eVTOL er et nytt begrep - AW&ST

eVTOL Gains Momentum in Mainstream Rotorcraft World Guy Norris and Tony Osborne  Urban air mobility and electric vertical-takeoff-and-landing (eVTOL) vehicles turned out to be a major talking point at this year’s Heli-Expo convention in, where the coming wave appears to be welcomed rather than feared by established helicopter manufacturers. Sparked into life in 2016 largely by ride-hailing company Uber, which is working with suppliers on five eVTOL configurations, the broader explosion in interest in electrical vertical flight has spawned a plethora of proposals. More than 50 eVTOL concepts are under study or in development, ranging from tilt-thrust designs like the A3 by Airbus-developed Vahana and Joby Aviation’s S4, to lift-and-cruise concepts such as Aurora Flight Sciences’ eVTOL and Zee Aero’s Z-P1. A series of more than 10 wingless configurations are also in the mix, including the Airbus Helicopters CityAirbus and Volocopter VC200. Other vertical-lift options cover a novel set of almost a dozen hover bike/seat concepts, such as the Kitty Hawk Flyer. With new entrants emerging every month and an estimated $1 billion-plus in investment cash pouring in, the urban air mobility gold rush shows no signs of ebbing. The 2018 Heli-Expo was the first time the mainstream commercial rotary industry has had the opportunity to broadly share its views of the potential threat posed by the eVTOL revolution, as well as the technical merits and realities of the on-demand mobility proposals. Airbus backs eVTOL plans by partnering with Blade on-demand helicopter service Terrafugia unveils VTOL urban air mobility and cargo concept Based on Uber’s original goals, most concepts are tending toward all-electric propulsion because of the lower cost of grid electricity versus aviation fuel and the higher efficiency of electric drives compared with combustion engines. Uber’s specifications for a four-seat eVTOL entering low-rate production in 2023 list a cruise speed of 170 mph at 1,000-ft. altitude and a range of 100 mi. carrying an 800-lb. payload. While key players Airbus Helicopters, Bell and Sikorsky are actively studying eVTOL concepts, the manufacturer potentially most at risk from the emerging competition is Robinson Helicopter Co. which, so far, has not shown its hand. However, the Los Angeles-based light helicopter manufacturer sees eVTOLs as being complementary rather than competitive. Despite the findings of a Boeing Research and Technology study that indicate a four-seat tilt-rotor eVTOL would have a 26% lower operating cost per seat-mile than the piston-powered Robinson R44, company President Kurt Robinson says: “Actually I’m looking forward to it. I think [eVTOL] is going to be a huge help.” vehicle, that’s great. But if I want to go, say from Los Angeles to Palm Springs, [California], then having that same pick-up spot—where I take them further with the same loads—then I think they become complementary. I really look forward to seeing the industry grow.”electricalReferencing the network of additional urban landing sites that will be required for the infrastructure of future air mobility networks, Robinson says: “The more areas you have [from where you can host] flights, the better. Generally, it is a very short flight and if it is some sort of

Terrafugia is studying two hybrid VTOL concepts dubbed the TF-2. One version is a tilt-rotor and the other is a lift-plus-push configuration combining fixed rotors and a pusher propeller. Credit: Terrafugia

 

Bell, which is one of the five airframe manufacturers working with Uber Elevate along with Boeing-owned Aurora Flight Sciences, Embraer, Pipistrel and Mooney, less surprisingly also sees eVTOL as a potential adjunct to future business alongside its traditional light helicopter products. Bell CEO Mitch Snyder says: “If you are moving people and it is quiet, at what level does it pick up the missions that light helicopters have been doing? If we could create a product that met that demand and could meet the requirements for safety, efficiency and quietness, and could carry four passengers, then that would impinge on what helicopters do today. But that’s great, that’s fine,” he stresses. As the first helicopter company to display a full-scale mockup of an urban air-taxi cabin concept at Heli-Expo, Bell is also pondering the challenges involved in shifting to a more automotivelike, high-rate production system for the eVTOL generation. “That’s a whole different way of thinking about building the product,” says Snyder. “They would go together differently . . . but it is a change for a company. You’ve got to be able to rapidly manufacture these very quickly—10, 15, 20, 30 a day, or even more.”  Engine-makers appear to be divided over realistic timescales for battery technology development to support the early development of all-electric VTOLs. Bruno Bellanger, executive vice president for programs at Safran, says the manufacturer “does not see full electrical architecture for platforms flying beyond 30 min. and carrying more than 100 kg [220 lb.] within the next two decades.” Instead, the French company believes there is likely be a longer reliance on turbine-driven hybrid propulsion systems. Rolls-Royce and Pratt & Whitney Canada (P&WC) are more optimistic, perhaps because both have access to wider electrical systems know-how within their respective industrial bases. Mike Mekhiche, the global head of electrical at Rolls-Royce, says the company’s pedigree in hybrid propulsion systems for trains and ships is “extremely critical” to driving the electrification process in aerospace. However, from an on-demand perspective, Mekhiche says the technology for all-battery driven propulsion systems “is not a matter of several decades. Depending on the platform size, it is already happening today. There are aircraft now that can carry two to three people, which is much more than 100 kg, and remain in flight for 3-4 hr.,” he asserts. Although more cautious on timescales, Nicolas Chabee, vice president of sales and marketing for helicopter engines at P&WC, says “urban mobility is out there and we want to be part of the conversation.” Referring to the company’s broad technology base, he adds, “We have UTC Aerospace Systems, because it is not just the powerplant we are talking about, it is the power-generation management system and the whole ecosystem. There are a lot of stakes out there that we need to resolve together.”  Airbus, which began test flights of its A3-developed Vahana single-seat eVTOL in Oregon on Jan. 31, is targeting the first flight of its CityAirbus eVTOL four-passenger demonstrator by year-end. Data to further optimize both designs is expected to emerge from a strategic partnering agreement with Blade, a U.S.-based on-demand helicopter flight service, which was announced at Heli-Expo. “We need to understand the demographics, and whether we need to fly four people for 10 min. or two people for 30 min.,” says Chris Emerson, president of Airbus Helicopters Inc. “Right now, we are at a crawling phase of understanding what this market is going  to be like in the future,” he adds. Currently operating in New York, New Jersey, Miami and Los Angeles, Blade plans to work with Airbus’ Airbus Ride venture in Dallas and is looking to expand overseas in the coming years. The company works with existing helicopter companies but is not an operator itself. “Each of our operators have expanded their markets,” says Rob Wiesenthal, CEO of Blade, “It has created another revenue stream for them.”

 

Airbus is targeting the first flight of its CityAirbus eVTOL four-passenger demonstrator at the end of 2018.  Credit: Guy Norris/AW&ST

 

Like Robinson, Wiesenthal foresees a time when eVTOL platforms and helicopters will work side by side, with helicopters performing the longer journeys. “The addressable market will be defined by how close their heliport or vertiport is to where they want to go,” he says. He notes, the “more cost-effective and quiet these aircraft are, the more options we are going to have to land, and the bigger business this will be for everyone.” Terrafugia, the roadable-aircraft developer recently acquired by Chinese carmaker Zhejiang Geely Holding Group, released details of two hybrid VTOL study concepts at the show. Both are dubbed the TF-2; one version is a tilt-rotor, the other is a lift-plus-push configuration combining fixed rotors and a pusher propeller. Each vehicle is designed to autonomously dock with a detachable cargo or passenger-carrying pod that, on landing, is transferred to a vehicle chassis for onward transport. Because his product is at the developmental stage, Carl Dietrich, co-founder and chief technology officer of Terrafugia, says he is at Heli-Expo to gain insights from operators. “The more we can absorb that perspective, the better the product will be,” he notes. The tilt-rotor has “greater mechanical complexity but flies a lot faster at 175 kt., while the lift-plus-push option is simpler but flies at around 125 kt.,” Dietrich adds. “We are expecting this to be a hybrid vehicle, at least to start with, and we’re still conducting trade studies and talking to engine manufacturers to see what we can piggyback on.” Both concepts have a 40-ft. span and will fit on a standard helipad. The combined weight of the piloted vehicle and the pod will be 11,000 lb., some 9,020 lb. of which will be the pod. It is designed to take four occupants plus 50 lb. of bags each. Because about 30% of Uber trips are to airports, “we think a lot of these trips in the air taxi model will involve taking stuff to the airport too,” he says. “The beauty of the pod idea is we can have really rapid and consistent 2-min. turnaround on the ground, so we keep the air vehicle in the air as much time as possible,” Dietrich adds. Chris Jaran, Terrafugia CEO and former managing director for Bell Helicopter China, says the piloted, hybrid approach will enable a faster track toward service entry. “Some want an all-electric vehicle, which we don’t think is right today, although it may be in the near future, when the battery technology gets there. They also want fully autonomous air vehicles that the FAA is not going to approve for a long time. So we have a commercial pilot flying the vehicle and a driver in the ground vehicle. As you look at all the pieces, everything is doable today. It’s not 10 years in the future when regulations can support it,” he asserts. The manned version will also build hours demonstrating the system and the technology until the state-of-the-art of autonomy and battery systems allows the pilot and driver to be substituted, says Jaran. Terrafugia plans to begin flights of a subscale prototype this year and full-scale tests in 2019. “We are looking at a development cycle that puts this into service in 2023,” he adds. Full-scale flight tests will take place at an undisclosed location on the U.S. East Coast; subscale testing is set to take place in California.