NASA eyes open-fan engine technology for future airliners

CLEVELAND - The National Aeronautics and Space Administration (NASA) is seeking industry proposals to develop a flight demonstration plan for open-fan aircraft propulsion technology, a concept that could help reduce fuel consumption and emissions in the next generation of commercial airliners.

The solicitation, issued by NASA's Glenn Research Center in Cleveland under the agency's Subsonic Vehicle Technologies and Tools (SVTT) project, calls for industry teams to provide a detailed roadmap for a potential open-fan flight demonstration and optional risk-reduction activities.

Open-fan propulsion systems, sometimes called unducted fans, differ from conventional turbofan engines by eliminating the nacelle that surrounds the engine fan. Instead, large fan blades are exposed to the airflow, allowing the propulsion system to achieve higher propulsive efficiency through larger fan diameters and lower rotational speeds.

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The technology has attracted growing interest from aircraft and engine manufacturers because it could offer substantial reductions in fuel burn compared with today's single-aisle aircraft propulsion systems. However, open-fan designs also introduce technical challenges in aerodynamics, noise, structural integration, safety, and certification, which require additional testing and validation.

Real-world tests needed

NASA said open fans strongly couple aerodynamic, acoustic, structural, and aircraft-configuration effects, making it difficult to accurately predict real-world performance using only ground tests and wind-tunnel experiments. The agency believes flight testing will be necessary to validate analytical models, reduce certification risks, and quantify operational performance and noise characteristics.

The solicitation focuses on single-aisle commercial aircraft capable of carrying 150 to 180 passengers, operating at cruise speeds between Mach 0.78 and 0.82, and supporting design ranges of approximately 3,500 nautical miles.

Selected contractors will develop a six-month flight demonstration plan addressing aircraft integration, structural impacts, propulsion reliability, certification considerations, noise, emissions, and operational requirements. Offerors also may propose optional risk-reduction activities lasting up to 12 months.

NASA is requesting comprehensive development roadmaps that outline required ground and flight demonstrations, technology maturation plans, system integration approaches, performance metrics, cost and schedule estimates, partnership requirements, and risk mitigation strategies.

Proposals must also include analyses of market opportunities and investment strategies for advanced narrowbody aircraft propulsion technologies expected to enter service between 2035 and 2040. Participants are asked to describe future aircraft concepts that incorporate open-fan propulsion and to identify the technologies required to achieve operational readiness.

Advanced Air Vehicles

The effort is part of NASA's Advanced Air Vehicles Program, which supports the development of technologies intended to accelerate the introduction of next-generation aircraft and propulsion systems. The SVTT project was created by consolidating several previous NASA aeronautics initiatives and focuses on technologies for commercial aircraft entering service during the 2030s and beyond.

NASA said the resulting flight demonstration plans will help guide future agency investments and potential flight-test programs designed to evaluate open-fan propulsion concepts under operational conditions. The plans are expected to provide insight into technology-development roadmaps, investment priorities, risk-reduction opportunities, and potential paths toward certification of future open-fan-powered aircraft.

NASA says responses to this project are due on 3 August 2026 at 5 p.m. Eastern. The agency named Hunter Butkovic as the primary point of contact for this inquiry. They can be reached via email at [email protected]. More information is available at https://sam.gov/workspace/contract/opp/191285d0a5f84145b500cdeb815f84e2/view.