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  1. #1
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    Down Wind Faster Than The Wind

    This seems impossible but I think there may be something to this. It has a flavor of a perpetual motion fraud yet, not. Apperantly, the laws of NRG(unbelievably, the real word is marked as spam) conservation are not violated. I am still trying to wrap my brain around this ingenious invention. The prop turns the opposite way from a windmill blade. The wind pushes the car which turns the wheels which, through a gearing, turns the prop to propel the car faster than the wind. If this turns out to be a fraud, I will end up looking more stupid than I already do. As you can see by the comments at the end of this article from physorg.com, it is hugely controversial.

    http://www.physorg.com/news194851568.html
    Cavallaro explained the car is able to move faster than the wind because the propeller is not turned by the wind. The wind pushes the vehicle forward, and once moving the wheels turn the propeller. The propeller spins in the opposite direction to that expected, pushing the wind backwards, which in turn pushes the car forwards, turning the wheels, and thus turning the propeller faster still.

    The Physics:

    The Demonstration Video:
    Last edited by phlipper; 06-13-2010 at 04:23 AM.

  2. #2
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    Re: Down Wind Faster Than The Wind

    This is awesomely clever, and at first reading it does appear to violate en3rgy conservation.

    I've done some reading, and still don't properly understand this. I'll look into it some more when I have some free time, it's a fascinating concept.

    So far my understanding is this: Much of the conservation-of-en3rgy confusion arises because we think of it as a sailboat. The wind alone isn't the pow3r for this machine, instead, it's the difference between windspeed and ground speed. It's like having two conveyer belts moving past one another at different speeds. You can attach a generator to one of them, let the other one spin the generator, and then use that pow3r to drive a car.

    In a sailboat, the forces you have depend on how fast you are travelling relative to the wind. As you go faster, the relative velocity of the wind decreases and so you can't keep accelerating. Once you're travelling at the same speed as the wind, there's nothing left to push you.

    In this case however, the forces depend on the difference between the wind and the ground. Since that value doesn't change based on your speed, you're not restricted by the usual limitations. Whether you're stationary, or moving at wind speed, the difference between wind and ground speeds is the same, so you don't lose your pow3r.


    In any case, good on these guys for coming up with a brilliant idea, and actually going ahead and building it.

  3. #3
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    Re: Down Wind Faster Than The Wind

    I am, by my nature, a very skeptical person. I have seen the Mythbusters youtube on this and also the airplane on a conveyor belt experiment. I am still a skeptic. I imagine there is momentum built up in the huge prop, as a gyroscope driven car would have. I can see that the car could travel a while on the extracted 'n'ergy. However, I have a problem with the acceleration after wind speed is reached. If the prop could be braked(i.e., alter blade pitch) and, through a differential gearing mechanism, transfer the momentum to the drive shaft then, yes, those things could happen. Somehow, I think there is an unknown(black box, if you will) that is being purposefully hidden. Sometimes, I hate the cynic in me. I have seen too many "front wheels turn the generator to p0wer the rear wheels motor" type frauds to be quick to jump on this particular band wagon. Once, I tried to pull myself up by my own bootstraps and broke my nose. I'm not falling for that one again, either.:zx11pissed:
    Last edited by phlipper; 06-14-2010 at 06:56 AM.

  4. #4
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    Re: Down Wind Faster Than The Wind

    http://skepticblog.org/2010/05/27/sa...than-the-wind/

    They cite a test cart built in the 1960ís, as a result of such a disagreement between two engineers at Douglas Aircraft. Reportedly, it managed to travel downwind at 1.2x true wind speed. The DDWFTTW has traveled at more than 2x true wind, and is aiming for 3x.

  5. #5
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    Re: Down Wind Faster Than The Wind

    http://www.fasterthanthewind.org/200...1_archive.html

    has construction pictures.

  6. #6
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    Re: Down Wind Faster Than The Wind

    Kinda reminds me of the old "perpetual motion (E.N.E.R.G.Y.) car", but the laws of thermodynamics put the brakes on that one too!

    Cheers, Pokes

  7. #7
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    Re: Down Wind Faster Than The Wind

    Quote Originally Posted by Ol Slow Poke View Post
    Kinda reminds me of the old "perpetual motion (E.N.E.R.G.Y.) car", but the laws of thermodynamics put the brakes on that one too!

    Cheers, Pokes
    Although the way it's explained in the original article gives that impression, this isn't violating ****** conservation. Kinetic ****** of the wind is converted into kinetic ****** of the car. If there is no wind, then the car won't work.

  8. #8
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    Re: Down Wind Faster Than The Wind

    Well that's true. It will be interesting to see how this works

  9. #9
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    Re: Down Wind Faster Than The Wind

    Hi folk. I'm JB and I'm one of the two primary designer/builders of the craft in the OP.

    It's not a scam (though with the internet controversy it has created I understand the interest here) and from conception to completion we were careful not to violate any laws ... local, state, national or physical.

    I'll try to go back through the posts on the thread and come up with some relevent comments over the next bit, but in the mean time feel free to fire away with any questions you might have.

    Basics:
    -- the spinning rotor is a propeller, not a turbine
    -- the wheels provide the torque to turn the rotor (always).
    -- the rotor does not provide the torque to turn the wheels (ever).
    -- it will take off from a standing start on it's own.
    -- we sometimes push it up to speed to save time during testing
    -- there's no "null point' at windspeed.
    -- It will maintain it's speed well above wind speed indefinitely
    -- By design, this particular one works best when aimed directly downwind.
    -- One can be built to go faster than the wind in any direction
    -- A simple gearing change will cause it to go upwind rather than down

    JB

  10. #10
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    Re: Down Wind Faster Than The Wind

    Also, for anyone who's interested in the 'scam or not' issue, it's now official just as of this morning that the NALSA record run (nalsa.org) attempts will occur at Smith Creek, Nev. from the 25th through the 27th of this month, weather permitting. Depending on weather and surface conditions it's possible that the effort will move south to the El Mirage lakebed as needed.

    NALSA is the premier international organization for the documentation and ratification of wind *****ed land speed records and they were the entity that somewhat recently ratified the new GreenBird land speed record of 126mph.

    The record we are shooting for is not based on top speed, but rather the highest multiple of windspeed ever while going directly downwind. We expect to be well over 2x and possibly over 3x the speed of the wind.

    NALSA BOD member and technical guru Bob Dill will be the point man for NALSA during the tests along with other BOD member observers per requirements.

    Anyone who wishes to come out is welcome.

    I have not seen a final copy of the newly written NALSA rules (I think they may be awaiting official ratification from the NALSA BOD), but I am familiar with what they contain in principle. I'll make sure and publish a copy on our project blog (FasterThanTheWind.org) once we get them from NALSA.

    JB

  11. #11
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    Re: Down Wind Faster Than The Wind

    Quote Originally Posted by ThinAirDesigns View Post
    -- One can be built to go faster than the wind in any direction
    -- A simple gearing change will cause it to go upwind rather than down
    Quote Originally Posted by iamwil View Post
    What do these last two mean exactly and what tests do you have in that regard?
    The device shown in the OP has been optimized for one task -- "directly downwind, faster than the wind, *****ed only by the wind, steady state". Within our budget constraints we have compromised little for any other consideration (other than safety of course).

    By sacrificing at bit of performance in the DDW direction (more losses through variable ratio transmission, etc), one can easily travel in all directions faster than the wind.

    We have tested our models both upwind, downwind and offwind, but have not built (nor intend to build) one that can go in all directions.

    Our purpose with the Blackbird machine (and our other models) has been merely an academic exercise to demonstrate the counterintuitive principles involved in this method of dynamic ****** extraction.

    JB

  12. #12
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    Re: Down Wind Faster Than The Wind

    Quote Originally Posted by ThinAirDesigns View Post
    Hi folk. I'm JB and I'm one of the two primary designer/builders of the craft in the OP.

    It's not a scam (though with the internet controversy it has created I understand the interest here) and from conception to completion we were careful not to violate any laws ... local, state, national or physical.

    I'll try to go back through the posts on the thread and come up with some relevent comments over the next bit, but in the mean time feel free to fire away with any questions you might have.

    Basics:
    -- the spinning rotor is a propeller, not a turbine
    -- the wheels provide the torque to turn the rotor (always).
    -- the rotor does not provide the torque to turn the wheels (ever).
    -- it will take off from a standing start on it's own.
    -- we sometimes push it up to speed to save time during testing
    -- there's no "null point' at windspeed.
    -- It will maintain it's speed well above wind speed indefinitely
    -- By design, this particular one works best when aimed directly downwind.
    -- One can be built to go faster than the wind in any direction
    -- A simple gearing change will cause it to go upwind rather than down

    JB
    JB, I picture, in my mind, a spring with a certain compression constant 'k', such that if I were to put my palm against the rear of the spring, on a frictionless track, and push the spring over a certain distance 'd', that, half way through that distance, the spring will have collapsed and start expanding to full length(and full final velocity) at the precise end of distance 'd'. Are these fundamentals related to the car's performance? In other words, the propellor, at first resists angular velocity(due to the fact the the pitch of the blades are opposite that of a windmill) but accomodates the forward push(through which the front wheels turn due to friction on the ground, which, in turn, divides the load, keeping the prop turning) along the vehicle's forward vector. As the relative rear wind speed falls to zero, the prop is free from rear wind resistance and bite into the air in front at full effectiveness. After that, I don't see that there isn't a terminal velocity whereupon the rear wind would be, once again, available for utilization. At a steady wind speed, would not the vehicle speed, eventually, become constant(a state of equillibrium)?
    Last edited by phlipper; 06-15-2010 at 11:39 AM.

  13. #13
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    Re: Down Wind Faster Than The Wind

    Quote Originally Posted by iamwil View Post
    I could be wrong but the wind pushes the surface of the prop...which now pushes the car, the wheels of the car turn the prop to push against the wind hence propelling it faster than the wind forward...

    It is actually quite simple...unless I am as well.
    No, you are seeing it as clearly as can be done, at this point! When you posted, I was in the middle of editing my response to try and clarify my otherwise quite muddled thought processes and sentence structures. You may re-read to see if I have made it worse.
    Simple is as simple does. I'm feeling pretty simple myself, right now.
    Last edited by phlipper; 06-15-2010 at 11:45 AM.

  14. #14
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    Re: Down Wind Faster Than The Wind

    Quote Originally Posted by ThinAirDesigns View Post
    -- It will maintain it's speed well above wind speed indefinitely

    JB
    I'm trying hard here but I'm fairly certain that this statement is false. Perhaps you will re-phrase it.
    If it works at all, it works by gathering, storing, then releasing the energ for a final acceleration push. At the risk of feeling foolish for not recognizing the first ever PPM when I see it, I must say this ---
    FACT: When the rear wind is absent, all frictional forces would, necessarily, convene to slow or stop the vehicle.
    Last edited by phlipper; 06-15-2010 at 12:10 PM.

  15. #15
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    Re: Down Wind Faster Than The Wind

    Quote Originally Posted by phlipper View Post
    I'm trying hard here but I'm fairly certain that this statement is false. Perhaps you will re-phrase this.

    It it works at all, it works by gathering, storing, then releasing the energ for a final acceleration push. When the rear wind is absent, all frictional forces would, necessarily, convene to stop the vehicle. That is a fact.
    Nope -- not a fact at all, because your initial premise (that the rear wind becomes "absent") is wrong. The true tailwind remains as long as the true tailwind blows.

    The aspect of this device that is counterintuitive is that it doesn't extract Nrgy from the air by slowing it down relative to *itself*, but by slowing down air relative *to the ground*.

    My statement above is not a mistake: This vehicle doesn't oscillate up and down through windspeed ... it accelerates from below windspeed up through windspeed and continues to accelerate until the drags and losses from the chassis and drivetrain balance out the thrust from the propeller and then it will stay there as long as you have sufficient wind and drivable terrain.

    JB

  16. #16
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    Re: Down Wind Faster Than The Wind

    Quote Originally Posted by ThinAirDesigns View Post
    Nope -- not a fact at all, because your initial premise (that the rear wind becomes "absent") is wrong. The true tailwind remains as long as the true tailwind blows.

    The aspect of this device that is counterintuitive is that it doesn't extract Nrgy from the air by slowing it down relative to *itself*, but by slowing down air relative *to the ground*.

    My statement above is not a mistake: This vehicle doesn't oscillate up and down through windspeed ... it accelerates from below windspeed up through windspeed and continues to accelerate until the drags and losses from the chassis and drivetrain balance out the thrust from the propeller and then it will stay there as long as you have sufficient wind and drivable terrain.

    JB
    Your quote:
    "The record we are shooting for is not based on top speed, but rather the highest multiple of windspeed ever while going directly downwind. We expect to be well over 2x and possibly over 3x the speed of the wind."
    :rasta:To misquote Everett Dirksen....A little smoke here, a few mirrors there, pretty soon, we're talking real obfuscation!
    Last edited by phlipper; 06-15-2010 at 12:42 PM.

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