Sunday January 29, 2023

Are electric jets ready for takeoff?

Published : 25 Jan 2023, 01:52

  By Andreas Spaeth, DW

Photo: via DW.

It could be the biggest revolution in the aviation industry since the invention of the jet engine, but there is still much in the way before electric passenger planes before take to the skies.

What the Concorde achieved among the fuel-guzzling types of planes, namely being the most beautiful aircraft of all times, could be replicated by an electric aircraft named Alice in the era of battery-powered flying machines. The electric passenger plane completed its maiden voyage on September 27, 2022, at Moses Lake airport in the US state of Washington.

Alice is so far the only passenger aircraft developed from scratch and capable of flying with battery power. It was conceived by Eviation, a company founded in Israel and now based in the Pacific Northwest of the United States.

The nine-seat aircraft has a very attractive appearance. Its aesthetic design, however, is purely on purpose seeking to optimize its flight characteristics. It is no longer the typical tube with wings and a tail attached, but it rather looks like a lean whale with a sharply cut nose, flattening out towards the bottom, and a fuselage that is tapering at the rear.

The shape of the airframe itself creates extra lift to help get the immense weight of the batteries off the ground. At the T-shaped tail, two Magni650 electric motors are installed, delivering 644 kilowatts (KW) each, supposedly enabling a cruise speed of 407 kilometers per hour (252 mph).

Heavy loads and filling order books

The biggest problem of electric flying continues to hamper Alice: The batteries are much too bulky and too heavy, and don't deliver enough energy for efficient and prolonged traveling.

After its successful first flight — a voyage of not more than eight minutes — the company drastically lowered Alice's expected travel range from 815 kilometers to 445 kilometers. This means that the electric aircraft can only be deployed on niche markets, but they are in demand nevertheless, Björn Nagel, the director of the Institute for System Architecture in Aeronautics (DLR) in Hamburg, told DW.

"Flying purely electrical is very sexy, as it has a very high degree of efficiency, close to 90% if you charge the batteries only with wind energy," Nagel said.

The first Alice deliveries to customers are planned for as early as 2027 if "battery technology evolves the way we expect it to," Eviation CEO Gregory Davis said. He added that certification of the plane would also need to go according to plan.

There is already an array of early adopters: Cape Air from the northeastern US, which was a launch customer, committed to buying 75 Alice planes. Aircraft charter firm GlobalX Airlines wants 50. Deutsche Post has announced orders for 12 of the plane's cargo version for its subsidiary DHL.

There is also a German passenger airline in the order book, Evia Aero — a startup and "sustainable regional airline" from Bremen — which signed a letter of intent to buy 25 planes. At the end of 2022, Eviation's first major passenger airline customer, Air New Zealand, signed options for 23 electric aircraft.

All-electric aircraft propulsion is also a focus of the aviation research cluster in Munich, where, for example, aerospace giant Airbus is trialing a variety of hybrid solutions for air taxis and other planes at its Ottobrunn facility.

Not far from there, Rolls-Royce Electrical is "pioneering sustainable electric aircraft technology to power the urban and regional air mobility markets of tomorrow."

The British aerospace company's test lab lies heavily secured behind thick steel doors, where a prototype of the Rolls-Royce RRP200D is currently being manufactured. The plane engine is hoped to unleash the biggest revolution in propulsion since the invention of the jet engine in 1937.

Aviation revolution in the making?

The motor itself isn't really impressive — a metal ring as big as a wagon wheel with a kind of five-armed spool rotating inside the wheel. This is the rotor with magnet and bearings, and showing an unbelievable degree of minimalism, compared with the complex monsters of combustion plane engines, consisting of about 18,000 moving parts. In an electric plane engine, there are merely 18 moving parts, underscoring the dramatic change that Rolls-Royce and the aviation industry are working on.

The quest for a sustainable battery-powered airliner has advanced a fair bit, but existing plane models are still far away from being capable of handling day-to-day flight operations. Unlike in the car industry, it's as yet impossible to power aircraft with the green power to achieve the industry's ambitious goal of more climate-friendly flying by 2035.

"As regards purely electric passenger planes, we are very pessimistic," Nagel said.

At Rolls-Royce, however, engineers are more upbeat. From 2026, they hope to provide two of their RRP200D motors to Norwegian regional carrier Wideroe, which wants to operate a nine-seat Italian-built propeller aircraft called Tecnam P-Volt on scheduled flights.

"If successful the motor will only hum lightly," said Stefan Breunig, head of strategy at Rolls-Royce Electrical, adding that researchers are currently testing a 2.5-megawatt generator that is supposed to power larger regional aircraft with up to 50 seats.

Persisting battery problems

Initially, Tecnam's P-Volt light electric aircraft won't be able to fly more than 150 kilometers on a fully charged battery, including a mandatory 30-minute energy reserve. The range could be sufficient to serve certain short-haul routes in Norway, but would be of little use elsewhere.

"I am skeptical about electric flights because of range restrictions," Lars Enghardt, the director of DLR's Institute of Electrified Aero Engines in Cottbus, told DW. Enghardt said the DLR didn't foresee "batteries with sizably increased energy density in the near-term future."

Range restrictions of purely electric propulsion, he said, would provide limited opportunities in niche markets such as Norway. But, on longer routes with larger aircraft, hybrid-electric concepts could be the way to go.

Enghardt's skeptical outlook for electric flying isn't, however, holding back Rolls-Royce's chief technology officer, Grazia Vittadini, who told DW that the jet engine maker is "serious" about electric flights. "We are going to find useful applications for it, step-by-step," said Vittadini, who is from Italy and once worked for Airbus..

Vittadini foresees great opportunities by 2030. "We will see all-electric aircraft of up to 30 seats flying," Vittadini said. "For us," she added, "Norway will be the absolute front-runner in Europe."

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