Rolls-Royce ACCEL

The Rolls-Royce ACCEL (Accelerating the Electrification of Flight) is an electric aircraft demonstrator developed by Rolls-Royce plc.

Development
Rolls-Royce developed the ACCEL as a racing aircraft to gain the all-electric air speed record, targeting over 260 kn. The existing electric aircraft record at that time was 182 kn, set in 2017 by a Siemens powered Extra 330.

Designed at Gloucestershire Airport, the project is partly funded by the UK government and involves partners such as electric motor and controller manufacturer YASA Limited and aviation start-up Electroflight.

The team aimed to reach the 1931 Schneider Trophy speed, which was won by a R-R-powered Supermarine S.6B, reaching 298 kn.

On 15 September 2021, Rolls-Royce announced the aircraft, named Spirit of Innovation, had successfully completed its first flight, flying from MoD Boscombe Down for fifteen minutes. It subsequently reached a top speed of 336 kn, and sustained 300 kn over 3 km, 287 kn over 15 km, and was able to climb to 3000 m in 3min 22s. The speeds achieved were accepted as world records for electric aircraft by the Fédération Aéronautique Internationale in January 2022.

Design
The 7.3 m span aircraft is powered by three axial flux motors with a high power density driving a single three-blade propeller spinning at 2,400 RPM, designed and manufactured by YASA. The 750 volt, 216 kWh battery has 6,480 cells, with cork insulation and active cooling. Battery output power will be 500 hp continuous, reaching 750 kW at maximum power.. It is designed to have the highest energy density for an aircraft, and should allow a 170 nmi range.

The aircraft is derived from the carbon fibre Sharp Nemesis NXT racer, which has a cruising speed of 282 kn with a 350 hp piston engine, but can reach 355 kn with a highly tuned engine. The maximum take-off weight of the NXT is 1,200 kg. Rolls-Royce intend the battery, motors and control equipment in a production system to weigh the same as the regular engine and fuel tank in a conventional aircraft, but the battery pack alone in the Spirit of Innovation currently weighs 1350 kg.