CRAZY WEDNESDAY: GALLOPING GERTIE RIDES AGAIN!

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Galloping Gertie rides again!

Like many former physics students, I have an abiding affection for the Tacoma Narrows Bridge. Not the present one, but the one nicknamed “Galloping Gertie”, which spanned the Tacoma Narrows for a brief four months, from July 1940 until its destruction on 7th November, 1940, in a mere 42 mph wind. Right from its opening, Gertie used to undulate in high winds, becoming quite a tourist attraction.. On the fateful day, however, the bridge started to twist in a way which had not happened previously, and caused the structure to collapse. It took decades before the mechanism of the collapse was fully understood, since it was the precise interplay of several different phenomena that was crucial. This Wikipedia article gives an exceedingly good overview.

While the lessons about the Tacoma Narrows bridge have now been learned, Gertie has provided new inspiration to inventor Shawn Frayne, recent winner of a prestigious Popular Mechanics Breakthrough Award. He realised that the same aeroelastic effects that were essential to the collapse of the bridge could be used in a membrane under tension to generate electricity. Using a 10 mph wind to drive the motion of the band fitted with a pair of magnets, which oscillate between metal coils, his design has demonstrated an induced current of 40 milliWatts. His invention, the “Windbelt” is 10 to 30 times more efficient than technologies in the same market, and is suitable for small or battery powered devices, such as clocks, LEDs and small plasma HD screens.

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Essentially, Frayne has found a way of harnessing wind power without using turbines. This is important to the developing world, where there is a need for relatively low current generation is needed. Conventional wind turbines do not downscale well, becoming increasingly inefficient as they are miniaturised. The other important factor in Frayne’s design is the simplicity of the design, something that cannot be said for solar technology. Peter Haas is the founder of the Appropriate Infrastructure Development Group, which aims to help people in developing countries to get access to clean water, sanitation and energy. He said, “If Shawn’s innovation breaks, locals can fix it. If a solar panel breaks, the family is out a panel.”

I’m always glad to see Gertie, and it seems poetic justice that the effects that caused her destruction might be put to good use. Contrary to some popular misunderstanding, it was made clear to me as a student that these effects are very complex, and the original bridge engineers could not possibly have foreseen the collapse. If, accidentally, they have inspired something that helps people, I hope that the unjust blame will be lifted.

Amanda

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3 Responses to “CRAZY WEDNESDAY: GALLOPING GERTIE RIDES AGAIN!”


  1. 1 Mike October 24, 2007 at 1:44 pm

    Yet another ‘Crazy Wednesday’ device that I would happily pay good money for and I sincerely hope that it gets to market. Although they are aiming at getting it to developing countries I think they are missing a trick if they ignore markets in Europe and the US.

    I’ll be honest and say that the main reason I want things such as this is because they press my ‘geek buttons’ but they can also be useful to those of us in the ‘developed’ world. I lost electricity for several days earlier this year thanks to extensive flooding in the city I live in. Some of the ‘Toys’ I had such as the wind-up radio (with built in torch) and solar powered mobile phone charger suddenly became rather important.

  2. 2 Cat Laine October 24, 2007 at 2:54 pm

    Hi Amanda,

    We have video from the PM Breakthrough Conference where Shawn talks a bit more about the ideas/inspiration that motivated his work on the Windbelt.

    http://www.aidg.org/component/option,com_jd-wp/Itemid,34/p,819/

  3. 3 Amanda October 24, 2007 at 5:02 pm

    Cat – thanks a lot for that. It really is interesting, especially given his historic inspiration.

    Mike – good points. Many of the innovations I blog about could do very well in the developed world, too, as you say, and I often think that the commercial opportunities could help fund the humanitarian aspects.

    Thanks both for your interest and comments.


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