A Twist on Wing Design

Tuesday, November 15th, 2016

MIT researchers are testing a shaping-changing wing that could replace the hinged flaps and ailerons of conventional flight controls:

They constructed the wing from tiny lightweight structural pieces made with Kapton foil on an aluminum frame, arranged in a lattice of cells like a honeycomb. The skin of the wing is made with overlapping strips of the flexible foil, layered like fish scales, allowing the pieces to slide across each other as the wing flexes, they said.

Flexible Wing from MIT

Two small motors apply a twisting pressure to each wingtip to control maneuvers in flight. They say this elastic airfoil can morph continuously to reduce drag, increase stall angle, and reduce vibration control flutter.

The Soft Robotics abstract:

We describe an approach for the discrete and reversible assembly of tunable and actively deformable structures using modular building block parts for robotic applications. The primary technical challenge addressed by this work is the use of this method to design and fabricate low density, highly compliant robotic structures with spatially tuned stiffness.

This approach offers a number of potential advantages over more conventional methods for constructing compliant robots. The discrete assembly reduces manufacturing complexity, as relatively simple parts can be batch-produced and joined to make complex structures. Global mechanical properties can be tuned based on sub-part ordering and geometry, because local stiffness and density can be independently set to a wide range of values and varied spatially. The structure’s intrinsic modularity can significantly simplify analysis and simulation. Simple analytical models for the behavior of each building block type can be calibrated with empirical testing and synthesized into a highly accurate and computationally efficient model of the full compliant system.

As a case study, we describe a modular and reversibly assembled wing that performs continuous span-wise twist deformation. It exhibits high performance aerodynamic characteristics, is lightweight and simple to fabricate and repair. The wing is constructed from discrete lattice elements, wherein the geometric and mechanical attributes of the building blocks determine the global mechanical properties of the wing. We describe the mechanical design and structural performance of the digital morphing wing, including their relationship to wind tunnel tests that suggest the ability to increase roll efficiency compared to a conventional rigid aileron system. We focus here on describing the approach to design, modeling, and construction as a generalizable approach for robotics that require very lightweight, tunable, and actively deformable structures.


  1. Bob Sykes says:

    The Wright brothers called it “wing warping”, and it was how the original Flyer was controlled. Glenn Curtiss invented the aileron, which proved more useful. The MIT team carries wing warping further than the Wrights. It will be interesting to see if it succeeds commercially or militarily.

  2. Ross says:

    They are evolving toward feathers! Cool!

  3. Slovenian Guest says:

    Speaking of wings, from howwingswork.pdf by Dr. Holger Babinsky:

    “The popular explanation of lift is common, quick, sounds logical and gives the correct answer, yet also introduces misconceptions, uses a nonsensical physical argument and misleadingly invokes Bernoulli’s equation. A simple analysis of pressure gradients and the curvature of streamlines is presented here to give a more correct explanation of lift.”

    He also has a poorly filmed lecture on YouTube.

  4. Alrenous says:

    The Bernoulli explanation of lift is not actually different than the Newton/reaction explanation, though they appear superficially different.

    If there’s a pressure difference, air will be forced downward, and if air is forced downward without a pre-existing pressure difference, it will cause an overpressure in the region it’s being forced down. Empirically they will look identical…as far as I know, anyway.

    I tried his ‘blow on paper’ experiment and got the opposite to the claimed result.

  5. Ross says:

    Things such as the Coanda Effect and wingtip vortex dragging have a profound (and usually unacknowledged) effect on lift.

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