Barely any engineering sector depends as much on the development of new technology as aerospace; and although it’s often defence that’s seen as the part of the sector where most development takes place, recent years have seen civil aerospace also being the cradle of much new development. The tightening of regulations on the environmental profile of flying, along with new materials and processes, have all driven R&D in the sector. For Airbus, the world’s second-largest aircraft manufacturer, it’s taken the technologies of flight in some unexpected directions.
The small size of the E-Fan aircraft has led some to dismiss the project as a sideshow, but Botti insists that it represents a serious long-term goal for Airbus. The ultimate aim of the project is to develop an electric airliner, initially with around 100 seats, which the company is currently calling E-Thrust. “This is a learning curve for us. We have to start with the small aircraft with power in kilovolts, and work up to megavolts. We couldn’t possibly do it in one go.”
Part of the goal of the E-Thrust project – but only part – is environmental. When the aircraft’s engines run on battery power, the aircraft produces no emissions. “If you look at where the world trends are heading by the 2030s, with increased numbers of people in cities and the rise of megacities, there will inevitably be more and more congestion and pollution,” Botti said. “And if you look at where the most polluted part of the city is, in general it’s around the airport; I’m not only talking about CO2 and NOx here, but also about noise pollution. It has to be better to take off and land with very quiet electric engines.” He added that aircraft could arrive and depart later at night and in the early hours without disturbing the neighbours.
As this implies, these electric airliners are likely to be hybrids, with an on-board generator charging the batteries and feeding the motors. This also allows the option of charging the batteries via ‘windmilling’ the propellers when the aircraft is slowing down; precisely analogous to recovering energy during braking in a hybrid car. “This does mean that you emit greenhouse gases when the aircraft is in cruise,” Botti admitted, “but certainly no more than a standard aircraft does; with windmilling, probably less.”
In formal terms, E-Thrust and its family won’t even be Airbus products; the company has created a new subsidiary called Voltair to commercialise the technology; symbolic of the clean break it represents from its more-established turbojet-powered aircraft families. “We didn’t want to mix the message,” Botti said. Voltair operates out of new premises in Toulouse: “When I created the plant that will make E-Fan, I had the objective that young engineers will start up and become the experts that we need in the future to make larger electric aircraft; that’s knowledge that currently doesn’t exist,” he added. Technology development is looking at new batteries and motors using high-temperature superconductors; Botti even mentioned the possibility of nuclear fusion to power such aircraft. “We are not looking at next year or even next decade with this project, and we want to keep such possibilities in mind, even if they seem very far-fetched now,” he said.