Aviation News Item: 07049

6th Apr 2010

Source: flightglobal.com

Making general aviation more environmentally friendly has in the past had an alternate fuels focus, but as batteries improve, all-electric aircraft are emerging in Europe. From Lange Aviation's Antares 20E in 2005 to this year's new entrant, the PC-Aero Elektra One, there is a growing European challenge to the likes of China's Yuneec and its E430 model that already has a sales office in the UK. But which is more likely to hold back worldwide industry for the electrification of private flight: technology or its regulation?

This week German company PC-Aero will unveil its battery-powered Elektra One at the Aero Friedrichshafen air show with the goal of having it fly by June and go on sale later this year. The single-pilot Elektra One follows Chinese company's Yuneec battery-powered E430 two-seater light sport aircraft, which flew in California last year.

As an all-battery electric two-seater that has already flown, it is a de facto market leader that Europeans need to challenge. According to Yuneec the E430 uses three lithium polymer (li-poly) battery packs to fly for 2h in an "optimum cruise" with two people on board. By increasing the battery packs to five, a single pilot can get 3h of flying time. Presented at Oshkosh last year, Yuneec's first prototype E430 undertook 22h of flying in Camarillo, California to be awarded its experimental certificate by the US Federal Aviation Administration so it could be demonstrated at the air show. Today Yuneec is aiming to sell its E430 from mid-2011.

CERTIFICATION CHALLENGES
Flight Design's approach is to minimise the challenges for certification as much as possible. The company also sees the use of an electric propulsion system alongside an internal combustion engine as a route to an all-electric tomorrow. Reinhardt says: "It will significantly support future development of all-electric aircraft propulsion."

Fuel cells have been the future power technology for some time. The technology's theoretical energy density - more energy in the same volume - is far greater than that of today's batteries, but difficulties such as in-flight hydrogen fuel storage are still holding back a fuel cell-powered product.

Instead governments and large corporations have investigated the technology for auxiliary power units and unmanned air vehicles and 2008 saw two different projects fly. The German aerospace centre DLR worked with Lange on the Antares DLR-H2. The Lange Aviation Antares motor glider was the basis for the DLR-H2 aircraft that was used to test a fuel cell system provided by the DLR's Institute of Technical Thermodynamics. It was developed to test fuel cell technology for possible future APUs on board Airbus airliners. The DLR now intends to operate its Antares DLR-H2 for research purposes until 2017.

But Lange's chief executive Axel Lange is does not intend to take that experience and offer a fuel cell or battery-powered manned aircraft. Instead he is working on a fuel cell-powered UAV technology demonstrator with an undisclosed partner. The UAV, called H3, will be optionally manned to enable safe test flights and could pave the way for H4, a long-endurance fuel cell-powered UAV being planned by Lange. As for the prospects for battery-powered flight, Lange says: "When battery energy density doubles then I will be interested."

In March 2008, Boeing Research and Technology Europe flew a fuel cell-powered modified Dimona motor-glider for 20min at its Spanish test site. The US company ended the project after that flight and would only say that the fuel cell technology would be used for other unidentified projects. Last month Boeing announced it would work with a Japanese company on fuel cell APUs for 2016.

But in Europe fuel cell manned flight work has carried on. In June 2009 a modified Alpi Aviation Pioneer 300 ultralight powered with batteries made a successful flight, reaching a speed of 135kt (250km/h). Called Skyspark, the team behind it is planning a flight for 2011 to demonstrate take-off and cruise using only fuel cell power. The aircraft's development is supported through donations of equipment and people's free time. "We are looking for sponsors and are working on establishing some research projects," says the Skyspark project's leader, aeronautical engineer and former European Space Agency astronaut Maurizio Cheli.

How confident is an independent expert like Seeley that the technology and certification hurdles will be overcome for a new world of electric flight in this decade? "I am extremely confident, 99% or more, that in 10 years electric general aviation aircraft will be flying." And Lange might want to rethink his attitude towards manned electric flight. "At our conference this April a Dr Jaephil Cho from South Korea is promising an eightfold increase in [battery] energy density."

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