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The EU-funded MAHEPA project is developing prototype planes using electric motors and modular power-generation systems. The light aircraft, designed to carry four passengers, is an important step towards potentially larger and longer-range commercial planes that run on alternative fuels or hydrogen with zero emissions. The first test flights will be conducted in 2020.
Although unlikely to compete with long-haul passenger planes soon, hybrid electric aircraft could revolutionise local and regional flights. This could dramatically reduce the environmental and noise impact of aviation.
“Hybrid-electric propulsion will change the way we travel,” says project coordinating partner Ivo Boscarol, CEO of Pipistrel Vertical Solutions, Slovenia. “We are contributing to the development of two different four-passenger aircraft which will be thoroughly tested in flight. This alone is a historic milestone, but with the envisioned scalability of hybrid electric propulsion technology we will soon see much larger environmentally friendly aircraft capable of flying 19 or more passengers across practical distances.”
Emission-free
A ‘power train’ is the mechanism that transmits the drive from the engine of a vehicle to its axle. MAHEPA uses a modular approach to develop the power-train components, making it easier to employ them in various types of aircraft. They will be flight tested on two different planes. Both aircraft will use the same 200-kilowatt electric motors, inverters, batteries and control modules designed to provide the optimum use of energy. However, one of the aircraft’s batteries will be charged by a generator driven by a conventional internal combustion engine, while the other prototype will be powered with hydrogen fuel cells.
“By using hydrogen produced from water electrolysis powered by wind and solar energy, emission-free air transportation can truly become a reality,” says Josef Kallo, coordinator of energy system integration at the German Aerospace Center, a project partner.
Scaling to larger passenger aircraft
The modular system should be scalable to larger aircraft designs. For example, the team envisages the same components being used to power a regional aircraft with five or more motors on each wing.
“We are taking a very pragmatic approach with an extensive flight-testing programme to validate all components and systems. Data will be analysed to extrapolate trends in emission reduction on short to medium-distance routes,” says project manager Igor Perkon of Pipistrel.
The team is using new materials to enhance power density and power transmission efficiency. They are also conducting simulations to test the feasibility of megawatt-scale power trains needed for larger commercial aircraft. Designing prototype hybrid electric power trains and testing their reliability in flight will require significant advances in systems integration and engineering, particularly to meet stringent aviation safety standards.
The project will therefore evaluate the regulatory implications, airport infrastructure requirements and operational safety of the aircraft. MAHEPA will also look at the operating costs for the aviation industry and environmental advantages over the longer term.
“We believe that the sky is the ultimate frontier, where good engineering is evaluated in terms of safety and robustness,” says Perkon. “The unique approach of MAHEPA is to combine and extrapolate real testing data to different future scenarios to model the environmental benefits of a hybrid electric fleet.”.