Rolls-Royce is spooling up its electric aviation division. Launched in January, Rolls-Royce Electrical now employs 450, is looking to hire another 150 by year’s end, and is focused on three main projects: the Vertical Aerospace VX4 UAM, the Embraer Eve UAM, and the Tecnam P-Volt P2010 commuter fixed-wing aircraft, according to Matheu Parr, Rolls-Royce Electrical’s customer director.
While the division is focused on those three projects, Rolls-Royce (Booth X93) has experience with electric aircraft dating back to 2013 across ten different platforms and 1,500 flights, in addition to testing motors on test beds for the equivalent of more than 200,000 kW hours, said Parr. He also noted the company’s experience with regard to electrification in power systems, marine, rail, and defense. “We’ve been looking at embedded generators for a while.”
Parr thinks electric propulsion and aviation are a natural mix. “Electric aviation is incredibly exciting, but the solution is only about 10 percent electrical engineering and the other 90 percent is the sort of thing aviation is good at: thermals, stress, materials, safety, and certification.” But it also presents an opportunity to benefit from the Herculean spade work already done on electric vehicles by the automotive industry and with it, the chance to graft appropriate manufacturing and assembly techniques from that business onto aviation, he said.
“The automotive investment into electrification gives us a fantastic basis from which to start, but we're seeing that the challenges of aerospace are taking us beyond the established manufacturing techniques. We are pursuing new opportunities which, from a supply chain perspective, means that we are engaging quite widely with suppliers to which we haven’t historically spoken and it’s opening a lot of new relationships in the aerospace market,” Parr said.
Parr said Rolls-Royce's focus has changed over the last year, from trying to adapt its long-selling M250 turboshaft engine into an electrical generator in a hybrid system to developing a complete suite of new electric aviation technologies. “We’ve seen a shift from customers in the past couple of years. When we talk to customers now, it’s not a conversation about emission reduction anymore. It's a conversation about zero emissions."
While Rolls-Royce gained valuable insight regarding the detailed engineering related to developing an existing gas turbine into a hybrid system, the M250 was not the optimal engine for the job as it has its design roots in the 1960s. “We actually made the decision last year to halt the M250 hybrid program at the critical design review level and instead tasked the team on development of a clean sheet gas turbine,” a turbogenerator, he said. After taking that leap, it was just a matter of logical extension to pursue the technologies that went along with it including electric motors, power electronics, controls, power distribution, and energy storage—the batteries.
“We looked at regional ability, when people want to start moving further than 150 nm. A turbogenerator gives you that option. You can still use the same front-end electric propulsion system, but it draws from a different energy source. Starting with a clean sheet design means we can focus on cost and [energy] density and really bring something special to the market,” Parr said. “Battery cells alone do not have enough energy density. You can’t enable 200 to 500 nm missions on the [electric] energy storage systems today. A turbogenerator in a hybrid system enables you to travel a longer range and you can of course use sustainable aviation fuel to power that system.”
At this juncture, Rolls-Royce plans to have its electric motors, power electronics, control, and electrical distribution system flying in Vertical Aerospace’s VX4 by 2024. It will do the entire electrical propulsion system on the Tecnam P-Volt that will enter service shortly thereafter. But Parr says working on these comparatively smaller aircraft is a warm-up act for the electrification of single-aisle, narrow-body airliners, a market Rolls-Royce plans to enter in the coming decades.
“We've really been using the general aviation market as the testbed for this area,” Parr said, adding that he thinks the timeline for developing future electric airliners is likely “2030 plus.”
Meanwhile, Rolls-Royce will continue to explore the boundaries of electric aviation. Parr said the company is currently looking into “transverse flux” electric motor technology that provides a different and more efficient method of rotating the motors through electromagnetic fields. “It’s an architecture that has a great development road map going forward and enables us to improve power density of it over time. And with that comes some new manufacturing techniques that we need to explore.”