EADS, Siemens Plot Way To Hybrid-Electric Propulsion

By Graham Warwick
Source: Aviation Week & Space Technology

The E-Star 2 also is a step closer to a marketable product. Its serial-hybrid drivetrain has a lighter, more compact electric motor from Siemens, a generator driven by a small Wankel from Austro Engine and EADS IW-prepared battery packs in the wings. Aircraft empty weight is reduced by about 100 kg (220 lb.). The motor weighs 13 kg including gearbox and control electronics, and runs off the generator, producing a continuous 65 kw. This is boosted by the batteries to 80 kw for takeoff and climb. The combustion engine runs at a constant 30 kw to generate power and recharge the batteries. Siemens believes series hybrid power will make its way soon into small aircraft and is scalable to commercial aircraft with 50-100 seats, reducing emissions 25%.

The PowerLab project, meanwhile, is targeting development of electric generators and motors with power densities of 10 kw per kilogram—twice that of the motor in the E-Star 2. Such a density would make a megawatt-class power system “quite reasonable to fly, and is not too far away,” says Jankers. Begun this summer, the PowerLab project is looking at how to generate, convert, distribute, buffer and store electrical power as well as design safety into the system and integrate two distinct types of electrical machine: fast-running, high-efficiency generators and low-rpm, high-torque motors.

The project will involve detail design studies and laboratory demonstrations of electrical propulsion, with the goal of “building a foundation for electric flight,” Jankers says, by creating a community centered on the Boelkow campus with expertise in aircraft hybrid propulsion. Although the technology is targeted at hybrid power, PowerLab is focused on the electric part, particularly how to use and manage battery cells and electrical machines “in a more intelligent way,” and understand their limits and how to protect the system.

“We need to understand the technology, and see where the gaps are,” he says.

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