Newfangled electric-vertical-take-off-and-landing (eVTOL) aircraft, also referred to as air taxis, are still at an early stage of development but are becoming a leading topic of discussion in the aviation industry.

More than 100 aviation companies and projects, including household names like Boeing and Embraer, are at various stages of vehicle development. In the past three weeks two major automakers – Hyundai and Toyota – have also entered the eVTOL arena with significant investments.

“Momentum is building and this industry is in this incredible spurt of growth and opportunity,” Uber’s engineering director of aviation and chief urban air mobility (UAM) evangelist Mark Moore tells a panel at this year’s Heli-Expo in Anaheim, California. 


Source: Joby Aviation

Joby Aviation’s S4

But making eVTOLs desirable to a wide swath of the non-aviation-geek population will require them to fulfill a list of requirements that go far beyond technological challenges.

For example, public acceptance is one primary hurdle if these vehicles are to become a viable mode of transportation in a sensible amount of time, Jim Sherman, the director of strategic development at the Vertical Flight Society says. The others are: infrastructure (heliports and vertiports), flying (piloted versus autonomous vehicles), and standards and regulation, he adds.

Focus groups have shown that a major issue for public acceptance, besides the safe operation of the vehicles, is ensuring that their noise level remains low.

“It’s easy to build a loud aircraft,” says Joby Aviation’s aeroacoustic lead Ben Goldman. Joby, a Santa Cruz, California-based aerospace company. “Compared to current aircraft, not only does the eVTOL have to be quieter, but it also has to be perceptually more pleasant to the listener.”

Joby announced earlier this month that it had raised $590 million in Series C funding led by Toyota Motor Corporation. It is also one of eight manufacturers working with Uber to design its eVTOL aircraft to be used for rideshare air taxi service. The company’s S4 aircraft, a piloted five-seater, can travel at speeds of 174kt (322 km/h) and fly 130nm (241km) on a single charge. The company claims it is “100 times quieter than conventional aircraft during takeoff and landing, and near-silent when flying overhead.”

“We have acoustic targets that we are trying to meet, and performance targets we know we have to meet,” Goldman says. “That will Involve a creative solution in which we recognize that we have to make compromises across the vehicle, but at the same time having so many noise sources gives us a lot of flexibility on where to put our emphasis on the noise reduction.”

The vehicle’s noise profile will be lower than a traditional helicopter due to tip speeds, lower thrust requirements and optimal directivity in cruise because the vehicle can travel like an airplane rather than a helicopter, Goldman says.

“The quiet revolution is here, I hope you didn’t hear it coming,” he adds.


Korean carmaker Hyundai also recently announced it was entering the urban air mobility space. It’s S-A1 aircraft is based on an all-electric aircraft design that Uber had shared previously as an open source concept intended to stimulate conversation in the budding eVTOL industry.

“Mobility itself is changing in terms of its nature, it is no longer the traditional market, so simply manufacturing the traditional combustible car is not what society needs anymore,” says Pamela 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 says, is to get the public’s input, help people understand 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, Moore says, and predicts that they will not be the only ones competing to provide eVTOL technology.

“In a year or two you will see every single automotive company involved in some sort of play in urban air mobility,” he adds.

“It’s a Wright Brothers era,” he says of Uber’s eight 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”


Regulatory approval of the vehicles is a tricky subject, as the governing bodies across different geographies are taking their own paths in assessing the value and safety of eVTOLs for passenger and cargo service.

Moore blasted the European Union Aviation Safety Agency (EASA) for dragging its feet on certification standards, adding that the regulatory body should be looking beyond its own region for solutions in this space.

“EASA and FAA are on very different paths for certification of the vehicles,” he says. “EASA is not totally informed on the requirements. They are only talking to EU developers, who are just one small portion of the entire design space.”

“In the last five years there has been a lot of progress on consensus standard,” he added. “It’s strange how the EU has stepped in and is now starting from a clean sheet after all this prior work gave a great foundation to work from.”

Working with the International Civil Aviation Organization (ICAO), the United Nations’ international air transport agency, is also an option, but panelists say that would be a much more complicated and bureaucratic process. Sherman says that the Vertical Flight Society will be meeting with ICAO representatives later this year to begin advising on infrastructure issues.