Video: Engineering the turbulence out of long, thin jet wings

Making the wings on passenger jets thinner and longer can go a long way toward reducing drag and making them more efficient, but they vibrate like crazy. Engineers at NASA and Boeing are now tackling the problem.

As a first step toward exploring the use of slimmed-down jumbo jet wings, the team recently completed wind-tunnel testing of a "higher aspect ratio wing model." The tests were conducted as part of NASA and Boeing's Integrated Adaptive Wing Technology Maturation collaboration, and sought a way to take advantage of the wings' improved efficiency while controlling the turbulence they produce.

“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.”

To carry out the tests, the team used a large-scale plane model created by NextGen Aeronautics. Looking like a jet that had been sawn down the middle, the model featured a thin 13-foot (3.9-m) wing that was put through its paces at NASA Langley’s Transonic Dynamics Tunnel, a facility that has a test section measuring 16 ft high by 16 ft wide (about 5 x 5 m). You can learn more about the testing in the following video.

The wing they tested was equipped with 10 movable panels along the wing's rear edge, known as control surfaces. By adjusting those surfaces, the team was able to take a considerable amount of shimmy out of the wing's performance.

“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.”

Now the NASA/Boeing team is analyzing the test data produced and, when complete, will share the information with the aviation community.

“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.”

The testing was conducted as part of NASA's Advanced Air Transport Technology project, an initiative that seeks to improve efficiency and reduce environmental impact in fixed-wing transport aircraft.

Source: NASA