What Scorpions Have To Teach Aircraft Designers

First time accepted submitter elloGov writes "The north African desert scorpion, Androctonus australis, is a hardy creature. Most animals that live in deserts dig burrows to protect themselves from the sand-laden wind. Not Androctonus; it usually toughs things out at the surface. Yet when the sand whips by at speeds that would strip paint away from steel, the scorpion is able to scurry off without apparent damage thanks to the unique structure of its carapace. Dr Han Zhiwu of Jilin University and colleagues have found that surface irregularities based on the scorpion's exoskeleton could substantially minimize atmospheric dust damage to aircraft."

Comments

Re:What about drag

[butalearner]

There are a few types of drag, but for now let's just consider skin friction drag and pressure drag. For a smooth sphere the size golf ball, pressure drag (or wake drag, caused by the flow separation), is significantly higher than the skin friction because the surface area of the sphere is so small. The dimples introduce turbulence in the boundary layer (increasing skin friction) in order to delay flow separation (significantly reducing wake drag).

For an airplane, however, this situation is reversed. The surface area is enormous, and since the shapes of the wings and the fuselage are such that they delay flow separation as long as possible, the skin friction drag is significantly higher than the wake drag. Introducing dimples will decrease wake drag like a golf ball, but it will increase the skin friction more, causing a net increase in drag.