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Flight dynamics and control of a scale model of the Canadair CL-84 tiltwing aircraft
Thesis   Open access

Flight dynamics and control of a scale model of the Canadair CL-84 tiltwing aircraft

Thomas Templin
Master of Science (M.S.), Drexel University
Jun 2018
DOI:
https://doi.org/10.17918/00000274
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Abstract

Electrical engineering Fluid dynamics (Space environment) H2 control Servomechanisms Drone aircraft Vertically rising aircraft CL-84
Tiltwing aircraft are a class of dual-flight-mode aircraft, which have been investigated and operated since the middle of the 20th century and combine the advantages of vertical (helicopter-mode) and horizontal (fixed-wing-mode) flight. Recent decades have witnessed a trend toward unmanned robotic aircraft (UAVs), including tiltwing designs, which has accelerated during the early 21st century. This thesis attempts to make a contribution to the understanding of the flight dynamics and control of dual-flight-mode UAVs, by presenting a mathematical model and simulation of a commercially available 1:41 scale model of the Canadair CL-84 tiltwing aircraft. Four exemplars of the full-size CL-84 were built between 1963 and 1974, and the airplane demonstrated relatively good flight characteristics, according to test-pilot accounts. The flight-dynamics model of the scale version accounts for the most relevant thrust-related and aerodynamic forces and moments. The model is simulated in the MATLAB/Simulink development environment, using a modular programming approach. Linear reduced state-space models were derived from the nonlinear dynamics model, by means of Jacobian linearization at trim points, for both helicopter-mode and fixed-wing-mode flight. Based on the state-space models, stabilizing linear tracking controllers were developed, using servomechanism linear quadratic regulator (LQR) control design. The stabilizing controllers shift the system poles to the left half-plane, balance stability and maneuverability, and are capable of counteracting input and state disturbances. The helicopter-mode and fixed-wing-mode controllers were combined during wing tilt, using a weighted sum of either controller, to develop a controller for the transition from hover to conventional forward flight and vice versa. Transition flight displays vehicle wallowing, typical of tiltwing aircraft during conversion. The modular flight-dynamics and control model is extensible, and its applicability and fidelity could be enhanced by including additional forces and moments, as well as aerodynamic derivatives, implementing gain scheduling of linear controllers extracted at multiple trim points, as well as by employing a more comprehensive controller model for stabilizing and transition control.

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