Commercial, Products

Rolls-Royce Eyes Potential For Hybrid-Electric Capabilities

By Amy Kluber | March 13, 2018
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Bell 407GXi

Bell 407GXi. Photo courtesy of Bell

The engine manufacturer for Bell's newly unveiled helicopter sees hybrid-electric propulsion technology a very real development in the short term.

Bell unveiled at Heli-Expo in Las Vegas last month its 407 GXi. New on the aircraft from its model predecessor, the 407 GXP, is the dual-channel FADEC engine — Rolls-Royce's M250 C47E/4.

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The new engine is a variant of the original M250-C47E and has the same horsepower as the previous engine featured on the 407 GXP, but provides a 4% improvement in fuel consumption and range.

Jason Propes, SVP of helicopters and light turboprop engines at Rolls-Royce, told R&WI how the improvements the company made on the engine perhaps set a foundation for future hybrid-electric propulsion efforts.

"With our latest engine ... we've modernized the state-of-the-art control system, provided additional safety capability, reduced pilot workload," he said. "It also enables an incremental approach to more electrification — which will come."

More electrification, he explained, would be in the form of hybrid-electric propulsion systems. The engine manufacturer in November partnered with Airbus Helicopters and Siemens to develop by 2020 a hybrid-electric flight demonstrator, the E-Fan X.

But full electrification, in the form of the technology companies like Uber and Bell are proposing to power their urban air mobility vehicles, presents questions regarding power density, duration and even operating costs.

"When you look at the power demands of aircraft in today's market and the weights and loads and payloads that need to be carried, electrical batteries aren't capable of providing enough power for customers to provide their missions as they perform them today," Propes said. "That's when you need the gas turbine power augmented with electrical power. Combined, you can perform today's missions, but the technology is not there yet for full electric propulsion."

Its a similar sentiment Safran Helicopter Engines also expressed in a media briefing at Heli-Expo with its new CEO, Franck Saudo.

“We do not see full electrical architecture for application for platforms flying beyond 30 minutes and carrying more than 100 kg within the next two decades because of battery capacity,” said Bruno Bellanger, EVP of programs at Safran Helicopter Engines.

“We believe at Safran Helicopter Engines that there will be a revolution in mobility in the decades coming,” Saudo said. “It will involve hybrid architectures involving gas turbines mixed with electrical power generation systems.”

In the E-Fan X, Rolls-Royce is tasked with developing the turboshaft engine, two-megawatt generator and power electronics. The company will also work on the fan technology into the existing nacelle and the Siemens electric motor.

As for what will be propelling future air taxis, Rolls-Royce is banking on hybrid electric.

"Our view on hybrid-electric [propulsion] is projecting where the market is going to go with our customers," Propes said. "There will be challenges in terms of regulatory approval for those types of passenger transit systems (air taxis). ... It needs to be an affordable mode of transportation. That's where hybrid electric really provides that ability to reduce direct operating costs."

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