Green Regional Airliners Could Break the Market Mold

Not so long ago, the perceived wisdom suggested that demand for sub-50-seat regional airliners would remain limited for the foreseeable future. But the pressure to bring reduced or zero carbon propulsion technology to market is changing the outlook and opening new possibilities to connect thousands of smaller communities that benefit from little or no scheduled airline service. 

Cranfield Aerospace Solutions (CAeS) expects to close the first stage of its Series B funding round at the end of July, allowing it to accelerate plans to bring a hydrogen-powered regional airliner to market. Delays in raising funds meant the UK start-up had to defer hardware purchases needed for its technology demonstrator. However, it remains intent on bringing the first converted nine-passenger Britten-Norman Islander into commercial service in 2027.

The plan calls for the replacement of the Islanders’ piston and turboprop engines with CAeS’s hydrogen fuel cell system, fully integrated into nacelles on the wing. Meanwhile, the UK company is now pursuing other applications for the technology with uncrewed cargo aircraft and to replace auxiliary power units (APUs) on existing airliners.

“We now have a very sophisticated hydrogen fuel cell system that we believe delivers the highest available energy density, which means we can be sure of producing 100% or more of the energy of the engines it is replacing, not just 40 to 50% as is the case with other systems,” CAeS chief executive Paul Hutton told AIN. He added the company aims to start flying a technology demonstrator by the end of July 2025, after completing ground tests.

The engineering team has used the time needed for fund-raising to refine its plans for packaging the propulsion system’s components efficiently, while also dealing with the complex thermal management challenges. “What we’ve got now is a miracle of packing, with all the high and low-temperature elements combined in a way that the weight is not too great for the stretcher [that attaches the nacelle to the wing] and while not creating too much drag,” Hutton explained. “So we’ve got full power at the right weight, fully packaged and with a way to get rid of the heat. No one else has done that.”

Prospective customers for the hydrogen-powered Islanders include UK regional carrier Loganair, Monte Aircraft Leasing, Germany-based start-up Evia Aero, and U.S. fractional aircraft provider Stratus 9. Working with Britten-Norman and other suppliers, CAeS will source in-service aircraft for conversion.

Hydrogen-Powered Cargo Drones

In October 2023, Dronamics agreed to acquire 1,290 of the CAeS propulsion systems for integration with its in-development Black Swan uncrewed cargo aircraft. The Cranfield team will work with UK-based Dronamics to help market the aircraft, which can carry a payload of 350 kilograms (770 pounds) to a range of 2,500 kilometers (1,359 nm). At the Farnborough International Airshow, it is presenting a three-dimensional model of the propulsion system.

At the same time, CAeS is stepping up discussions with several airlines eager to replace APUs that now account for around 20% of ground emissions of carbon dioxide from aircraft and 10% of all airport emissions. It seeks to demonstrate how hydrogen propulsion units ranging in power output from 125 to 500 kilowatts could cover the APU needs of all current airliners with equipment that would conveniently fit in the space currently occupied by the increasingly unwelcome equipment.

According to Hutton, CAeS enjoys an added advantage with its 30 years of experience as an approved provider of complex aircraft modifications, with a client list including Airbus, Boeing, Rolls-Royce, and L3 Harris. Initially, he said, the company will likely seek early adopters for its hydrogen APU by marketing its own supplemental type certificate for the conversion. In the longer term, it would like to work in partnership with airframers to offer OEM-approved modifications.

Hutton added that the longer-than-anticipated time taken to raise funds in a tight capital market for aviation start-ups has given CAeS time to rethink an important aspect of its business model. The company had anticipated that the early Islander conversions would run on gaseous hydrogen and at the earliest opportunity with liquid hydrogen, which presents more complex challenges to source and store.

“If anything the challenges [around liquid hydrogen] have got worse because of increased doubts over its availability to the air transport sector at a reasonable cost, and this means it won’t happen in aviation at least for the next two to four years,” Hutton said. “What we’ve now realized is that the design we have created has such high power density that we can see multiple other applications for it by looking sideways, rather than just going straight to larger, longer-range aircraft.”

30-Seater Hybrid Commuter Coming to Market 

Heart Aerospace plans to reveal a technology demonstrator for its ES-30 hybrid-electric regional airliner in the fall. The Sweden-based company has changed the architecture for the 30-seater’s propulsion system to an independent hybrid configuration it said will allow more missions to be flown in all-electric mode.

Instead of the earlier series hybrid configuration, the aircraft will now use a pair of as-yet-unspecified turboprop engines installed on the outboard section of the wing and two electric motors inboard. The company confirmed the decision to drop the series hybrid configuration with a turbogenerator in May, leading to other design changes including moving the battery bay from the lower fuselage and removing winglets and strut-braced wings.

Despite the extensive engineering work required by the program’s latest changes, Heart president and chief commercial officer Simon Newitt told AIN it is still aiming to achieve initial EASA type certification in 2028. The company set the timeline in 2022, when Heart dropped earlier plans for the all-electric ES-19 model, in response to feedback from prospective airline customers who said they needed greater range and payload promised with the 19-seater.

In May, Heart opened a research and development facility in California, where its team plays a key role in completing the design of the ES-30 and determining a plan for ground and flight testing. The company has reached an advanced stage in testing hardware for the demonstrator, which also serves as part of a research project in Sweden backed by airport operator Swedavia and the airline group SAS.

According to Newitt, the hybrid propulsion configuration will give airlines the option of flying all-electric missions without using the turboprops at all. “The turboprop [propellers] could be feathered so that they can take off using just the inboard motors and fly up to 200 kilometers [109 mm] from entry into service,” he explained. “The outboard engines will be sized to be turned on to allow for range extension [of up to 800 kilometers] and operators can have everything working at the same time for some improved takeoff performance.”

Newitt, who formerly worked with Embraer, said Heart is now “deep in the detail” in determining which partners it might select for key systems such as the motors and turboprops. He said the company aims for “disruptive” ways it works with partners to avoid the sort of budget overruns and program delays that have made it hard for the aerospace industry to bring new products to market and avoid frustrating investors who want to see progress.

Heart has reported around 250 firm orders or purchase agreements for the ES-30, along with purchase rights, options, and letters of intent covering another 200 aircraft. On July 3, the company held its latest advisory board meeting attended by representatives from United Airlines and its regional affiliate Mesa, as well as SAS and Braathens, Air New Zealand, Republic, Icelandair, and KLM.

As part of efforts to develop a supportive network of wider stakeholders, in late June Heart launched a collaboration with the Swedish island Gotland. Counting about 61,000 permanent residents, the regional government wants to encourage net zero carbon flights to connect the Baltic Sea community with the mainland and other European destinations.

Earlier this year, Heart closed a Series B funding round that raised $107 million. Newitt said the company intends to seek the further backing it needs from a mix of equity issues, debt instruments, strategic investments, and public support. The company also wants to see stronger political commitments from governments to encourage aviation to invest in new green aircraft.

“This is fundamental; we hear a lot of talk but we need action, and we need to see the companies [trying to introduce new propulsion technology] having a level [competitive] playing field,” Newitt concluded. “This isn’t just a play around sustainable aviation fuel, which is more for longer-haul flights with larger aircraft. If we don’t invest now, we’re not going to hit the [net zero carbon] targets. Governments need to be more informed so they are not in denial over the need for support that could be a mix of carrots and sticks.”

Delay at Deutsche Aircraft

Deutsche Aircraft is pushing back the projected service entry for its D328eco regional airliner until the end of 2027. The German manufacturer has been working to modernize the 1990s-era twin turboprop and has aimed to achieve EASA  type certification in 2026 following the first flight of a prototype in the third quarter of 2025.

In a statement issued on July 5, Deutsche Aircraft said it decided to delay the program after a detailed internal review and discussions with prospective customers, which include charter and corporate shuttle flight operator Private Wings. The company added that unspecified regulatory changes forced the shift in the program timeline and hence the certification process.

The 40-passenger D328eco will feature a pair of new Pratt & Whitney PW127XT-S engines that will initially run on power-to-liquid sustainable aviation fuel. In the longer term, Deutsche Aircraft intends to introduce a hydrogen-powered version. It has conducted studies with Universal Hydrogen, the California-based start-up that went out of business last week, and also with German hydrogen propulsion developer H2Fly.

In June 2023, Deutsche Aircraft, which bases operations at Wessling near Munich, announced a materials management agreement with Thyssenkrupp Aerospace. The D328eco’s flight deck will use a Garmin avionics suite.

“While we have had to realign the entry into service for our D328eco, we are taking this opportunity to investigate further product enhancements and we are satisfied by the tremendous progress of the program to date,” said Dave Jackson, CEO of Deutsche Aircraft. “Our certification panels with EASA are advancing successfully, the start of construction for our final assembly line in Leipzig has begun and we have secured over 95% of our suppliers, including those providing access to strategic growth markets.”

VoltAero Close to Flying Cassio Prototype

Later this year, French start-up VoltAero plans to start test flights with a prototype of its Cassio hybrid-electric aircraft. The four-seat entry-level Cassio 330 model will serve as the prototype. The company also continues work on the larger Cassio 480 and 600 models, meant to carry between six and 12 passengers on a variety of regional airline and private aviation applications.

VoltAero’s patented powertrain incorporates a pair of Safran EngineUs electric motors, a turbogenerator, and an aft-mounted pusher propeller. The company expects the aircraft to have a hybrid-electric range of up to around 695 nm and just 82 nm while operating in all-electric mode.

Founded by former Airbus executive Jean Botti, the company claims to have reached sales agreements covering more than 220 Cassio aircraft. It also works with Kawasaki on longer-term plans for a hydrogen-electric version.