Quiet Wings, With Shape Memory Alloy

It’s a fact of operating an aircraft, that the make noise. If you’re an aviator you might want to quiet your craft to avoid annoying people nearby, or you might even want to operate in stealth mode. It turns out that there are different sources of noise on a plane depending upon the phase of flight. A NASA study found that when landing, a gap between the wing and leading edge slats causes air to cavitate causing unnecessary noise. Blocking that hole would allow for quieter landings, but there was no material suitable for both normal flight and the landing. That is, until Texas A&M researchers devised a way to use a shape memory alloy to do it.

In addition to two different shape memory alloy configurations, the study looks at a more conventional fiberglass composite, although this would only work for a limited number of wing configurations.

Quite a bit of the paper is pretty high-octane math simulations, but if you are serious about quieting down your next winged drone design it might be worth wading through.

We don’t see many shape memory projects, but the technology is accessible. We recently saw a clever use of leading-edge slats in a scrappy experimental aircraft.

12 thoughts on “Quiet Wings, With Shape Memory Alloy

  1. It’s a bit misleading to say “to block that hole”.. is a method of reducing noise. The idea behind the leading edge slat is to impose a structure ahead of the wing that gives the wing more lift so the plane can land at a slower speed. You can not block the hole between the slat and wing or you’ll produce no additional lift. I looked at the paper and what it says is that there is turbulence created between the slat and wing which creates noise. The paper describes creating a filler on the slat that partially fills the gap between the slat and leading edge of the wing and thus prevents the turbulence and its noise. They presented multiple ways of doing this with shape memory alloy being one of them.

    Incidentally, noise production in aerodynamics signals inefficiency. The very best efficient designs make little noise.

    1. Not to mention the fact that air flowing between the slat and leading edge is kind of the point of the slats (yes, I know it’s much more complex than that). Block that off and slats are nothing more than leading edge extensions, which probably would do little to reduce the wing’s stall speed.

  2. Now if they were really smart, they would have taken it a step further by simplifying flight. You can do this by removing the exceptionally complex engines and instead make the wing able to rapidly deform in multiple directions. Then maybe replace the pilots with a built-in cognitive system and replace the need to manufacture fuel by using a metabolic system. Birds, they should have invented birds. :)

  3. Air doesn’t “cavitate.” It can become turbulent and cause a separation with the smooth flow of air away from the wing contour. It can also set up a resonance within a cavity such as is formed between the slat and the remainder of the wing.

    This looks like an interesting approach; it would be good to see an implementation.

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