It’s true that more than 155 vertical takeoff and landing (VTOL) vehicles are under development by some impressive companies. However, most will never see daylight under their wheels. As Mike Hirschberg, executive director of the Vertical Flight Society, said at a recent VTOL conference in Atlanta, “It’s easy to design an aircraft if you don’t know how.”
The issues facing VTOL are many—battery technology, air traffic control management, ground infrastructure, aircraft noise, safety, and public acceptance—especially for autonomous flight with humans on board.
Most of the VTOL concepts floating around are some variation on ducted vertical lift rotorcraft—similar to the quadcopters on drones. Generally, the presumption is that these will be electrically powered—or eVTOL. While all of that may someday come true, the early days of this urban air mobility (UAM) evolution will likely use manned tilt-rotor aircraft powered by conventional engines or a hybrid of engines and electric motors. Eric Bartsch, chief operating officer of VerdeGo Aero, believes that hybrids will have about a 20-year life cycle before pure electric propulsion is robust enough to consistently operate in a commercial environment. VerdeGo Aero is a company focused on developing what it calls integrated distributed electric propulsion. In other words, multiple electric motors driving multiple propellers or rotors in harmony—distributing the thrust across multiple systems to improve safety and efficiency. In his view of the future, pure electric vehicles will be used for short-range intracity trips, the way we might use Uber or a taxi today. Electric and fuel-burning hybrid vehicles will be used for longer urban trips and high-density flight routes between urban vertistops or airports—like commuter buses. Direct drive fuel-burning vehicles will be used for regional city-to-city flights on routes not practically served by today’s regional jetliners.
Whatever these vehicles look like, noise is going to be an issue, according to many presenters at the Aviation Week UAM Americas conference in Atlanta. Although the electric motors themselves may be quiet, the rotors they drive—even if ducted—will create significant noise. Those who have heard eVTOLs fly seem to agree that the challenge will be having these vehicles fit into the normal noise signature of a city. To accomplish that, many will follow defined pathways where noise already exists—over freeways, for example. Or they will follow rivers or other overwater routes to keep noise away from residents.
So, with all of these challenges, why do so many see a bright future for such vehicles? Why are companies like Boeing, Bell, Airbus, Uber, Lockheed Martin, and others spending billions to figure out solutions?
Because the need is real. The pace of Los Angeles traffic has slowed from about 40 mph 20 years ago to about 20 mph today, according to Douglas Gates, global chair of industrial manufacturing at auditing giant KPMG. Cities worldwide, especially in countries with newly emerging middle classes, are seeing traffic gridlock that demands creative new solutions. Converging technologies related to electric and hybrid propulsion; 5G networks for high-speed, low-altitude air traffic management; and artificial intelligence are making solutions possible that were unimaginable a decade ago. None is mature enough to launch a large commercial effort to solve urban air mobility issues, but all of them maturing together will certainly influence the future of aviation.
The “when” is less clear. Mitch Snyder, president and CEO of Bell, believes his company will be flying a manned eVTOL or hybrid VTOL with passengers by 2025. Autonomous flight will occur much later. Most important will be initial success with moving packages over urban areas in unmanned vehicles. Success there will help build experience for air traffic management and inspire confidence from the public. Already, human organs have flown over urban areas in drones. A drone moved a kidney over Maryland earlier this year—leading to a successful transplant. Some 50 percent of donated blood in Rwanda is moved by drones. In addition to package delivery, the military will likely be an early adopter of VTOL, moving equipment and supplies to remote and dangerous areas in unmanned vehicles.
Meanwhile, urban general aviation airports will be an important part of the VTOL ground infrastructure. With automobile parking, open space for takeoffs and landings, terminals, maintenance facilities, and electric power available, GA airports may see a renaissance as commuter ports. Our goal is to remind local communities that the airport in their neighborhood today, which they may not care about or may even oppose, could be a key transportation resource in their commute in the future.