Urban air mobility evangelists would have you believe it is an entirely modern concept in a hurry to establish itself as part of the fabric of 21st-century life. However, others would say it’s not really modern at all, with helicopters having provided flight connections in built-up areas for many decades.
Regardless of these differing perspectives, it now seems clear that the scope and scale of urban air mobility are on the cusp of radical evolution driven by new power and flight control technology. There are now anywhere between 150 and 200 new aircraft programs at various stages of development—ranging from pipe dreams to those within sight of service entry.
Many of these aircraft are harnessing electrical power in a bid to be more environmentally and economically sustainable, with multiple electric vertical takeoff and landing (eVTOL) aircraft taking shape. Other programs are looking beyond electricity to alternative energy sources such as hydrogen fuel cells.
Autonomous operations (i.e. no pilot on board) are also on the horizon for both cargo- and passenger-carrying flights. According to Guillaume Thibault, a partner with consultants Oliver Wyman, operators could reduce costs by as much as 30 to 40 percent without pilots on the payroll.
However, given the technical and regulatory complexity of introducing new power sources and autonomous flight controls, it is not surprising that many of the innovators are taking a more gradual or hybrid approach on both scores. So, many of the new aircraft feature a conventional engine driving electric motors and others are being developed to be optionally piloted.
Similarly, not everyone is taking the VTOL path. Others are opting for new short takeoff and landing (STOL) designs combining fixed- or tilt-wings and electrical power.
In fact, the various architectures being advanced by the urban mobility pioneers are bafflingly diverse, encompassing concepts such as multicopters (with as many as two dozen mini rotors), lift-and-cruise combinations, tiltwings, and tiltrotors.
Some companies are focusing on aircraft with a tight mission specification to serve short hops of little more than 20 miles in dense, urban areas. Others are developing platforms to challenge conventional airliners on flights as long as 700 miles or more.
Bullish Market Projections
The more bullish contenders would have us believe that the first of the new wave of aircraft could be in commercial service on a limited basis as soon as 2023. Their critics would argue that, given the complexity of the change process, this is fanciful propaganda propagated to keep investors motivated. More conservative elements believe that it will be closer to 2030 before urban air mobility has put down sustainable roots.
Overall, there is a growing consensus that urban air mobility will, sooner or later, represent a viable element in the wider business aviation and air transport equations. The Change is in the air study by accountants Deloitte published earlier this year forecast that in the U.S. alone, the eVTOL market could be valued at $17.7 billion annually by 2040, after rising steeply from $3.4 billion in 2025.
In August 2019, Nexa Advisors in association with the Vertical Flight Society published its Urban Air Mobility—Economics and Global Markets report, which forecast a 20-year market value of $318 billion between eVTOL aircraft manufacturers, operators, and infrastructure providers. The report sees growth being concentrated across some 74 metropolitan cities around the world.
In a similar vein, a June 2019 report by investment bank UBS predicted that the introduction of hybrid electric powerplant for aircraft engaged in both urban air mobility and regional airline service could generate a new market worth $178 billion as soon as 2028. A key component of the UBS research is testimony from more than 2,000 travelers in the U.S. and Germany about the extent to which they are reducing their air travel use on environmental grounds. Overall, 22 percent said they had already reduced air travel for this reason and 38 percent said they would be willing to fly in hybrid-electric aircraft, a proportion that rose above 50 percent among respondents aged between 18 and 44.
Part of Business Aviation’s Future?
In any case, the business aviation community appears to be coming more open to the idea this new wave of innovation could and should be a significant part of its future. This is reflected in the agenda for the 2019 NBAA-BACE show in Las Vegas, with several sessions planned around urban air mobility and the technology driving it. The trend is also apparent among exhibitors, which include several of the key innovators in this fast-emerging field.
By around the end of 2020, Airbus (N5216) expects to have a clear picture of its long-term plans to develop new aircraft to serving what it views as growing needs for more efficient urban air mobility. The European airframer is very well aware that smaller and much younger startup companies are pursuing more urgent timelines that could see new eVTOL aircraft enter commercial service as early as 2023 but says that it prefers to take more time to ensure it delivers the right product.
Airbus has now completed flight testing of its single-seat Vahana eVTOL concept, which has flown more than 100 flights since January 2018. Over the next 12 months or so it will conclude its evaluation of the four-seat CityAirbus model. What it learns from these programs will inform the company’s next steps in this sector, according to Eduardo Dominguez-Puerta, Airbus senior vice president for urban mobility.
The Vahana program has been led by A3 by Airbus, the group’s Silicon Valley-based technology hub, while CityAirbus is in the hands of Airbus Helicopters. It is still to be determined which part of the Airbus empire will take the lead in taking a series production eVTOL aircraft to market. For now, it has created a division called Urban Air Mobility and this includes its Voom helicopter charter partnership.
“Having lived and worked in Silicon Valley, I’m well aware of the fail-safe-fail-cheap philosophy of many tech startups there, but this approach doesn’t work when you are planning to fly people over people,” Dominguez-Puerta told AIN. “We have a strong safety brand and because of our track record the regulators know we are serious about this. So, we don’t want to take a short-term approach.”
With recent developments, such as the July 2019 announcement by the European Union Aviation Safety Agency (EASA) of its new SC-VTOL rules, the regulatory path to getting eVTOL aircraft certified is getting somewhat clearer. However, Airbus feels there is still some way to go before the type certification process for the new generation of urban air mobility aircraft is established.
What’s more, Airbus sees more progress required to establish a clear legal, environmental, and social policy foundation for operating these aircraft in urban environments. Behind the scenes, the group is committing significant resources to working with all stakeholders to resolve these issues. It also sees significant challenges in terms of integrating the new category of aviation into the air traffic management system and believes that its in-house expertise in this area will give it an edge over new market entrants with shallow aviation roots.
Airbus’s extensive research into prospective urban air mobility markets has confirmed that an insistence that the new aircraft don’t add to existing levels of air pollution. Noise, “visual pollution” and privacy concerns have also been identified as significant factors in terms of social acceptability.
At Boeing (N50202), the year-old NeXt division appears to be hedging its bets in the eVTOL market. The U.S. aerospace group’s Aurora Flight Sciences has been developing its Passenger Air Vehicle, which made a first flight in January 2019. The prototype suffered a crash during its fifth flight on June 4, and, as of early September, had yet to confirm when flight testing would resume or how the development timeline might be impacted.
Boeing has since announced a strategic partnership with start-up company Kitty Hawk to develop its Cora eVTOL aircraft. It has yet to publish a clear timeline for its plans to enter the urban air mobility market, but there appear to be strong indications that the company considers this a priority.
Another leading business aircraft manufacturer, Embraer (C9008) also is setting its sights on the urban air mobility and has been quietly working on concepts under a working project title DreamMaker. Earlier this year, the Brazilian airframer issued an open invitation for customers and prospective customers to propose a name for the program.
At the Uber Elevate Summit held by rideshare technology giant Uber in early June, the company’s U.S.-based EmbraerX division unveiled a lift-and-cruise all-electric design, while providing almost no detail as to its projected performance and specifications. Nonetheless, Uber has named Embraer as one of six prospective aircraft partners for its planned air taxi service.
The concept shown at the Washington, D.C. Uber event features a pair of aft ducted fans and eight lift rotors. EmbraerX, which has operations in Melbourne, Florida, as well as Silicon Valley and Boston, said the design is based on “a broad range of tests and simulations, aiming at operational optimization for the urban environment” and promises high reliability, as well as low operating costs and noise. The aircraft is ultimately intended for autonomous operations.
Helicopter manufacturers Sikorsky (IS10) and Leonardo (C13018) both have worked on plans to extend their product range beyond conventional rotorcraft, but neither appears to be progressing these for the time being. By contrast, Textron (C9343) subsidiary Bell unveiled its Nexus eVTOL aircraft early in 2019.
In 2010, Sikorsky started working on the Firefly program, which was a technology demonstrator for an electrically powered helicopter based on the Schweizer S-300C model. Despite apparently making some progress, the company abandoned the project two years later, perhaps due to a realization that battery technology still had some ways to progress.
Leonardo also started work on its Project Zero AW1038 electric tiltrotor aircraft in 2010. As recently as early 2016, it was still demonstrating a prototype on the international airshow circuit but the Italian company’s work on the ducted fan model appears to have slowed, or at least gone underground, since then.
Endurance for the all-electric technology demonstrator was said to be no more than around 10 minutes and Leonardo indicated it intended to work on a hybrid version, backed up with a diesel engine. However, program leader Dr. James Wang has since left the company and now serves as chief technical advisor to start-up eVTOL developer XTI Aircraft.
Meanwhile, Bell unveiled the new Nexus aircraft at the Consumer Electronics Show in January 2019. The design features a central wing, integrated landing skids, and a modified V tail topped by a short horizontal stabilizer. Its first flight is projected for 2020, with the aircraft expected to be certified in 2023.
The Nexus is one of just a few eVTOL programs being advanced by a major manufacturer with relevant experience of bringing aircraft developed with related technology (i.e. helicopters) to market. What's more, Bell has firm partnership commitments from experienced aerospace groups including Safran (engines), Thales (flight controls), Moog (flight control systems), Garmin (avionics integration), EPS (energy storage), and Sumitomo (logistics and transportation).
The aircraft will be powered by a hybrid/electric distributed propulsion system feeding six tilting ducted fans, each powered by individual electric motors. The six-fan design is a compromise between quad- and octo-rotor designs seen on other urban VTOL designs to provide system redundancy and space for passengers to safely embark and disembark the vehicle while operating. The ducted fans also offer improved performance and a quieter noise signature than comparable open rotor designs, according to the company.
The Nexus propulsion system incorporates a series hybrid layout in which a turbine engine feeds an electrical distribution system, which in turn routes power to a battery pack that drives the fan motors. In addition to providing system redundancy in the event of turbine failure, the series hybrid architecture offers an upgrade path towards eventual fuel cell and/or full-electric propulsion.
The prototype's cabin is configured in a "4+1" layout with room for a single pilot/operator in addition to four passengers. Projected range is 150 miles, with cruise speeds of around 178 mph anticipated.
Engine Makers Step Up
At face value, you might think that conventional engine makers could feel threatened by the advent of electrically powered aircraft. But companies such as Rolls-Royce (C8312), Safran (C11237), Honeywell (N4302), GE Aviation (C10030), and Pratt & Whitney Canada (C1183) have embraced the opportunity to show leadership in the move toward alternative powerplants.
In March 2019, Rolls-Royce started ground testing a hybrid-electric propulsion based on its M250 turboshaft engine. This will be used to test Airbus's E-fanX airliner development program from 2020, with a first flight projected for 2021. The engine is projected to generate between 500kW and 1 mW of power.
The UK-based engine maker also hopes to find applications with eVTOL programs. In June 2019, Rolls-Royce confirmed plans to purchase the electric propulsion division of Siemens and expects to complete this transaction by year-end.
In July, XTI Aircraft selected GE Aviation’s new Catalyst turboprop engine to provide power for its hybrid-electric TriFan 600 VTOL aircraft. The manufacturer has yet to build a full-size prototype, but GE is advancing work on the Catalyst.
GE is also partnered with U.S. eVTOL start-up Jetoptera to develop a so-called “Fluidic Propulsion System” as an alternative energy source to electric batteries for the motors on its Jetoptera 2000 aircraft. The current status of this work is unknown.
In September, Boeing and Safran announced a joint investment in energy storage specialist Electric Power Systems (EPS). The undisclosed investment amount committed during a Series A funding round will help Utah-based EPS to develop a highly automated industrial base capable of producing aviation-grade batteries at far higher rates than is possible today. It will also support work to reduce the cost of the batteries, making them more viable for electric aircraft.
France-based Safran is actively involved in a number of eVTOL aircraft developments, including Bell’s Nexus, for which it is providing a new turboshaft to support its hybrid-electric powerplant. It has also been involved in Zunum’s ZA-10 fixed-wing program, which appears to be stalled due to a lack of funds, and, reportedly with MetroSkyways’ City Hawk.
EPS is already providing energy storage units for the Nexus model. It is also supporting Bye Aerospace’s electrically powered eFlyer fixed-wing aircraft.
Safran views the eVTOL sector as a launch pad for introducing electrical power to larger aircraft, and, in its view, improving the efficiency of energy storage is a key factor in achieving this. “We think that eVTOL is a significant business opportunity that still faces a lot of uncertainty,” Hervé Blanc, vice president of the group’s Electrical & Power division told AIN. “The eVTOL aircraft are perfect for demonstrating the benefits of electric and hybrid power solutions and we expect them to drive other opportunities with larger aircraft.
According to Safran, weight constraints for energy storage units are a far greater challenge for aviation than they are in the automotive sector. So too, are the ability to meet safety standards and to produce large numbers of batteries at an acceptable cost.
In Blanc’s view, power is more of a challenge for eVTOL aircraft developers than autonomous flight controls. “Autonomy is easier with aircraft than for a car,” he argued. “You take off from one fixed point and land in another, following a clear channel on the way so it’s much easier to define how this is done than it is for an autonomous car in the middle of traffic.”
Safran believes it may well take another five years to get eVTOL aircraft certified and in commercial service, and that operations will likely start with cargo operations. “It is fairly easy to do a flight demonstration with just one prototype but getting a fleet of aircraft into service with the right level of safety and reliability will be another story and demonstrating that the industry can achieve that will require a step by step approach,” Blanc commented. Safran also is working on algorithms to ensure that operators will know with a high degree of accuracy how much charge is left in batteries so that they can be sure of landing safely.
The company is looking to support both hybrid and all-electric aircraft. It sees the latter as being limited to flights of up to around 30 minutes with currently available energy storage technology, but it sees this shifting as the power-to-weight ratio of batteries improves. “Getting to 300 kW/kg will be a game changer,” said Blanc. “The question is whether that will take one to two years or five to 10 years.”
Safran also has invested in Oxis Energy, which is developing new lithium-sulfur batteries. In July 2019, it acquired Neelogy, a France-based specialist in electrical current sensors.
Meanwhile, Honeywell is developing a new hybrid-electric turbo generator that combines its 1,100-shp HTS gas turbine engine with a pair of 200-kilovolt generators. It believes this technology will provide a quieter, cleaner and more fuel-efficient powerplant for urban air mobility aircraft.
Transcend Air Corporation has selected Pratt & Whitney Canada to provide a version of its 1,700-shp PT6 turboprop to provide power for its hybrid-electric Vy 400 eVTOL model. The current status of this program is unclear.
Along with Honeywell, several leading aerospace groups are taking a leading role in developing avionics, flight controls and other cockpit systems for the new generation aircraft. These include Collins Aerospace (C10808), Thales (C13239), and GE Aviation (C10030).
In May 2019, Collins announced plans for a new electrical power development facility called The Grid in Rockford, Illinois, to harness expertise in this area from across the group. This includes UTC Aerospace Systems, which United Technologies merged with Rockwell Collins when it acquired the company.
Honeywell’s engagement with the urban air mobility wider electric aircraft sector is extensive. For Slovakia-based Pipistrel’s 801 fixed-wing model, it is providing avionics and flight controls. For Jaunt Air Mobility’s ROSA program, it is to supply avionics, navigation systems, flight controls and powerplant too. It is also partnered with the UK’s Vertical Aerospace to provide flight controls for its Vertical eVTOL project.
For the Eviation Alice aircraft, Honeywell is supplying flight controls. Hartzell Propeller (C7235) is providing propellers for this model.
Thales is providing flight control’s for Bell’s Nexus aircraft, with Garmin supplying other avionics. Meanwhile, Kearfott Corporation (C9836) is due to supply guidance and navigation systems for the CityHawk eVTOL model being developed by Israel’s Metro Skyways.
Several NBAA show exhibitors are involved in developing the critical unmanned air traffic management capability on which these new generation urban air mobility concepts will depend. In fact, the challenges associated with safely integrating especially those aircraft intended for autonomous (i.e. pilotless) operation into public airspace have been identified as the biggest roadblock to these aircraft entering service. GE Aviation subsidiary AirXos is involved in development work to this end, as is Harris Corporation (C8222) and Boeing NeXt with its partner Skygrid.
Brazilian helicopter operator Flapper (C8325d) has been identified as a prospective eVTOL pioneer operator in South America. True Blue Power (C8717) is involved in battery technology in this field. California’s Hollister Airport (N3728) has emerged as a center for testing eVTOL prototypes.