Halldór Jónsson

28.9.2020 | 23:21

Rafmagnsflugvélin er komin

Bye plans to retire its developmental testbed as it progresses toward the conforming eFlyer 2 prototype.

Credit: Bye Aerospace

Bye Aerospace is looking to advances in battery technology for future six- and nine-seat all-electric aircraft it plans will follow the two- and four-seat eFlyer 2 and 4 now in development.

The company is working with the UK’s Oxis Energy to test lithium-sulfur battery packs with higher energy density than the lithium-ion system used in the eFlyer 2 and 4. Improved battery performance is key to offering greater range in the planned eFlyer X and Envoy, CEO George Bye said in a video interview recorded for Aviation Week’s upcoming online Business Aviation Week 2020.

The eFlyer 2 is aimed at the flight school market, the two-seater optimized for typical training sorties of up to 1.3 hr. with 20-min. recharging between flights. Designed for aerodynamic efficiency to maximize performance on available batteries, the aircraft has a lift-to-drag ratio of more than 20 compared with around 10 for a Cessna 172.

From the slim nacelle enclosing the 90-kW Rolls-Royce RRP70D electric motor, the 46-in.-wide cabin, efficient 37.8-ft.-span wing and 75 kWh battery pack in the wing, to the battery management system computers and motor controller–“all those are laid out in an advantageous way,” Bye said.

The eFlyer 4 is essentially a stretch of the two-seater, sharing common aerodynamic and structural DNA, and uses the same battery technology with roughly a doubling of the pack size. “There’s a significant gross weight increase, 1,200-1,300 lb., kind of like going from a Cessna 172 to a 182 or 206,” he said.

The planned eFlyer X will fly higher and faster, a “lightly pressurized” single-motor six-seater designed to cruise at 25,000 ft. The aircraft will have retractable gear where the eFlyer 2 and 4 have fixed gear.

Illustrating an advantage of electric propulsion, Bye noted the company’s eFlyer 2 developmental prototype has the same climb rate at 9,000 ft. as at sea level. “There’s no combustion, just electrons to torque. The bottom line is electric loves to fly high and the calibrated airspeed to true airspeed benefits are fully realized–and the ability to get there, the climb rate all the way up, is not diminished.”

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