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A “radically new” wing made from hundreds of small identical pieces automatically adjusts its shape in response to aerodynamic load, a step that could have major implications for aircraft efficiency and manufacture.

The material structure, which is designed to be assembled by ‘swarms’ of small assembly robots, could also be adapted for other modern structures such as space antennas or increasingly large wind turbine blades.

Created by ambitious engineers at NASA, MIT, Cornell University, the University of California, Kaunas University of Technology in Lithuania and Qualified Technical Services in California, the wing’s adaptability could allow much greater flexibility in aircraft design and manufacture.

Instead of requiring separate moveable surfaces such as ailerons to control the roll and pitch of the plane, 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 structure. The tiny ‘subassemblies’, bolted together to form an open, lightweight lattice framework, are covered with a thin layer of similar polymer material as the framework. The result, said the researchers, is a wing that is much lighter and therefore much more energy efficient than conventional wings, whether made from metal or composites.

A step further

Each phase of flight – take-off and landing, cruising and manoeuvring, for example – has a different set of optimal wing parameters, said MIT’s Benjamin Jenett. This means that conventional wings are a compromise, and not completely suited for any phase. A wing that is constantly deformable could come much closer to the best configuration for each stage.

It would be possible to include motors and cables to deform the wing, the researchers said. Instead, they claim to have “gone a step further”, designing a system that automatically responds to changes in aerodynamic loading by changing shape.

The self-adjusting, passive wing configuration was enabled 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. The lattice reportedly has the same stiffness as rubber, but with much lower density – 5.6kg per m3, compared to 1,500kg.

The ‘meta-material’ could be particularly suited for integrated body and wing structures, which might be efficient for many applications. Simple building, testing and modification could allow greater flexibility in design and manufacture, while its light weight and adaptability could make aircraft much more efficient – a key goal for the aerospace sector as manufacturers and operators seek to counter rising emissions.

The same system could be used for other structures such as wind turbine blades, said Jenett. On-site assembly could help avoid the problems of transporting ever-longer blades. Similar assemblies are being developed for space structures, and could eventually be useful for bridges and other high-performance structures.

The work was supported by the NASA ARMD Convergent Aeronautics Solutions Programme and the MIT Centre for Bits and Atoms.

Content published by Professional Engineering does not necessarily represent the views of the Institution of Mechanical Engineers.