Analytical Modeling and Experimental Evaluation of a Passively Morphing Ornithopter Wing
نویسندگان
چکیده
Title of Document: ANALYTICAL MODELING AND EXPERIMENTAL EVALUATION OF A PASSIVELY MORPHING ORNITHOPTER WING Aimy Wissa, Doctor of Philosophy, 2014 Directed By: Langley Distinguished Professor, James E. Hubbard, Jr., Department of Aerospace Engineering Ornithopters or flapping wing Unmanned Aerial Vehicles (UAVs) have potential applications in both civil and military sectors. Amongst all categories of UAVs, ornithopters have a unique ability to fly in low Reynolds number flight regimes and have the agility and maneuverability of rotary wing aircraft. In nature, birds achieve such performance by exploiting various wing kinematics known as gaits. The objective of this work was to improve the steady level flight performance of an ornithopter by implementing the Continuous Vortex Gait using a novel passive compliant mechanism. A compliant mechanism, called a compliant spine, was fabricated, and integrated in the ornithopter's wing leading edge spar. Each compliant spine was designed to be flexible in bending during the wing upstroke and stiff in bending during the wing downstroke. Inserting a variable stiffness compliant mechanism in the leading edge spar of the ornithopter could affect its structural stability. An analytical model was developed to determine the structural stability of the ornithopter leading edge spar. The model was validated using experimental measurements. After ensuring the structural stability of the leading edge spar, a test ornithopter was tested in air and in vacuum as well as in free and constrained flight with various compliant spine designs inserted in its wings. Results from all the tests, proved that feasibility and efficacy of passive wing morphing using a compliant mechanism in improving the steady level flight performance of the test ornithopter. Inserting the compliant spine into the leading edge spar of the ornithopter during free flight reduced the baseline configuration body vertical center of mass positive acceleration by 69%, which translates into overall lift gains. It also increased the horizontal propulsive force by 300%, which translates into thrust gains. ANALYTICAL MODELING AND EXPERIMENTAL EVALUATION OF A PASSIVELY MORPHING ORNITHOPTER WING
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Flight Testing of Novel Compliant Spines for Passive Wing Morphing on Ornithopters
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