Rolls-Royce is claiming three world records for its Spirit of Innovation technology demonstrator, which it says is now the world’s fastest all-electric aircraft. The aero engines group has submitted data to the Fédération Aéronautique International, seeking validation of records it says were set in flights this week at the UK Ministry of Defence’s Boscombe Down experimental aircraft testing site.
On November 16, the company says, the converted NXT Next kitplane reached a speed of 345.4 mph over a three-km distance, beating the previous top speed of just 132 mph set in 2017 by France’s Jean Luc Soullier in an Extra 330LE aircraft powered by an electric motor developed by Siemens. In subsequent flights, the Spirit of Innovation reached a speed of 330 mph over a 15-km distance, which was 182 mph faster than the previous record, and also set a new record for climbing to an altitude of 3,000 meters (9,843 feet) in 202 seconds (60 seconds faster than the existing record).
In one of the flights, Rolls-Royce says, the aircraft achieved a maximum speed of 387.4 mph, and it is on this basis that it is claiming the world’s-fastest-electric- aircraft record. By way of comparison, this is slightly higher than the top speeds of high-performance single-turboprop aircraft like Daher-Socata’s TBM 900 and Epic’ E1000 GX, both of which can reach around 380 mph.
The Spirit of Innovation was developed by the Accelerating the Electrification of Flight (ACCEL) team led by Rolls-Royce. The aircraft was converted to use a 400-kW (500+ hp) electric propulsion system developed jointly by the aero-engines group with battery specialist Electroflight and lightweight motor and controller manufacturer Yasa.
Rolls-Royce’s director of flight operations, Phill O’Dell, was at the controls for the initial record-breaking flight on November 16. Electroflight pilot Steve Jones flew the 15-km sortie and also set the claimed climb-to-3,000-meters record.
According to Electroflight, the aircraft’s battery pack is the most power-dense ever assembled with a rating of 72 kW/hr. The 1,200 cells are arranged in three parallel channels along with the aircraft’s three sets of motors and inverters in a thermally contained box lined with cork. At 450 kg, the box and its contents are lighter than most equivalent equipment for electric cars, the company said.
The Aerospace Technology Institute (ATI) provided half the funding for the ACCEL program, which is a partnership between the UK government’s Department for Business, Energy, and Industrial Strategy and industry group Innovate UK. The government is seeking to demonstrate its commitment to achieving zero carbon air transportation by 2050.
According to Rolls-Royce, the data harvested from the flight test program, which got underway in September, will be fed into plans to develop electric propulsion for new eVTOL and hybrid-electric regional fixed-wing aircraft. The company is a key supplier to the UK’s Vertical Aerospace for its four-passenger VA-X4 eVTOL design and is also working with Italy’s Tecnam to develop a nine-passenger commuter aircraft called the P-Volt.
“The advanced battery and propulsion technology developed for this program has exciting applications for the advanced air mobility market,” commented Rolls-Royce CEO Warren East. He said that the program is especially relevant in the context of the recent COP26 United Nations climate change conference and the UK government’s so-called "jet zero" objective of achieving net zero carbon air transportation by 2050.
Electroflight managing director Stjohn Youngman said his team intends to adapt its battery technology for other aerospace applications. Along with Yasa, the UK company has a background in the motorsports industry.