MIT and NASA engineers demonstrate a new kind of airplane wing

MIT and NASA engineers demonstrate a new kind of airplane wing
New way of fabricating aircraft wings could enable radical new designs, such as this concept, which could be more efficient for some applications. Credit: Eli Gershenfeld, NASA Ames Research Center

A team of engineers has built and tested a radically new kind of airplane wing, assembled from hundreds of tiny identical pieces. The wing can change shape to control the plane's flight, and could provide a significant boost in aircraft production, flight, and maintenance efficiency, the researchers say.

The new approach to construction could afford greater flexibility in the design and manufacturing of future aircraft. The new wing design was tested in a NASA wind tunnel and is described today in a paper in the journal Smart Materials and Structures, co-authored by research engineer Nicholas Cramer at NASA Ames in California; MIT alumnus Kenneth Cheung SM '07 Ph.D. '12, now at NASA Ames; Benjamin Jenett, a graduate student in MIT's Center for Bits and Atoms; and eight others.

Instead of requiring separate movable surfaces such as ailerons to control the roll and pitch of the plane, as conventional wings do, the new assembly system makes it possible to deform the whole wing, or parts of it, by incorporating a mix of stiff and flexible components in its . The tiny subassemblies, which are bolted together to form an open, lightweight lattice framework, are then covered with a thin layer of similar polymer material as the framework.

The result is a wing that is much lighter, and thus much more energy efficient, than those with conventional designs, whether made from metal or composites, the researchers say. Because the structure, comprising thousands of tiny triangles of matchstick-like struts, is composed mostly of empty space, it forms a mechanical "metamaterial" that combines the structural stiffness of a rubber-like polymer and the extreme lightness and low density of an .

Jenett explains that for each of the phases of a flight—takeoff and landing, cruising, maneuvering and so on—each has its own, different set of optimal wing parameters, so a conventional wing is necessarily a compromise that is not optimized for any of these, and therefore sacrifices efficiency. A wing that is constantly deformable could provide a much better approximation of the best configuration for each stage.

MIT and NASA engineers demonstrate a new kind of airplane wing
Wing assembly is seen under construction, assembled from hundreds of identical subunits. The wing was tested in a NASA wind tunnel. Credit: Kenny Cheung, NASA Ames Research Center

While it would be possible to include motors and cables to produce the forces needed to deform the wings, the team has taken this a step further and designed a system that automatically responds to changes in its aerodynamic loading conditions by shifting its shape—a sort of self-adjusting, passive wing-reconfiguration process.

"We're able to gain efficiency by matching the shape to the loads at different angles of attack," says Cramer, the paper's lead author. "We're able to produce the exact same behavior you would do actively, but we did it passively."

This is all accomplished by the careful design of the relative positions of struts with different amounts of flexibility or stiffness, designed so that the wing, or sections of it, bend in specific ways in response to particular kinds of stresses.

Cheung and others demonstrated the basic underlying principle a few years ago, producing a wing about a meter long, comparable to the size of typical remote-controlled model aircraft. The new version, about five times as long, is comparable in size to the wing of a real single-seater plane and could be easy to manufacture.

While this version was hand-assembled by a team of graduate students, the repetitive process is designed to be easily accomplished by a swarm of small, simple autonomous assembly robots. The design and testing of the robotic assembly system is the subject of an upcoming paper, Jenett says.

MIT and NASA engineers demonstrate a new kind of airplane wing
For testing purposes, this initial wing was hand-assembled, but future versions could be assembled by specialized miniature robots. Credit: Kenny Cheung, NASA Ames Research Center

The individual parts for the previous wing were cut using a waterjet system, and it took several minutes to make each part, Jenett says. The new system uses injection molding with polyethylene resin in a complex 3-D mold, and produces each part—essentially a hollow cube made up of matchstick-size struts along each edge—in just 17 seconds, he says, which brings it a long way closer to scalable production levels.

"Now we have a manufacturing method," he says. While there's an upfront investment in tooling, once that's done, "the parts are cheap," he says. "We have boxes and boxes of them, all the same."

The resulting lattice, he says, has a density of 5.6 kilograms per cubic meter. By way of comparison, rubber has a density of about 1,500 kilograms per cubic meter. "They have the same stiffness, but ours has less than roughly one-thousandth of the density," Jenett says.

Because the overall configuration of the wing or other structure is built up from tiny subunits, it really doesn't matter what the shape is. "You can make any geometry you want," he says. "The fact that most aircraft are the same shape"—essentially a tube with wings—"is because of expense. It's not always the most efficient shape." But massive investments in design, tooling, and production processes make it easier to stay with long-established configurations.

Studies have shown that an integrated body and wing structure could be far more efficient for many applications, he says, and with this system those could be easily built, tested, modified, and retested.

MIT and NASA engineers demonstrate a new kind of airplane wing
Artists concept shows integrated wing-body aircraft, enabled by the new construction method being assembled by a group of specialized robots, shown in orange. Credit: Eli Gershenfeld, NASA Ames Research Center

"The research shows promise for reducing cost and increasing the performance for large, light weight, stiff structures," says Daniel Campbell, a structures researcher at Aurora Flight Sciences, a Boeing company, who was not involved in this research. "Most promising near-term applications are structural applications for airships and space-based structures, such as antennas."

The new wing was designed to be as large as could be accommodated in NASA's high-speed wind tunnel at Langley Research Center, where it performed even a bit better than predicted, Jenett says.

The same system could be used to make other structures as well, Jenett says, including the wing-like blades of wind turbines, where the ability to do on-site assembly could avoid the problems of transporting ever-longer blades. Similar assemblies are being developed to build space structures, and could eventually be useful for bridges and other high performance structures.


Explore further

'Morphing' wing could enable more efficient plane manufacturing and flight

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Apr 01, 2019
The threshold of human-powered flight?

Apr 01, 2019
Isn't it better to have less moving parts? If I'm reading it right that each part moves individually which means this has nothing but moving parts. There are several hundred or thousand in each air frame. It sounds like a great idea if it's not too expensive to replace the parts.

Apr 01, 2019
Isn't it better to have less moving parts?
Fewer. The right word is fewer, not less. 'Less movement' would be proper.

Todays anal post brought to you by otto.

Apr 01, 2019
This piece, and all publicity about the idea, ought to give credited in passing to Wilbur and Orville Wright, who championed 'wing-warp' as the best control mechanism for powered flight.

Apr 01, 2019
FWIW, the Wright Brother's flyer had wings that warped, not ailerons. The latter were invented by Glenn Curtis to get around the Wright patent.

One wonders how the plastic in these wings will stay ductile at the -40 degree temperatures encountered at high altitude.

Apr 01, 2019
This piece, and all publicity about the idea, ought to give credited in passing to Wilbur and Orville Wright, who championed 'wing-warp' as the best control mechanism for powered flight.
But it seems to be a problem for 20th century technology. Given 21st century materials and data processing, we can start operating wings more as gliding birds do it. And, much more primitively, sailboat sailors.

Apr 02, 2019
There will never be true human-powered flight of any duration. Human bone structure and weight prevent it. The best we can hope for are better ways to glide.

Apr 02, 2019
Human bone structure and weight prevent it.
Human-powered flight was accomplished decades ago. The exceptional lightness of the design—it's compared to aerogel—means a sea-change in what we previously thought of as an almost theoretical barrier to avian-like human flight.
Let's see if we can push the envelope to the max. Suppose each of these matchstick struts themselves were constructed out of framework sub-elements? Now suppose we choose boron filaments as the construction material for these elements? As for the airfoil geometry, we're talking slow speeds anyway, for which a thick wing is optimum. Now a thick wing is suited to usefully fill with helium. But if our theoretical max isn't concerned with safety, we'll use hydrogen. Scaled up sufficiently, and remembering the old cube-law scaling advantage, a ten-meter wing on either side may start to tip neutral buoyancy, or better...

And let's not talk about an 80 kg pilot, but a 40 kg body-building superstar...

Apr 02, 2019
FWIW, the Wright Brother's flyer had wings that warped, not ailerons. The latter were invented by Glenn Curtis to get around the Wright patent.

One wonders how the plastic in these wings will stay ductile at the -40 degree temperatures encountered at high altitude.


Conduct heat from the engines through the wings in a vascular system with tubes of heated fluid. this would be like how the heart and blood vessels work and would also be good for de-icing aerodynamic surfaces.

By the way, I love this concept, similar to the Starship stainless steel design, sometimes a simpler design performs better. Biomimicry is the way!

Apr 02, 2019
...how the plastic in these wings will stay ductile at the -40 degree temperatures encountered at high altitude.
Conduct heat from the engines through the wings in a vascular system with tubes of heated fluid. this would be like how the heart and blood vessels work and would also be good for de-icing aerodynamic surfaces.


By 'ductile' I think 'flexible' is the word; the former means extrudibly plastic. By the time they actually get around to building working airframes, they'll be flexible—or stiff, as needs be— off-shelf material for the struts. As for icing, the article mentions plastic surfaces, and again, as the time rolls around for the concept to be realized, they'll probably have plastics with the toughness of polypropylene and the slickness of PTFE. And in concert with the latter, airfoil configurability that would, say, temporarily cause boundary layer separation and turbulent flow that would easily rip ice off an already un-adhering teflonlike substrate.

Apr 06, 2019
Not into aerospace, but it does not seem like the structural density of these many parts would not withstand supersonic flight. I see the first image looks very much like a B-2 Spirit.

Am i missing something here. An SR-71 Blackbird flew around 3 mach + and had major issues with heating of surfaces at those speeds, and they were made of titanium if I remember correctly.

Seems like heating would be a limiting factor here.

Apr 08, 2019
Unlikely to work. too many nuts and bolts

Apr 08, 2019
We need to separate the effects of wing morphing from basic air-vehicle design. A flying wing that is thick enough to contain passengers and freight has one kind of advantages and a self-morphing wing another set. However in the latter case the structural needs are scarcely different from a conventional wing and so the whole thing is bound to be heavier. The swept flying wing is definitely lighter, but various stability problems have ruled it out in the past, (such as the HP 117 project, which incidentally also included boundary-layer suction for low profile drag).

Apr 12, 2019
I wonder how robust this wing would be if struck by some object, like a large bird. This week, there was a jet which got caught by a gust of wind and tipped so much that its wing tip hit a sign along the runway during takeoff. Left quite a dent, but was probably stopped by the stronger interior structure. I can see an object simply going through this wing. All those little pieces would just snap, one after the other... Very interesting though.

Apr 16, 2019
Nice, concept on the path to future soliton holographic faster than light propulsion.

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