Electric aviation company Ampaire has accomplished the longest flight to date for any commercial aircraft employing electric propulsion, in this case a hybrid-electric propulsion system. The Electric EEL, a six-seat Cessna 337 twin-engine aircraft modified with an electric motor in the nose and traditional combustion engine in the rear, took off from Camarillo Airport just north of Los Angeles and test pilot Justin Gillen and flight test engineer Russel Newman flew up California's Central Valley before landing at Hayward Executive airport. The straight line distance was 292 statute miles, and the route as flown was 341 statute miles.

Speed during the cruise portion of the two hour, 32-minute flight averaged around 135 mph. “The mission was a quite normal cross-country flight that we could imagine electrified aircraft making every day just a few years from now,” Gillen says.

This milestone in electric aviation took place after four weeks of flight testing in the Camarillo area for this second Electric EEL test aircraft, which first flew on 10 September. In that period, the aircraft flew over 30 hours during 23 flights in 28 days, with 100 per cent dispatch reliability. “Our success in taking this aircraft in a short period from the test environment to the normal, everyday operating environment is a testament to our development and test organisation, and to the systems maturity we have achieved with our second aircraft,” comments Ampaire general manager Doug Shane. “The ability to put innovative electric technologies into the air rapidly in order to assess and refine them is central to Ampaire's strategy to introduce low-emissions aircraft for regional airlines and charter operators within just a few years.”

The EEL flown to Hayward is dubbed the Hawaii Bird as it will take part later this year in a series of demonstration flights with Hawaii-based Mokulele Airlines on its short-haul routes. The flight trials with Mokulele will not only demonstrate the capabilities of the EEL but will help to define the infrastructure required for wide adoption of electric aviation by airlines and airports.

The EEL can generate fuel and emissions savings up to 50 per cent on shorter regional routes where the aircraft's electrical propulsion unit can be run at high power settings, and generate savings of about 30 per cent on longer regional routes such as the Camarillo to Hayward flight.

“The Electric EEL is our first step in pioneering new electric aircraft designs,” states Ampaire CEO Kevin Noertker. “Our next step will likely be a 19-seat hybrid electric retrofit programme that will lower emissions and operating costs, benefiting regional carriers, their passengers and their communities.”

Ampaire, with funding from NASA and others, is in the midst of design studies for such an aircraft based on the popular de Havilland Twin Otter aircraft. Ampaire has named the hybrid-electric 19-seater aircraft the Eco Otter SX.