NASA researchers successfully completed a high-speed taxi test of a scale model of a design that could make future aircraft more efficient by improving how air flows across a wing’s surface, saving fuel and money.

On Jan. 12, the Crossflow Attenuated Natural Laminar Flow (CATNLF) test article reached speeds of approximately 144 mph, marking its first major milestone. The 3-foot-tall scale model looks like a fin mounted under the belly of one of the agency’s research F-15B testbed jets. However, it’s a scale model of a wing, mounted vertically instead of horizontally. The setup allows NASA to flight-test the wing design using an existing aircraft.

The CATNLF concept aims to increase a phenomenon known as laminar flow and reduce wind resistance, also known as drag.

A NASA computational study conducted between 2014 and 2017 estimated that applying a CATNLF wing design to a large, long-range aircraft like the Boeing 777 could achieve annual fuel savings of up to 10%.  Although quantifying the exact savings this technology could achieve is difficult, the study indicates it could approach millions of dollars per aircraft each year.

“Even small improvements in efficiency can add up to significant reductions in fuel burn and emissions for commercial airlines,” said Mike Frederick, principal investigator for CATNLF at NASA’s Armstrong Flight Research Center in Edwards, California.

Reducing drag is key to improving efficiency. During flight, a thin cover of air known as the boundary layer forms very near an aircraft’s surface. In this area, most aircraft experience increasing friction, also known as turbulent flow, where air abruptly changes direction. These abrupt changes increase drag and fuel consumption. CATNLF increases laminar flow, or the smooth motion of air, within the boundary layer. The result is more efficient aerodynamics, reduced friction, and less fuel burn.

The CATNLF testing falls under NASA’s Flight Demonstrations and Capabilities project, a part of the agency’s Integrated Aviation Systems Program under the Aeronautics Research Mission Directorate. The concept of was first developed by NASA’s Advanced Air Transport Technology project, and in 2019, NASA Armstrong researchers developed the initial shape and parameters of the model. The design was later refined for efficiency at NASA’s Langley Research Center in Hampton, Virginia.

“Laminar flow technology has been studied and used on airplanes to reduce drag for many decades now, but laminar flow has historically been limited in application,” said Michelle Banchy, Langley principal investigator for CATNLF.

This limitation is due to crossflow, an aerodynamic phenomenon on angled surfaces that can prematurely end laminar flow. While large, swept wings like those found on most commercial aircraft provide aerodynamic efficiencies, crossflow tendencies remain.

In a 2018 wind tunnel test at Langley, researchers confirmed that the CATNLF design successfully achieved prolonged laminar flow.

“After the positive results in the wind tunnel test, NASA saw enough promise in the technology to progress to flight testing,” Banchy said. “Flight testing allows us to increase the size of the model and fly in air that has less turbulence than a wind tunnel environment, which are great things for studying laminar flow.”

NASA Armstrong’s F-15B testbed aircraft provides the necessary flight environment for laminar flow testing, Banchy said. The aircraft enables researchers to address fundamental questions about the technology while keeping costs lower than alternatives, such as replacing a test aircraft’s wing with a full-scale CATNLF model or building a dedicated demonstrator aircraft.

CATNLF currently focuses on commercial aviation, which has steadily increased over the past 20 years, with passenger numbers expected to double in the next 20, according to the International Civil Aviation Organization. Commercial passenger aircraft fly at subsonic speeds, or slower than the speed of sound.

“Most of us fly subsonic, so that’s where this technology would have the greatest impact right now,” Frederick said. NASA’s previous computational studies also confirmed that technology like CATNLF could be adapted for supersonic application.

In the coming weeks, CATNLF is expected to begin its first flight, kicking off a series of test flights designed to evaluate the design’s performance and capabilities in flight.

Looking ahead, NASA’s work on CATNLF could lay the groundwork for more efficient commercial air travel and might one day extend similar capabilities to supersonic flight, improving fuel efficiency at even higher speeds.

“The CATNLF flight test at NASA Armstrong will bring laminar technology one step closer to being implemented on next-generation aircraft,” Banchy said.

The airliner you board in the future could look a lot different from today’s, with longer, thinner wings that provide a smoother ride while saving fuel.

Those wings would be a revolutionary design for commercial aircraft, but like any breakthrough technology, they come with their own development challenges – which experts from NASA and Boeing are now working to solve. 

When creating lift, longer, thinner wings can reduce drag, making them efficient. However, they can become very flexible in flight.

Through their Integrated Adaptive Wing Technology Maturation collaboration, NASA and Boeing recently completed wind tunnel tests of a “higher aspect ratio wing model” looking for ways to get the efficiency gains without the potential issues these kinds of wings can experience. 

“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 the right engineering, long, thin wings could potentially bend or experience a condition known as wing flutter, causing aircraft to vibrate and shake in gusting winds.  

“Flutter is a very violent interaction,” Pinkerton said. “When the flow over a wing interacts with the aircraft structure and the natural frequencies of the wing are excited, wing oscillations are amplified and can grow exponentially, leading to potentially catastrophic failure. Part of the testing we do is to characterize aeroelastic instabilities like flutter for aircraft concepts so that in actual flight, those instabilities can be safely avoided.” 

To help demonstrate and understand this, researchers from NASA and Boeing sought to soften the impacts of wind gusts on the aircraft, lessen the wing loads from aircraft turns and movements, and suppress wing flutter.

Reducing or controlling those factors can have a significant impact on an aircraft’s performance, fuel efficiency, and passenger comfort. 

Testing for this in a controlled environment is impossible with a full-sized commercial airliner, as no wind tunnel could accommodate one.

However, NASA Langley’s Transonic Dynamics Tunnel, which has been contributing to the design of U.S. commercial transports, military aircraft, launch vehicles, and spacecraft for over 60 years, features a test section 16 feet high by 16 feet wide, big enough for large-scale models. 

 To shrink a full-size plane down to scale, NASA and Boeing worked with NextGen Aeronautics, which designed and fabricated a complex model resembling an aircraft divided down the middle, with one 13-foot wing.

Mounted to the wall of the wind tunnel, the model was outfitted with 10 control surfaces – moveable panels – along the wing’s rear edge. Researchers adjusted those control surfaces to control airflow and reduce the forces that were causing the wing to vibrate.

Instruments and sensors mounted inside the model measured the forces acting on the model, as well as the vehicle’s responses.

The model wing represented a leap in sophistication from a smaller one developed during a previous NASA-Boeing collaboration called the Subsonic Ultra Green Aircraft Research (SUGAR).

“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 set of tests, conducted in 2024, gave experts baseline readings that they compared to NASA computational simulations, allowing them to refine their models. A second set of tests in 2025 used the additional control surfaces in new configurations.

The most visible benefits of these new capabilities appeared during testing to alleviate the forces from gusting winds, when researchers saw the wing’s shaking greatly reduced.

With testing completed, NASA and Boeing experts are analyzing data and preparing to share their results with the aviation community. Airlines and original equipment manufacturers can learn and benefit from the lessons learned, deciding which to apply to the next generation of 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 works to advance aircraft design and technology under the agency’s Advanced Air Vehicles program, which studies, evaluates, and develops technologies and capabilities for new aircraft systems. The project and program fall within NASA’s Aeronautics Research Mission Directorate. 

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