Ampaire’s Second Hybrid-Electric Preps for Flight Trials in Hawaii

The latest Ampaire hybrid Cessna 337 prototype moved the battery pack to a separate pod slung beneath the aircraft. Ampaire

Kahului, Hawaii based Mokulele Airlines has joined with California-based Ampaire to begin testing the second prototype Cessna 337 “Electric EEL” hybrid-electric aircraft conversion. Ampaire successfully flew the second demonstrator on September 10. The new prototype builds on previous aircraft that the company has test flown in other markets.

Ampaire calls the new flight test aircraft the Hawai’i Bird because it will be flown on air routes in Hawaii later this year in a series of demonstration flights. When the aircraft flies on Maui, it will be the first time an electrically powered aircraft has flown under an FAA “market survey” experimental aircraft certificate in order to gain real-world flight experience, according to the company. An aircraft like Ampaire’s Electric EEL can cut direct operating costs and emissions by 40 to 50 percent of conventional aircraft, playing an essential part in helping Hawaii reach its goal of 100 percent renewable energy for electricity by 2045.

The Hawai’i Bird is powered by a conventional 310-horsepower Continental IO-550 rear engine and a 200 kW-capable electric motor limited to 120 kW in front. This updated Ampaire conversion moved the aircraft’s battery pack out of the cabin to a composite aero-optimized shell the underside of the fuselage. The new configuration frees cabin space for flight test engineers, test equipment, and observers.

The electric power unit (EPU) used by the EEL, designed for improved energy efficiency at a lower weight, includes better thermal margins thanks to a liquid cooling system that replaced the conventional air-cooling system. Designed to cruise at 120 knots for 1 hour and 15 minutes, plus a 30- minute reserve, The Hawai’i Bird can fly most Mokulele routes round trip before a required recharge.

Rob MarkAuthor
Rob Mark is an award-winning journalist, business jet pilot, flight instructor, and blogger.

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