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Author Topic: Directorly Downwind Faster than the Wind  (Read 147629 times)

spinn_MP

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Re: Directorly Downwind Faster than the Wind
« Reply #210 on: January 03, 2011, 02:31:05 PM »
Thanks, helicalred, for a good post.

I guess this topic will call for new contributions...

It's all about the "conservation  of energy", but let it roll... At least for a while.
Cheers!

ramset

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Re: Directorly Downwind Faster than the Wind
« Reply #211 on: January 03, 2011, 02:32:00 PM »
Bill,
There is also the outside chance [albeit slim]
That we really don't know everything about every thing!

Chet

tagor

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Re: Directorly Downwind Faster than the Wind
« Reply #212 on: January 03, 2011, 02:38:01 PM »

Mike. J. Furness

do you have time to learn basic physic ?
( before saying IT IS NOT WORKING !!) 

helicalred

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Re: Directorly Downwind Faster than the Wind
« Reply #213 on: January 03, 2011, 02:59:26 PM »
Quote
There is also the outside chance [albeit slim]
That we really don't know everything about every thing!

Chet,

Never a truer word spoken.
And I think the Faster Than the Wind folk intend to keep it that way!

- Bill

Subduction Zone

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Re: Directorly Downwind Faster than the Wind
« Reply #214 on: January 13, 2011, 07:05:37 PM »
Hello there.  I am new to this forum, but have followed this for a while.  I am not an expert, but I may be able to clear up some misconceptions on how these vehicles work.  And they do work as advertised.  One concept that helped me is that they run off of the difference in speed between two media.  That is they run off of the difference between the speed of the air, and the speed of the ground.  That way regardless of your frame of reference there is always a potential source of energy as long as the wind is blowing.  Likewise if there is no wind, then the difference between the speed of the air and the speed of the ground is zero.  There is not potential source of energy there.

I will be prepared for flame from Mike Furness.

Mike Furness

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Re: Directorly Downwind Faster than the Wind
« Reply #215 on: January 14, 2011, 05:32:34 PM »
hello 'no name', I'm not sure if you have followed this topic from the start, or what argument you seek with me?
Your statement that if there is no RELAIVE wind speed says all!
Of course, if there is substantial wind,(relative to ground) sufficient to generate power from a propellor, then it can be sufficient to provide some motive power forward, this is not in dispute

In case you have 'lost the plot,' the disputed claim is that in 'still air', when you have accellerated the vehicle to a given velocity, sufficient energy exists in the wind such that the vehicle can continue to run, and indeed go faster from it's own generated wind.

Mike.

Mike.J. Furness

Subduction Zone

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Re: Directorly Downwind Faster than the Wind
« Reply #216 on: January 14, 2011, 11:57:11 PM »
Mike, I think I have followed this argument far longer than you have, and you seem not to understand how it works.  First off it is not over unity or perpetual motion in any way.  It runs off of the power of the wind and if the wind is not blowing the cart does not work. 

Lets first define wind before I go any further.  Wind in this case is the actual movement of the air over the ground, not the apparent wind that an observer on the vehicle feels.  Even when the vehicle is moving at the velocity of the wind the actual wind is still moving over the ground and is a potential source of energy.

Now how does the cart work?  The wind does not directly turn the propeller, in fact if you lifted the wheels off of the ground the propeller would rotate in the opposite direction that it does when running.  At very low speeds it works on bluff body forces, the wind hits the body of the cart and the prop and pushes it in the same manner that a square rigged sail works.  As the cart moves forward the wheels turn the propeller which adds thrust to the cart.  If you compared it to a sail boat it would be very similar to a boat sailing on a downwind reach.  In fact if you unspiral the path that the propeller takes you would see that it is in the form of a downwind reach.  No good sailor denies that a boat, especially an ice boat or land yacht, cannot beat the wind by sailing downwind and jibing back and forth.  It is very counterintuitive, but it breaks no laws of physics. 

Subduction Zone

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Re: Directorly Downwind Faster than the Wind
« Reply #217 on: January 15, 2011, 12:43:10 AM »
I have looked at quite a few posts here and even those who believe that it works very often have it wrong.   There is nothing any more revolutionary to this concept than that of a boat sailing either into the wind by tacking or by sailing with a velocity made good greater than wind speed directly downwind by jibing.  The prop only allows the vehicle to do this in a straight line.  In both of those cases sailboats slow the speed of the air that they interact with relative to the ground.  The same with the cart.  It slows down the speed of the air that it interacts with relative to the ground.  That is why it only works when the real wind is blowing over the ground.  If the air is not moving over the ground there is no energy to gain by slowing it down.

Mike your idea of modeling the cart at wind speed by using a stationary car on a windless day is flawed because the air is not moving over the ground.  A much better way to do it would be to put the cart on a conveyor belt, or even a treadmill.  By a simple Galilean Transformation you can see that the cart would react the same on the treadmill on a day where the speed of the wind was the speed of the treadmill. If it moved forward on the treadmill it would move faster than the wind on  the road.

quarktoo

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Re: Directorly Downwind Faster than the Wind
« Reply #218 on: January 15, 2011, 05:48:51 AM »
What about friction or traction.

You are converting the speed of the wind and the torque of the larger propeller into traction on the wheel or propeller.

There is a video of the boat on youtube somewhere and it is patented. It would not make a god boat or a good car - non-starter.

Subduction Zone

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Re: Directorly Downwind Faster than the Wind
« Reply #219 on: January 15, 2011, 07:41:02 AM »
What?  Forget about the torque.  You are converting the speed of the wind into energy going into the cart. 

quarktoo

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Re: Directorly Downwind Faster than the Wind
« Reply #220 on: January 15, 2011, 01:00:29 PM »
What?  Forget about the torque.  You are converting the speed of the wind into energy going into the cart.
Make that propeller and way you want just don't exceed the diameter of the wheel. You just invented REVERSE.

Of course you need higher wind speed otherwise it would also be impossible . It takes both - I just saying don't ignore traction and torque aspects.

blueweaver

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Re: Directorly Downwind Faster than the Wind
« Reply #221 on: October 24, 2011, 06:14:36 AM »
I just got this, watching these videos:
At start-up the prop is acting like a sail - its resistance to the tail wind, pushes the cart in the direction of the wind. This reaction occurs entirely thru the thrust-bearing on the prop, the prop-shaft is pushing the cart.

The prop never turns the wheels, it is always vica-versa - the wheels drag on the ground , and turn the prop.

At start-up speeds, the prop does not spin fast enough to have a propeller effect - it is as though it is a stationary sail and the wind is "pushing" it.

However, as it speeds up, and matches wind speed, something changes, maybe even before "hitting neutral" (this may not even be an important moment). The propeller now, driven by the wheels, is literally pulling the cart, by thrust created by the spinning blades. Now the "apparent wind" the blades are experiencing is much faster than the relative wind - the blades, by spinning, are creating their own wind (and most likely a significant low-pessure field on front faces of propeller airfoils that is pulling it all forward), and therefore a significant thrusts. This thrust is transferred by the shaft , thru the thrust-bearing into the body of the car and thereby rubbing the wheels on the desert surface making them turn and they in turn, by the chain, drive the prop. There are 3 elements here, in kind of circle.

It looks to me like the same principle as tacking across the wind - on a windsurfer or good sail boat: one creates a higher "apparent wind" speed by going at this angle. This propeller-car does it by spinning the propeller - that creates the higher the wind-speed that the propeller sees - literally a spinning sail.

Gotta think about it a while to see if it can go cross or upwind and use similar principles. It would be cool to design a wind-generator that could use these too....

onthecuttingedge2005

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Re: Directorly Downwind Faster than the Wind
« Reply #222 on: October 24, 2011, 07:22:55 AM »
I can see it now, trying to avoid all those mobile wind sails in motion. what a horror.

Cloxxki

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Re: Directorly Downwind Faster than the Wind
« Reply #223 on: October 24, 2011, 05:10:49 PM »
I just got this, watching these videos:
At start-up the prop is acting like a sail - its resistance to the tail wind, pushes the cart in the direction of the wind. This reaction occurs entirely thru the thrust-bearing on the prop, the prop-shaft is pushing the cart.

The prop never turns the wheels, it is always vica-versa - the wheels drag on the ground , and turn the prop.

At start-up speeds, the prop does not spin fast enough to have a propeller effect - it is as though it is a stationary sail and the wind is "pushing" it.

However, as it speeds up, and matches wind speed, something changes, maybe even before "hitting neutral" (this may not even be an important moment). The propeller now, driven by the wheels, is literally pulling the cart, by thrust created by the spinning blades. Now the "apparent wind" the blades are experiencing is much faster than the relative wind - the blades, by spinning, are creating their own wind (and most likely a significant low-pessure field on front faces of propeller airfoils that is pulling it all forward), and therefore a significant thrusts. This thrust is transferred by the shaft , thru the thrust-bearing into the body of the car and thereby rubbing the wheels on the desert surface making them turn and they in turn, by the chain, drive the prop. There are 3 elements here, in kind of circle.

It looks to me like the same principle as tacking across the wind - on a windsurfer or good sail boat: one creates a higher "apparent wind" speed by going at this angle. This propeller-car does it by spinning the propeller - that creates the higher the wind-speed that the propeller sees - literally a spinning sail.

Gotta think about it a while to see if it can go cross or upwind and use similar principles. It would be cool to design a wind-generator that could use these too....
Nice first post, welcome!

Great isn't it? I suppose when the baldes are just slicing the wind, like a neutral, the cart has similar speed as when it would have had stationary blades. Of course there it more to the cart than just the blades creating air drag towards propulsion. The non-blades part though, is the part that resists it to go beyond wind speed. That's why it's such an aero vehicle, while it in fact travels straight downwind. Stick such a prop on a regular car and it won't do as well. It will still bring a great fuel saving of course, the full prop's worth.

I am thinking more and more about vehicles which have a huge part, or all of their frontal surface, taking up by an air intake. the air is funneled into a much narrower channel, where it's sped and/or compressed up to fit. The opposite would happen on the back. Adjacent to the narrow air duct, and where the turbine engine is placed, there will be room for payload. Effectively the vehicle will eternally resemble a simple cilinder. Open front and rear, like a tube. It's airodynamics properties would be such also. The thrust of the engine will not be used to drag an attached vehicle, as the vehicle is inside the "engine".
Stick this thing on specially designed maglev tracks and crazy speeds can be attained with limited engine power. The compress/decompress effect of the airflow should be more or less neutral. And more on topic, a DDWFTTW vehicle of this shape could be greatly efficient when going directly downwind. Little overhead air friction. With sidewinds, retractable sails would unfold. Thin permanently opened vertical fins could even be hinged and damper-centered, to immediately kick in for tacking with the first gust of side wind.
The maglev type vehicle would be great as an alternative to vacume tube capsules. If vacume is too cumbersom, then just fill up the tunnel with a verhicle, and suck all air right through. Couple this to tracks where boarding stations are at sea level and tracks dive hundreds of meters below it to build up speed, and you have a very efficient system. Acceleration to 500-600kph takes up no energy at all, cruising is efficient as heck, and decelleration is done by gravity again. No brakes necessary, just back-up systems. The maglev tracks could be used for propulsion as well, the prop duct merely reducing effective air drag to zero. I wonder how much energy it would take to channel air through a 3.5m across tube of long length with a 1m bottleneck in it, at say 500kph. Just to keep it at 500kph. Preferably an off-center bottleneck to create some living space aboard.
if an aerodynamicist is interested to work with me on this, write me on hotmail please.