Browse Topic: Urban air mobility (UAM)
One of the biggest goals for companies in the field of artificial intelligence (AI) is developing “agentic” systems. These metaphorical agents can perform tasks without a guiding human hand. This parallels the goals of the emerging urban air mobility industry, which hopes to bring autonomous flying vehicles to cities around the world. One company wants to do both and got a head start with some help from NASA.
ABSTRACT Single microphone measurements lack the ability to separate nondeterministic noise sources on multipropulsor vehicles, limiting their usefulness to understand the dominant noise generation mechanisms. To advance the state-of-the-art for measuring multipropulsor aircraft in support of future Urban Air Mobility (UAM) and Future Vertical Lift (FVL) testing, a 117-channel phased array was deployed during an Army/NASA acoustic flight test of an MD530F helicopter. A time-domain beamforming algorithm, namely, the ROtating Source Identifier (ROSI), was utilized to track the aircraft's forward motion and main rotor rotation. This process isolates nondeterministic sources of the main rotor, effectively filtering out contributions of the tail rotor and other nonrotating components. Source maps are provided for low-speed forward flight and illustrate aeroacoustic sources near the main rotor blade tips over a broad frequency range. Particular emphasis is given on the benefits of flying at
ABSTRACT Piloted evaluations form a critical part of Handling Qualities (HQ) testing. Military rotorcraft standard ADS-33 outlines the widely accepted approach to perform HQ testing, including both methods to determine predicted and assigned HQs (Ref. 1). Recently, ADS-33 has been replaced with MIL-DTL-32742, which includes updates to previously defined criteria and tasks (Ref. 2). Assigned HQs are awarded using short-look tasks, so-called Mission Task Elements (MTEs), stylized to represent mission requirements. Test courses focus on external visual cues, used by the pilot to judge position. Setting up external courses is usually expensive and may not be feasibly possible. The MCRUER (Means of Compliance Requirements for UAM Evaluations and Ratings) system intends to support HQ evaluations, replacing physical test courses using virtual displays. Four MTEs were successfully demonstrated in flight by three pilots using a variable stability rotorcraft. HQ evaluations were performed both
ABSTRACT Vertical lift technologies present a promising solution for civil transportation between separated metropolitan and urban regions. This paper introduces the University of California Air transportation Link (UCAirLink), an electric vertical takeoff and landing (eVTOL)-based air transportation system for reducing overall commute times between regions. By leveraging flight operations in the National Airspace System (NAS), the UCAirLink connects the four northernmost University of California (UC) or the Center for Information Technology Research in the Interest of Society and the Banatao Institute (CITRIS) campuses. The UCAirLink addresses key aspects of urban air mobility (UAM) including optimal vehicle selection, infrastructure design, and flight route planning given regulations from the Federal Aviation Administration (FAA). A detailed trade study is presented for the selection of an optimal eVTOL aircraft. The eVTOL's flight routes cruise primarily in Class E and G airspaces
ABSTRACT Electric vertical take-off and landing vehicles are proposed as a viable solution for urban air mobility due to their potential for reducing carbon emissions, noise, and operational costs. However, the shift towards electrified aircraft introduces new thermal management issues due to the excess heat generated by electric motors and power electronics. This heat is challenging to dissipate during the mission, resulting in transient motor temperatures, especially during high-power mission segments. In addition, electrified aircraft also encounter design challenges associated with the fixed weight of electric motors and batteries. To address these challenges, this work presents a multifidelity framework for performing shape optimization of an electric motor subject to performance, geometric, and thermal transient constraints. A preliminary sizing of the electric motor is performed using a low fidelity Fourier series model. Next, the sizing is refined by utilizing a coupled
ABSTRACT Electric vertical takeoff and landing aircraft (eVTOL) have swiftly risen to prominence since the early 2000's due to their potential to serve as a sustainable and scalable improvement in urban air mobility. In edgewise forward flight, these aircraft can experience significant time-varying aerodynamic loads due to being variable RPM vehicles. Their fuselage, booms and auxiliary lifting surfaces are often very lightly damped, lightweight and highly stiff. Thus, multiple bending and torsional modes of vibration can be excited and result in unacceptably high stress levels. Particle impact dampers (PIDs) are an attractive vibration mitigation strategy as they can target more than one mode of vibration. The potential use of a PID to target a bending mode of vibration is experimentally and numerically studied within this work. Experimental forced response analysis shows a 53% attenuation in amplitude of vibrations at the cost of a 5% mass penalty. A reduced order model was developed
ABSTRACT Urban Air Mobility (UAM) is quickly developing with the objective of transporting passengers and cargo in urban areas using electric vertical take-off and landing aircraft (EVTOLs). This paper presents the process developed to design and optimize the noise control treatment in EVTOLs. The process leverages CAE simulation models to predict the acoustic performance inside the aircraft due to the propellers acoustic noise sources and the turbulent flow around the fuselage during cruising. The model includes a representation of the noise control treatments modeled as multi-layer poro-elastic materials and allows performing multi-attribute optimization to balance the vibro-acoustic performance with the costs, weight, and packaging constraints. This process has been applied successfully to support the development of EVTOLS before physical prototypes become available, therefore reducing the development time and corresponding costs. A demonstrator model serves as an example to
ABSTRACT Acoustic flight testing of rotorcraft often involves generating noise source hemispheres to gain an understanding about the aircraft's acoustic emissions. However, aerodynamically complex Urban Air Mobility and Future Vertical Lift vehicles may not maintain a steady aerodynamic state during flight, making source hemispheres measured using traditional linear arrays unreliable or difficult to interpret. To address this challenge, all emission angles need to be measured simultaneously. This has lead to the concept of the two dimensional 'snapshot' array layout. A mathematically defined microphone distribution was utilized to achieve uniform coverage on the source hemisphere. Within the chosen distribution, two lower microphone count distributions are embedded, allowing for a comparison of the effects of number of microphones. The array was deployed as part of a joint Army/NASA acoustic research flight test in July of 2024. Data were collected using an MD530F helicopter as the
ABSTRACT A novel multirotor concept is proposed for airlifting the emergency medical personnel without the use of a rescue helicopter (designed for patient transport) during the first line emergency services. Based on this concept, two configurations are designed and introduced, comprising a common quadrotor system with single and dual pusher propellers, respectively. An initial flight performance assessment is conducted for the introduced configurations by means of trim calculations in two distinctive flight modes across the entire designated flight speed range, initially without rotor-rotor interactions, and subsequently, with their inclusion. For this purpose, an existing mid-fidelity rotor-rotor interaction method is extended to capture the interactions in all three directions between the rotors that are arbitrarily positioned and oriented to each other. The trim calculations including rotor-rotor interactions show a 10% increase in the vehicle power at the maximum flight speed
ABSTRACT A joint acoustic flight test was conducted by NASA Langley Research Center and the U.S. Army Combat Capabilities Development Command Aviation & Missile Center, with the goal of investigating new methods for acoustic data collection. The impetus for the effort is the anticipated growth of Urban Air Mobility and Future Vertical Lift vehicles. Many of these vehicles are expected to have distributed propulsion systems that may result in unsteady vehicle state conditions even during steady flight. This work examines the acoustic measurements collected during purposefully unsteady maneuvers performed by an MD530F helicopter. A snapshot microphone array design was deployed for this test to capture the acoustic signature on the ground from the helicopter under maneuver conditions. An analysis of the acoustic emissions indicated the presence of blade-vortex interactions, not only during the rolls towards the advancing side of the main rotor, but also rolls towards the retreating side
ABSTRACT A multifidelity, multipoint aerodynamic blade shape optimization was conducted to design a realistic, full-sized proprotor, representative of recent industry tiltrotor and lift+cruise UAM vehicle designs. The proprotor was designed to achieve a disk loading of 8 psf in hover at sea level standard day and 1.9 psf in cruise at an altitude of 4000 ft above ground level with a multipoint efficiency optimization target. A low-fidelity optimization was first conducted using a differential evolution algorithm with CAMRAD II's uniform inflow model, followed by a mid-fidelity trim using CAMRAD II's nonuniform inflow and free-wake models, a high-fidelity verification using a hybrid RANS/LES approach in FUN3D, and finally a high-fidelity optimization on the low-fidelity optimized blade shape with a gradient-based method using a uRANS approach in FUN3D. The low-fidelity optimization resulted in a proprotor that achieved a hover figure of merit of 0.830 and a propulsive efficiency in
ABSTRACT This study investigates the effects of chord-to-radius ratio (c/R) and blade count on the aerodynamic and aeroacoustic performance of cyclorotors through experimental testing and a low-fidelity streamtube model. Cyclorotors with c/R ratios between 0.3 to 0.75 and blade counts ranging from 5 to 9 were tested across pitch amplitudes up to 51°. For a 5-bladed configuration, the pitch amplitude that maximizes the force-to-power coefficient (CF/CP) increases with c/R from approximately 32° at low c/R to around 51° at high c/R. However, the peak attainable CF/CP decreases with increasing c/R, indicating a trade-off between optimal pitch amplitude and aerodynamic efficiency. Increasing blade count enhances the generated force but reduces efficiency in all cases except for the lowest c/R configuration (0.3). Aeroacoustic analysis shows that tonal noise is primarily driven by pitch amplitude and intensifies with increasing c/R, while additional blades effectively mitigate it. In
ABSTRACT Urban Air Mobility (UAM) aircraft are highly susceptible to turbulent wind disturbances when operating near buildings in complex urban environments. Microscale wind phenomena, combined with the unconventional designs of UAM aircraft, increase the risk of performance deviation, the overall duration, and the cost of flight tests for certification. A way to overcome this would be through simulation-based flight tests. Therefore, this study simulates a UAM aircraft landing vertically behind an isolated tall building, considering four different wind scenarios: no wind, uniform wind fields at low and high spatial resolutions (assumed constant across the airframe), and non-uniform fields with spatially varying velocity profiles at individual rotor hubs. The resultant flight test data are then used to quantify the impact of microscale wind characteristics on landing performance by systematically analyzing the rotor performance, aerodynamics, control response, and trajectory deviation.
ABSTRACT In support of research and development for Urban Air Mobility (UAM) operations, the National Aeronautics and Space Administration (NASA) is developing a fleet of Vertical Takeoff and Landing (VTOL) concept vehicles. These vehicles aim to identify key areas for technological growth and provide reference data to the UAM community. A six-passenger Tiltwing concept recently added to the fleet offers new opportunities to explore the UAM design space through trade studies of the power and propulsion systems. In this paper, a turboelectric powertrain is designed and analyzed using the Numerical Propulsion System Simulation (NPSS) tool, the NPSS Power System Library, and a motor drivetrain optimization tool. Direct and geared motor drivetrains are designed and compared across a UAM design mission. Sensitivity of the Tiltwing maximum takeoff weight to motor drivetrain weights and efficiencies is estimated and used to inform optimal motor and gearbox selection. Results indicate that
ABSTRACT Electric Vertical Takeoff and Landing (eVTOL) vehicles undergoing advanced air mobility (AAM) operations feature increasingly autonomous systems (IAS) with non-traditional role allocations. Ensuring the safety of these operations and their novel human–machine teaming (HMT) paradigms requires an appropriate body of knowledge created through relevant, reproducible research. In this paper, we briefly examine the meaning of teaming; current regulation, standards, and guidance; and the knowledge required to build resilient HMTs before turning our attention to how this knowledge is being created by recent research and what conclusions or recommendations can be made. We identify the need for further research into the holistic performance of HMTs, the effect of novel allocations of roles between humans and machines, the ability of humans to provide resilience to unforeseen dangers when acting as a part of these teams; and the characteristics required for clear, timely, and accurate
ABSTRACT The operation of Urban Air Mobility Vehicles (UAMVs) presents significant technical and operational challenges, particularly in the areas of safety, training, and cost management. This paper explores how advanced simulation models and predictive algorithms can address these challenges. A digital transformation framework is developed and applied in an Urban Air Mobility (UAM) case study to illustrate the effectiveness of these tools. Through the development of simulation models, critical insights are provided on damage detection, impact analysis, and maintenance optimization. The application of predictive algorithms enables quick damage assessment, improving safety by facilitating timely maintenance and repair decisions. To help showcase the benefits of this research, a demonstration was designed and built that allows users to interact with the developed tools and get a better understanding through hands-on training.
ABSTRACT This study presents the development and application of a refined momentum source term methodology for synthetic turbulence generation in urban flow simulations. By embedding divergence-free, three-dimensional turbulence fields consistent with the von Kármán energy spectrum directly within the computational domain, the approach enables flexible and efficient turbulence generation with minimal sensitivity to grid stretching. The method is validated through Large Eddy Simulations (LES) of flow around a representative urban vertiport model under varying turbulence intensities (10%, 20%, and 30%). Results demonstrate that the generated synthetic turbulence significantly alters the flow field, reducing recirculation zones, promoting earlier shear-layer reattachment, and stabilizing the flow above the vertiport platform—key factors for safe eVTOL operations. Instantaneous flow analyses reveal that secondary tip vortices (STVs) persist even in the presence of strong inflow turbulence
ABSTRACT A follow-on study to the 2024 paper by Kottapalli, Silva, and Boyd is presented with improved acoustics tools to examine whether the Vertical Aviation International (VAI) Fly Neighborly operational recommendations that are designed for single main rotor/tail rotor configurations will hold for non-conventional UAM rotorcraft with multiple rotors. The 6-occupant quadrotor concept vehicle designed under the NASA Revolutionary Vertical Lift Technology (RVLT) Project is studied. The tip speed is 550 ft/sec, with three blades per rotor. Predictions are made for three steady maneuvers: level turns, descending turns, and climbing turns. The RVLT Toolchain is exercised using CAMRAD II, pyaaron/AARON/ANOPP2 and AMAT (ANOPP2 Mission Analysis Tool). Quadrotor noise trends are analyzed using Sound Exposure Level (SEL) ground maps because it is anticipated that the upcoming updated Fly Neighborly recommendations will involve SEL maps. Importantly, unlike conventional helicopters with a
ABSTRACT A hybrid RANS/LES simulation of the Ideally Twisted Rotor (ITR) in hover was interrogated to identify bluntness vortex shedding (BVS) and determine the contribution to the predicted rotor broadband self-noise. Three rotor blade stations were extracted to study spanwise variations in the BVS shedding frequency and amplitude. Corresponding 2-D airfoil simulations were performed to evaluate a simplified modeling approach that effectively isolates BVS. The BVS shedding frequencies predicted by the 2-D airfoil simulations differed by less than 2% from the corresponding rotor stations in the 3-D simulation. The increased computational cost incurred by performing 3-D airfoil simulations did not lead to a worthwhile increase in simulation fidelity. Farfield noise was predicted for the three rotor stations and the 2-D airfoil simulations, and trends in frequency agreed well. The 2-D approach overpredicted the 3-D peak amplitudes by 5 - 10 dB. This work demonstrates that 2-D hybrid RANS
ABSTRACT Small, highly maneuverable Urban Air Mobility (UAM) air taxis might exhibit motions during hover and low-speed flight that are unfamiliar to many passengers, and for which there are no established guidelines to predict passenger comfort. Researchers performed a study in the Armstrong Virtual Reality Passenger Ride Quality Laboratory to identify relationships between sudden motion characteristics and UAM passenger comfort and acceptance. Twenty-three volunteer test subjects from the Armstrong workforce each completed a 15-minute experience as a passenger in a virtual air taxi simulation. Subjects evaluated a series of flight maneuvers with varying levels of sudden motion using a five-point rating scale and indicated which motion(s) they found uncomfortable. Researchers then administered a post-test questionnaire to relate the passengers’ ratings to their willingness to fly on a real air taxi with similar levels of motion. The study results relate peak heave acceleration and
ABSTRACT This study investigates the aerodynamic behavior of lift rotors in a representative lift+cruise electric vertical takeoff and landing (eVTOL) configuration using high-fidelity Computational Fluid Dynamics (CFD) simulations. As lift+cruise concepts gain prominence for Urban Air Mobility (UAM) applications due to their operational simplicity, flight performance, and reduced cruise noise, a detailed understanding of rotor aerodynamics during transition and cruise is critical. CFD analysis was conducted for both slowed rotors at high advance ratios and fully stopped rotors, where traditional predictive tools become inaccurate. Results show that lift rotors operating at advance ratios approaching three exhibit quasi-steady behavior similar to stopped rotors. The influence of rotor lock orientation on aerodynamic loads was characterized, with a freestream-aligned lock angle minimizing drag and asymmetry. A rotor hub fairing was found to reduce blade root separation and drag, though
Recent advancements in electric vertical take-off and landing (eVTOL) aircraft and the broader advanced air mobility (AAM) movement have generated significant interest within and beyond the traditional aviation industry. Many new applications have been identified and are under development, with considerable potential for market growth and exciting potential. However, talent resources are the most critical parameters to make or break the AAM vision, and significantly more talent is needed than the traditional aviation industry is able to currently generate. One possible solution—leverage rapid advancements of artificial intelligence (AI) technology and the gaming industry to help attract, identify, educate, and encourage current and future generations to engage in various aspects of the AAM industry. Beyond Aviation: Embedded Gaming, Artificial Intelligence, Training, and Recruitment for the Advanced Air Mobility Industry discusses how the modern gaming population of 3.3 million
This paper explores the groundbreaking applications of plasma propulsion engines and advanced nanomaterials in low-altitude aircraft, addressing the challenges and recent technological advancements that make such applications feasible. Traditional space plasma thrusters operate effectively in near-vacuum conditions by taking advantage of the ease of plasma ignition at low pressures. However, these thrusters face significant difficulties when operated at near-atmospheric pressures found in low-altitude environments, where plasma ignition is challenging. This paper highlights recent breakthroughs in high-pressure plasma glow discharge technology and the integration of nanomaterials, which together enable the use of plasma propulsion engines in low-altitude aircraft. These innovations offer substantial advantages over conventional engines, including higher efficiency, reduced emissions, and the potential to fundamentally change the propulsion systems of low-altitude aircraft.
Yaw control for aircraft using the rudder faces challenges in resisting fast time-varying uncertainty due to the relatively slower response of the rudder. In hybrid unmanned aerial vehicles equipped with both rudders and rotors, the introduction of powered yaw control offers novel solutions for addressing fast time-varying uncertainty by leveraging the quicker response of rotors compared to traditional rudders. This paper presents a hierarchical yaw control approach for hybrid unmanned aerial vehicles, comprising a nominal control for rudders to achieve the desired yaw tracking and a constrained powered yaw control for rotors to resist fast time-varying uncertainty. Given the constrained amplitude of powered yaw control, it is imperative that the designed auxiliary input guarantees adherence to its constraint. Firstly, a nonlinear control for nominal hybrid unmanned aerial vehicle system is formulated to deal with the nonlinearity model, rendering a modest nominal control for rudders
In the realm of low-altitude flight power systems, such as electric vertical take-off and landing (eVTOL), ensuring the safety and optimal performance of batteries is of utmost importance. Lithium (Li) plating, a phenomenon that affects battery performance and safety, has garnered significant attention in recent years. This study investigates the intricate relationship between Li plating and the growth profile of cell thickness in Li-ion batteries. Previous research often overlooked this critical aspect, but our investigation reveals compelling insights. Notably, even during early stage of capacity fade (~ 5%), Li plating persists, leading to a remarkable final cell thickness growth exceeding 20% at an alarming 80% capacity fade. These findings suggest the potential of utilizing cell thickness growth as a novel criterion for qualifying and selecting cells, in addition to the conventional measure of capacity degradation. Monitoring the growth profile of cell thickness can enhance the
This study aims to explore the multifaceted influencing factors of market acceptance and consumer behavior of low-altitude flight services through online surveys and advanced neuroscientific methods (such as functional magnetic resonance imaging fMRI, electroencephalography EEG, functional near-infrared spectroscopy fNIRS) combined with artificial intelligence and video advertisement quantitative analysis. We conducted an in-depth study of the current trends in low-altitude flight vehicle development and customer acceptance of low-altitude services, focusing particularly on the survey methods used for market acceptance. To overcome the influence of strong opinion leaders in volunteer group experiments, we designed specialized surveys targeting broader online and social media groups. Utilizing specialized knowledge in aviation psychology, we designed a distinctive questionnaire and, within just 7 days of its launch, gathered a significant number of valid responses. The data was then
Urban Air Mobility (UAM) envisions heterogenous airborne entities like crewed and uncrewed passenger and cargo vehicles within, and between urban and rural environment. To achieve this, a paradigm shift to a cooperative operating environment similar to Extensible Traffic Management (xTM) is needed. This requires the blending of traditional Air Traffic Services (ATS) with the new generation UAM vehicles having their unique flight dynamics and handling characteristics. A hybrid environment needs to be established with enhanced shared situational awareness for all stakeholders, enabling equitable airspace access, minimizing risk, optimized airspace use, and providing flexible and adaptable airspace rules. This paper introduces a novel concept of distributed airspace management which would be apt for all kinds of operational scenarios perceived for UAM. The proposal is centered around the efficiency and safety in air space management being achieved by self-discipline. It utilizes
ABSTRACT Hazard assessment is an engineering activity that produces insight into which states of thing being engineered might be hazardous. In aviation contexts, it is often performed for certification credit at both the aircraft and system levels during the early design phase of the system's lifecycle. However, novel aircraft paradigms such as urban air mobility (UAM) operations might either violate assumptions on which traditional aviation hazard assessment is based or simply possess attributes that would make other approaches more effective. In this paper, we define the key concepts underpinning hazard assessment and identify the limitations and assumptions inherent in hazard analysis. We analyze popular techniques to show how they embody these key concepts. We identify ways in which hazard assessment may be scoped and tailored to an application. And, using worked examples, we discuss how, where, and why such tailoring might be needed, especially in novel contexts.
ABSTRACT Advanced and Urban Air Mobility aircraft development is revolutionizing the aerospace industry by providing a realizable path towards affordable on-demand passenger-carrying operations in metropolitan areas. Many aircraft concepts are in development, and as they start to mature, there is a need for higher fidelity design and analysis tools that have improved modeling of component-wake interactions. Unfortunately, the current generation of CFD-based high fidelity tools is unsuitable for many daily design and analysis applications due to computational cost, expertise and setup requirements. Conversely, current design tools often rely on empirical relationships to represent many interactional effects, or become increasingly inaccurate in regions where the wakes trailed and shed from aerodynamic component becomes highly distorted. This paper describes recent work by Continuum Dynamics, Inc. to develop a mid-fidelity analysis tool, embedded within the CHARM analysis package, which
ABSTRACT In recent years, the electrically powered Urban Air Mobility (UAM) market has witnessed significant growth, fueled by advances in electric motor and high-power-density lithium battery technologies. This surge of interest has prompted an exploration into the design and functionality of electric vertical take-off and landing (eVTOL) vehicles, particularly those with multi-tilt-rotor configurations. These eVTOL vehicles, capable of operating at higher RPMs than traditional helicopters, face unique challenges, especially under adverse environmental conditions such as icing. Aircraft airframe icing is known to severely compromise the operational efficiency and safety of aerodynamic surfaces, posing a significant threat to the operational capabilities of eVTOL vehicles. This paper presents the development and testing of a full-scale eVTOL rotor test stand that was designed to assess the impact of icing on these novel vehicles. The study focuses on evaluating eVTOL configurations
ABSTRACT Flight mechanics modeling and real-time simulation of rotorcraft have many challenges including the aerodynamics and dynamics of the rotor system, rotor inflow, and wake-airframe interactions. Furthermore, interactional aerodynamic effects are difficult to characterize, in particular during early configuration down-selection. Rotorcraft configurations under consideration for advanced air mobility applications are trending toward designs with coaxial rotor systems and multiple distributed propellers / rotors in close-proximity with one another and the airframe. This proximity leads to strong coupling between the rotor inflow and lifting surfaces (e.g., tiltwing and lift+cruise urban air mobility concepts). This paper describes recent work toward the development of a general-purpose modeling framework for flight mechanics analysis and simulation of rotorcraft and aircraft configurations proposed for advanced air mobility applications. This modeling framework was developed for
ABSTRACT NASA has previously designed and described set of concept aircraft to serve as reference vehicles for Urban Air Mobility (UAM), to encourage public discussion and research. These vehicles are used in this paper to quantify how suitable UAM aircraft might be for missions other than their primary commercial design missions. A set of representative public good missions are described, along with design requirements and equipage. For two of these missions, the additional weight, power, and cost to facilitate a basic vehicle which may be built or configured with the ability to perform these missions is quantified. Special layout and other considerations which may impact vehicle design are described. For aircraft designed to the NASA UAM reference mission, the addition of some meaningful public good missions causes less than 10% growth in weight and power for fossil-fueled aircraft; advanced battery-electric powered aircraft grow by a significantly larger amount and may only be
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