Airbus announced in November that it had joined forces with Rolls-Royce and Siemens to develop a near-term flight demonstrator — dubbed the E-Fan X — that will significantly advance the use of hybrid-electric propulsion in commercial aircraft. The E-Fan X is a flight demonstrator on the scale of a commuter jet that will see the replacement of one of the engines with an electric motor driven by an integrated gas turbine-generator in the fuselage.
It is, however, only the latest in a long line of electric flight demonstrators, starting with the Cri-Cri, that most recently included the E-Fan family of light training aircraft that Airbus has been developing since 2010. Watch our electrification achievements since 2010 in the below video:
The roots of the E-Fan X project lie in 2010 when Airbus sponsored an electric variant of the Colomban Cri-Cri, a small, French home built aeroplane. Its two, single-piston, 15hp engines were replaced with four MGM Compro units twirling contra-rotating propellers and producing 60hp.
With less than 30 minutes of endurance, it had limited utility but it was an important proof of what is possible and the beginning of our electric flight journey.
The Cri-Cri was followed by a record-setting, long-endurance flight of an electric motor glider called the e-Genius, which was able to cover a distance of 400 km in 2.5 hours.
By 2013, the next step was to move from a battery-powered, all-electric airplane that was inherently limited by the energy density of batteries to a hybrid-electric architecture that — much like a Toyota Prius — still relied on the combustion energy of hydrocarbon fuel but combined it with the flexibility of an electric propulsion system.
Together with Siemens, we flew the first-ever serial hybrid airplane — the E-Star. It had a 30kW internal combustion engine running at constant speed and a 70kW electric motor powering the propeller.
It highlighted one of the key advantages of a hybrid-electric architecture — the ability to downsize the power generation capacity for cruise flight while augmenting it with stored electrical energy for takeoff and climb.
The E-Star was followed by the E-Star 2, which introduced an integrated drive system, significantly improving the power-to-weight ratio of the hybrid-electric propulsion system.
Then came the E-Fan 1.x series; the E-Fan 1.0 and 1.1 further improved the efficiency of electric flight with a purpose-built aircraft that successfully flew across the English Channel in 2016 on the anniversary of Louis Bleriot’s historic first crossing. Airbus also exhibited at Oshkosh the E-Fan 1.2, a series hybrid variant with a single motor-generator powering two electric fans.
In 2016, Airbus’ partner Siemens had an aircraft that had nearly 10X the power level of all its predecessors. Called the Extra 330LE, it is a high-performance aerobatic airplane, which has been modified to fly with an electric motor delivering 260kW of power (348 hp) in a 50 kg package — a 5X improvement in power density over previous generations of motors. In December 2016, it set a world record for fastest-climbing airplane in its class.
Electric Aircraft Systems House
Airbus and Siemens have partnered on a ground test facility in Munich called the Electric Aircraft Systems House (EAS House). It is our primary development laboratory for electric propulsion technology and is able to test power systems in excess of 20MW. It is where we are developing the power system behind CityAirbus — our much larger, four-seat, all-electric VTOL aircraft that is core to our Urban Air Mobility strategy. We anticipate a first flight to take place next year.
The steep upward technology curve in electrical power systems is nothing short of extraordinary — a few years ago, the state-of-the-art in flight-weight components was in the tens of kW, today it is in the hundreds of kW. We believe that with a strong push, we could demo a 2MW flight-weight hybrid-electric power system in about three years.
Called the E-Fan X, this flight demonstrator on the scale of a commuter jet will see one of the engines replaced by an electric motor driven by an integrated turbine-generator in the fuselage — a serial hybrid architecture. We have picked on 2MW because we see this is at the upper limit of what’s attainable with more-or-less conventional power distribution technology — without having to master superconductivity or other exotic approaches.
We see it as a logical demonstrator to retire some of the integration risks associated with a serial hybrid architecture at this scale. Integration risks such as thermal management; electromagnetic interference; arcing; partial discharge, and radiation effects on high-power electrical systems at altitude.
The ultimate goal is to enable a hybrid-electric propulsion architecture for a single-aisle aircraft — at the scale of the A320 family. This takes us into the range of around 20MW for cruise and 40MW of max power. So another order of magnitude over the E-Fan X.
If you would like to help us solve these issues and build a more environmentally sound future for the way we fly, then why not get in touch with us.