

Airbus has a vision of an electric-powered hybrid 80-90-seat regional airliner that will be available to the market in the 2030s.

With high-density energy storage in the wings, Airbus engineers foresee a new generation of highly efficient electric motors that can produce megawatts of output enabling an electric-powered airliner turboprop to be operated at the fraction of the cost of the current-generation ones.

At the same time, says Jean Botti, Airbus Group chief technical officer, the electric airliner could be more heavily utilized, allowing operators to fly around the clock and circumvent strict noise regulations increasingly being imposed around the world. The company also argues that as air travel demand grows, electric-powered low-emission flight may be one of the only ways to meet the European Union’s challenging Flightpath 2050 targets of reducing aviation carbon dioxide emissions by 75%, nitrous oxide emissions by 90% and noise levels by 65% from year-2000 levels.

Hybrid power, probably from a kerosene or biofuel generator, would help to recharge the batteries on the ground or inflight, lengthening endurance or reducing turnaround times at airports.

To produce Europe’s first wholly electric-powered aircraft the Airbus Group is partnering with French industry and entering the light aircraft market. A new subsidiary, VoltAir, will be set up in the coming months to develop and produce the two-seat E-Fan 2.0 and the four-seat E-Fan 4.0. The two models are being aimed at the general aviation market, and officials say prices will be competitive with those of current piston-engine light aircraft—around $300,000—but with operating costs that are less than a fraction of those aircraft, as well as potentially significantly lower maintenance costs.

Airbus hopes the project will be a stepping-stone in terms of knowledge, technologies and production processes for larger aircraft.

The Airbus Group has been researching electric-powered flight for the last decade and proactively demonstrating its progress. EADS’s Innovation Works and French general aviation company Aero Composites Saintonge (ACS) demonstrated an electric-powered version of the Cri-Cri twin-piston-engine light aircraft in 2010, and in 2011 Eurocopter demonstrated the use of an electric motor that could provide emergency power to a helicopter during autorotation.

Based on lessons learned with the Cri-Cri, the Airbus Group gave the go-ahead for development of a purpose-built electric aircraft demonstrator in October 2012. The E-Fan, formally unveiled in Bordeaux on April 25, is the first known aircraft to be developed from the ground up

as an electric-powered aircraft. Other aircraft were modified to be electrically powered. Like the Cri-Cri, the E-Fan was built by ACS, but with significant input from Safran, Zodiac Aerospace, Siemens and Daher-Socata.

Built entirely out of composites, the E-Fan demonstrator weighs 580 kg (1,280 lb.) and can seat two in a tandem configuration. A standard monoplane with a T-tail, the aircraft is fitted with two 30-kw electric motors that drive an eight-blade ducted fan,which engineers say boosts the levels of static thrust.

The E-Fan carries 127 kg of lithium-ion polymer batteries that deliver 250 volts and 100 amps of electrical power. The battery compartments, in the inboard section of the wings and away from the cockpit, are well vented and passively cool the batteries, a result of lessons from Boeing 787 Li-on battery problems. Cruising speed is around 86 kt. (160 kph). In the cockpit is a Garmin 1000 digital avionics suite and radio system. Landing gear consists of two pogo wheels on the wings, a main wheel and steerable nose gear. In an effort to save power, the E-Fan can be taxied to the runway using its motorized main wheel gear; once at the runway, the engines are simply switched on and takeoff power is quickly available to the pilot. The motorized wheel can also assist in the takeoff run, helping to accelerate the aircraft to 60 kph.

E-Fan test pilot and designer Didier Esteyne has flown 15 hr. of a 50-hr. flight-test program, with the longest flight so far lasting 37 min. Airbus wants to achieve endurance of 1 hr., plus 15 min. of reserve power to prove the potential of the machine as a training aircraft. However, this will not be possible with the current batteries. A more efficient battery solution, currently being worked on by E-Fan partners, is to be installed later. Company literature states that maximum endurance is currently 45 min.

According to engineers, among the greatest challenges has been working to deal with electromagnetic interference in systems such as the radios and dealing with the effects of vibration on aircraft wiring, despite the fact that the E-Fan enjoys significantly less impact from vibration than its piston-engine equivalent. Other elements of the project have included the development of an energy management system, dubbed the e-Fadec.

While some electric cars have been criticized for the time required to charge batteries, Esteyne says a specially designed charging unit developed for the E-Fan can deliver a full charge to its batteries in just 1.5 hr.

Development of the prototype E-Fan has been financed by Airbus, French civil aviation regulator the DGAC and a number of regional and European funds. The DGAC has been involved in the technical process, urging engineers to ensure that flight capabilities and parameters are similar to those of existing training aircraft to avoid completely new training requirements, although it is unclear what certification hurdles the aircraft might face from regulators before it enters production.

Current production plans call for the aircraft to be built in a new factory north of Bordeaux’s Merignac Airport (see article below) in a configuration similar to the E-Fan demonstrator, with a streamlined, non-retractable landing gear and the two motors fitted to the rear fuselage. Airbus hopes to achieve 95% parts commonality between the two aircraft, with the four-seat variant just 35 cm (14 in.) longer than the two-seat version.

Engineers are working on what they call a range extender, an optional system that would turn the aircraft into a hybrid, with a generator, described as similar to a lawn mower engine, to charge the onboard batteries. Engineers are hopeful the generator could raise the endurance of the four-seater to 3.5 hr. from 2 hr.

Airbus expects the facility at Bordeaux will have capacity to build as many as 80 E-Fan aircraft each year and believes the market is strong, particularly from training schools. While no contracts have been signed for the aircraft, the French national flying school, the L’Ecole Nationale de l’Aviation Civile (ENAC) in Toulouse has become a signatory to the project.

Botti points out that in France, some light aircraft flying is banned during certain times of the day to reduce environmental impact, but the electric aircraft’s noise levels would help avoid such a limitation.

The E-Fan 2.0 is expected to fly by the end of 2017, while the E-Fan 4.0 will follow two years later.