Vanilla 1.1.9 is a product of Lussumo. More Information: Documentation, Community Support.

    •  
      CommentAuthoraber0der
    • CommentTimeJun 2nd 2010
     
    Wind-Powered Car Travels Downwind Faster Than the Wind

    http://www.wired.com/autopia/2010/06/downwind-faster-than-the-wind/
    • CommentAuthornova
    • CommentTimeJun 2nd 2010
     
    Originally I thought that this is against real physics but with some very deep thought I can think of a way that this may be real. In a distorted sort of analysis of the process could possibly lead to the claim being true.
    • CommentAuthorMileHigh
    • CommentTimeJun 2nd 2010
     
    It's BS. The implication is that you don't need any wind at all. Just push it forward and the magic feedback loop will start and away you go. They must be hiding some coils in that thing.
    • CommentAuthorjoshs
    • CommentTimeJun 3rd 2010
     
    Intuitively I have trouble seeing how such a thing would work. But it isn't a new argument.
    •  
      CommentAuthoraber0der
    • CommentTimeJun 3rd 2010
     
    I don't know how it could possibly work, but it may be a counter intuitive configuration of the principles that allow one to sail against the wind.
    • CommentAuthorjoshs
    • CommentTimeJun 3rd 2010
     
    Maybe. It doesn't make sense to me, but I have been tripped up before. If it works, it is a thrust / drag relationship. The air velocity over the air foils depends on how fast they spin as well as the relative wind to the vehicle. The thrust that propels the vehicle depends on the air velocity over the air foils and their area.
  1.  
    Didn't we go through this before? And didn't someone actually build a nice model, and show it on YT? Who was that fellow...all I can think of is "Tom Tomorrow" but that can't be it...
    It's a matter of gearing and prop ratios. But yes, I had the same objection as MH: You'd think that you could just give it a push on a calm day, and its own relative wind would keep it going, accelerating all the while, until it breaks the confines of the parking lot and disappears into the sunset....
    •  
      CommentAuthormaryyugo
    • CommentTimeJun 3rd 2010
     
    That would be a heck of an elaborate hoax. I wonder what's happening.
  2.  
    Well, it wouldn't be the first elaborate hoax, if you see where I'm going with that...
    •  
      CommentAuthorDerrickA
    • CommentTimeJun 3rd 2010
     
    "Sure it works in practice, but it will never work in theory!"
    • CommentAuthorenginerd
    • CommentTimeJun 3rd 2010
     
    Actually, the theory is pretty clear and we have seen demonstrations before (like that cool toy on the treadmill).

    What you need is a driving force. So the wind has to be going faster than the ground, and the vehicle has to be engaged with the ground.

    It's not perpetual motion. If the wind stops (relative to the ground) the car stops.
    •  
      CommentAuthorTrim
    • CommentTimeJun 3rd 2010
     
    With a wind speed of just 30mph (48kmh), British engineer Richard Jenkins has set a new land speed record for a wind-powered vehicle at blistering 126.1mph.
    • CommentAuthorcwatters
    • CommentTimeJun 3rd 2010
     
    It's worth looking at how an individual prop blade moves. Because they are rotating they aren't going directly downwind. They allways travels at an angle to the wind. Many sailing boats can go across wind faster than the wind.
    • CommentAuthornova
    • CommentTimeJun 3rd 2010
     
    Posted By: joshsMaybe. It doesn't make sense to me, but I have been tripped up before. If it works, it is a thrust / drag relationship. The air velocity over the air foils depends on how fast they spin as well as the relative wind to the vehicle. The thrust that propels the vehicle depends on the air velocity over the air foils and their area.
    As the propeller spins a high pressure is built behind the propeller and a low pressure in front of the propeller. The wind is pushing against the high pressure (two winds pushing against one another) into the low pressure until equilibrium is reached. This is my analysis of the way it MAY work.
    What makes this hard to imagine is the wind that causes the propeller to at first spin then causes the propeller to spin by pushing the craft over the ground via the mechanical linkage.
    • CommentAuthorCrastney
    • CommentTimeJun 3rd 2010
     
    you're all nuts - it's been proven to work, just like the ventomobile was, on this forum.
    it's a controversial idea, that you believe shouldn't work, and don't believe it when someone shows that it does work.

    compare it with Orbo - the theory was proven ages ago, it's just the engineering to get one working.
    • CommentAuthorjoshs
    • CommentTimeJun 3rd 2010
     
    Posted By: Crastneyyou're all nuts - it's been proven to work, just like the ventomobile was, on this forum.
    it's a controversial idea, that you believe shouldn't work, and don't believe it when someone shows that it does work.

    compare it with Orbo - the theory was proven ages ago, it's just the engineering to get one working.
    LOL! No form of Orbomination has ever been either demonstrated to appear to work, or proven to work.
  3.  
    Posted By: alsetalokinDidn't we go through this before? And didn't someone actually build a nice model, and show it on YT? Who was that fellow...all I can think of is "Tom Tomorrow" but that can't be it...
    It's a matter of gearing and prop ratios. But yes, I had the same objection as MH: You'd think that you could just give it a push on a calm day, and its own relative wind would keep it going, accelerating all the while, until it breaks the confines of the parking lot and disappears into the sunset....
    His name is Thomas, he also showed it was possible to move directly against the wind.
  4.  
    Posted By: Crastney
    compare it with Orbo - the theory was proven ages ago, it's just the engineering to get one working.


    I thought it was always proven to work? Now it requires engineering. I must have missed the theory proof too. I've certainly asked for one enough times.

    The downwind thingy is interesting. I can't get my brain to accept that it works - it just seems wrong, but it seems to. I think I need to re-read the various explanations of it.
  5.  
    Thomas had some videoes but I cannot find them, but there is this one.
    http://www.youtube.com/watch?v=oKqC5JsurOk
    • CommentAuthornova
    • CommentTimeJun 3rd 2010
     
    Posted By: nova[quote aria-level=0 aria-posinset=0 aria-setsize=0As the propeller spins a high pressure is built behind the propeller and a low pressure in front of the propeller. The wind is pushing against the high pressure (two winds pushing against one another) into the low pressure until equilibrium is reached. This is my analysis of the way it MAY work.
    What makes this hard to imagine is the wind that causes the propeller to at first spin then causes the propeller to spin by pushing the craft over the ground via the mechanical linkage.
    I now see how this can work. The wind pushes against the propeller as if pushing against a sail and then as the craft moves across the ground the mechanical linkage would cause the propeller to spin causing a low pressure in front of the propeller and a high pressure behind the propeller. This would effectively cause the apparent wind to he higher than actual wind causing the craft to go faster than the actual wind.