New Delhi,July 22, 2018: Airliners are not a very elegant solution to the problem of mass transit. While they’re great at covering long distances at high speed, and are reasonably efficiently in terms of passenger-mile, take-offs and landings are loud and fuel-inefficient.
Helicopters, meanwhile, have a spot landing capability, which means they can access crowded urban areas, but this advantage over airplanes is compromised by their noise, which makes city-center heliports unpopular with planners. Helicopters are also slow and burn a lot of fuel.
These factors have created buzz around the proposed new class of electric vertical take-off and landing (eVTOL) aircraft—they pollute less; don’t need a lot of space to land; and, because they’re quieter than traditional aircraft, their landing sites can be closer to where people actually want to go.
Signs that these aircraft may be the next big thing in aviation were evident at this week’s Farnborough Airshow, the U.K.’s biggest showcase of flying machines and technology. Rolls-Royce announced an air taxi concept, a vertical takeoff aircraft that can carry up to five passengers, using six propellers driven by electric motors for lift in helicopter mode and thrust in airplane mode. But best of all, it uses technology that already exists.
Rolls-Royce calls this a hybrid. The motors run off a battery, but an onboard gas-turbine engine keeps the battery charged. So a 500-mile range without stopping to refuel sounds entirely plausible.
The propellers are mounted on tilting wings and a tilting tail—they are aligned vertically for a landing, then transition to horizontal for cruising once in the air. The wing takes part of the load in cruise mode, leaving more power for going fast. Rolls-Royce says the craft can reach a realistic-sounding 250 miles per hour according to barrons.com.
Rolls-Royce is not the only traditional aviation company in this sphere. Uber’s interest in flying cars has helped boost interest in piloted or autonomous urban mobility solutions. Brazilian plane maker Embraer, whose new airliners partnership with Boeing was formally announced at Farnborough, unveiled an eVTOL concept at the Uber Elevate conference in Los Angeles back in May.
Bell, the U.S. helicopter maker, is teaming up with French turbine company Safran to devise a hybrid propulsion system that will form part of the air taxi vision of Uber Elevate.
Meanwhile, Airbus, the European maker of airliners and helicopters, flew its Vahana all-electric, autonomous eVTOL aircraft for the first time this year. It is also working on the drone-like CityAirbus, which would be piloted initially but is intended to be autonomous.
But despite bullish promises from Uber—flying taxi demonstrations by 2020 and commercial operations by 2023, with Dallas, Los Angeles, and perhaps Dubai as test cities—there are fundamental issues still to be solved.
Technology for unpiloted air taxis is far from perfected. Then there’s the problems of rules and technology required to ensure the safe movement of swarms of drones in cities.
Some of the most seasoned industry watchers are skeptical about the most fanciful air taxi concepts. Richard Aboulafia, vice-president of analysis at the Virginia-based Teal Group, asks: “If this is such a great idea, why not prove it with existing technology?”
That’s exactly what Rolls-Royce is trying to do.