Hybrid-electric Islander would have 'three-year payback'

A new hybrid-electric powertrain for the Britten-Norman BN-2 Islander could be ready for service entry by 2024, with savings on fuel expenditure enabling operators to pay off the conversion cost in around three years.

Announced last week, Project Fresson is an ambitious effort backed by the UK government to bring to market a hybrid-electric aircraft designed for short “sub-regional” sectors.

It will replace the standard powerplants on the nine-seat BN-2 with battery-powered electric motors backed up by a “range extender” engine acting as a generator.

Paul Hutton, chief executive of Cranfield Aerospace Solutions, which is leading the effort, says the aim of the 30-month project – due to conclude in April 2022 – is to deliver a modification for the Islander that can be delivered via a Supplemental Type Certificate.

Both turbine and piston engines are being evaluated for the range-extender application, says Hutton; although fuel cells were also considered, they were ruled out in the short term over maturity concerns.

“This project is very much about what is the quickest way of getting a commercial passenger-carrying aircraft electrified,” he says.

While Britten-Norman is still building new examples of the Islander, Hutton says the project’s focus is on the roughly 400-strong inventory of used aircraft.

Conversion of the BN-2 will cost an estimated £500,000 ($645,000), says Hutton, but with electricity around 20% cheaper than avgas, that capital cost could be repaid over around three years.

An additional two phases of the project are envisaged: integrating the propulsion system on a larger type with up to 19 seats such as a Viking Aircraft DHC-6 Twin Otter and eventually leading to the development of a clean-sheet design.

But Hutton says the second phase could be skipped if the technology proves to be sufficiently mature.

Carriers including Scottish regional carrier Loganair have been recruited to provide operator input into the project.

While Hutton concedes there is a limited airline market for nine-seaters at present, he points out that the lower operating costs promised by electric aircraft could see smaller aircraft push out larger types.

“The nine- to 19-seat market has really been neglected for the last two or three decades because airline economics have dictated a need for larger aircraft to offset fuel costs.

“But with electric aircraft the cost is a fraction of avgas – there is a segment there that turns those economics on their head.”

Partners in Project Fresson include Rolls-Royce (which will supply the power management system), Denis Ferranti Group (electric motors); Delta Motorsport (battery packs), Warwick University offshoot WMG (battery testing and characterisation), and Britten-Norman. The UK government has provided £9 million in funding through its ATI initiative.