Electric propulsion systems developer Ampaire last week achieved its longest flight with the Cessna 337 Skymaster that it has converted to hybrid-electric power. On October 8, the six-seat, Electric EEL aircraft took off from the Los Angeles area Camarillo Airport and made a 341-mile flight to Hayward Executive Airport in the San Francisco area in 2 hours and 35 minutes. Ampaire, claims this was the longest flight to date for what it defines as a "commercially relevant" aircraft using electric propulsion.
The Electric EEL is powered by a 310-hp Continental IO-550 engine installed in the tail of the aircraft and an electric motor in the nose. In an announcement issued on October 12, Ampaire did not provide a breakdown of how these two power sources were employed at various stages of the flight.
The flight was piloted by test pilot Justin Gillen and flight test engineer Russell Newman, the flight averaged 135 mph as it traversed California’s Central Valley at an altitude of 8,500 feet. “The mission was a quite normal cross-country flight that we could imagine electrified aircraft making every day just a few years from now,” said Gillen.
The demonstration took place little more than a year after the first EEL made its first flight, and just four weeks after this aircraft, the second in the program, took to the skies. Known as the Hawai’i Bird, this airframe will now be partially-disassembled at Hayward and shipped to Hawaii to take part later this year in a series of proving flights with Mokulele Airlines on its short-haul routes. That test program will be partially funded by Elemental Accelerator, a green-technology financial support platform.
“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,” said Ampaire general manager Doug Shane, adding "the ability to put innovative electric technologies into the air rapidly in order 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."
According to the company, the EEL can cut fuel use and emissions in half on shorter routes where its electric powerplant can run at higher power settings, and generate similar reductions of up to 30 percent on longer regional routes such as Camarillo to Hayward.
The Electric EEL program is viewed as just a stepping stone towards a larger goal, said company CEO Kevin Noertker. "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 explained. "Ampaire, with funding from NASA and others, is in the midst of design studies for such an aircraft based on the popular de Havilland [now Viking Air] Twin Otter aircraft. That hybrid-electric aircraft will be called the Eco Otter SX.