NASA's strange wing design could lead to futuristic, fuel-efficient planes

A recent version of the wing concept reinforced by transonic armor in a wind tunnel at NASA's Langley Research Center. They carried out tests between September and November 2019. (Harlen Capen / NASA /)

In January, Boeing piloted its new elegant wide-body aircraft for the first time. Called the 777x, the most striking feature of the aircraft is the wings which literally fold at its ends. The wings are longer than those of previous versions of this aircraft, a change in design which increases the overall energy efficiency of the ship. Meanwhile, the spikes fold back when they are on the ground so that you can crawl up to the airport gate.

And in late April, Boeing flew second 777x test aircraft for almost three hours.

In addition to the fact that the wings extend over a long distance and then articulate at the ends to the ground, the new 777x aircraft, designed to carry up to 426 passengers, basically resembles any other aircraft you've ever seen. It is a tube with wings that protrude directly.

But since 2008, NASA and Boeing have been looking for a fascinating wing design that is best suited to small commercial aircraft, such as the 737 or A320, which can accommodate around 220 or 240 people. And the shape of the wing is unlike anything that has flown before. The long and slim wings of the new design promise to create less drag, as with the 777x, the resulting fuel economy is quite significant, but the extra armor under the wings supports its long clearance . NASA tested different versions of the design in wind tunnels in California and Virginia, and the most recent tests took place in a wind tunnel at its Langley Research Center in the fall of last year.

They call the design reinforced wing transonic armor, or TTBW. While a standard 737 has a wingspan of around 118 feet, the wings of this ship could extend up to 170 feet in length. They also leaned at the ends to enter the door.

But you can probably imagine the problems that such a structure could create. "If the wing lengthens and thins, it becomes more flexible," said Richard Wahls, strategic technical advisor for NASA's advanced air vehicle program. No passenger wants to look out the window and see very long wings flapping and moving around them.

In fact, the dire situation in which a long, thin wing can be found is known as aeroelastic floating. At "bad frequencies," says Wahls, a wing or other structure that floats will fail catastrophically. A classic example is the Tacoma Narrows Bridge, which beat until it collapsed in 1940, but the same kind of fate can happen to an airplane wing. Kevin James, aerospace research engineer at NASA's Ames Research Center, compares what can happen to a wing like the flapping, twisted or twisted wing that you may notice a stop sign manifesting by strong winds. "The long thin wings also want to do it, and it would be a very bad day, it's not a good experience for the passengers," jokes James.

A test at the Ames research center. (Dominic Hart / NASA /)

It's physics

With planes like the TTBW, aerospace engineers love the idea of ​​long, thin wings because they can reduce wing drag. Wings like this ideally produce weak and not strong vortices at their ends. Weaker vortices can generate less drag and hopefully more fuel economy. "At the end of the wing, where there are no more wings beyond what the air can see, the air is very intelligent and just spin around the tip, "says James. "The more we can make wings (stretch), the more lift we can generate, more efficiently."

But of course, NASA and future aircraft manufacturers don't want their long, fuel-efficient wing to flex and take off as well.

The large trusses provide the necessary support, giving the structure another connection point to the fuselage and preventing the runaway beat. Another problem is the weight: long, thin wings without trusses should be so rigid and heavy that they would negate fuel economy. After all, you wouldn't want to add a spoiler to your car if it were to be solid lead.

According to NASA Wahls, the new wing configuration could save approximately 9% of the fuel consumption of a future TTBW aircraft.

Another advantage of the design is that instead of fixing the wing in the center or at the bottom of the fuselage, this configuration has the wings mounted on top. This allows any aircraft manufacturer to hang larger engines under the wing (larger diameter engines are also more fuel efficient) without worrying about scratching the ground.

While aircraft manufacturers like Boeing will never build a plane with a design like this, Wahls says they would like to bring the technology to a place where it could be "legitimately considered" in the 2030s.

Meanwhile, when it comes to futuristic planes that are as efficient and durable as possible, after all, more efficient a flying machine