Personal air mobility: Will this dream really fly?

At this summer’s Farnborough Air Show, Rolls Royce unveiled a concept vertical-takeoff-and-landing (VTOL) aircraft with six electrically powered propellers for applications including personal and public transportation. Seating four or five passengers and with top speeds of approximately 400 kph, the aircraft has onboard battery storage, which is charged by Rolls’ venerated M250 gas turbine engine, making it an electric hybrid. The wings rotate 90° to enable both vertical takeoff/landing and horizontal flight.

The same week, Aston Martin announced an autonomous, three-passenger VTOL hybrid electric concept vehicle, tabbed the Volante Vision Concept, presumably aimed to serve the luxury personal transportation market. Both Rolls Royce and Aston Martin project that these vehicles could be ready for sale by the early- to mid-2020s, citing increasing vehicle congestion in major cities and value in reducing commuting times.

Rolls Royce and Aston Martin join a lengthy list of companies in pursuit of the dream of the “flying car,” or what is now being called “personal air mobility.” Going back to “The Jetsons” cartoons of the 1960s and the 1985 movie, “Back to the Future,” flying cars have remained more in the realm of science fiction than science reality. Until now, it seems.

Personal air mobility, of course, has existed since the invention of the airplane, unless you go back to hot-air balloons. At its peak in 1978, the general aviation segment produced almost 18,000 general aircraft in the US alone. This market, however, fell precipitously in 1983 and has remained low ever since. In 2016, global shipments totaled 2,262 aircraft, according to the General Aviation Manufacturers Assn. (Washington, DC, US), and this included small personal aircraft and executive jets. While several flying cars, notably the Terrafugia (Woburn, MA, US) Transition and the Aeromobil (Bratislava, Slovakia) 4.0, have announced delivery dates in 2019 and 2020, respectively, they share the same limitations as their winged predecessors — they need a runway – or at least a lengthy stretch of open road — on which to take off and land. This severely limits their practicality.

The recent concepts announced at Farnborough, on the other hand, and those previously promoted by Airbus, Joby Aviation, Volocopter, and Google founder Larry Page’s Kitty Hawk, among others, aren’t so limited. Based on VTOL technology, with many operating in tiltrotor fashion, and thus able to transition from vertical to forward thrust for flight and vice versa for landing, they open the landscape for take off and landing on a much smaller footprint, akin to that required by helicopters. 

The vision, then, is to relieve ground-based commuter congestion with airborne commuting in large metro areas. Much like taxis or ride-sharing services operate today, and at similar costs, these new takes on personal air mobility could easily operate from the tops of buildings or parking structures. Unlike today’s helicopters, with a single propeller and a tail rotor, these concept craft feature four to 12 propellers, most energized by electric motors. Although some will be combustion engine/battery hybrids, a number will be battery only, with charging stations at each end of a route.

Despite the enthusiasm, major questions loom: Is there a viable commercial need for these vehicles? Will the US Federal Aviation Admin. (FAA, Washington, DC, US) permit their operation and, if so, how will they be certified? Will they only be able to operate in weather-friendly climates? Will the costs be prohibitive and limit the market only to the well-heeled?

Uber (San Francisco, CA, US) has done extensive studies of the vision’s viability and plans trials in 2020 in several cities, including Dallas and Los Angeles. It is working closely with the FAA on how such aircraft would operate in cities. In terms of cost, at low volumes (100/yr), the estimate is US$1.2 million per vehicle, with batteries at US$400/kWh. At intermediate volumes (500/yr), vehicle cost drops to US$600,000, with batteries at US$200/kWh. At rates closer to today’s low-volume automobiles, vehicle price drops to $200,000 and battery technology falls to the $100/kWh range.

Should this commuting transformation happen, composites are sure to play a major role, due to their lightweighting potential in battery-laden air vehicles. Most platforms now in design or prototype stage make extensive use of carbon fiber structures to achieve strength and aesthetics. Propellers, seats and other components are excellent candidates for composites. If volumes truly hit 5,000 or more per year, high speed, lower cost (compared to autoclave) techniques such as RTM and compression molding are sure to be employed.

Will we see widespread, air-based ride-sharing services happen? Or will vehicles and services be limited to the luxury market? I’m hoping we can make the first option a reality, but we must overcome some big hurdles along the way.