The implementation of Urban Air Mobility represents a complex challenge in aviation due to the high degree of innovation required across various domains to realize it. From the use of advanced aircraft powered by novel technologies, the management of the air space to enable high density operations, to the operation of vertidromes serving as a start and end point of the flights, Urban Air Mobility paradigm necessitates significant innovation in many aspects of civil aviation as we know it today. In order to understand and assess the many facets of this new paradigm, a Collaborative Agent-Based Simulation is developed to holistically evaluate the System of Systems through the modeling of the stakeholders and their interactions as per the envisioned Concept of Operations. To this end, models of vertidrome air-side operations, unmanned/manned air space management, demand estimation and passenger mode choice, vehicle operator cost and revenues, vehicle design, and fleet management are brought together into a System of Systems Simulation of Urban Air Mobility. Through collaboration, higher fidelity models of each domain can be integrated into a single environment achieving fidelity levels not easily achievable otherwise. Furthermore, the integration enables the capture of cross-domain effects and allows domain-specific studies to be evaluated at a holistic level. This work demonstrates the Collaborative Simulation and the process of building it through the integration of several geographically distributed tools into an Agent-Based Simulation without the need for sharing code.

Urban Air Mobility (UAM) has emerged as a potential game changer for urban transportation, promising faster, more efficient and affordable services. However, beyond the visionary concepts, it is crucial to explore and discuss the opportunities and challenges of UAM and vertidrome operations also from a research perspective. The DLR research project HorizonUAM aimed at a holistic research approach in which vertidromes and vertidrome networks play a significant role. This vertidrome centered project report covers various aspects and methodological approaches addressing design and operation, UAM airspace management, network optimization and the integration of air taxi operations into airport environment. Moreover, the conceptual and temporary development of a modular 1:4 scale model city lays the foundation for future UAM flight trials. Based on three years of dedicated research within HorizonUAM, we focus here on operational challenges, proposed solutions and required frameworks to ensure safe and efficient vertidrome operations

Urban Air Mobility (UAM) is a new air transportation system for passengers and cargo in urban environments, enabled by new technologies and integrated into multimodal transportation systems. The vision of UAM comprises the mass use in urban and suburban environments, complementing existing transportation systems and contributing to the decarbonization of the transport sector. Initial attempts to create a market for urban air transportation in the last century failed due to lack of profitability and community acceptance. Technological advances in numerous fields over the past few decades have led to a renewed interest in urban air transportation. UAM is expected to benefit users and to also have a positive impact on the economy by creating new markets and employment opportunities for manufacturing and operation of UAM vehicles and the construction of related ground infrastructure. However, there are also concerns about noise, safety and security, privacy and environmental impacts. Therefore, the UAM system needs to be designed carefully to become safe, affordable, accessible, environmentally friendly, economically viable and thus sustainable. This paper provides an overview of selected key research topics related to UAM and how the German Aerospace Center (DLR) contributed to this research in the project "HorizonUAM - Urban Air Mobility Research at the German Aerospace Center (DLR)". Selected research results on the topics of market potential and public acceptance, vehicle design (including battery degradation, onboard systems, cabin design, cabin simulation), infrastructure, operations (including U-space, safe autonomy, navigation, communication, cost modeling) and overall system modeling are briefly presented.

Urban Air Mobility (UAM) is a new air transportation system for passengers and cargo in urban environments, enabled by new technologies and integrated into multimodal transportation systems. The vision of UAM comprises the mass use in urban and suburban environments, complementing existing transportation systems and contributing to the decarbonization of the transport sector. Initial attempts to create a market for urban air transportation in the last century failed due to lack of profitability and community acceptance. Technological advances in numerous fields over the past few decades have led to a renewed interest in urban air transportation. UAM is expected to benefit users and to also have a positive impact on the economy by creating new markets and employment opportunities for manufacturing and operation of UAM vehicles and the construction of related ground infrastructure. However, there are also concerns about noise, safety and security, privacy and environmental impacts. Therefore, the UAM system needs to be designed carefully to become safe, affordable, accessible, environmentally friendly, economically viable and thus sustainable. This paper provides an overview of selected key research topics related to UAM and how the German Aerospace Center (DLR) contributed to this research in the project "HorizonUAM - Urban Air Mobility Research at the German Aerospace Center (DLR)". Selected research results that support the realization of the UAM vision are briefly presented.

This study examines the impact of wind/gust speed conditions on airside traffic flows at vertiports in the context of on-demand urban air mobility based on the Vertidrome Airside Level of Service Framework. A wind-dependent operational concept introducing four wind speed categories with corresponding wind-dependent separation values is developed and applied in simulation. A decade (2011–2020) of historical METAR wind/gust speed reports are analyzed for a potential vertiport location at Hamburg and Munich airport, and a representative year of wind speed data is selected for each location as simulation input. Both locations experience performance degradation during the first quarter of the simulated year, which contains over 50% of the annual flight cancellations, and exceed wind-operating conditions, especially during midday and early afternoon hours. This study discusses the importance of wind-dependent coordination of flight schedules and analyzes the challenge of determining appropriate wind speed category thresholds. Lower thresholds result in an increased frequency of operationally unfavorable wind/gust conditions. Additional sensitivity analyses are performed to study the effects of wind-dependent separation deltas and wind-(in)dependent scheduling approaches. In conclusion, the presented approach enables planners and operators to make informed decisions about vertiport traffic flow characteristics and performance, vertiport location, and business cases.

This paper presents the Vertidrome Airside Level of Service (VALoS) framework, a novel performance metric designed to evaluate airside traffic flow operations at vertidromes in the context of Urban Air Mobility (UAM). As the UAM industry rapidly evolves, the need for a comprehensive evaluation framework becomes increasingly important. The VALoS framework provides a performance-based approach to evaluating vertidrome traffic flow performance, considering metrics like average passenger delay, air taxi in-flight delay, and vertidrome punctuality. Unlike existing Level of Service approaches, the VALoS framework unifies the requirements of various stakeholders, the passenger, the air taxi operator, and the vertidrome operator each with their own performance metric and target. It provides a multi-faceted approach covering airside air and ground traffic flows, arrivals and departures, and performance changes during strategic planning and tactical execution phases. The VALoS is evaluated at 15-min intervals while considering changing stakeholder performance targets and operational uncertainties. For the reference use case, the study demonstrates the significant impact of short-term disruptions, while stochastic deviations can be neglected. Higher traffic volumes due to changing demand/capacity ratios result in higher VALoS variability. The VALoS framework, together with a fast-time simulation, provides a versatile method for exploring future vertidrome traffic flows and supporting strategic vertidrome airside planning and integration. This integrated approach is essential for the evolving UAM vertidrome industry; aligning the interests of different stakeholders and promoting sustainable and efficient vertidrome planning and operation.

Urban air mobility is a rapidly growing field of research. While drones or unmanned aerial vehicles have been operated mainly in the private and military sector in the past, an increasing range of opportunities is opening up for commercial applications. A new multitude of passenger-carrying drone or air taxi concepts promises to fulfill the dream of flying above congested urban areas. While early research has been focusing on vehicle development, solutions for urban air traffic management are lagging behind. This paper collects and reviews the main findings of past urban-air-mobility-related research projects at the German Aerospace Center (DLR) to serve as a basis for ongoing research from an air traffic management perspective.

In the course of the European project CORUS-XUAM, a very large-scale demonstration was conducted for the metropolitan area of Frankfurt, for which a newly developed U-space route structure was conceptually elaborated. The demonstration exercise focuses on the initial definition and a near-term implementation of urban U-space corridors inside controlled airspace (class D) connecting terminal 2 of the Frankfurt Airport and the Frankfurt Trade Fair via air taxi services operating as airport shuttles. With advancements in navigation performance, monitoring, surveillance, communication technology and increasing operating experience, U-space corridors can transition to free flight trajectories. Local constraints such as approaching fixed-wing traffic, flights operating under visual flight rules (VFR) including helicopter emergency medical services, heliport operations, and a VFR holding pattern were taken into account in order to elaborate the course of the U-space corridors. Of special interest is the harmonization of airspace users inside and outside of U-space while ensuring safe and efficient conflict detection and resolution. A set of fast-time simulations have been conducted to evaluate the developed U-space route structure and its operating concept based on historic air traffic data for the metropolitan area of Frankfurt. Following the hypotheses that every 120 seconds an air taxi departure can be performed without causing a negative impact on airport operations, we evaluate the metrics U-space corridor usage, occupancy, throughput, number of resolved conflicts and occurring/imposed delay. In addition, we elaborate where conflicts occur and whether another air taxi or the background traffic caused them. Furthermore, we show how they can be resolved, i.e., how often and to what extend delaying and/or re-routing is applied throughout different scenarios. Using the selected separation values, it is possible to have air taxis departing every 90 s at both vertiports. This certainly changes when different separation thresholds are used. Additionally, we showed that all conflicts can be solved by applying a small ground delay or by simply choosing a different U-space corridor.

In many cities the (public) transportation system already faces challenges to adjust appropriately to the growing population. Lifting the transportation offer into the third dimension by introducing Urban Air Mobility (UAM) may be a promising step towards an improvement. But what characteristics does UAM need to offer in order to represent successfully an extension to our traditional (public) transportation system and to fit into the concept of Mobility-as-a-Service (MaaS) where various modes of transportation are bundled and accessible on demand? On the one hand, the supporting ground infrastructure specialized in accommodating UAM and vertical take-off and landing (VTOL) operations, in this research named vertidrome, and on the other hand a consortium of stakeholders (vehicle operator, vertidrome operator, air traffic management, passenger, city councils, etc.) will determine a considerable portion of these requirements. The vertidrome is a UAM traffic junction, which merges airside and landside operations and interactions between the vertidrome infrastructure components, the vehicles and the passengers. This research work focuses on the exemplary development of a vertidromes airside operation considering a UAM application at the Munich trade fair (Germany). Following this objective, we analyze the unique characteristics of UAM, review the current state of the art regarding UAM ground infrastructure designs and introduce a new and VTOL-specific terminology vertidrome. In addition, we define an exemplary vertidrome concept of operations: a linear and expandable drive-through (LIEDT) topology, distinct approach and departure mission profiles based on the VTOL vehicle Volocopter 2X, as well as operating (airside air) and traffic (airside ground) rules for arriving and departing vehicles. The results will contribute to the development of a corresponding discrete event-based simulation (DES) depicting the elaborated vertidrome's airside structure and operations followed by the development of a performance assessment method evaluating a vertidrome's airside traffic flow (Vertidrome Airside Level of Service - VALoS).

Novel electric aircraft designs coupled with intense efforts from academia, government and industry led to a paradigm shift in urban transportation by introducing UAM. While UAM promises to introduce a new mode of transport, it depends on ground infrastructure to operate safely and efficiently in a highly constrained urban environment. Due to its novelty, the research of UAM ground infrastructure is widely scattered. Therefore, this paper selects, categorizes and summarizes existing literature in a systematic fashion and strives to support the harmonization process of contributions made by industry, research and regulatory authorities. Through a document term matrix approach, we identified 49 Scopus-listed scientific publications (2016–2021) addressing the topic of UAM ground infrastructure with respect to airspace operation followed by design, location and network, throughput and capacity, ground operations, cost, safety, regulation, weather and lastly noise and security. Last listed topics from cost onwards appear to be substantially under-represented, but will be influencing current developments and challenges. This manuscript further presents regulatory considerations (Europe, U.S., international) and introduces additional noteworthy scientific publications and industry contributions. Initial uncertainties in naming UAM ground infrastructure seem to be overcome; vertiport is now being predominantly used when speaking about vertical take-off and landing UAM operations.

The term Urban Air Mobility covers many several applications to meet different transport needs. The cross-institutional and interdisciplinary research project "HorizonUAM – Urban Air Mobility Research at the German Aerospace Center (DLR)" brings together a wide variety of departments from the DLR research fields to research on the vision of Urban Air Mobility. This paper describes the five use cases Intra-City, Mega-City, Airport-Shuttle, Sub-Urban and Inter-City, which were defined in order to create a common working basis for the project. In addition to the description of the transport needs, the paper presents technology scenarios, mission profiles, concepts of operation, vehicle configurations and infrastructure related to the use cases. Based on the defined use cases, technical feasibility, efficiency, sustainability, market development potential and social acceptance will be investigated in the course of the project.

Efficiency, safety, feasibility, sustainability and affordability are among the key characteristics of future urban mobility. The project “HorizonUAM – Urban Air Mobility Research at the German Aerospace Center (DLR)” provides first answers to this vision by pooling existing competencies of individual institutes within DLR. HorizonUAM combines research about urban air mobility (UAM) vehicles, the corresponding infrastructure, the operation of UAM services, as well as public acceptance and market development of future urban air transportation. Competencies and current research topics including propulsion technologies, flight system technologies, communication and navigation go along in conjunction with the findings of modern flight guidance and airport technology techniques. The project analyses possible UAM market scenarios up to the year 2050 and assesses economic aspects such as the degree of vehicle utilization or cost-benefit potential via an overall system model. Furthermore, the system design for future air taxis is carried out on the basis of vehicle family concepts, onboard systems, aspects of safety and security as well as the certification of autonomy functions. The analysis of flight guidance concepts and the sequencing of air taxis at vertidromes is another central part of the project. Selected concepts for flight guidance, communication and navigation technology will also be demonstrated with drones in a scaled urban scenario. This paper gives an overview of the topics covered in the HorizonUAM project, running from mid-2020 to mid-2023, as well as an early progress

View Video Presentation: https://doi.org/10.2514/6.2021-3201.vid The vertidrome, a ground infrastructure supporting vertical take-off and landing (VTOL) operations, is one of the key elements of Urban Air Mobility (UAM). It accommodates UAM airside and landside operations and may provide connection to other transportation modes. A vertidromes' processing performance needs to be predictable and reliable in order to plan and execute satisfactorily passenger and cargo UAM transportation requests with respect to all stakeholders involved. Therefore, we propose a new performance assessment concept to predict and evaluate the performance of a vertidrome's airside traffic flow with respect to specific stakeholder requirements, here defined as the passenger, the VTOL-vehicle operator and the vertidrome operator. Based on their individual objectives, each stakeholder defines a specific performance indicator, which in this paper is including but not limited to delay and punctuality. The proposed Vertidrome Airside Level of Service Concept (VALoS) is based on existent performance rating methods (level of service) for highway traffic and airport terminal facilities. After adjusting the level of service paradigm to UAM specifics, a new framework is proposed considering a vertidrome's airside operation. Furthermore, the applicability of the VALoS framework is demonstrated. For this purpose, two exemplary use cases are defined considering a vertidrome layout change (reduction of gate parking positions) and an off-nominal condition causing deviations from the schedule (deviations of flight time/ gate service time).