It is a first in Clean Aviation’s history: today, partners of four closely linked projects (PHARES, OSYRYS, HERACLES and DEMETRA) launched their coordinated activities to push forward the technology maturation for the next generation of Ultra-Efficient Regional Aircraft. With a dedicated collaboration agreement and joint kick-off meetings, this close cooperation promises to accelerate the maturation and validation of relevant systems and components, such as hybrid-electric propulsion and so-called more-electric systems. A major goal: Deliver a hybrid-electric flight test to validate technologies for an aircraft that will enter into service by 2035 and achieve at least a 30% reduction in CO₂ emissions compared with a 2020 state-of-the-art regional aircraft.

Complementary building blocks for a common aircraft concept

The projects bring together aircraft manufacturers, original equipment manufacturers focusing on engines, system suppliers, research centres, universities, as well as certification authorities from different European countries. Each project will deliver complementary building blocks that will contribute to a common aircraft concept and demonstration pathway: while PHARES will focus on the development of the propulsion system, OSYRYS will address systems to manage challenges related to hybrid-electric propulsion. HERACLES, on the other hand, will develop the integrated aircraft design, and DEMETRA the Flight Test Demonstrator to demonstrate and validate key hybrid-electric technologies under real operational flight conditions (Technology Readiness Level 6).

To accelerate certification and define a clear pathway towards Certification Readiness Level 6, the European Aviation Safety Authority (EASA) will be involved at each stage of the different projects.

All in all, the projects will receive €140 million funds from Clean Aviation, complemented by more than €200 million of in-kind contributions.

Fast progress, maximum impact

According to Clean Aviation’s Executive Director Axel Krein, “We are now in a crucial phase of the Clean Aviation programme where we accelerate the development and maturation of new technologies through integrated demonstration. The collaboration between the four consortia, together with EASA, will allow swift progress within a highly innovative ecosystem that advances technology maturity, shares risk, and maximizes impact.”

The projects’ successful implementation will be a decisive step towards sustainable regional aviation, explains María Calvo, Head of Clean Aviation’s Project Management Unit: “The kick-off meetings have already shown the strength of the collaboration framework: The consortia are working with a single mindset from day one to align breakthrough technologies, system integration, flight demonstration, and certification readiness. Together with project partners, we are building a solid and credible foundation for the next generation of regional aircraft.”

Further information about the projects

PHARES: Advancing Hybrid-Electric Propulsion

The PHARES project focuses on the development of an advanced hybrid-electric propulsion system, combining:

- a next-generation turboprop engine with improved thermal efficiency

- an integrated electric motor and power electronics and

- an optimized propeller designed for higher efficiency and lower noise.

PHARES is expected to deliver up to 20% of the overall 30% fuel-burn and CO₂ reduction target relative to a 2020 state-of-the-art reference. The project also ensures readiness for operation with 100% Sustainable Aviation Fuels (SAF), aligning propulsion innovation with sustainable fuel strategies.

PHARES will culminate in a ground demonstration at Technology Readiness Level (TRL) 5 and will also deliver the key system to support flight demonstration (TRL 6) within the DEMETRA project. Its consortium leverages strong synergies between European and Canadian technology programmes, reinforcing Clean Aviation’s international reach.

OSYRYS: Enabling the “More-Electric” Aircraft and hybrid-electric propulsion

Hybrid-electric propulsion introduces unprecedented challenges in electrical power generation, distribution, thermal management, and energy management, particularly when handling megawatt-class power levels safely on board an aircraft.

OSYRYS addresses these challenges by developing critical on-board systems technologies, with a special focus on:

- electrical power generation and distribution systems suitable for electric propulsion and more-electric non-propulsive systems

- thermal management systems capable of handling high power densities

- avionics and energy management system solutions to ensure safe, efficient operation.

In close synergy with the other projects, OSYRYS will culminate in integrated demonstrations up to Technology Readiness Level (TRL) 6, delivering system-level readiness essential for the Ultra-Efficient Hybrid-Electric Regional Aircraft.

HERACLES: Defining the Ultra-Efficient Regional Aircraft Concept

While DEMETRA, OSYRYS and PHARES focus on technology demonstration, HERACLES plays a central role in defining the integrated Ultra-Efficient Regional Aircraft (UERA) concept and flight-test demonstrator configuration.

HERACLES brings together:

- hybrid-electric propulsion with high-performance batteries

- an optimized thermal engine operating on 100% SAF

- advanced propeller concepts

- a highly optimized airframe, supported by an upcoming project to be selected as part of Clean Aviation’s fourth Call for Proposals.

- enabling technologies for a more-electric aircraft.

The project targets a minimum 30% CO₂ reduction on typical regional routes, compared with a 2020 reference aircraft. Close collaboration with the other Regional Thrust projects ensures that technologies reaching Technology Readiness Levels (TRL) 5/6 are coherently integrated into a credible aircraft architecture for a 2035 Entry-Into-Service.

DEMETRA: Bringing Hybrid-Electric Technologies to the Sky

DEMETRA is the flagship flight-demonstration project of the Regional Aircraft Thrust. Its objective is to demonstrate and validate key hybrid-electric technologies under real operational flight conditions using a representative CS-25 regional aircraft platform. This requires significant and modifications to the aircraft, including:

- integration of the hybrid powerplant,

- electric and thermal management systems,

- high energy density batteries,

- instrumentation, avionics, and supporting systems for safe and comprehensive testing.

In parallel with flight-testing activities, DEMETRA will validate enabling technologies through ground-based testing, such as:

- wind-tunnel tests of an innovative propeller integrated with nacelle and wing, assessing aerodynamic and acoustic performance,

- development and validation of new control logics, including a single-lever control concept, tested on dedicated avionics benches.

A strong emphasis is placed on certification, with DEMETRA providing critical return of experience on aircraft modification, system integration, and hybrid-electric operations. This will directly support Certification Readiness Level (CRL) maturation towards CRL6 and ensure the technologies are not only innovative, but certifiable for a 2035 entry-into-service.