Safran Logs 400 Hours Testing CFM RISE Open Fan Acoustics

Safran Aircraft Engines has completed more than 400 hours of wind tunnel testing on its 1/5-scale ECOENGInE demonstrator, advancing the acoustic and aerodynamic validation of the CFM RISE Open Fan architecture.

In a press release published on June 12, 2026, the manufacturer detailed its progress following the 32nd American Institute of Aeronautics and Astronautics (AIAA) and Council of European Aerospace Societies (CEAS) Aeroacoustics Conference held in Brussels, Belgium, on May 28, 2026. The testing program addresses the primary environmental and regulatory hurdle for open rotor engines: managing noise emissions without a traditional engine nacelle.

Validating the Open Fan architecture

The ECOENGInE demonstrator testing took place at the ONERA S1MA wind tunnel in France and the DNW Large Low-speed Facility in the Netherlands. The test campaign stems from a framework agreement announced on January 19, 2024, between Safran and ONERA. The French Civil Aviation Authority (DGAC) supports the initiative through the Civil Aviation Research Council (CORAC) plan, which funds research to simulate real-world airspeeds and validate the fan module’s performance.

The 400 hours of accumulated testing provide physical data to verify numerical simulations of the Open Fan configuration as it would be installed on a commercial aircraft wing. This physical validation is required to prove that the computer models accurately predict how the airflows and sound waves will behave in flight.

Acoustic challenges of the CFM RISE program

The CFM Revolutionary Innovation for Sustainable Engines (RISE) program is managed by CFM International, a 50/50 joint company between Safran Aircraft Engines and GE Aerospace. The program targets a 20% reduction in fuel consumption and carbon dioxide emissions compared to current-generation commercial aircraft engines, with an entry-into-service goal of 2035 for next-generation single-aisle jets.

Removing the engine nacelle is central to achieving these efficiency gains through a significantly higher bypass ratio. However, the un-ducted design exposes the fan blades, creating complex aeroacoustic phenomena. Engineers must mitigate this noise to comply with stringent airport community noise regulations and ensure passenger cabin comfort.

At the AIAA/CEAS conference, Safran authored or co-authored approximately 12 technical papers detailing these efforts. The research involves collaboration with multiple European institutions, including the German Aerospace Center (DLR), the Royal Netherlands Aerospace Centre (NLR), the von Karman Institute for Fluid Dynamics in Belgium, and the École Centrale de Lyon in France.

AirPro News analysis

We view the accumulation of 400 wind tunnel test hours as a critical de-risking step for the CFM RISE program. While the targeted 20% fuel burn reduction offers a clear economic incentive for airlines, acoustic certification remains the most significant technical barrier for any open rotor architecture. Historical attempts at un-ducted fans in the 1980s faltered largely due to insurmountable cabin and community noise issues.

By demonstrating that modern numerical acoustic modeling aligns with physical wind tunnel data, Safran and GE Aerospace are building the foundational environmental case required by the Federal Aviation Administration (FAA) and the European Union Aviation Safety Agency (EASA). The extensive involvement of European academic and state research institutions also indicates a broad regulatory and governmental alignment behind the Open Fan concept ahead of the 2035 target date.

Sources: Safran Group