Electric aircraft company Ampaire has flown its hybrid-electric powered Cessna 337 Skymaster on what it calls an “actual airline route”, between two of Hawaii’s islands.
On 22 November, the company flew the modified aircraft, which it calls the Electric EEL, round trip from Kahului to Hana, both on Maui.
Kahului and Hana are about 24nm (45km) apart, making for one-way flights lasting about 20min, the company says.
The Electric EEL completed the round trip on a single charge of the aircraft’s batteries, it says.
Los Angeles-based Ampaire is among several companies working to equip existing small aircraft with electric-propulsion systems. Other projects have outfitted a Grand Caravan and de Havilland DHC-2 Beaver with electric propulsion.
Ampaire says the Kahului-Hana flight makes it the first company “to complete a demonstration flight of a hybrid-electric aircraft along an actual airline route”.
Ampaire is performing demonstration flights in Hawaii via a partnership with local intra-island carrier Mokulele Airlines.
It expects to fly the EEL on the Kahului-Hana route “regularly” as part of a “one-month demonstration programme” with Mokulele.
Ampaire has authority to fly the EEL with “crew and essential personnel” under an FAA experimental certification, it adds.
Kevin Noertker, Ampaire chief executive, says the flights will demonstrate the “robustness of Ampaire’s technology” and aid development of future related projects involving larger aircraft.
Cessna 337s typically have two piston engines – one driving a forward-facing prop, the other driving a pusher prop. For the EEL, Ampaire replaced the six-seat aircraft’s forward engine with an electric system “capable” of producing 119hp (160kW), it says.
The aircraft carries a battery pack in an “under-fuselage aero-optimised shell”, and the forward piston engine produces 300hp.
That configuration provides a 40-50% reduction in fuel consumption, says Ampaire.
Mokulele has signed a “letter of interest” to acquire aircraft from Ampaire, and the EEL project has support from Mokulele parent Southern Airways.
“We expect to put hybrid and all-electric designs into service as soon as possible”, says Southern chief executive Stan Little.