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Hybrid electric trailblazer goes on sale
For sale - a hybrid electric retrofit aircraft that Ampaire hopes will lead the way in decarbonising aviation. The twin-engine Cessna 337 Skymaster has been modified to fly with one conventional engine and one electric.
Ampaire believes hybrid electric retrofits will lead the way in decarbonising aviation.

Ampaire, a pioneer in practical applications of electric power for aviation, is now accepting letters of intent for its Ampaire Electric EEL hybrid electric aircraft. The EEL is a retrofit of a Cessna 337 Skymaster and has a conventional combustion engine plus an electric motor/battery pack drivetrain. The company already has more than a dozen letters of interest from regional airlines and charter providers.

“The Ampaire Electric EEL is the first step in bringing lower emissions, lower-operating costs and quieter operations to general aviation through electrification,” according to CEO Kevin Noertker. “The original Cessna 337 provided great utility, and this hybrid electric conversion retains those advantages while reducing fuel cost and maintenance by about 50 per cent.”

The EEL made its first test flight in June and is in the process of systems evaluation and envelope expansion. It has made flights of more than one hour's duration and demonstrated single-engine climb on each powerplant. The test programme will last about 30 months, with additional propulsion configurations tested, culminating in STC certification by the end of 2021.

Customers will be offered two versions. The first will include an avgas-burning Continental IO-550 310 hp piston engine and a 215 hp (160 kW) electric propulsion system. The second will include a Continental CD-300 Jet A diesel 300 hp engine and the same 215 hp (160 kW) electric system.

The company will offer pressurised and unpressurised versions of the aircraft. Winglets and STOL kit are standard. The interior can be equipped with four or six seats and aircraft cost will be competitive with comparable current production piston twins.

“This is something new and exciting in general aviation, twin engine redundancy and performance on as little as 10 gallons per hour in cruise flight,” adds Noertker. “Plus the opportunity to reduce your environmental footprint and still enjoy the freedom and flexibility to fly as you wish.”

The company's roadmap toward new all-electric commuter aircraft begins with the rapid introduction of electric powertrains on currently certified aircraft. This approach addresses two major problems in commercial aviation today; high operating costs and the environmental impact of CO2 and other emissions.

The Electric EEL will enter flight trials on commercial routes with Mokulele Airlines in Hawaii later this year, a partnership enabled by a Hawaii-based startup accelerator, Elemental Excelerator. FAA certification of the Electric EEL is projected for 2021.

“The most practical way to achieve an all-electric future is to jump start the market with a partially-electric present,” Noertker continues. “We're pursuing a pragmatic, step-by-step approach, a scalable plan to quickly commercialise and expand the electric airplane market. This approach recognises that other development programmes for clean-sheet all-electric aircraft will consume hundreds of millions of dollars in R&D and potentially require a decade or more to certify.

“Such programmes will be complicated by the rapid evolution and improvement of electric battery and powertrain technology, and the lack of experience of regulators in the area of electric aircraft.

“By contrast, Ampaire is demonstrating the ability to cut fuel consumption by half and reduce emissions accordingly. The development cost of modifying an existing aircraft is relatively low and manageable versus a clean-sheet design. Both Ampaire and the FAA have an opportunity to work together to develop a regulatory framework that promotes safety and creates a predictable, manageable path for certifying electric aircraft.

“The Cessna 337 modification is a first step. The next may be a hybrid or fully electric retrofit of a nine- to 19-passenger commuter/cargo aircraft. As batteries and powertrains mature, we will shift our focus to clean-sheet designs such as our nine-passenger, zero-emissions Tailwind concept.

“By that time, we will have established strong cash flow from retrofit programmes as well as engineering and certification expertise that will earn the confidence of investors, partners, aircraft operators and regulators.” Noertker points to UBS's recent estimate of a $200 billion market for hybrid electric aircraft.

Ampaire is a Los Angeles-based aircraft electrification company, initially retrofitting existing passenger aircraft to electric power as a fast and capital efficient approach to making commercial electric air travel a reality. Ampaire’s vision is to make flights more accessible to more people from more airports by providing electric aircraft that are clean, quiet, and less costly to operate. Ampaire is a portfolio company of the Los Angeles Cleantech Incubator, with additional support from Starburst Accelerator and others.

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