El. fly - UKs vei fremover - RAE

Scottish regional airline Loganair is working with Cranfield University on a project to convert a Britten-Norman Islander to provide the world’s first electric aircraft passenger-carrying flights. BILL READ FRAeS reports.

Pipistrel Panthera electric aircraft. (Ajdovščina)

In recent years, advances in both electric motor and battery technology have enabled the development of small electric-powered aircraft. With the return of rising fuel prices and concerns about the effect of fossil-fuels on the environment, there has been increased interest into the development of battery-powered electric aircraft large enough to carry passengers.

A number of companies are currently working on electric-powered commercial aircraft designs. These include a project from Rolls-Royce Airbus and Siemens to adapt a BAe 146 regional jet to a hybrid-electric aircraft. Zunum Aero, together with Boeing and JetBlue, are developing a family of 10-50-seat hybrid electric regional aircraft while US-based Wright Electric is working with easyJet to develop an all-electric passenger aircraft by 2027. Israel Aerospace Industries also announced plans in 2018 to develop a short-haul electric airliner. 

Artist’s concept of EasyJet electric aircraft. (EasyJet)

However, there are still some challenges to be resolved before such aircraft can be developed for practical commercial operations. Battery technology is currently at a stage where electric only flight is only practical for small aircraft flying on short journeys of less than 60 minutes. Safety considerations have also concentrated attention on ‘hybrid’ aircraft designs fitted with an additional conventional powerplant to recharge the batteries or to be used as a back-up engine.

Project Fresson

Loganair Islander in snow at Fair Isle. (Dave Wheeler)

One organisation involved in research into electric aircraft is aerospace university Cranfield University. Together with its wholly-owned CAA/EASA approved aircraft design and production organisation subsidiary, Cranfield Aerospace Solutions (CAeS), Cranfield University are partners with Aston Martin and Rolls-Royce in the Volante Vision Concept autonomous hybrid-electric VTOL vehicle.

In addition, Cranfield and CAeS are also working on another project to develop the world’s first passenger-carrying commercial electric aircraft. Named ‘Project Fresson’ after Scottish aviation pioneer Earnest Fresson, this project aims to modify an existing aircraft design – the twin-turboprop Britten-Norman Islander – with an electric propulsion system. If successful, the project hopes to have the aircraft EASA-approved by 2021/22 ready to launch the world’s first commercial electric air transport routes.

Orkney testbed

Papa Westray airport. (me677)

The first routes targeted to be operated by the electric Islander are in the Orkney Islands where Scottish regional airline Loganair operates a number of short-haul flights between Kirkwall on mainland Orkney to Sanday, Stronsay, Eday and North Ronaldsay – the longest of which takes 15 minutes. Holding the Guinness World Record as the world’s shortest commercial flight route is the 1.7 mile flight between Westray and Papa Westray which can be completed in under two minutes, including taxiing.

The project has been enthusiastically welcomed by Britten-Norman Islander operators Loganair, as well as aviation services provider Airtask which provides PSO (public service obligation) services to the Hebrides and the Shetland Islands. Loganair has started discussions with local government organisations in the islands. There have also been ‘positive discussions’ with Highlands and Islands Enterprise, HITRANS (Highlands and Islands Transport Partnership) and HIAL (Highlands and Islands Airports Ltd).

Speaking at the ERA General Assembly in October, Loganair MD Jonathan Hinkles explained how the Orkneys were an ideal testbed for electric aircraft operations, as the Islanders were very keen on renewable energy and were already self-sufficient in energy, including projects which produced hydrogen using wind and tidal energy.

If successful, the plan is to then extend the use of electric aircraft on other short island-hopping routes of Highlands Airport network (Orkneys, Shetlands, Hebrides).  The Project Fresson organisers see a number of other advantages in using an electric aircraft on Highlands & Islands routes, including lower operating costs (enabling lower subsidy costs or an increased number of flights or locations served), quieter operations, reduced maintenance costs and job opportunities for engineers. There is also the fact that the Highlands & Islands have an abundance of renewable energy and are, therefore, an ideal location to replace fossil fuel powered aircraft with electric in support of the ‘Low Carbon Economic Strategy for Scotland’.

Funding application

Funding for the project is to come from a combination of public and private investment with Cranfield CEO, Paul Hutton, quoting a figure of £10m to create and safety test the adapted battery aircraft. To help support the project, CAeS and Cranfield University are seeking from assistance from the UK government and have submitted a funding bid to the ATI-run UK Aerospace Research and Technology Programme. If the application for government funds is successful, the project could be completed within three years with all-electric commercial flights potentially commencing in 2021.

Ideal Islander

The airframe of the Britten-Norman Islander has already been flight certified. (Mark Harkin)

The Britten-Norman Islander was chosen as a test-bed for electric propulsion for a number of reasons. Firstly, it is already flight certified, thus enabling the conversion to an electric aircraft to be quicker and less risky. “By using an existing airframe we can keep a number of parameters locked down without having to certificate an all new airframe,” said Iain Gray, Director of Aerospace, School of Aerospace, Transport and Manufacturing, Cranfield University.

Secondly, the nine-seat short take-off and landing (STOL) Islander is small enough to be powered by batteries and is already operated on short ‘island-hopping’ routes which would be well within the capabilities of existing battery technology. Loganair MD Jonathan Hinkles also said at the ERA conference how they had also looked an converting a single-engine turboprop, such as a Cessna Caravan. However, the idea had been abandoned because the aircraft was too fast when landing and couldn’t use a reverse prop on gravel runway.

The plan is to replace the Islander’s two existing engines with two electric motors. However, it is not yet confirmed whether the aircraft will rely entirely on electric power or will be fitted with an additional avgas engine to either recharge the batteries or to provide an alternative power source. “We may need a level of hybridisation to cover diversion requirements,” said Iain Gray, Director of Aerospace, School of Aerospace, Transport and Manufacturing, Cranfield University. “We are looking at alternative solutions with better generating capability versus weight and fuel usage and also very low emissions.”

The exact configuration of the aircraft is still being determined. No engine supplier has yet been identified (“We are in discussion with a number of potential providers,” said Iain Gray). The location of the batteries in either the wings or the fuselage is also not yet finalised. (Iain Gray: “We are looking at both locations and the final configuration has yet to be determined.”)

Also under discussion is whether the batteries will be swapped in and out between flights or recharged while remaining inside the aircraft. “The aim is to be able to turn the aircraft around within existing inter-island schedules, so we are working very closely with aircraft operators (Loganair and Airtask) and airport operators (Highlands and Islands Airports Ltd) to explore the best way of managing this,” explained Gray. Islander manufacturer Britten-Norman will also be involved in the project, although Gray said that the company’s specific role has yet to be decided.

Iain Gray admits that the speed, range and performance of the electric-powered Islander will not compare with the conventionally-fuelled version. “Getting the same range from pure electric as the existing conventionally-fuelled version is not possible,” he said. “However, we will look at options for hybridisation and then identify the appropriate mix to balance operational needs with the best technical and environmental solutions.”

The next stage

Stage 2 of the Fresson Project envisages converting a larger 19-seat Twin Otter to electric propulsion. (Loganair)

Flight-testing the electric Islander will be carried out by CAeS as part of the development and certification process. The aircraft will be certificated by CAA and EASA. No timescale has yet been confirmed for when the electric Islander might begin its first commercial flights, as much depends on funding and the pace of development progress but the aim is that it be ready by the early 2020s. “We expect to have a flying demonstrator by 2020 and a fully certified version by 2022,” states Iain Gray.

However, the ‘electrification’ of the Islander is only the first stage of a ambitious three-stage project. Phase 2 involves utilising the electric architecture from Phase 1 to create a hybrid-electric modification of a 19-seat aircraft (such as a DHC-6 or Twin Otter). This will be followed by the design and manufacture of an all new 19-seat electric aircraft designed around the hybrid electric system certified during Phase 2. “The emphasis is to fast track Phase 1 of the project and provide the pathway for other projects.,” said Iain Gray. “However, although the initial development is based on a conversion of a Brittan Norman Islander to an electric or hybrid-electric format, the project is not just about the aircraft but about shaping the infrastructure and demonstrating a pathway for the safety case and certification to provide a full electric aircraft passenger service.

The project organisers are also hoping that the platforms created in the Fresson Project will lead to similar applications in the UK and abroad. “There are extensive export opportunities, as many countries around the world also use small aircraft in the island-hopping role,” concludes Iain Gray.

Ernest Fresson – aviation pioneer

Fresson is commemorated with a statue at Inverness Airport.