There are many different special tricks used to aid animals in flight. From dynamic soaring to gliding, animals have found numerous ways to get airborne. One trick in particular is whats called “clap-flinging.” It is a trick primarily used by insects, especially small ones, to increase lift during take-off. Without it they could not gain enough lift to be able to get off the ground.
Essentially the animal will take their wings and “clap” them together above themselves on the up stroke. The wings are then peeled apart and “flung,” followed by a regular downstroke. This increases lift by reducing the Wagner Effect, which can be a great problem for small insects. When an animal first starts moving it’s wing it can take a while for the bound vortex, which produces lift, to build up. This can cause a large decrease in lift during the beginning of the downstroke. This effect is caused both by interference from the starting vortex and acceleration. This decrease in lift is magnified in small insects due to the viscosity of the air.
However, the clap-fling mechanism allows animals to overcome the Wagner Effect. The leading edges of the wings separate first after the clap, while the trailing edges remain together. Then the trailing edges separate into a normal downstroke. This eliminates the starting vortex and causes the bound vortex to form near the beginning of the downstroke. A counter vortex is also produced which creates low-pressure above the animal. All this allows the animal to start generating lift far earlier than in a regular downstroke.
This technique is mainly used by insects but can also be seen in larger animals. Pigeons use this technique during lift-off, as shown above. This is what causes the distinctive sound made when pigeons takeoff. However, clap-flinging is mostly seen in very tiny insects. It was first observed in the minuscule parasitic wasps by Weis-Fogh, but many tiny insects use it during regular flight. A video of clap-flinging can be seen here.
Alexander, David. Nature’s Flyers: Birds, Insects, and the Biomechanics of Flight Birds, Insects and the Iomechanics of Flight. Baltimore: Johns Hopkins UP, 2002. 93-95. Print.
Dudley, Robert. The Biomechanics of Insect Flight: Form, Function, Evolution. Princeton, NJ: Princeton UP, 2000. 130-31. Print.
Habib, Michael. “Clap and Fling.” Aerial Evolution. 13 June 2012. Web. 5 Dec. 2012. <http://aeroevo.blogspot.com/2012/06/clap- and-fling.html>.
Lighthill- Weis-Fogh Mechanism in 3D [Video]. (2009). Retrieved 5 Dec. 2012, from <http://www.youtube.com/watch?v=tX7ajlcfcIA&feature=youtu.be>.