Recent developments in the shipping industry have opened some unprecedented trade opportunities on various levels. Be it individual consumption or business needs, the thought of receiving a package on the same day or within 4-hour from some other business or industry in the urban area is worth appreciating. The congestion on ground transportation modes is higher than ever. Since currently the same-day delivery in urban areas is carried mainly by ground modes, the catchment area of this delivery service is limited. The On-Demand Mobility for cargo can elevate the concept of express shipping in revolutionary ways. It will not only increase the catchment area thereby encompassing more business and consumers but will also expedite the delivery as these vehicles will fly over the ground traffic. The objective of this study was to estimate the total demand for ODM Cargo operations and study its effect on ODM passenger operations. The area of interest for this study was Northern California (17 counties). Annual cargo flows in the study area were rigorously analyzed through databases like Transearch, Freight Analysis Framework-4, and T-100 International for freight. The results of this study are presented through a parametric analysis of market share. The end product also includes the flight trajectories (with flight plan) of daily ODM cargo flights in the study region. The On-Demand Mobility cargo operations are expected to complement passenger On-Demand Mobility operations. Therefore, the effect of ODM cargo operations on the passenger ODM operations was also analyzed in this study. The major challenge faced in this study was the unavailability of datasets with the desired level of details and refinements. Since the movement of cargo is mostly done by private companies, the detailed records of shipments are often not public knowledge. / Master of Science / The recent advancements in shipping industry has made transfer of goods both domestic and international, swifter and more reliable. Nowadays, some business and consumers in urban areas have the options of few-hours or same day delivery. Currently the same-day delivery in urban areas is carried mainly by ground modes (trucks) and hence the catchment area of this delivery service is limited. Adding to it, the traffic congestion on the urban roads is a major hinderance in growth of such services. The On-Demand Mobility for cargo can reform express shipping in revolutionary ways. The concept vehicle can fly over the ground traffic. Therefore, it will increase the catchment area thereby encompassing more business and consumers, along with faster delivery options in currently serviced areas. For the study, we analyzed different databases for annual cargo flows in the region. Seventeen counties in the Northern California were chosen as the study area (or region). The study was focused on estimating the potential market (demand) for the On-Demand Mobility Cargo operations. Multiple set of results were calculated for different market shares that On-Demand Mobility can potentially capture in cargo operations. Flight trajectories (with flight plan) for daily ODM cargo flights were the final product. The On-Demand Mobility cargo operations are expected to complement passenger ODM operations. Therefore, the effect of ODM cargo operations on the passenger ODM operations was also analyzed in this study. The major challenge faced in this study was the unavailability of datasets with the desired level of details and refinements.

Electrically powered vertical takeoff and landing (eVTOL) aircraft could provide a new mode of air transportation of people and cargo that is low-cost, on-demand, and able to reach more areas than is possible with current technology. They have the unique ability to takeoff and land in congested spaces yet efficiently travel long distances which makes them a promising technology for applications such as rapid medical assistance, automated package delivery, or human transportation. This type of aircraft has only recently become a possibility, owing to advancements in battery technology, computing power, and sensor technologies, and thus support for eVTOLs is lacking among high-fidelity graphics simulation software. High-fidelity graphics are important for the goal of fully autonomous eVTOL aircraft in order to accurately simulate vision-based navigation using camera sensors. In this work, we present VTOL-AirSim, an extension of Microsoft AirSim with full integration of a tiltrotor eVTOL aircraft. Built on Unreal Engine, a high-end graphics game engine, it includes photorealistic graphics for simulated camera images and for high-quality presentations. We created the visual components of a fully animated tiltrotor vehicle and a detailed city environment for it to fly in. The tiltrotor can be controlled via motor PWM commands, by overriding its state in the world with the use of an external dynamics simulation, or by using the PX4 Autopilot. We give a tutorial on how to use VTOL-AirSim where we provide examples for each method of control, including scripts for controlling the tiltrotor via a geometric controller and control allocation module developed by others in the BYU MAGICC Lab. We also show how to further develop VTOL-AirSim, and how to add custom aircraft or custom environments so that others may use it in their own research.

The development of high-energy-density batteries, advanced sensor technologies, and advanced control algorithms for multirotor electric vertical takeoff and landing (eVTOL) unmanned aerial vehicles (UAVs) has led to interest in using these vehicles for a variety of applications including surveillance, package delivery, and even human transportation. In each of these cases, the ideal vehicle is one that can maneuver in congested spaces, but is efficient for traveling long distances. The combination of wings and vectored thrust make winged eVTOLs the obvious choice. However, these aircraft experience a much wider range of flight conditions that makes them challenging to model and control. This thesis contributes an aerodynamic model and a planning and control method for small, 1-2 m wingspan, winged eVTOLs. We develop the aerodynamic model based on first-principles, lumped-element aerodynamics, extending the lift and drag models to consider high-angle-of-attack flight conditions using models proposed in the literature. We present two methods for generating spline trajectories, one that uses the singular value decomposition to find a minimum-derivative polynomial spline, and one that uses B-splines to produce trajectories in the convex hull of a set of waypoints. We compare the quality of trajectories produced by both methods. Current control methods for winged eVTOL UAVs consider the vehicle primarily as a fixed-wing aircraft with the addition of vertical thrust used only during takeoff and landing. These methods provide good long-range flight handling but fail to consider the full dynamics of the vehicle for tracking complex trajectories. We present a trajectory tracking controller for the full dynamics of a winged eVTOL UAV in hover, fixed-wing, and partially transitioned flight scenarios. We show that in low- to moderate-speed flight, trajectory tracking can be achieved using a variety of pitch angles. In these conditions, the pitch of the vehicle is a free variable that we use to minimize the necessary thrust, and therefore energy consumption, of the vehicle. We use a geometric attitude controller and an airspeed-dependent control allocation scheme to operate the vehicle at a wide range of airspeeds, flight path angles, and angles of attack. We provide theoretical guarantees for the stability of the proposed control scheme assuming a standard aerodynamic model, and we present simulation results showing an average tracking error of 20 cm, an average computation rate of 800 Hz, and an 85% reduction in tracking error versus using a multirotor controller for low-speed flight.

No description available.

The vortex particle method (VPM) is a mesh-free approach to computational fluid dynamics (CFD) solving the Navier-Stokes equations in their velocity-vorticity form. The VPM uses a Lagrangian scheme, which not only avoids the hurdles of mesh generation, but it also conserves vortical structures over long distances with minimal numerical dissipation while being orders of magnitude faster than conventional mesh-based CFD. However, VPM is known to be numerically unstable when vortical structures break down close to the turbulent regime. In this study, we reformulate the VPM as a large eddy simulation (LES) in a scheme that is numerically stable, without increasing its computational cost. A new set of VPM governing equations are derived from the LES-filtered Navier-Stokes equations. The new equations reinforce conservation of mass and angular momentum by reshaping the vortex elements subject to vortex stretching. In addition to the VPM reformulation, a new anisotropic dynamic model of subfilter-scale (SFS) vortex stretching is developed. This SFS model is well suited for turbulent flows with coherent vortical structures where the predominant cascade mechanism is vortex stretching. Extensive validation is presented, asserting the scheme comprised of the reformulated VPM and SFS model as a meshless LES that accurately resolves large-scale features of turbulent flow. Advection, viscous diffusion, and vortex stretching are validated through simulation of isolated and leapfrogging vortex rings. Mean and fluctuating components of turbulent flow are validated through simulation of a turbulent round jet, in which Reynolds stresses are resolved directly and compared to experimental measurements. Finally, the computational efficiency of the scheme is showcased in the simulation of an aircraft rotor in hover, showing our meshless LES to be 100x faster than a mesh-based LES with similar fidelity. The ability to accurately and rapidly assess unsteady interactional aerodynamics is a shortcoming and bottleneck in the design of various next-generation aerospace systems: from electric vertical takeoff and landing (eVTOL) aircraft to airborne wind energy and wind farms. For instance, current models used in preliminary design fail to predict and assess configurations that may lead to the wake of a rotor impinging on another rotor or a wing during an eVTOL transition maneuver. In the second part of this dissertation, we address this shortcoming as we present a variable-fidelity CFD framework based on the reformulated VPM for simulating complex interactional aerodynamics. We further develop our meshless LES scheme to include rotors and wings in the computational domain through actuator models. A novel, vorticity-based, actuator surface model (ASM) is developed for wings, which is suitable for rotor-wing interactions when a wake impinges on the surface of a wing. This ASM imposes the no-flow-through condition at the airfoil centerline by calculating the circulation that meets this condition and by immersing the associated vorticity following a pressure-like distribution. Extensive validation of rotor-rotor and rotor-wing interactions predicted with our LES is presented, simulating two side-by-side rotors in hover, a tailplane with tip-mounted propellers, and a wing with propellers mounted mid-span. To conclude, the capabilities of the framework are showcased through the simulation of a multirotor tiltwing vehicle. The vehicle is simulated mid maneuver as it transitions from powered lift to wing-borne flight, featuring rotors with variable RPM and variable pitch, tilting of wings and rotors, and significant rotor-rotor and rotor-wing interactions from hover to cruise. Thus, the reformulated VPM provides aircraft designers with a high-fidelity LES tool that is orders of magnitude faster than mesh-based CFD, while also featuring variable-fidelity capabilities.

The electric vertical take-off and landing (EVTOL) platform is opening a new market segment that is disrupting the commercial and military aircraft industry. This particular vehicle platform is filling the gap between road vehicles and aircrafts. The main idea is to avoid the gridlock in major metropolitan cities where a journey that should take 30 minutes now takes more than one hour. Key enablers such as the newly developed infrastructures known as Vertiports and the move of electrification of aircrafts have driven this new market segment with fast time to market. To enable the deployment of these EVTOLs in the commercial world, their fault behavior needs to be known as faults will happen, a fault mitigation strategy must be developed to ensure that when the fault happens, the EVTOL and its passengers along with its surrounding are protected from catastrophic failures. To give a brief context on what these EVTOL platforms are, potential and developed EVTOLs in the market currently are introduced. The categorization of these platforms is done within four types of categories being Helicopters, Multi-Rotor, Lift & Thrust and Tilt-X. Their general advantages and disadvantages are discussed and the categories are rated in terms of which platform could be the most viable option to be in service by 2024. Their main electrical distribution system is introduced with their critical components and how they can fail. Each critical component such as the battery, electrical propulsion unit (EPU), protection devices, power distribution units and auxiliary electrical loads are discussed in details. The thesis discusses one of the main safety aspects of an EVTOL, which is protection of a propulsion unit. The critical electrical faults in the EPU are introduced along with their behavior on the EVTOL electrical distribution system (EDS). Open circuit faults and short circuit faults from the inverter and its power devices to the electric motor are analyzed. Furthermore, the sensor failures such as the rotor position sensor and the current and voltage sensors are discussed. The controller stage failures are discussed as well as it becomes a critical component that can fail in many ways. Once the electrical faults are discussed, a fault mitigation strategy (FMS) is introduced for each fault ranging from a simple inverter disabling strategy, to a sensorless control law for the loss of position sensor. A protection device known as the solid state power controller (SSPC) is inserted at the input of the EPU and its design is discussed for a 270VDC/180A modular architecture. This SSPC becomes the redundant and final protection stage of the EPU to ensure if the developed FMS fail to protect the EPU, the SSPC can isolate the EPU from the rest of the EVTOL EDS. The main contribution of the thesis is the systematic approach to fault analysis and mitigation/protection strategies that were not addressed in literature so far for this type of platform. The use of a single FMS for multiple faults is introduced where the aim is to reduce the efforts for verification and validation (V&V) of the corresponding software and firmware. Finally, the practical implementation challenges of the SSPC are discussed and shown in experimental lab setups. / Dissertation / Doctor of Philosophy (PhD)

Urban air mobility has gained increased attention in recent years due to the emergence of novel technologies. Several use cases within different industries exist. These services can substitute existing services as well as offering entirely new ones. Previous research has focused on novel technologies and changes needed to be made in order for the technology to be established in the market. However, non-technological aspects are lacking, specifically concerning suitable business models. Thus, the role of business models, and changes related to these, required for a commercialization of urban air mobility services constitutes a research gap and are of interest for further exploration. To understand how actors are changing their business models to commercialize urban air mobility three different case studies were conducted on three projects focusing on use cases connected to urban air mobility. Interviews were used as the primary data gathering method, and in total 13 were conducted. The theoretical STOF framework, which delimits the business model into four domains, was used to identify potential changes. The main results indicate important future actors in a commercialization, the degree of change of these actors and potential challenges for them. Due to the uncertainty of the role business models play in a commercialization of urban air mobility services, this thesis will contribute to bridging this research gap. Concrete changes are identified, as well as specific business model areas in need of more attention. Furthermore, the thesis contributes to the literature concerning challenges related to urban air mobility services, as well as suggesting how they can be handled. Finally, the thesis evaluates and explains how the STOF framework can be extended to new industries. / Urban air mobility har fått ökad uppmärksamhet de senaste åren på grund av uppkomsten av nya teknologier. Flera användningsområden inom olika branscher existerar. Dessa tjänster kan ersätta befintliga tjänster samt erbjuda helt nya. Tidigare forskning har främst fokuserat på nya teknologier och förändringar som behöver göras för att tekniken ska etableras på marknaden. Emellertid saknas aspekter som inte är teknologiska, särskilt lämpliga affärsmodeller. Därmed är inte affärsmodellens roll samt nödvändiga förändringar relaterade till den för en kommersialisering av urban air mobility tillräckligt belysta och är därför intressant för vidare forskning. För att förstå hur aktörer ändrar sina affärsmodeller för att kommersialisera urban air mobility genomfördes tre olika fallstudier på tre projekt som fokuserar på användningsområden kopplade till urban air mobility. Den teoretiska STOF modellen, som avgränsar affärsmodellen i fyra områden, användes för att identifiera potentiella förändringar för de olika projektaktörernas affärsmodeller. De främsta resultaten indikerar vilka de viktiga framtida aktörerna i en kommersialisering är, graden av affärsmodellsförändring för dem, samt potentiella utmaningar. På grund av osäkerheten kring vilken roll affärsmodeller har vid kommersialisering av tjänster relaterade till urban air mobility bidrar denna avhandling till att ytterligare belysa detta forskningsområde. Konkret identifierar avhandlingen nödvändiga affärsmodellsförändringar för de olika aktörerna, samt specifika områden inom affärsmodellen som behöver mer uppmärksamhet. Dessutom bidrar avhandlingen till forskningslitteraturen om utmaningar relaterade till urban air mobility tjänster, samt föreslår hur de kan hanteras. Slutligen utvärderar och förklarar avhandlingen hur STOF modellen kan utökas till fler branscher än internetbaserade tjänster.

This work provides an experimental analysis of the acoustic footprint of a hexacopter in hover and low speed forward flight, comparison of aerodynamic performance and noise of eVTOL rotors operating in multiple facilities, and analysis of the noise associated with an outrunner brushless DC motor. Empirical and low-order models are used to predict aerodynamic performance, tonal noise, and broadband noise for isolated eVTOL rotors. In addition, a low noise, swept rotor design was evaluated. The acoustic footprint of a DJI Matrice 600 Pro hexacopter in hover and low speed forward flight was measured in the Virginia Tech Drone Park. The noise radiated by this vehicle was found to be dominated by tonal noise at low frequencies and dominated by broadband noise at high frequencies indicating that both are important when assessing the noise of these aircraft. Three distinct regions were observed in the frequency spectra of the noise. A-weighting measured acoustic spectra highlighted the importance of the mid-frequency broadband noise, in particular. The radiated noise in hover was also found to be similar to the noise of the vehicle during low-speed flyovers. Given this, significantly less complex measurements of an aircraft in hover or those associated with a rotor at static conditions may be used to assess the footprint of an eVTOL aircraft in low speed forward flight. The total vehicle noise was then decomposed by studying the performance and noise of isolated eVTOL rotors in multiple facilities and under different operating conditions. Facility effects on performance and noise were first assessed by experimentally studying two commercially available eVTOL rotors in an enclosed anechoic environment and an open environment. For experimental measurements that were conducted in the anechoic chamber, recirculation effects were shown to increase harmonic amplitudes more than 8 dB. Varying solidity screens were placed in the downstream wake of each rotor to delay the onset of recirculation. Placing the screens in the wake did not produce a noticeable effect on or delay recirculation within the confined testing environment. Measurements of the BPF and higher order harmonics of each rotor were found to be much more consistent in time when testing outdoors in an open-air environment. Amplitudes of these tones were also found to be like that of the spectral levels of the measurements conducted in the anechoic chamber once recirculation had been established. While the tonal levels were much more consistent throughout each measurement in the open-air environment, a significant amount of background noise was present and made characterizing the noise at low frequencies difficult. Environmental factors, mainly windspeed, were also found to impact the noise measurements which also added difficulty in characterizing the noise of the two tested rotors. In indoor facilities, the rotor inflow becomes contaminated due to recirculation shortly after the rotor reaches steady state and spectral levels of tones increased with increasing spectral averaging times. In outdoor environments, the inflow to the rotor disc becomes distorted due to changing wind conditions and turbulence in the atmosphere. Spectral levels of tones in the outdoor environment remained consistent in amplitude but exceeded those of the anechoic chamber significantly. Given this, environmental factors and recirculation were found to both increase the higher order harmonics. To mitigate these facility effects, measurements of force and noise were also conducted for the same two rotors in an anechoic open jet. Additionally, measurements were also conducted for a commercially available rotor along with a newly designed low noise swept rotor. Each of these rotors were tested in the anechoic open jet facility at static conditions and with the tunnel on. These measurements were accompanied with predictions of aerodynamic performance and tonal and broadband self-noise. BEMT was used to predict aerodynamic performance. Tonal noise associated with the rotor blade loading and thickness was predicted using F1A and rotor broadband self-noise was predicted using the model of BPM. The measured noise in this facility along with that from measurements in the anechoic chamber and outdoor environment were separated into tonal and broadband components by applying a phase averaging technique to the measured acoustic pressure time history. These results also show that in the indoor facility that the noise produced at the BPF is dominated by tonal sources, but the higher order harmonics can be attributed to broadband interactions particularly at static conditions. Broadband noise was drastically reduced by driving the tunnel at minimal inflow for the smallest rotor studied (R_tip= 120 mm). For the larger rotors (R_tip≥ 267 mm) broadband noise associated with BWI or TIN were not mitigated at low inflow speeds. Predictions of tonal noise at the BPF were within 3 dB for all observer locations when considering the smallest rotor studied. Predictions of the measured directivity at the BPF for the larger rotors were inaccurate although predictions of thrust agreed with the measured. The largest rotors tested were equal in diameter to that of the open jet inlet. Thus, the limits of the testing facility were exceeded and increased noise was produced as the rotor blades interacted with the shear layer of the open jet. Directivity patterns of each rotor were also found to vary with increasing rotational rate. Overall, these results show that for analyzing the noise at hover conditions, introducing a small amount of inflow may be a good option when trying to understand the tonal noise and allows one to characterize the tonal noise independent of the broadband. However, this was also shown to be heavily dependent on the rotor diameter with regards to the open jet inlet and experimentalist must take this into consideration. While these measurements provide an analysis of the noise in hover and low speed ascent, they do not assess the noise of the vehicle operating in forward flight. In forward flight the rotors are subjected to edgewise flows which have an effect on the radiated noise thus analyzing the noise of these rotors operating at an angle of attack to the incoming flow was assessed. These effects were investigated by experimentally measuring the performance and noise of the smallest rotor studied when operating at a yaw relative to the incoming flow. For increasing yaw at the examined wind tunnel velocities, the measured thrust was found to converge to the value for zero inflow. Contours of SPL as a function of yaw angle for no inflow and an inflow speed of 8 m/s showed spectral levels to be minimal for an in-plane observer from 5×BPF to 30×BPF. The broadband noise was found to increase significantly for increasing yaw angle and tunnel inflow speed. These results show once again that the broadband noise is especially important during forward flight and new methods that consider wake interaction are needed to predict the noise in this flight regime. The rotor geometric parameter of sweep was also assessed from measurements in the anechoic open jet by comparing the aerodynamic performance and noise of a commercially available 762 mm diameter CF30x10.5 T-motor eVTOL rotor to that of an in house designed low noise swept rotor. The addition of sweep was found to reduce noise associated with BWI or TIN as the separated broadband noise was found to be less than that of the commercially available rotor. Comparison of thrust at static conditions and with increasing advance ratios showed both rotors to have similar performance, thus the addition of sweep was effective at reducing noise without sacrificing performance. Lastly, the noise associated with the electric drive system of these aircraft which consists of an ESC and brushless DC motor was analyzed. Acoustic measurements were made with and without an acoustic enclosure installed on a brushless DC motor and was found to be effective at reducing noise associated with the electric motor. The effects of two ESC's as well as their switching rates were also studied. The noise was found to be similar for both ESCs at low frequencies. At high frequencies the measured noise spectrum was found to be different when controlling the motor with different ESC's and a higher switching rate was found to reduce the noise with increasing switching rate although not completely monotonically. / Doctor of Philosophy / A new class of multi-rotor VTOL electric aircraft is becoming a dominant advanced vehicle concept. Urban Air Mobility (UAM) vehicles are designed for short routes within urban environments carrying only a few passengers during each flight. Other smaller Unmanned Aerial Systems (UAS) are increasingly being used for delivery services or to perform tasks which are more easily accessed with this technology like inspection or photography. Thus, these vehicles are expected to operate in close proximity to the general populace exposing it to aircraft noise which is currently limited to communities surrounding airports. For successful integration into the airspace with minimal community annoyance, the mechanisms responsible for generation of the noise must be understood. Traditionally, for conventional rotorcraft (one main rotor), the tonal noise has been more of a concern than the broadband component. eVTOL vehicles are often equipped with multiple rotors that are lightly loaded and operate at lower tip speeds which can be time varying. Thus, there is an increased significance of broadband noise. Lastly, these aircraft are equipped with an electric drive system that gives rise to an additional noise source that is not present for conventional aircraft. Best practices for measuring eVTOL noise are not currently established. Measurement of eVTOL rotor noise is complicated by the increased significance of the broadband sources. These have been shown to be facility dependent. Given this, there is a need for high quality experimental data and an analysis of experimental data in multiple facilities for these rotors and drive systems. Capabilities of traditional models to predict conventional rotorcraft noise also need to be assessed for these rotors. These two issues have been assessed in this work by first assessing the character of an eVTOL aircraft in hover and low speed flyovers. Both tonal and broadband components of the radiated noise were found to be significant. A-weighting, which is a metric used to assess the response of the human ear to the radiated noise showed increased significance of the broadband noise. This was followed by a characterization of the noise of isolated eVTOL rotors in multiple environments. Facility effects were addressed, and a low order prediction model was developed using methods that are traditionally used to predict noise associated with conventional rotorcraft. Lastly, the noise associated with the electric drive system of these vehicles was assessed and recommendations on how to reduce this source of noise were made. These results can be used to guide experimentalists when performing measurements of eVTOL rotor noise at static conditions and provide an eVTOL rotor noise data set that can be used to validate existing and forthcoming aerodynamic and acoustic prediction methods.

This thesis presents a dedicated GPS-denied landing system designed for electric vertical takeoff and landing (eVTOL) aircraft. The system employs active fiducial light pattern localization (AFLPL), which provides highly accurate and reliable navigation during critical landing phases. AFLPL utilizes images of a constellation comprised of modulating infrared lights strategically positioned on the landing site, to determine the aircraft pose through the use of a perspective-n-point (PnP) solver. The AFLPL system underwent thorough development, enhancement, and implementation to address and demonstrate its potential in navigation and its inherent limitations. A proposed method addresses the limitations of AFLPL by using an extended Kalman filter (EKF) to fuse PnP camera pose estimates with sensor measurements from an inertial measurement unit (IMU), attitude heading reference system (AHRS), and optional global positioning system (GPS). The EKF estimation is reported to significantly enhance the accuracy, reliability, and update frequency of the aircraft state estimation. To refine and validate the AFLPL and EKF algorithms, a simulation was developed, consisting of an eVTOL executing a glideslope landing trajectory. Furthermore, a hardware system consisting of a multirotor and infrared light ground units was implemented to test these methods under real-world conditions. This research culminated in the successful demonstration of the AFLPL-based estimation system's efficacy through an autonomous, GPS-denied landing flight test, affirming its potential to improve the navigation and control of eVTOL aircraft lacking access to GPS information.

<p>As Urban Air Mobility (UAM) is developed and brought into fruition via electric vertical takeoff and landing (eVTOL) vehicles, contingencies associated with this new distributed electric propulsion technology in metropolitan areas must be considered. On the state of knowledge on contingencies for eVTOL vehicles, these can be Epistemological Risks or Ontological Risks. Epistemological Risks include known-knowns (probabilistic risks) and known-unknowns (gaps in knowledge). Ontological Risks include, unknown-knowns (hidden knowledge), unknown-unknowns (fog of ignorance). As UAM operations at large scale do not have as much historical accidents data as General Aviation or Commercial Aviation, it is challenging to estimate its accident failure rate per 100,000 flight hours. While battery thermal runaway, battery energy uncertainty, software issues, and common mode power failures are some failure cases listed in this thesis, it is the undiscovered contingency (i.e., unknown-unknown) or unprepared contingency (i.e., unknown-known), along with other external factors, that can lead to an accident. UAM is expected to operate at 1500 feet AGL and at high frequencies over dense metropolitan areas. In an in-flight emergency at these altitudes, any startle response experienced by on-board or remote pilots can lead to longer response times. This study aims to create a framework for contingency planning and risk mitigation using a Reachable Ground Footprint model for eVTOL aircraft under 100% power failure scenarios in-flight. This framework utilizes all existing, public aerodrome infrastructures in metropolitan areas as potential contingency landing sites. Metrics such as Contingency Landing Assurance Percentage and Cruise Altitude Floor requirement are introduced to quantitatively measuring the safety of any UAM trip and provide recommendations on safe cruising altitudes. A demonstration case in the Chicago Metropolitan Area between DuPage Regional Airport and John H. Stroger Hospital Helipad is shown and discussed. Furthermore, aggregate analysis of 434 UAM trips in Chicago Metropolitan Area between Regional Airports, between Regional and Heliports, and between Heliports is performed, along with sensitivity studies involving wind and turn control restrictions. The results discuss variations in Cruise Altitude Floor, Flight Time, and Energy Consumption of these trips using an eVTOL vehicle.</p>