Two French companies, The EADS Group and Aero Composites Saintonge (ACS), have collaborated to create the E-Fan, a fully electric, general aviation training aircraft made from composites. It’s part of an initiative by aerospace company EADS to develop technologies that reduce aircraft carbon dioxide emissions.
Three years ago, EADS and ACS unveiled the first all-electric aerobatic plane and smallest manned aircraft with four engines. The plane took part in numerous performance flight tests where engineers gathered information on energy recovery and variable pitch propellers, which allow pilots to change the blade pitch during operation. This research became the catalyst for the E-Fan project.
Unlike most electric planes, which mimic conventionally-powered crafts, the E-Fan design was engineered from the ground up. “I designed the original structure of the aircraft from scratch and did the first calculations before approaching EADS and ACS’ owners,” says Didier Esteyne, technical director at ACS.
EADS was responsible for the electrical system, while ACS designed and built the rest of the aircraft, which can fly a maximum of 137 mph. “The lowest possible airframe weight is of critical importance for an all-electric aircraft,” says Esteyne. “And using carbon fiber composites was an obvious choice because of its better strength-to-weight ratio compared to aluminum alloys.” The entire fuselage, including the fin and empennage, as well as the wings and main spar were made from composites. The E-Fan has a 31-foot wingspan and a maximum weight of 1,212 pounds, fitting inside the light sports aircraft (LSA) weight parameters.
The two-seat E-Fan was created for short training missions such as basic pilot training, glider towing and aerobatics. The E-Fan’s fully electric propulsion system features two electric motors with a combined power of 60 kilowatts, each driving a ducted, variable pitch fan. Since the engines are located near the center line of the aircraft, the E-Fan is easily controlled during single-engine flights. This propulsion system eliminates carbon dioxide or nitrous oxide emissions during flights, reduces the engines’ noise levels and reduces vibrations compared to aircraft powered by combustion engines.
Powered by multi-cell lithium ion polymer batteries, the E-Fan aircraft can fly for one hour before recharging. EADS expects to upgrade to batteries with higher energy density down the line, increasing flight time to one hour and 30 minutes.
The E-Fan’s landing gear is another innovative feature of this aircraft. It consists of two electrically-actuated retractable wheels – one in the front and one near the rear under the fuselage – plus two small wheels under the wings. The rear main wheel is driven by a six kilowatt electric motor providing power to accelerate up to 68 mph during take-off, which reduces the electrical power consumption in daily flight operations.
The French Directorate General for Civil Aviation, along with regional government institutions in southwest France, are financing the E-Fan project through the European Regional Development Fund.
The E-Fan’s first flight will take place this fall. The next step is commercialization and certification so aerospace training facilities can use the E-Fan, according to EADS. The company expects this to take three years, as current certification rules don’t cover electric propulsion.