FUNDAMENTAL UNDERSTANDING OF HELICOPTER AEROMECHANICS ON MARS THROUGH CHAMBER TESTING AND HIGH-FIDELITY ANALYSIS
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The fundamental aeromechanics of rotary-wing flight on Mars is explored. The exploration is based on chamber testing of Mars-like low Reynolds number rotors and the development of comprehensive analysis and comprehensive analysis coupled with computational fluid dynamics for systematic investigation of aeromechanical phenomena--critical for weights and packaging for Mars. The investigation includes rotor airloads, structural loads, and control loads, comparison of hingeless and articulated hubs, hover and forward flight, and the impact of fuselage aerodynamics. The coaxial configuration is the baseline platform for this work. The use of a helicopter on Mars would dramatically increase the speed, range, and coverage of exploration by providing access to caves, craters, over polar ice, along icy scarps and recurring slope lineae that are just plain inaccessible or too dangerous for rovers. Many factors go into the design of a Mars helicopter from launch/entry loads to power to controls to packaging. Aeromechanics is only one factor, but the principal factor for efficient and effective flight that impacts everything else. This work is focused on this principal factor. Current knowledge extrapolated from Earth would allow for short hops into the Mars atmosphere. Deeper understanding of Martian aeromechanics is needed to design larger more capable aircraft. Accurate predictions are needed for performance, blade loads, control loads, and blade strike behavior. True high-fidelity is needed for unlike on Earth decades of data sets do not exist on Mars. In fact there is not even a single data set. Thus clever and innovative means of verification and validation must be found. The objective of this thesis is to carry out all of these tasks. The key conclusions are: (1) the design of aircraft, hub, blades, and controls are substantially different on Mars because of its unique aeromechanics, (2) an articulated hub can in fact have lesser danger of blade strike, (2) a hingeless hub can experience lower or only marginally higher (6-7%) flap bending moments, (3) control / pitch link loads are dramatically impacted more by choice of Mars airfoils than rotor hubs, (4) lifting-line analysis does not even begin to capture the precise magnitudes of blade passage impulsive loads, and (5) fuselage aerodynamics is irrelevant in preliminary design. These, and other interesting phenomena will be the topics of this dissertation.