Rolls-Royce has issued a new update on its project to develop a high-performance electric aircraft, capable of flying at speeds in excess of 300mph (480km/h). First flight is targeted for 2020.

The project is part of an initiative called ACCEL – short for “Accelerating the Electrification of Flight”. ACCEL is partly funded by the UK government and involves several partners including electric motor and controller manufacturer YASA and the aviation start-up Electroflight.

According to Rolls-Royce, the aircraft will feature the most energy-dense battery pack ever assembled for an aircraft, providing enough power to fly 200 miles (London to Paris) on a single charge. Its 6,000 cells will be packaged for maximum lightness and thermal protection. An advanced cooling system can withstand the extreme temperatures and high-current demands during flight.

The propeller is  driven by three high power density electric motors designed and manufactured by YASA in the UK. Compared to a conventional plane, the propeller blades spin at a far lower RPM to deliver a more stable and quieter ride. Combined, they will be designed to continuously deliver more than 500 horsepower.

The all-electric powertrain will be designed to run at 750 volts, delivering 90% energy efficiency with zero emissions. Sensors will collect in-flight information each second across more than 20,000 points on the powertrain, measuring battery voltage, temperature and general performance metrics.

Rolls-Royce is already exploring hybrid-electric propulsion – using a gas turbine engine as a generator to power an electric fan – for regional commercial aircraft through the E-Fan X demonstrator programme with Airbus and Siemens, announced in November 2017.