Harbour Air Beaver aircraft Harbour Air
Vancouver-based Harbour Air plans to convert its fleet, including Beavers (foreground) and Otters, to electric propulsion.

Electric Propulsion Shows Promise For Short-Haul Operations

Niche short-range operators see potential in converting their aircraft to electric power to reduce energy costs and emissions.

Printed headline: Short Sweet Spot

 

A new market to modify aircraft from piston and turbine engines to electric power may be emerging as industry explores the potential to reduce energy consumption and direct emissions.

Harbour Air, North America’s largest seaplane airline, has partnered with motor developer MagniX to convert its fleet to electric propulsion. The companies plan to begin by replacing the radial piston engine in one of the airline’s de Havilland Canada DHC-2 Beavers with the startup’s 750-hp electric motor.

United Technologies Corp. (UTC), now the aerospace industry’s largest suppliers plans to convert a Bombardier Dash 8 Q100 regional turboprop into a hybrid-electric propulsion X-plane. UTC is eyeing a commercial market for the system, which is being developed by Collins Aerospace Systems and Pratt & Whitney Canada under the new United Technologies Advanced Projects organization.

Hawaiian commuter airline Mokulele Airlines has signed a letter of interest with U.S. startup Ampaire to potentially convert its Cessna Caravans to electric power. Others that have signed similar agreements are Seattle’s Kenmore Air, Tropic Air of Belize, Puerto Rico-based Vieques Air Link, Southern Airways Express of Memphis, Guernsey’s Aurigny and Star Marianas Air, based in the Northern Mariana Islands.

What connects these projects is range, whether it is Harbour Air’s island-hopping flights in the Pacific Northwest or the Dash 8’s short-haul regional services. Long range is not required, and this makes electric propulsion feasible, whether it is the battery-powered Beaver or the hybrid-electric Dash 8.

Ampaire

Ampaire plans to fly a modified Cessna 337 hybrid-electric testbed on regional airline routes.

Vancouver, British Columbia-based Harbour Air operates 12 routes to islands and other locations in the Pacific Northwest. A typical Beaver flight lasts 10-20 min. “We can do that with today’s batteries, let alone with 2022 batteries, which will provide longer range,” says Roei Ganzarski, MagniX CEO.

“Harbour Air understands what we can do today. For Seattle-Vancouver flights they use a Cessna Caravan. We can’t do that with today’s batteries,” he says. “We can’t do 200 mi., but a Beaver flying 65-70 mi. between islands does make sense.”

The “remotored” Beaver is expected to fly by the end of 2019 and will be used as the test aircraft for supplemental type certification (STC) of the conversion. Harbour Air plans to begin commercial service with the electric-powered Beaver by 2022, says Ganzarski, and wants to convert its entire fleet of almost 35 seaplanes, including the larger DHC-3 Otter, DHC-3T Turbine Otter and DHC-6 Twin Otter.

MagniX is developing the 750-hp mangi500 motor to replace the popular Pratt & Whitney Canada PT6A turboprop in utility aircraft such as the Caravan and Beechcraft King Air, with short-haul cargo carriers and island-hopping airlines as target markets. “Which came first depended on who had the most foresight,” says Ganzarski. “Harbour Air is leaning forward because it sees the value electrification will bring to its business model.”

Harbour Air operations also led them to electric propulsion, with frequent stops during which batteries can be recharged. “We are aiming for a 1:1 to 1:0.75 ratio—1 hr. flying to 1 hr. or 0.75 hr. charging,” he says. “A 20-min. flight, 20 min. charging, and Harbour Air’s turnaround times are 30 min. to 1 hr. They can do this without changing the aircraft or their business model.”

At 750 hp, the magni500 motor is significantly more powerful than the Pratt & Whitney R-985 radial engine powering the DHC-2, but Ganzarski says operators are already re-engining their Beavers with the more-powerful PT6A. “If they are looking for more power, we can make it clean. And an electric motor is not affected by altitude,” he says, noting piston and turbine engines lose power with altitude.

The cost of “remotoring” an aircraft like the Beaver “should be equivalent to re-engining with a PT6,” says Ganzarski, but the operating cost should be significantly less because of the lower maintenance required by electric motors. “The five-year life-cycle cost should be 70-80% cheaper than today.”

Under the partnership, Harbour Air will help with engineering of the modification and hold the STC to convert its own fleet and those of other operators. The plan is to begin with certification of the Beaver, then move on to the DHC-3 Otter, DHC-3T Turbo Otter and the DHC-6 Twin Otter. MagniX is responsible for all aspects of the electrification, including the charging infrastructure, he says.

Ampaire has modified a Cessna 337 Skymaster to a propulsion testbed for electric-powered regional aircraft. The Skymaster’s push-pull configuration allows the forward piston engine to be retained for safety while flight-testing the electric drivetrain that replaces the rear engine.

MagniX

MagniX is using a Cessna Caravan airframe for ground testing of the 350-hp electric motor driving a propeller.

Based in Hawthorne, California, the startup has received funding support from Starburst Accelerator and in August 2018 was one of the first 10 companies inducted into the Techstars Energy Accelerator In Partnership With Equinor. This is incubator Techstars’ first Nordic accelerator, and involves Norwegian energy company Equinor and engineering group Kongsberg. Kevin Noertker, Ampaire co-founder and CEO says the company is working with Norway, which wants all short-haul flights to be electric by 2040.

Beginning later this year, Ampaire plans to fly its experimental aircraft on routes flown by Mokulele between Kahului and Hana under a program funded by Hawaii’s Elemental Excelerator, a nonprofit incubator. The six-month trial will look at how to incorporate hybrid-electric aircraft into a fleet. Mokulele hopes to begin electric flights in 2021 after FAA certification of the conversion.

Interested airlines such as Mokulele want to keep their aircraft but convert them to electric power, says Noertker. In the Skymaster testbed, the rear Continental piston engine is replaced by an off-the-shelf electric motor, but Ampaire—like MagniX—is targeting replacing the popular PT6A turboprop that powers aircraft such as the Caravan and Twin Otter.

UTC, meanwhile, is designing the hybrid-electric electric propulsion system for the Dash 8 X-plane with certification and production in mind. Installed in place of P&WC’s 2,150-shp (1.6-megawatt) PW121 turboprop—on one side only for safety—the 2-megawatt system comprises a 1-megawatt turbine engine and a 1-megawatt electric motor, both driving the propeller via the same gearbox.

For takeoff and climb, both the turbine engine and electric motor are used. In cruise, only the turbine engine operates. And on descent, the motor operates as a generator and uses excess turbine-engine power to recharge the lithium-ion battery pack installed under the cabin floor.

By downsizing the turbine engine and operating it at its optimum point throughout the flight, UTC expects fuel savings of at least 30% on a 1-hr., 200-250-nm flight. There is a penalty: Operating empty weight increases, and fuel capacity is reduced by about 50%. Range is reduced to 600 nm from a baseline 1,000 nm, but UTC says 99% of 30-50-seat Dash 8 missions are shorter than 500 nm.

Range is the key, but in niche short-haul markets it is beginning to look possible, even likely, that electrification can bring a new lease on life to long-established aircraft types—and a new modification revenue stream for the industry. 

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