MIAMI – California-based Ampaire set a new record for electric aviation last week. The company’s hybrid-electric demonstrator, named the Electric EEL, made a two-and-a-half-hour flight on October 8. According to Ampaire, it was the “longest flight to date for any commercially relevant aircraft employing electric propulsion.”

The aircraft took off from Camarillo Airport (CMA) at 12:20 pm PDT. It flew a distance of 341mi (549km) and reached an altitude of 8,500ft (2,591m). It then landed at Hayward Executive Airport (HWD) at 2:52 pm PDT. Test Pilot Justin Gillen and Flight Engineer Russell Newman were at the controls of the aircraft.

In cruise, the Electric EEL averaged a speed of around 135mph (217kmh). “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. The aircraft was in testing for four weeks prior to its milestone flight.

Electrifying the Skymaster

The Electric EEL is a modified version of the Cessna 337 Skymaster. Introduced in 1962, the Skymaster serves as a utility aircraft. It has a unique design, featuring a twin-boom tail, and two engines in an inline, push-pull configuration. The aircraft has been a popular testbed for research projects.

A Continental IO-550 sits in the aft fuselage of the Electric EEL, while a 174 hp (130 kw) electric motor occupies the nose. That motor replaces what would be a second IO-550. Ampaire, however, is not the first company to fit a Skymaster with an electric propulsion system.

VoltAero, a startup French aerospace company, is also developing a hybrid-electric aircraft based on the Skymaster. Its version is called the Cassio. Unlike the Electric EEL, Cassio has an additional two Safran EngineUS electric motors mounted on the wings.

Ampaire Electric EEL. Photo: Ampaire

Demonstration Flights with Mokulele Airlines

The Electric EEL will be disassembled and shipped to Hawaii where it will perform a series of demonstration flights. Ampaire is working with Mokulele Airlines (9X) and Elemental Excelerator to prove the value of electric aviation in Hawaii. “The state’s challenging geography makes surface transport arduous and inefficient. Our electric technology yields significant cuts in operating costs, allowing faster and more frequent travel among the islands’ small airports,” says Ampaire.

Additionally, Ampaire says that its project makes it the first to operate a series of mock-operational flights with typical payloads. “The trial flights 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,” Doug Shane, Ampaire’s General Manager, explains.

“The ability to put innovative electric technologies into the air rapidly 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,” he adds.

Mokulele Airlines Cessna 208B Grand Caravan. Photo: Ken Fielding via Wikimedia

The Next Step

CEO Kevin Noertker remarks that the Electric EEL is Ampaire’s first step towards pioneering new electric aircraft designs. “Our next step will likely be a 19-seat hybrid-electric retrofit program that will lower emissions and operating costs, benefitting regional carriers, their passengers, and their communities,” he says.

Ampaire is collaborating with the National Aeronautics and Space Administration (NASA) for its next program. The aircraft, dubbed Eco Otter SX, is based on the De Havilland DHC-6 Twin Otter. It has been under development since October 2019.

Featured image: Ampaire Electric EEL in flight. Photo: Ampaire