The ((Quiet)) Electric VTOL Revolution
As Urban Air Mobility advances toward becoming reality, the industry is taking public perception seriously and is working to understand eVTOL noise signatures and how they will be perceived by the public and educate communities on how they will be a benefit. VFS held an expert panel to discuss this critical issue.
By Jim Sherman
VFS Director of Strategic Development
Electric vertical takeoff and landing (eVTOL) aircraft promise to be quieter than helicopters, but how much quieter? And how will that shape the future of urban air mobility (UAM)?
These are some of the questions that were addressed at “The ((Quiet)) Electric VTOL Revolution,” the third annual VFS eVTOL panel at the annual Helicopter Association International (HAI) Heli-Expo 2020 trade show. The panel featured an all-star lineup of Juliet Page of the Volpe National Transportation Systems Center, Ben Goldman of Joby Aviation, Pamela Cohn of Hyundai Motor Group’s UAM division, and Mark Moore of Uber Technologies; Elan Head of Vertical Magazine and eVTOL.com moderated. VFS Director of Strategic Development Jim Sherman led off the discussion with an overview of eVTOL developments and the Vertical Flight Society’s leadership efforts.
Page delved into the details of why noise is such an issue with helicopters, and why eVTOL developers and operators need to work with the local community to ensure successful integration in the transportation system. Page commented that “Noise is a key area that needs to be addressed in the eVTOL community in order to scale up operations and make [the industry] economically viable.” This involves “operational noise, the physics and mechanics of the vehicle and how you fly it, and community engagement.” She noted that it is important for eVTOL manufacturers to avail themselves of the variety of integrated, simulated and dual-use aircraft noise models that have been developed over the years by NASA, the US Federal Aviation Administration (FAA) and the US Department of Defense, as well as the latest advanced acoustics models, in designing their aircraft to be as quiet as practicable.
As the chair of the HAI Fly Neighborly Working Group, Page also stressed the importance of the community engagement: “There are noise challenges in various areas of the country when it comes to helicopters and it is often difficult to put the genie back in the bottle.” She said industry approaches, including Fly Neighborly, can assist eVTOL developers and other industry stakeholders with community engagement.
Goldman, the acoustics lead for eVTOL developer Joby Aviation, stressed that the perception of noise and its sound is just as critical in winning public acceptance as actual decibel levels. “Quiet helicopters can still be annoying,” he said, but added that the independent, multi-rotor system designs presented an opportunity to “tailor” noise so it is less objectionable to the human ear via “psychoacoustics.”
“Independent rotor systems give designers an enormous amount of flexibility to tailor noise,” he said. Goldman said that disc loading, blade speed, location, shape and thickness are all factors in the equation as is blade vortex interaction. Finally, offloading blade noise via vehicles transitioning onto a fixed-wing for cruise flight not only provides more efficient flight and better vehicle economics, it also significantly reduces noise, he noted.
“The quiet revolution is here,” he said. “I hope you didn’t hear it coming.”
“Mobility itself is changing in terms of its nature, it is no longer the traditional market, so simply manufacturing the traditional combustion engine car is not what society needs anymore,” said Cohn, vice president of global operations and strategy at Hyundai’s UAM division. “Mobility is going to be integrated, different, and change dramatically as our cities and communities change in the next 10, 20, 30, 40 years.”
Hyundai’s approach, she said, is to get the public’s input, and educate them on what UAM actually means, and also how issues like noise, downwash, access and accessibility will affect communities so that the carmaker can tailor its approach to the complex issues around mobility in the 21st century.
The fact that car companies like Hyundai and Toyota are entering the UAM business speaks volumes, Uber’s Moore said, and predicts that they will not be the only ones competing to provide eVTOL technology. Many others have also been studying it for quite some time. “In a year or two you will see every single automotive company will be involved in some sort of play in urban air mobility,” he adds.
“It’s a Wright Brothers era,” he said of Uber’s eight announced UAM partner projects. “No two vehicles are alike. Everyone is pursuing a different route, incredible new technologies, and no one knows the best way to do it yet, so we are at an exciting stage where the genetic algorithm on these vehicles is running wild.”
Moore reiterated that Uber is looking to begin test flights this year, but did not say when or where. “I expect that’s still going to happen but can’t announce it right now.”
Presentation slides from the panel can be downloaded at https://evtol.news/2020/01/27/vfs-heli-expo-2020/