Anxious to assure us it is not entirely anchored in the now by Airbus, EADS at Paris unveiled a distributed hybrid-electric propulsion concept it is working on with engine manufacturer Rolls-Royce. The idea is similar to the turboelectric distributed propulsion (TeDP) work under way at NASA. EADS Innovation Works has incorporated the initial E-Thrust distributed propulsion configuration into its eConcept vision for a 2050-timeframe airliner.
Concepts: EADS Innovation Works
The EADS IW concept uses a single large turbine engine to generate electricity to power six ducted fans that provide thrust. This allows propulsive and thermal efficiency to be optimized separately. The turbine engine can be optimized for thermal efficiency (turning fuel into shaft power) while the ducted fans increase effective bypass ratio and therefore propulsion efficient (turning shaft power into thrust).
The single turbine engine is embedded in the tail so that it ingests the fuselage boundary layer and re-energizes the wake to reduce drag. It has a long exhaust duct to minimize noise and allow for particle filtration. The electric fans have a combined bypass ratio exceeding 20:1 (more than twice today’s engines) and are integrated into the wing to reduce drag and noise.
As with NASA’s TeDP, superconductivity is key to the concept. The turbine engine drives a hub-mounted superconducting motor. Power is extracted, and cryogenic coolant is circulated through the motor, via structural stator vanes behind the fan that recover thrust from the swirling air.
EADS’s concept includes advanced lithium-air batteries for energy storage. For take-off and climb, the turbine and batteries power the ducted fans. In the cruise, the turbine powers the fans and recharges the batteries. During the gliding descent, the windmilling fans generate regenerative power to top up the batteries. On landing, the turbine powers the fans. At all times, the batteries have sufficient energy to power the aircraft if the turbine fails.
EADS IW, with Rolls-Royce and Cranfield University, is working on the Distributed Electrical Aerospace Propulsion (DEAP) project funded by the UK Technology Strategy Board. Rolls and EADS IW also are working with Magnifye and Cambridge University on a programmable alternating-current superconducting machine – described as a powerful, lighter and lower-loss design incorporating high-temperature superconducting coils embedded in a lightweight epoxy structure.