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Creation  Volume 27Issue 2 Cover

Creation 27(2):56
March 2005

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By Design
by Dr Jonathan Sarfati

US $15.00
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Flighty flippers

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See the bumps on the front of a humpback whale’s flipper? [Picture available only in Creation magazine.] What sort of designer would design such a thing, rather than a smooth, sleek flipper?

Engineers and US Naval Academy scientists have inadvertently answered that question: an incredibly ingenious designer—one whom aircraft designers can learn much from!1

They used scale models of a flipper 56 cm (22 inches) long. One was smooth, and the other had the little bumps, called tubercles. In a wind tunnel, the smooth one behaved like a typical aeroplane wing. But the one with the tubercles had 8% better lift and an astounding 32% less drag. It also resisted stalling (drastically losing lift) at a 40% steeper wing angle.

If that could be applied to aeroplanes, the better lift would make takeoff and landing easier; the lower drag would mean less fuel would be wasted; and the better stall resistance would be a huge safety advantage. The researchers propose that the tubercle design would also greatly benefit propellers, helicopter rotors and ship rudders.2

So why does this bumpy structure work so much better? The tubercles at the front of the flipper break up the flow of fluid (liquid or gas), and force it into the fluted valleys in between. This generates vortices (eddies) that keep the flow attached to the top surface of the flipper. This increases lift and resists stalling.

Humpback whales are huge—up to 40 tons and about 9–18 m (30–60 ft) long. But they are very agile, and the flipper design explains why. In today’s fallen world, a humpback whale catches a school of fish with a unique ‘bubble net’ (picture only available in magazine). It swims in a circle under its prey, exhaling through its blowhole, making a cylindrical trap with air ‘walls’. Then the whale swims through the centre with its mouth wide open, scooping up the fish.

When we study living creatures, we are constantly amazed by how much human designers have to learn from the Master Designer (Romans 1:18–32).

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References

  1. Miklosovic, D.S., Murray, M.M., Howle, L.E. and Fish, F.E., Leading-edge tubercles delay stall on humpback whale (Megaptera novaeangliae) flippers, Physics of Fluids 16(5):L39–L42, May 2004. Return to text.
  2. Hill, D., Mimicking humpback whale flippers may improve airplane wing design, Duke News and Communications, www.dukenews.duke.edu/news/design_0504.html, 11 May 2004. Return to text.

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