With the recent emergence of Urban Air Mobility (UAM) as a potential solution to alleviate congested urban transportation, concerns have arisen regarding adherence to noise emission regulations and general public acceptance. With the design of new and innovative air vehicles utilizing electric Vertical Takeoff and Landing (eVTOL) propulsion systems for UAM applications, significant gaps remain in the understanding of their aerodynamic and acoustic performance, particularly when interacting with disturbances such as turbulence generated by buildings. To address safety, noise, and performance challenges, effective optimization methods must be developed. However, there is a lack of sufficient experimental data to support these advancements. This study investigates the aerodynamic and acoustic performance of a scaled eVTOL propeller operating in both axial and non-axial flight. A comprehensive summary of the experimental propeller's design is provided. Thrust, torque, and sound pressure data are acquired from wind tunnel testing of the experimental propeller operating with various blade pitch angles, yaw angles, and under several inflow velocities. The experimental results are subsequently compared to a custom-developed Blade Element Momentum Theory (BEMT) utility for low-fidelity predictions. The findings aim to provide baseline data for Computational Fluid Dynamic (CFD) validation, enhancing predictive tools for advancing safe and efficient urban air transportation. Experimental results exhibit positive correlations between thrust, torque, and acoustic intensity with increasing yaw angle. The acoustic profile of the propeller at large yaw angles features an increase in broadband noise, a characteristic feature of Blade-Wake Interaction. Additionally, BEMT calculations predict thrust and torque within 10% accuracy of the measured data across most conditions. Supplementary calculations of the induced velocity fields offer preliminary insights into the distortion effects for future studies on interactions between eVTOL propellers and turbulent flows. / Master of Science / Urban Air Mobility (UAM) is viewed as a solution to congested transportation in urban areas. Newly designed aircraft, essentially "air taxis", seek to provide transportation in and around urban landscapes. A great concern with the operation of UAM aircraft in densely populated environments is their noise emissions. Methods must be developed to optimize vehicle performance while balancing the goal of being quiet enough for public acceptance. However, there remain knowledge gaps about how these vehicles will perform in such environments where turbulent flows are common. Therefore, experimental data must be acquired to provide a better understanding of how to model their performance and interactions. This study presents a comprehensive overview of the design and wind tunnel experimentation of a scaled air taxi propeller. Experimental results on aerodynamic and acoustic performance are collected and analyzed to provide baseline data for the validation of computational methods. Experimental results show trends of increasing thrust, torque, and acoustic intensity with increasing propeller tilt angle. The acoustic profile of the propeller at large tilt angles features an increase in broadband noise, which is characteristic of an increased presence of unsteady interaction. Lastly, low-fidelity calculations accurately predict thrust and torque within 10% error of the measured data for most conditions.

The design, analysis, construction and flight testing of a miniature Vertical Take-Off and Landing (VTOL) tail-sitter Unmanned Aerial Vehicle (UAV) prototype is presented in detail. Classic aircraft design methods were combined with numerical analysis to estimate the aircraft performance and flight characteristics. The numerical analysis employed a propeller blade-element theory coupled with momentum equations to predict the influence of a propeller slipstream on the freestream flow field, then the aircraft was analyzed using 3-D vortex lifting-line theory to model finite wings immersed in the flow field. Four prototypes were designed, built, and tested and the evolution of these prototypes is presented. The final prototype design is discussed in detail. A method for sizing control surfaces for a tail-sitter was defined. The final prototype successfully demonstrated controllability both in horizontal flight and vertical flight. Significant contributions included the development of a control system that was effective in hover as well as descending vertical flight, and the development of a strong but light weight airframe. The aircraft had a payload weight fraction of 14.5% and a maximum dimension of one meter, making it the smallest tail-sitter UAV to carry a useful payload. This project is expected to provide a knowledge base for the future design of small electric VTOL tail-sitter aircraft and to provide an airframe for future use in tail-sitter research.