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Rolls-Royce’s all-electric ‘Spirit of Innovation’ completes taxi testing

Rolls-Royce has successfully completed the taxiing of its ‘Spirit of Innovation’ aircraft, the latest milestone on its way to becoming the world’s fastest all-electric plane. (Earlier post.) The plane is part of a Rolls-Royce initiative called ACCEL, short for “Accelerating the Electrification of Flight”. The ACCEL project team includes key partners YASA, the electric motor and controller manufacturer, and aviation start-up Electroflight.


For the first time, the plane powered along a runway propelled by its 500 hp (400 kW) electric powertrain and the latest energy storage technology developed to set world speed records and enable a new generation of urban air mobility concepts.

The taxiing of the plane is a critical test of the integration of the aircraft’s propulsion system, ahead of actual flight-testing. The first flight is planned for the Spring and when at full power the combination of electrical powertrain and advanced battery system will power the aircraft to more than 300 mph, setting a new world speed record for electric flight.


Half of the project’s funding is provided by the Aerospace Technology Institute (ATI), in partnership with the Department for Business, Energy & Industrial Strategy and Innovate UK.

The characteristics that air-taxis require from batteries are very similar to what is being developed for the ‘Spirit of Innovation’ so that it can reach record-breaking speeds. Rolls-Royce will be using the technology from the ACCEL project and applying it to products for the market.



I don't get this design at all.  The long tail and huge empennage are something you'd put on an aircraft which needs a lot of control authority, such as a twin-engine which has to deal with asymmetric thrust.  There's no such requirement here, as it's single-engine; the excess area just creates parasite drag.

What gives?

A Facebook User

I think the wide angle lens grossly distorts the appearance. The Rolls ACCEL site links to Flicker for more pictures which may allay your concerns.


More space for the sponsor’s logos. ;-)


Neat! One really cool thing about electric drive and aviation speed records is the fact that there is no "lapse rate" or loss of HP at altitude. Nearly forever, aircraft engine designers have used various methods (turbocharging, supercharging, flat rating and sandbagging) to achieve adequate HP at high altitudes.

The fact that Electric aircraft can operate at altitudes, such as 50,000 feet and up with no loss in power is likely to result in some interesting records being broken.

However, as with all aviation speed records, it's almost impossible to overcome the usefulness of massive amounts of combustion heat, which make very high engine discharge velocities a reality. (remember the speed of sound increases with temperature and any engine's discharge velocity (prop or jet) is limited by the speed of sound.


The top image doesn't show significant distortions characteristic of a wide-angle lens (curvature of straight lines) and the bottom image definitely doesn't have any, as shown by the vertical lines of the background remaining vertical from left to right.

There's also the issue of what looks like too much ground clearance for the prop.  Why not use a bigger prop turning slower to get a higher Froude efficiency?  I'd expect optimizations like that in a speed-record aircraft.


The real news here is a seriously large aircraft engine maker is looking at electric motors, albeit small motors as yet. Nevertheless RR is spending money on electricity solutions and development will follow.

Account Deleted

To get a proper perspective of this aircraft look at the blueprint on https://www.rolls-royce.com/innovation/accel.aspx#motors. The tail assembly does not appear to be large in proportion to the overall aircraft design.
As far as propeller size, Rolls Royce probably knows a lot more about airfoil design than most of us. Also, you could look at one of the fastest propeller aircraft of all time, the Focke Wulf Ta 152 H-1 which had a top speed of 472 mph with GM-1 Nitrous Oxide injection for use at high altitude. The nitrous TA 152 H-1 has a 3 blade, relatively small propeller.

Account Deleted

According to Wikipedia, the Rolls Royce "Spirit of Innovation" is based on the Sharp Nemesis NXT aircraft and uses HARTZELL 3 blade propellers. The Sharp Nemesis kit based, all composite aircraft is capable of speeds in excess of 400 mph.

James Bruce

There are thermal limitations to all powerplants at altitude because as air gets thinner (less dense) it offers less cooling capacity. Even though it is generally colder at altitude, that is more than offset by the lower density. Many turbocharged engines require special cooling arrangements to cope.

In addition the airfoils on the wing and propeller must travel faster through the less dense air in order o generate the same lift.

I'd say one of the biggest problems is that as batteries discharge their weight does not change but as you burn fuel the aircraft gets lighter. About 20% of our 1957 Bonanza's weight was the 6 gallons of fuel we carried.

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