| Abstract: | This thesis describes the design, development, and flight testing of a quad-cyclocopter weighing 25 kilograms and 1.8 m x 1.4 m x 0.8 m in dimension. This cyclocopter features four cantilevered cyclorotors with a unique five-bar blade pitching mechanism. The cyclorotor design is chosen through systematic parametric studies using an in-house 2-D computational fluid dynamics (CFD) solver. Based on the parametric studies, the final design selected is a 6-bladed cyclorotor with 0.64 chord-to-radius ratio, symmetric NACA 0015 airfoil, 45% chordwise pitch axis location, and pitch amplitude of 45° because it provided high thrust and power loading (thrust/power) at a low operating rotational speed of 700 RPM. The cyclorotor blades are manufactured with a foam core and carbon fiber skin resulting in lightweight blades with large bending and torsional stiffness. The rotor supporting structure and transmission is designed to be lightweight and resilient to large centrifugal loads and dynamic torques. A minimum mass airframe is designed and constructed from carbon fiber tubes to handle the vibratory loads from cyclorotors, mount electronics, and provide attachment points for the carbon fiber cowling. The attitude control strategy utilizes a combination of RPM control and thrust vectoring of the four cyclorotors (eight independent control parameters), resulting in an over-actuated system. A custom autopilot uses a closed-loop cascaded proportional-integral-derivative (PID) controller to stabilize the aircraft in hovering flight. The vehicle has been flight-tested and achieved lift-off. The electronic version of this dissertation is accessible from https://hdl.handle.net/1969.1/198531 |
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