Those high aspect ratio wings promise lower drag and better efficiency, but their increased flexibility introduces structural and control challenges that engineers must address before airlines can adopt them.

As part of the Integrated Adaptive Wing Technology Maturation collaboration, NASA and Boeing have carried out wind tunnel experiments on a higher aspect ratio wing model to investigate how to capture aerodynamic benefits while limiting unwanted motion.

"When you have a very flexible wing, you're getting into greater motions," said Jennifer Pinkerton, a NASA aerospace engineer at NASA Langley Research Center in Hampton, Virginia. "Things like gust loads and maneuver loads can cause even more of an excitation than with a smaller aspect ratio wing. Higher aspect ratio wings also tend to be more fuel efficient, so we're trying to take advantage of that while simultaneously controlling the aeroelastic response."

Without appropriate control systems and structural design, long, thin wings can bend significantly or enter wing flutter, a condition in which airflow interacts with the structure and excites natural frequencies, driving oscillations that can grow rapidly and threaten the airframe.

To map and manage these behaviors, NASA and Boeing set out to reduce the impact of wind gusts on the wing, lessen loads during turns and maneuvers, and suppress flutter across the operating envelope.

These factors directly influence aircraft performance, fuel consumption, and passenger comfort, but cannot be tested on full-size jetliners in a wind tunnel because no facility can accommodate an entire commercial aircraft.

Instead, the campaign used NASA Langley's Transonic Dynamics Tunnel in Hampton, Virginia, a facility with a 16-by-16-foot test section that has supported the development of U.S. commercial, military, launch vehicle, and spacecraft designs for more than six decades.

To create a suitable model, NASA and Boeing worked with NextGen Aeronautics, which designed and built a complex half-aircraft configuration mounted to the tunnel wall, featuring a single 13-foot wing representing a scaled transport.

Along the trailing edge of that wing, the team installed 10 movable control surfaces that could be adjusted to shape airflow and counteract aerodynamic forces responsible for wing vibration and structural loading.

Sensors and instruments embedded in the model measured both the aerodynamic forces applied to the structure and the resulting motions, providing data needed to understand the aeroelastic response under different test conditions.

This wing model extends earlier work from the Subsonic Ultra Green Aircraft Research program, which used a smaller configuration with fewer active surfaces to explore advanced transport concepts.

"The SUGAR model had two active control surfaces," said Patrick S. Heaney, principal investigator at NASA for the Integrated Adaptive Wing Technology Maturation collaboration. "And now on this particular model we have ten. We're increasing the complexity as well as expanding what our control objectives are."

A first test series in 2024 produced baseline measurements that researchers compared with NASA computational simulations, allowing them to tune analytical models and improve prediction accuracy.

A follow-on campaign in 2025 used the additional control surfaces in new arrangements, enabling trials of updated control laws and strategies for managing wing motion and loads.

The most visible gains were seen in runs aimed at alleviating the effects of gusting winds, where the active wing showed much less shaking than in uncontrolled cases, indicating that the control approach can substantially reduce gust response.

With the tunnel work finished, NASA and Boeing engineers are processing the results and preparing to brief the wider aviation sector so that airlines and airframe manufacturers can assess which elements to incorporate into future aircraft.

"Initial data analyses have shown that controllers developed by NASA and Boeing and used during the test demonstrated large performance improvements," Heaney said. "We're excited to continue analyzing the data and sharing results in the months to come."

NASA's Advanced Air Transport Technology project, within the Advanced Air Vehicles program of the Aeronautics Research Mission Directorate, leads this work to mature wing and control concepts that could be integrated into upcoming ultra-efficient transport designs.

Related Links
NASA Aeronautics Research Mission
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