Aircraft

MIT and NASA develop auto-morphing "metamaterial" wing made of hundreds of tiny parts

View 4 Images
Wing assembly is seen under construction, assembled from hundreds of identical subunits. The wing was tested in a NASA wind tunnel
NASA
The new way of fabricating aircraft wings could enable radical new designs, such as this concept, which could be more efficient for some applications
Eli Gershenfeld/NASA Ames Research Center
Wing assembly is seen under construction, assembled from hundreds of identical subunits. The wing was tested in a NASA wind tunnel
NASA
For testing purposes, this initial wing was hand-assembled, but future versions could be assembled by specialized miniature robots
Kenny Cheung/NASA Ames Research Center
Artist's concept shows integrated wing-body aircraft, enabled by the new construction method being assembled by a group of specialized robots, shown in orange
Eli Gershenfeld/NASA Ames Research Center
View gallery - 4 images

A team of researchers led by NASA and MIT have come up with a radical new wing design that is not only much lighter than conventional wings, but also has the potential to automatically reconfigure itself to meet the flight conditions of the moment. Built out of tiny, identical polymer tiles connected by struts, the new mechanical "metamaterial" promises faster, cheaper aircraft production and maintenance.

Airplane wings are complicated structures that are expensive to design, build, and maintain. In order to do their job, they require an intricate system of control surfaces, motors, cables, and hydraulics to function so that a rigid wing can use rigid control surfaces that slide and tilt to control the flow of air passing over them.

The problem is that such rigid surfaces are nowhere near as efficient as they could be. Worse, every wing is a compromise – not with an ideal wing, but between an entire series of ideal wing shapes that would be needed to provide the best performance while taking off, landing, and every other flight condition in between.

The new way of fabricating aircraft wings could enable radical new designs, such as this concept, which could be more efficient for some applications
Eli Gershenfeld/NASA Ames Research Center

This a major reason why aircraft are so expensive to build and also why their design is almost invariably the sub-optimal one of a pair of wings stuck onto a tube.

However, the NASA/MIT team has an alternative in the form of a morphing wing. That idea isn't new. The very first Wright Flyer in 1903 used a morphing wing for controls, but the new idea is to build the wing out of tiles in the form of tiny, identical, hollow, rubber-like polymer cubes, triangles, or other shapes made up of matchstick-size struts along each edge. These can be bolted together to form an open, lightweight lattice framework that is covered by a thin layer of a similar polymer as a skin.

According to MIT, the result is a mechanical "metamaterial" that has the same stiffness as a conventional wing, but the density of an aerogel. In terms of numbers, that means reducing the density of rubber from 1,500 kg per cubic meter down to 5.6 kg per cubic meter. This not only makes the wing much lighter, but also capable of reshaping itself to meet flight conditions.

Artist's concept shows integrated wing-body aircraft, enabled by the new construction method being assembled by a group of specialized robots, shown in orange
Eli Gershenfeld/NASA Ames Research Center

But the clever bit is that the design can be made even simpler and lighter by removing the need for complex, heavy actuators and cables to do the reconfiguring. The team says that by matching the flexibility and relative position of the struts in the wing material to the loads placed on it, it can passively and automatically reconfigure itself into the needed form.

The first version of the material was made by hand using water jets to produce each tile in a matter of minutes, but a new injection molding method has cut this down to 17 seconds. By combining this with robotic assembly, it will be possible to not only scale up the system while keeping down costs, but it will also free up engineers to use more efficient aircraft designs, such as a blended wing where the hull and wing meld into one another. In addition, the system could also be used to build large wind turbines on site or for manufacturing structures in space.

Source: MIT

View gallery - 4 images
  • Facebook
  • Twitter
  • Flipboard
  • LinkedIn
7 comments
Bob Stuart
Given that every bolted connection costs weight - cable suspension bridges are ten times longer than chain supported ones - the strength of this scheme must be barely adequate for a static model.
toyhouse
Fascinating. Covered with a polymer skin. When I was young building rc gliders, I learned quickly that the bulk of strength came from the covering. But I'm not sure that's where the bulk of strength comes from here. It appears to be used as a way to smooth the changing shape being generated? What's also not mentioned here is control. The passive portion of adapting to changing flight needs is mentioned, (though a drawing would be nice),. Control surfaces aren't clearly visible from the images above - possibly in the artist rendering? So does that mean flight controls are part of the tiles re-configuring themselves somehow?
bullfrog84
Getting there. Another step in the right direction. However, like Bob said; the connections, in many ways, are already something that could be assumed to cause unnecessary stress on the craft.
Paul Muad'Dib
The shape of the airfoil looks like it's made from 3 flat panels, this is aerodynamically inefficient. Remember the Lockheed F-117 Nighthawk? In the illustration the airplane's surface looks like it's pretty bumpy, which is also aerodynamically inefficient.
ChairmanLMAO
seems to me like the organ connecting the milliflaps is a series of stretchable tendons connected at the wingtip spread through guides and then connected to a motor for fine control and uniformity throughout the surface causing more action on the closer flaps and less the farther out. no need for actuators or even computers. just engineered tendons and 3d printed flaps
ljaques
Um, YOU FIRST! What happens to a wing when subjected to a bird strike or large hail? Does it become frangible when iced? A polymer skin seems fragile enough to be less than ideal when it's the only thing holding the "dense as aerogel" pieces together. I'm going to guess that this stuff does not scale up to usable size well, but it may find its niche in drones and RC craft.
Ralf Biernacki
This idea has been around for a long time---it's called a truss. Look at a construction crane: you could describe its column and beam as being "light as aerogel" because they're mostly empty. The innovations here are 1. covering a cellular truss structure with a membrane to make it streamlined, and 2. designing the structure using computer modeling so that its deformation under stress is aerodynamically advantageous. But I doubt bolting is the optimal way of connecting the truss cells here. And I think inadequate stiffness will prove a problem, eating away most of the lightness advantage.