Among the few electric aircraft this week at EAA AirVenture 2024 were two Harbour Air electric de Havilland DHC-2 Beavers, one of which was supposed to be the afternoon flying display on Tuesday, but a rapidly developing rain shower prevented the flight. But with one eBeaver parked at the seaplane base and another on the show grounds, there were plenty of opportunities to see these unique machines at AirVenture. They were both disassembled and shipped to the Oshkosh, Wisconsin venue in containers and then reassembled onsite.
Harbour Air has been working with electric propulsion developer MagniX for many years and first flew the eBeaver in December 2019 from Fraser River in Vancouver, Canada, for an eight-minute flight. The original version was powered by a 500-kilowatt magni500 motor derated to 338 kilowatts to match the Beaver’s 450-hp piston engine. The eBeavers on display at AirVenture have a magni650 capable of 650 kilowatts but are still derated so pilots don’t have to get used to a different power output.
For Harbour Air, an electric airplane capable of short flights while carrying its normal load of one pilot and five passengers makes a lot of sense. “We were very unsure at the time that this was going to be able to be commercialized,” said Erika Holtz, Harbour Air’s lead engineer for the electrification program. “Our predictions originally were that we would only be able to have an eight-minute flight, which is not really [commercially viable] for flying passenger aircraft.”
Further research and a ground simulator that enabled extensive testing of the eBeaver in a variety of conditions and configurations showed that a commercially viable electric airplane should be achievable.
“We performed almost 90 flights with this exploring the performance of the aircraft,” she said. It turned out that the original Beaver at 5,600 pounds needs 62% of its maximum power to fly level. The eBeaver needs only 41%, thanks to significant reduction in drag with the sleeker cowling, less cooling drag, and a more efficient propeller. The result of all this research showed that the eBeaver could achieve a 33-minute flight, which is long enough for many of the short-range routes that Harbour Air offers.
“Anybody who's flown a Beaver knows that it does not really like to climb,” Holtz said. “Our climb performance is spectacular. And, of course, noise. Most of it comes from the propeller; we can't change that but we are spinning it slower. And [the propeller] is a little bit shorter. So the tip speed is less. We did some company testing and on average we're about 20 decibels, less noise in every phase of flight, which is quite significant.”
The electric installation in the eBeaver makes an older design look much more modern. Batteries are installed in front of the firewall, under the floor, and behind the passengers. Firewall forward, everything is clean and new and the cowl shape is pointy instead of round. The instrument panel is nearly original but with instruments suited to electric power.
The radial flux magni650 motor is a direct-drive unit so no reduction gearbox is required. Shaft rpm is 1,900 to 2,300. Cooling is required for the power electronics and the motor itself, and MagniX came up with a clever way to provide liquid cooling without using any exotic, hard-to-source chemicals. The Hartzell propeller requires a governor, which needs oil to operate. So MagniX added a Crane Aerospace mechanical pump to the front of the motor housing, driven by a shaft off the motor’s main shaft. The pump circulates ordinary turbine engine oil to cool and lubricate the motor bearings and the power electronics, and to run the prop governor.
MagniX is planning to certify the electric propulsion system as an engine under Part 33 regulations, for which the regulator has set 19 special conditions. So far, MagniX has submitted 20 white papers covering the means of compliance. “We’re developing test plans and running them to see if they work,” said Riona Armesmith, MagniX's chief technical officer. The next step is to build conforming hardware in preparation for engine certification in 2027 and completion of the supplemental type certification for the eBeaver.
“We're finishing our experimental development vehicle,” Harbour Air’s Holtz said. “We're continuing to change architectures on that and learn things. For example, the first version of the battery system was a bus. This one we're working on now is a single string per inverter. We're trying to explore the architectures and see what that means from a system-safety analysis and from a use case. We're taking the lessons learned from the experimental ones so we can apply it to the cert builds. Once we get these certified and have the path, we want to continue to design and certify modifications to the existing aircraft fleet to decarbonize as much as possible. We're going to do that through building a sustainable aviation hub in Vancouver, BC [British Columbia].”
While the cost of electricity for flying the eBeaver is tiny—a 34-minute flight consumed only $6 worth, according to Armesmith—the direct operating costs of flying an original Beaver and the eBeaver are similar.
“We've been evaluating that,” said Holtz, “and it's very sensitive to the cost of the batteries and the cycle life of the batteries. It's going to depend on how you operate the aircraft and how often you want to fast charge. But we found the direct operating costs relatively similar, and that's because [of fuel costs]. Over the next couple of years, we fully expect [that] in BC, we'll be seeing $3 a liter for fuel so the direct operating costs are going to even out pretty good, and as we scale up to our larger aircraft, the direct operating costs actually get significantly better.”