aerial systems, (UAS), face a growing market. Multicopters, being one of the most popular UAS, can both be bought and built rather easily due to the fairly simple design and low cost. However, lack of regulations and absence of research of structural properties of the rotor blades motivates the purpose of this project, as better knowledge results in safer products with an increased operational envelope. The out of plane deflection and the change in pitch of two commercially available multicopter UAS rotor blades, one plastic and one carbon fiber reinforced, have thus been studied for an isolated rotor in hover mode. The deformation was measured using both a Digital Single-Lens Reflex (DSLR) camera and tailored photogrammetry with two cameras for a rotation speed range. The results were compared to analytical expressions of coning angle from helicopter theory and to one model that was developed for a finite element simulation was evaluated. The conclusion is that for the plastic blades the out of plane deflection is negative quadratic to linear relation to the rotation speed while the pitch has a trend of decreasing angle. For the carbon fiber blades the relation is more linear to quadratic for the deflection while the pitch is almost constant.