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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."
They teach aircraft designers that "Rock You Like A Hurricane" fits perfectly at air shows.
Mythbusters did it to a car, and increased gas mileage. This was just using clay. If someone used decent materials, there is likely a huge gain to be had in performance. Of course, the surfaces on a plane NEED to interact with the air, so too much disturbance may not be a good thing.
no, no it would NOT be cool if scorpions could fly D:
When I was young a friend of mine, an aviation mechanic once told me the properties of how a plane flies. He then proceeded to say the armed forces ignore that and use the philosophy "put enough power behind it, anything can fly"
It doesn't? The F-117 can't even fly without a computer constantly making tiny adjustments. I'm not kidding either, it would literally crash if you tried to fly it manually. It's a flying brick.
The Nighthawk was still designed as much as possible like a true airplane; it's only unstable because they couldn't build a more aerodynamic stealthy shape using only flat surfaces (they used flat surfaces because the math for radar deflection depended on computer simulations, and computers couldn't do good enough calculations for curved surfaces in the late '70s).
Calling it a brick is really quite inaccurate. It had an amazingly narrow wingspan, but it's still a plane and it still produced sufficient lift to fly straight on a reasonable power budget. It wasn't stable without computer correction, but that doesn't mean it's a brick. It's not as if they simply strapped enough rockets onto a random shape to get it airborne.
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.
[snip] Ok I just scared myself into never going out again.
And if you are anything like me, that did not really change your life radically
...if scorpions could fly.
G.
Exactly. How exactly does the scorpion using bumps on their skin to be less aerodynamic apply to airplanes? Planes already exist with "shark skin" texture to reduce drag, there was even a Mythbusters episode about it.
And why does the wikipedia article read exactly like this news story? "Androctonus australis is a hardy North African desert scorpion. Unlike Most other animals that live in deserts, Androctonus does not dig burrows to protect itself from a sandstorm. Instead, it can withstand sandstorms powerful enough to strip paint off steel, without any apparent damage."
Really? That's the best first three sentences for a encyclopedia entry of this creature? Other animals include a detailed description and locations they are found. Strange that the Wikipedia entry was created just 6 days ago.
Methinks slashdot and the economist has been duped by this "first time accepted submitter" elloGov
my karma will be here long after I'm gone