Gaining valuable experience with E-Fan

New E-Fan Plus updates mark progress on Airbus’ roadmap toward more electric airplanes with reduced emissions and quieter flight

In converting E-Fan to its new “Plus” hybrid configuration, Airbus has made changes to this demonstrator aircraft that go more than skin deep.

The E-Fan “Plus” configuration already has yielded many “lessons learned” for hybrid e-aircraft

The most visible modifications for E-Fan Plus are the installation of a thermal (internal combustion) engine as a flight range extender, along with the accompanying addition of two upper fuselage-mounted air intakes for its cooling airflow, and exhaust/ventilation outlets on each side of the aircraft.

By integrating this two-stroke thermal engine from German manufacturer SOLO Aircraft Engines, the flight time for E-Fan Plus will more than double – increasing to approximately 2 hours and 15 minutes, compared to one hour when making its historic all-electric crossing of the English Channel in July 2015. 

A transformation for E-Fan

The technical improvements to E-Fan "Plus" were publicly debuted at EAA AirVenture Oshkosh 2016

Less evident, but equally important, is the significant transformation of the electrical system aboard E-Fan Plus, performed under the guidance of Airbus Innovations – the Airbus’s corporate-level global research and technology network.

The aircraft’s voltage was increased from 270 V to a new level of 400 V, providing better electrical performance in powering E-Fan’s two electric propulsion motors, according to Denis Chapuis, who heads the Global Innovation Network for Electronics and Sensors in Airbus’s Corporate Technical Office. 

Accompanying the step-up in voltage was a redesign of E-Fan’s electrical architecture and the adaption of its power controllers. Additionally, a purpose-designed command and control computer was added to safely manage the aircraft’s transition within its different operating modes, using the power of its batteries and/or employing the thermal engine as a range extender.

Higher power with new batteries

E-Fan "Plus" takes off on one of its test flights in France

Another modification was the change-out of Panasonic lithium-ion batteries that equipped E-Fan for its English Channel crossing, replaced by lithium-ion batteries from LG that are 15 percent more powerful.  

E-Fan’s total battery weight of 168 kg. for the English Channel flight was reduced to 63 kg. in the “Plus” configuration to compensate for the thermal engine system’s installed weight, and a passive cooling system was introduced to provide better temperature management for the higher-intensity batteries.

“Start small, solve small”

E-Fan’s updates are key steps on Airbus’ e-aircraft roadmap

Valuable experience also was gained on electromagnetic interference (EMI) and electromagnetic compatibility (EMC) issues for electric propulsion systems aboard aircraft such as E-Fan, that are built with a significant percentage of composites – the materials of choice for new-generation airplanes.

“Evolving E-Fan to its Plus configuration presented a very complex integration challenge that yielded many ‘lessons learned’ at the system level, representing an essential step forward in Airbus’s electric aircraft roadmap,” Chapuis concluded. “Even if we are working with comparatively low power levels on E-Fan today, the transition to its hybrid arrangement is providing us with valuable experience for the future by using the ‘start small, solve small’ approach.”

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