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• TWIK
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  Hey,
  I've read the article and I'm a little disappointed about it. At my high school (in the Netherlands) the children who are in their first year (about 100 each year) make a little cart that rides against the wind, called a "TWIK" (tegen de wind in karretje; against the wind cart). First one of our teachers didn't believe it would work so he made a bet with some students... and he lost so he had to give them chocolate or something. But what my point is: it IS possible to make a cart like this, over 100 children a year make it at our school. Even better: everyone can order these TWIKS from www.opitec.com, a big postal order company in Europe, so I suppose there must be thousands of people making them. There is an instruction for making one at http://www.uk.opitec.com/cgi/ITANZBD%20%20%20%20%20%20%20142832023106?P_L=E&P_S=E&P_V=504376825-&P_PGM=&P_1=101773&P_2=H&P_3=&P_4=&P_5=&P_6=&P_M=
  I made one myself with a four-wheel drive using a elastic bend between the axles.
  Have a good time making your own "TWIK"
  Greatings from Holland,
  Daniël

  Posted by Daniël-Linschoten on November 27, 2007 at 05:51:10 Pacific Time

• TWIK
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  Very interesting! But as my article said, the challenge was to make a cart that would begin by running with the wind behind it, and gradually reach the same speed as the wind, and then continue traveling into the wind (i.e. with a net headwind).
  
  If you increase the mechanical advantage of the propeller by using correctly sized pulleys, I have no doubt you can make your cart move into the wind. Even the one that I built moved a little into the wind when the belt was twisted appropriately.
  
  But to build a cart that starts with the wind blowing from behind it and continues to travel into the wind, you will have to change the direction the propeller turns the wheels (by reversing the belt) when the net wind direction changes.

  Posted by charlesplatt on November 27, 2007 at 09:47:26 Pacific Time

• TWIK
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  Unfortunately Mr. Platt attempted to make something that he himself didn't understand. Several of us have in fact made a cart of the sort Jack Goodman (and Andrew Bauer originally) made. Ours do exactly what Mr. Platt says cannot be done, and they don't require changing the gearing or direction of the propeller drive at any time. You can see a synopsis of what we've done here: http://www.youtube.com/watch?v=xHsXcHoJu-A
  
  If Make Magazine is willing to allow the record to be set straight I will submit an article detailing exactly how anyone can make such a cart for themselves using $40 of off-the-shelf parts.
  

  Posted by spork on November 29, 2008 at 23:19:31 Pacific Time

• still waiting
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  I have reviewed the impressive array of cart designs in the video referenced by the previous message. Unfortunately only two are depicted in free motion: Mr. Goodman's original version (which does not show a clear view of the space in front of his cart, thus failing to eliminate the possibility that someone may have been towing it on a piece of fishing line) and a very short clip right at the end, which appears to be genuine but does not give any indication of wind direction or speed, so that there is no way of knowing if the cart exceeds the speed of the wind.
  
  In this forum and in others hosted by Make I have explained repeatedly why a treadmill demonstration does not satisfy my original requirement. The cart should be on a level surface, experiencing a steady tailwind; it should accelerate up to the speed of the wind and should then exceed the speed of the wind. This is what Mr. Goodman claimed to have achieved. For reasons stated in my original article, I believe it is impossible.
  
  Note that any video should show the space around the cart to eliminate any suspicion of fakery. It's especially difficult to overcome this suspicion in a treadmill test, since a thin piece of thread could easily be held by someone off-camera.
  
  A huge amount of time and effort has gone into building some very nice cart designs. Why is no one willing to expend the small amount of additional effort to make a video that shows what Mr. Goodman's video claims to have shown? Why hasn't Mr. Goodman remade his own video showing his cart in a way that removes all suspicion?
  
  I have also proposed a variant of the Goodman experiment for those who have complained that they don't have access to a flat, level, smooth surface outdoors, on a day when a steady wind is blowing. In an indoor area where there is no movement of air, steer or tether a cart so that it will run in a circle. Use a hand-held electric fan pointed from behind the cart, and follow the cart with the fan. Scatter small styrofoam fragments during this test to show that the cart begins by moving more slowly than the air from the fan and eventually moves faster than the air from the fan. Note that if the cart can do this, logically it should continue moving forever, even when the fan is taken away. Does no one else find this a little implausible?
  
  In the absence of such a fair demonstration, I tend to believe that the well intentioned and sincere people who are trying to replicate the Goodman video are influenced by a certain amount of wishful thinking.
  
  --Charles

  Posted by charlesplatt on November 30, 2008 at 05:44:18 Pacific Time

• still waiting
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  Mr Platt,
  
  You may think I'm indulging in wishful thinking, but I'm confident enough that my cart will do exactly what you request that I've offered you a 10 to 1 wager for $100K. You've chosen not to respond to that offer.
  
  If you allow me to publish an article setting the record straight, you'll see ample proof of exactly what you request - both indoors and out.
  
  I'll be curious to see how you respond to this challenge.

  Posted by spork on November 30, 2008 at 08:55:37 Pacific Time

• still waiting
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  Spork, I don't read the list every day, and I don't read every message. I'm sorry, but I just don't have time for it (and I certainly don't get paid for it). So, I didn't see the challenge you refer to.
  
  The first step is for you to make a video which depicts the cart in one of the two ways that I have suggested, or in another way that I can agree to. The lack of such a video is a source of endless puzzlement and speculation for me. If you can show me something that looks plausible (and does not involve a treadmill), then I will take the time (my own time) to follow up, so long as I don't have to incur air fares to far-off parts of the country.
  
  I also have a workshop where you can bring your cart if you wish, and it has a flat concrete floor which would be ideal for an indoor test of the type I have suggested. The workshop is in Rancho Cucamonga, California. However I will be moving out of that space, to a remote part of Arizona, in January.
  
  Regarding a feature in Make, I have queried Mark Frauenfelder to see if he is interested, and am waiting for a reply.
  
  Your challenge of a 10:1 bet is interesting, but I hope you will forgive me for wondering if you really have $100,000 to lose.
  
  Charles Platt

  Posted by charlesplatt on November 30, 2008 at 09:10:14 Pacific Time

• still waiting
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  "Your challenge of a 10:1 bet is interesting, but I hope you will forgive me for wondering if you really have $100,000 to lose."
  
  There's no reason to wonder about that. You will put your $10K in a joint escrow account with my $100K. The proceeds will go to the winner of the wager. This is even easier to prove than the cart going faster than the wind directly downwind, outdoors.
  
  But you really should respond to my email so we don't have to have this debate in public. I would hope your magazine would have the intellectual integrity to allow the record to be set straight.
  
  
  

  Posted by spork on November 30, 2008 at 09:21:53 Pacific Time

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  I believe the following document clearly explains how this sort of device can move faster than the wind. I believe it also describes a machine that travels DDFTTW without any moving parts.
  
  http://www.greglondon.com/tumbleweed/
  
  There's a lot of mumbo jumbo going on around this thing. Once you understand it, it's about as interesting as a block and tackle. It helps if someone could explain it that simply.
  
  

  Posted by GregLondon on December 06, 2008 at 02:32:12 Pacific Time

• Success at El Mirage - DDWFTTW
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  http://www.fasterthanthewind.org photos, videos, etc

  Posted by DavidGlover on July 08, 2010 at 12:08:09 Pacific Time

• Success at El Mirage - DDWFTTW
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  So far as I can tell, by reading the description, the very impressive looking vehicle has reversible gearing between wheels and propeller. Supposedly this was added to "improve the acceleration." In fact my original article stated that reversible gearing would be necessary for it to work at all. Without the ability to reverse the drive from wheels to propeller, you will be in one of two situations: either the wheels will be fighting the propeller prior to the point where the cart is moving at wind speed, or the wheels will be fighting the propeller when you are moving faster than wind speed. In view of the abusive messages I received when trying to convey this very basic concept, it is ironic that the builders have apparently been forced to acknowledge it now.

  Posted by Charles Platt on July 08, 2010 at 12:16:13 Pacific Time

• Success at El Mirage - DDWFTTW
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  Let's consider the abusive messages. First we can look at the last line of Platt's original article, in which he disparages an honest engineer that's infinitely sharper than Platt. Then we can look at the insulting messages Platt has sent me (which I'll be happy to post).
  Platt now congratulates us on our achievement, but presumably still insists on welching on the bet he had with Emilio. Apparently Platt can't come up with $1000.00 to save what's left of his name.
  And finally, everything in his above post is just as wrong as his article. We have NOT implented reverse gearing in our cart. In fact it works just fine with fixed gearing and fixed pitch as the videos at Ivanpah will attest.
  It's hard to tell whether Platt is simply ignorant, or dishonest.

  Posted by spork on September 05, 2010 at 23:58:41 Pacific Time