Ampaire Demonstrates Hybrid Bridge To Electrified Regional Flights

Ampaire’s Electric EEL taxis in at Kirkwall Airport on Orkney with its forward electric motor shut down.
Credit: Angus Batey / Aviation Week

ORKNEY, Scotland/WASHINGTON—Ampaire is relocating its hybrid-electric propulsion test aircraft to Exeter, England, after completing flight tests in Orkney, Scotland. 

The flight demonstrations are being conducted under projects funded by the UK government’s Future Flight Challenge.

The U.S. startup’s Electric EEL—a Cessna 337 Skymaster modified to parallel hybrid-electric propulsion—completed several flights on a representative regional airline route from Kirkwall Airport (KOI) on the island of Orkney to Wick John O’Groats Airport (WIC) some 40 mi. away on the Scottish mainland.

The flights involved the first operations over water for the testbed, which late last year completed a series of test flights on a regional airline route in Hawaii. The choice of Orkney to follow Hawaii was logical, Ampaire cofounder and CEO Kevin Noertker told Aviation Week.

“One of the real strong similarities we see is that, in these regions, aviation matters,” he said. “These are literally lifelines for communities. And what we see is a consistency in how people think about aviation and its importance to their local communities.”

Ampaire is part of a 13-member consortium involved in the Sustainable Aviation Test Environment (SATE) project led by Highlands and Islands Airports (HAIL), the state-funded operator of 11 remote Scottish airports. SATE will trial a range of alternatively fueled and piloted aviation technologies including drones and aircraft with low-carbon propulsion.

The project will provide partners with a dedicated test facility at Kirkwall Airport, including a hangar, apron and taxiway, as well as access to 100% renewably sourced electrical charging, green hydrogen and sustainable aviation fuels. Kirkwall offers an operational airport in uncontrolled Class G airspace with a network of island and mainland routes that can be flown.

While the modified Skymaster is not a representative commercial platform, the flights completed between Kirkwall and Wick demonstrated the viability of the hybrid-electric concept for current operations, said Justin Gillen, Ampaire’s test pilot.

“It’s about 20 min. of air time. We’d planned to do it four times a day—eight flights—and we can do that without significant recharging,” he said. Weather during the Orkney deployment, and voluntary company restrictions on flight operations, meant the aircraft was only able to fly on three days, but the team completed multiple flights each day that flying was possible.

The Electric EEL has the forward of its two centerline piston engines replaced with an electric motor, powered by batteries housed in a pannier under the fuselage. “In this configuration, the airplane uses roughly 30% less gas than the baseline Skymaster,” Gillen said. “The whole point is to demonstrate that we can operate this route more economically than the original airplane, using today’s technology.”

Hybrid propulsion avoids the need for battery-charging infrastructure at every airport served, at least initially. “In most of these regions, it’s challenging to get the right type of power, or enough power to charge the planes initially,” Noertker said. “If we required it all to be charged, with charging stations on the ground, then very few airports would actually be able to receive these planes in the near term.”

The Electric EEL is now planned to conduct a second series of UK demonstration flights between Exeter Airport (EXT) and Cornwall Airport Newquay (NQY) in Southwest England under the Ampaire-led Towards Zero Emissions in Regional Aircraft Operations (2ZERO) project. Like SATE, 2ZERO is supported by government funds via the UK Research and Innovation (UKRI) body.

UKRI is preparing the invite bids for Phase 3 of the Future Flight Challenge, which is supported by £125 million ($171 million) of government funding matched by £175 million from industry. Under the proposed Phase 3 of 2ZERO, the partners plan to integrate a 1-megawatt hybrid-electric power train into a 19-seat De Havilland Canada Twin Otter for UK flight demonstrations.

Graham Warwick

Graham leads Aviation Week's coverage of technology, focusing on engineering and technology across the aerospace industry, with a special focus on identifying technologies of strategic importance to aviation, aerospace and defense.