On September 12, Europe’s EADS unexpectedly assigned a schedule and a market segment to its “E-Thrust” hybrid propulsion concept, which was revealed at the Paris Air Show this year with Rolls-Royce. The “E-Airbus,” under its new moniker, is to enter into service in 2030 as a regional aircraft, probably a 70- to 100-seater. The announcement came during a conference organized by the French government in Paris about its industrial policy.
According to EADS chief technology officer Jean Botti, who introduced the project, the E-Airbus will have six electric fans. One gas power unit (in short, a gas turbine connected to a generator) will provide the electric power for the six fans and for the recharging of the energy storage. During part of the descent phase, the fans will windmill and produce electricity.
The serial hybrid architecture offers the possibility to improve overall efficiency by allowing the separate optimization of the thermal efficiency of the gas power unit (producing electrical power) and the propulsive efficiency of the fans (producing thrust). The hybrid concept makes it possible to downsize the gas power unit and to optimize it for cruise. The electric energy storage will provide the additional power required for takeoff.
The bypass ratio (or its equivalent number for such a distributed propulsion system) is expected to be greater than 20. Among the hoped-for enabling technologies are lithium-air batteries as well as superconducting cables, generators and motors. A dedicated fan, driven by the gas turbine, will re-energize the wake, thus reducing drag.
Botti referred to Europe’s Flightpath 2050 goals of a 75-percent reduction in CO2 emissions, 90 percent in NOx emissions and 65 percent in noise, compared to 2000 levels, without clarifying where the E-Airbus would position itself in 2030.
As a stepping stone to a larger aircraft, EADS is developing the E-Fan technology demonstrator of an electric two-seat GA training aircraft. Another unexpected announcement was that EADS is planning to build a factory in Bordeaux to manufacture “hundreds” of E-Fans, Botti said.
Separately, the European group has a continuing partnership with Siemens and Diamond Aircraft on serial hybrid propulsion. In June the three companies flew a DA36 E-Star 2 motor-glider, the propeller of which was driven by an electric motor. The batteries were recharged in flight via a small Wankel-type rotary engine.