- 11 Dec 2021 07:47 AM
Laying the Groundwork for Urban Air Mobility
By Dan Gettinger, Managing Editor
Vertiflite, Nov/Dec 2021
The 5th VFS Workshop on eVTOL Infrastructure is another great success, digging deep into the challenges and opportunities for urban air mobility.
Amid a maturing market for electric vertical takeoff and landing (eVTOL) aircraft, aerospace industry professionals and regulators have increasingly turned their attention to considering the types of infrastructure required to support these operations. The Vertical Flight Society’s fifth semi-annual “Workshop on eVTOL Infrastructure for Urban Air Mobility (UAM)” offered stakeholders and interested parties a forum for exploring key questions involving future eVTOL operations. In a series of panel discussions and presentations over two days, experts from around the aerospace industry engaged in conversations on the defining challenges facing the UAM community in vertiport design and development as it pertains to aircraft operational limitations, fire safety and weather safety. The workshop offered stakeholders a range of essential perspectives on strategies for enabling future UAM concepts of operations.
Given the potential noise reduction and environmental advantages compared to traditional helicopters, eVTOL aircraft could significantly increase air travel — and traffic — in urban environments. Doing so will require infrastructure capable of supporting both the specific requirements of electrically powered aircraft and those of operating safely within urban environments. Vertiports will serve as nodes in the urban core for aircraft passenger boarding and disembarkation, as well as cargo distribution. Most experts agree that vertiports will share many characteristics of today’s heliports, such as designated areas for takeoff and landing, parking areas, support facilities and passenger waiting areas. However, unlike heliports, vertiports will be designed to accommodate a widely varying range of aircraft designs that may be piloted or autonomous.
Building the infrastructure to support eVTOL operations at vertiports could require radically different approaches than those associated with airports or heliports, explained Jonathan Daniels, CEO and founder of Praxis Aerospace Concepts International, in the first panel of the workshop. Vertiports will need to support the high degree of automation and electrification embedded in eVTOL aircraft, requiring a consistent and reliable electrical power source. Some vertiports will be multimodal hubs, enabling passengers to rapidly transition from one transportation mode to another. The means by which an aircraft approaches the vertiport could change, too, evolving from today’s visual flight rules (VFR) and instrument flight rules (IFR) to something akin to a “digital flight rules” (DFR) system — one that relies on both automated vehicle-to-ground and vehicle-to-vehicle communications to provide separation between aircraft — to include prioritizing and sequencing aircraft to assigned landing pads.
Operations at vertiports could be highly automated to accommodate a high throughput of aircraft, particularly those that involve certain use cases, such as urban passenger air metro services. Crown Consulting’s Joseph Block presented a study of a concept of operations that relies heavily on automation to manage vertiport resources, such as takeoff and landing pads, aircraft parking and charging services. Doing so, said Block, could increase the tempo of operations to and from the vertiport by minimizing turnaround time and optimizing the efficient allocation of resources. Even so, said Ray Adams, CEO of Urban Low Altitude Transport Association (ULTRA), without a central authority to direct traffic, the level of passenger and aircraft congestion at vertiports could pose problems for future operations. An air traffic management system attached to vertiports, explained Adams, could help handle off-nominal and dynamic effects produced by weather and other unforeseen events.
Aircraft Performance and Vertiport Design
Navigating the introduction of eVTOL aircraft into the national airspace will require a close collaboration between industry and regulators, said Wisk Aero Product Manager Torrie Meliska in the second panel of the workshop. Aircraft manufacturers, such as Wisk, are looking to regulators to develop standards for vertiports that they are able to incorporate into the aircraft design process. David Webber, a flight test engineer for the US Federal Aviation Administration (FAA) Aircraft Certification Service, said that the FAA seeks a balance of standards that will enable new operational use cases. It is critical to establish appropriate aircraft certification requirements for eVTOL aircraft, said Webber. Certain operations could drive requirements for the aircraft; for example, Webber expects that aircraft will need to be able to fly in instrument conditions if customers are to expect on-demand air mobility in inclement weather. Both Meliska and Webber said that the possibility of an automated DFR system is worth exploring.
As in the air, the introduction of eVTOL aircraft could drive new requirements for buildings on the ground. Rory Feely, former Commanding Officer of the US Naval Test Pilot School and Marine Corps test pilot and the moderator of the panel, observed that eVTOL aircraft could lead to a massive change in the typical power requirements for buildings. In the same way that airports are required to maintain aviation fuel reserves, the physical infrastructure of airports will need to change to accommodate eVTOL charging stations. Terrence McKenna, the test and experimentation lead for the US Air Force’s Agility Prime initiative, noted that discussions involving power frequently involve stakeholders, like utility companies, that may not be familiar with the workings of the aerospace industry. McKenna suggested that the experiences of the electric automobile industry as they relate to the installation of charging stations could be a helpful analogue to eVTOL power requirements in future discussions with utilities and other stakeholders.
Vertiport Fire Safety
A significant factor in the opening and operation of vertiports will be whether these facilities are compliant with fire protection codes. David Phelan, an associate of Davidson Code Concepts, observed that eVTOL aircraft do not fit into current codes or fire protection models. For example, at the present moment, fire protection codes for passenger terminals, facilities and aircraft models are based on liquid-based fuels. The introduction of stored electric energy or hydrogen will likely require local municipalities, counties and states to develop new firefighting codes for these facilities.
Furthermore, Phelan said, municipal firefighters that are currently equipped to deal largely with structural fires will need to be trained in aircraft firefighting techniques and operations, especially given that eVTOL operations are expected to largely occur in urban areas and potentially involve high-rise buildings. The adoption and implementation of the new fire protection codes and emergency response tactics could lag behind their development, leading to potential project delays.
The eVTOL and vertiport industry should begin working with the emergency preparedness community, said Michael Gorin, program manager for emerging issues at the National Fire Protection Association (NFPA). Energy storage systems and hybridand electric-fuel vehicles, the technology for which initially outpaced codes and regulations, could offer a useful analogue for integrating electric aircraft into existing infrastructure.
As with energy storage systems and electric fuel vehicles, education and awareness are essential components for planning for the adoption of eVTOL aircraft, particularly as best practices continue to evolve. For example, one of the thermal management challenges currently confronting fire services is the fact that batteries for electric vehicles are typically contained in a steel casing, making it difficult for firefighters to access with fire suppression methods. Standardizing certain manufacturing practices and ensuring that first responders are comfortable dealing with eVTOL emergencies will be critical to the future of the industry, said Gorin.
Vertiport Weather & Turbulence
As with emergency preparedness, when it comes to weather effects on future eVTOL operations, there are unique challenges facing the UAM community. Dr. Colleen Reiche, aviation business lead at Quantitative Scientific Solutions, observed that eVTOL aircraft will be smaller and more sensitive to adverse weather than larger aircraft. Moreover, many of these operations are likely to occur at lower altitudes and within urban environments, which will introduce weather effects like urban island heating that are less of a factor for commercial aviation today.
Even minor weather effects could have a negative impact on passenger comfort, which will be a major factor in passenger acceptance of urban air taxis, said Dr. Peter Zaal, principal system architect with Metis Technology Solutions, supporting the NASA SimLabs at Ames Research Center. The combination of wind gusts and turbulence with vehicle maneuvers in urban environments could produce passenger discomfort from vehicle motion.
Speaking on the second day of the workshop, Perry Comeau, chief research test pilot at the National Research Council of Canada (NRC) Flight Research Laboratory, observed that there is frequently a high amount of turbulence between buildings and little room to maneuver to avoid these effects. By expanding simulated flight tests and data collection, aerospace planners can begin to build the models to reduce uncertainty and increase predictability in future eVTOL operations. Equipping eVTOL aircraft with weather sensors, Reiche suggested, would provide planners with a three-dimensional picture of the weather conditions where these aircraft are operating and improve forecasting models.
Heliport Case Studies
Even if eVTOL urban vertiport operations are some years away, aerospace planners can learn from the experiences of today’s heliport operators. Danny Sitnam, president and CEO of Helijet International, a Vancouver-based helicopter airline that operates several heliports in the area, observed that infrastructure community acceptance is critical to helicopter operations. According to Sitnam, heliports in the Vancouver area depend on Helijet’s regularly scheduled passenger flights for revenue, without which the heliports would not have been able to succeed.
Patricia Wagner, general manager for Atlantic Aviation, said that one driver of revenues at New York City’s East 34th Street Heliport has been helicopter companies like Blade that offer group rates and package deals.
Community relations are a key element of heliport operations. According to Sitnam, every noise complaint involving his company’s helicopters receives a personalized response from an executive to ensure that they properly address the concerns. Wagner noted that even if heliport operations are uninterrupted, community pressures on other airports and facilities that accept helicopter flights has the potential to significantly interrupt services.
Jeff Hyman, CEO of Helo Holding Inc. (HHI) — which operates the busy heliport in Kearney, New Jersey (see “Serving the Big Apple: The Kearny Heliport,” Vertiflite, July/Aug 2021) — said that the success of heliports depended on a close relationship with the local municipality. Hyman hopes that the advantages that eVTOL aircraft offer in terms of reduced noise and pollution will appeal to local municipalities and alleviate some of the public concerns regarding traditional helicopters.
Both Sitnam and Hyman are taking steps to transition from a reliance on fossil fuels and prepare their heliports for the eventual introduction of eVTOL operations. Sitnam said they are working on electrifying groundside facilities to accommodate electric charging systems and switching to an all-electric fleet of shuttle vans next year. Hyman’s HHI, meanwhile, is working with an eVTOL company to install an eVTOL-friendly charging station.
Still, Hyman said, eVTOL manufacturers will need to match or exceed the mission parameters and comfort of traditional helicopters and have the right power profile to deal with weather conditions and other hazards. For Sitnam, the imperative that the transition to eVTOL operations is as seamless and smooth for the customer as possible. Ideally, his company would like to see manufacturers offer high-speed, long-range aircraft with a cabin capacity of 7 to 10 passengers to replace its existing Sikorsky S-76 fleet. In a city like Vancouver, where inclement weather is frequently not conducive to VFR operations, Sitnam said that future eVTOL aircraft will need to be capable of IFR operations if they are to succeed.
Hazards & Risk Analysis for UAM Operations
Many existing resources and studies can inform eVTOL and vertiport developers about the risks from potential hazards, such as wildlife and powerlines. Phyllis Miller, the manager of the National Wildlife Strike Database, which catalogues over 252,0000 reports of wildlife strikes to aircraft in over 108 countries between 1990 and 2020, said that as much as future vertiport operations may differ from standard airports, existing data on strikes and wildlife patterns can help aerospace planners anticipate hazards to eVTOL aircraft. The impact of bird strikes on aircraft sensors should be a significant consideration for future aircraft developers, said Richard Dolbeer, a scientist at the US Department of Agriculture’s Animal and Plant Health Inspection Service Wildlife Services.
In addition to wildlife, Dr. Alexia Payan, a member of the research faculty at the Georgia Institute of Technology’s Aerospace Systems Design Laboratory (ASDL), noted that UAM vehicles will need to consider the risk posed by wires such as powerlines, given that many of these vehicles will be flying in the lowaltitude environment. In simulations of wire strikes, Payan found that a combination of mechanically actuated wire-cutters located on the aircraft fuselage and an integrated wire-cutter below the rotor could protect light helicopters from up to 80% of wire strike-caused crashes. The ASDL study also sought to develop algorithms for locating utility poles from satellite imagery and a framework for identifying VFR and IFR approach paths that may be unsuitable for low-altitude missions.
Solving the Infrastructure Challenge
This fifth workshop highlighted UAM infrastructure operations and safety. Through these five solution-focused workshops on eVTOL infrastructure, VFS has laid out the fundamental challenges of developing vertiports for UAM aircraft. Links to the videos and/or presentations for each workshop are available through www.vtol.org/infrastructure.
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