Down wind faster than the wind

[humber]

When the cart is stationary on solid ground and a wind is hitting the propeller, the lateral and rotational forces exerted on the propeller will be translated to forces exerted on the road by the wheels. As soon as the cart starts rolling, the force exerted on the road over the distance the cart travels is energy. Can you say that the road is not taking nor supplying this energy?

Well perhaps not, but I find that I have to put fuel in my car, whereas spilling it on the road seems to have no effect.
If the direction of the energy is consistently maintained, then it does not matter. Electrical current is said to flow from + to -, but the electrons 'flow' the other way.

I would expect the arbiter to setup and perform the test so there is no access to rig the results by anyone with a stake in the outcome.

Perhaps you misunderstood me, Dan O. I was not suggesting that holding the cart the wind would be interference, but if the cart were to be launched from an agreed initial velocity, that may allow a short and therefore practical 'wind tunnel' to be built.

Ynot has had many ideas. One that I like is the guide wire running the length of the treadmill. It controls the horizontal positioning of the cart with minimum interference in the direction of travel.

I have no objections to that, either. I was referring to the turntable design. The treadmill as it stands, cannot serve to prove that cart. I think that we first need to settle that. I will put forward my objections in one post.

 

[humber]

Humber, the prop is always driven by the wheels. As soon as the cart starts to move, the gearing between the wheels and the prop forces the prop to turn. As the speed of the cart increases, the prop spins faster, still linked to and powered by the wheels. When the cart reaches windspeed, the wheels are powering the prop. The air is still but the prop pushes against that still air - and the ground moving under the wheels powers the wheels, which powers the prop.

When the cart is outside, the wind pushes the cart forward. The forward motion drives the wheels which turns the prop. The wind provides the energy to turn the wheels by forcing the cart to move across the ground.

When the cart is on the treadmill, the wheels are powered directly by the treadmill.

I understand that Mender, but that is speculative. If the cart could do that, then there would be no contest, because a lot of other machines would have already exploited this, and would be part of the standard view on the nature of force and energy.
You are arguing for the use of the treadmill, which you know I do not acknowledge as valid. I imagine that most skeptics would want to see proof based upon common ground. Introducing air flow is one way that can be met, being common to both points of view.

The matter of equivalence is the issue. As I wrote to Dan O, we need to settle that, so I will answer this in a post on that subject, so that we can both at least have common starting point.

The questions concerning the propeller were for information only, so that I can reject or consider ideas for the test. Thanks for the that.

 

[Dan O.]

For the purpose of our test, the road is simply a flat surface moving at a constant velocity upon which the cart can roll. The treadmill is a valid simulation of the road since the only function of the motor is to keep the surface of the treadmill moving at a fixed speed.

If it would help, imagine that the motor is replaced with a giant flywheel. After all, the road is atached to a giant flywheel that keeps it moving at over 250 kilometers per hour.

 

[mender]

If the cart could do that, then there would be no contest, because a lot of other machines would have already exploited this, and would be part of the standard view on the nature of force and energy.

The questions concerning the propeller were for information only, so that I can reject or consider ideas for the test. Thanks for the that.

The first statement implies that there is nothing left to learn. I don't believe that, and I doubt that you really do either. Your reasoning that this would already be in use implies that it would have a practical application. It doesn't. It has been known by a few people for quite a while, people who had everything to gain if this was practical.

You're welcome for the prop info. Hope a test can be agreed upon.

 

[GreyICE]

I understand that Mender, but that is speculative. If the cart could do that, then there would be no contest, because a lot of other machines would have already exploited this, and would be part of the standard view on the nature of force and energy.
You are arguing for the use of the treadmill, which you know I do not acknowledge as valid. I imagine that most skeptics would want to see proof based upon common ground. Introducing air flow is one way that can be met, being common to both points of view.

If you're talking about using the same force to achieve different velocities, we do that all the stinking time. Look up 'hydraulic jack' someday.

If you're talking about wind powered vessels, the only ones commonly in use are sailboats, and they already exploit this.

 

[Michael C]

I've been thinking some more about the ride-on version. I realise that I wasn't thinking clearly enough about the variable pitch propellor. Here are my revised ideas on the question:

If the propellor has a fixed pitch, it's going to make starting a pretty wild experience. It will also require considerable force to stop the cart. It's a bit like always driving a car in top gear, with no possibility of controlling the power the engine is providing. In a few of Spork's videos we can see how fast the little cart takes off ("like a bat out of hell", I think he said). In order to permit smooth starts and stops, what is needed is a variable pitch propellor where the blades can be rotated to provide both forward and backward thrust.

Imagine first the cart at rest on the ground, ready to start out in the direction of the wind. The propellor blades are turned parallel to the direction of travel of the cart, so the propellor creates no thrust at all. Unless the drag from the wind on the rest of the machine exceeds the frictional resistance in the wheels, the machine will be stationary.

The pitch of the propellor in this position is theoretically infinite. Now start slowly turning the blades in a direction that will produce backward thrust when the wheels turn forwards (the opposite way round than the direction necessary for DDWFTTW travel). As soon as the blades catch enough wind, the cart will move forward, slowly. If we then leave the pitch at a high value in this direction, the cart will keep moving at a steady speed, much slower than the wind.

We can now control acceleration by gradually decreasing the pitch. As the pitch gets close to zero, we should be moving near to wind speed (how near will be governed by the losses due to unwanted drag and friction). When the pitch is exactly zero, the propellor is like a flat rotating disk.

Now we start increasing the pitch again, in the opposite direction, to produce forward thrust. From now on, DDWFTTW becomes possible. We can continue increasing the pitch until we get to the optimum speed.

To decelerate and bring the cart smoothly to a stop, reverse the process.

I think it's highly likely that Bauer's original vehicle used this method.

 

[humber]

If you're talking about using the same force to achieve different velocities, we do that all the stinking time. Look up 'hydraulic jack' someday.

If you're talking about wind powered vessels, the only ones commonly in use are sailboats, and they already exploit this.

Well, you seem to have covered two of the things I was not thinking of.
Hydraulic jacks are transformers. They change the relationship between v and f while keeping the product constant. There is no power gain.

Mender,
Well, I wouldn't propose the lack of exploitation as a formal argument, so I certainly agree. If the cart can operate as claimed, then I think that would be outside of what is currently understood to be possible, is what I meant to say.
I think that I can put forward a good argument for this view, and will do so.

 

[screensnot]

Humber, this is getting ridiculous.

The cart does not claim to do anything that is 'outside of what is currently understood to be possible'. It uses the wind to travel at a speed that is faster than the wind itself. Sailboats, windmill vanes, and other things have been doing this for some time.

Yes, this appears to be the first device that can outrun the wind, straight downwind. And, I'll admit that I thought it was some kind of trickery when I started reading the OP. But, even I (who is an not expert on anything) can grasp the concept. I can understand that it's not a question about whether the idea can overcome the forces against it (friction), but understand that the question is "What is the minimum wind speed you'd need to make it work?" Is 5 mph enough? Or would 100 mph be needed? Of course, me not being the skeptic that you are, I take the videos on the treadmill to be demonstrations that normal wind speeds will suffice.

Humber, I'd like to know if you believe it's possible to construct a device that will travel directly into the wind, using only the wind as power?

 

[Brian-M]

As you have it; Top wheel to Gear 1 (x2). Gear 1 to Gear 2 (x2). Gear 2 to Wheel 2 (x1/4) Answer = 1, Ft = Fc.

It's probably pointless responding, but your numbers seemed to add up, which had me confused for a bit, so I couldn't help but think it over until I realised where you went wrong.

The amount of force gear 1 is using to to turn gear 2 is identical to the force gear 2 is being turned by gear 1.

So... Top wheel to Gear 1 (x2). Gear 1 to Gear 2 (x1). Gear 2 to Wheel 2 (x1/4) Answer = 1/2, Ft = Fc/2.

 

[Brian-M]

If you gave the cart say, a 5 mph headwind while it is rolling on the treadmill, you are creating the same situation as the cart exceeding it's tailwind by 5 mph on the road. If it could continue for an appreciable length of time, it would prove the cart could go faster than it's tailwind.

Not really. If the cart was going into a 5 mph headwind on the road (ie. 5 mph faster than the wind), then the wheels would be turning 5 mph faster than the wind.

By giving it a 5 mph headwind with a fan on the treadmill, you don't get the increase in wheel speed. As the propeller is driven by the wheels, this means the propeller won't be spinning fast enough to push the cart against the wind, or even fast enough to hold it in place.

 

[Brian-M]

Ynot,
If I understand correctly, then the arm (tether) will provide a reaction path for the force of the wheels, other than the propeller. I would expect the cart would match the turntable, without a propellor.

No, the tether will move freely on the post. It's only there to keep the cart from moving off the turntable.

Would the cart outpacing bubbles from a bubble-making machine on a level outdoor road satisfy tou for this bet?

 

[humber]

Humber, this is getting ridiculous.

The cart does not claim to do anything that is 'outside of what is currently understood to be possible'. It uses the wind to travel at a speed that is faster than the wind itself. Sailboats, windmill vanes, and other things have been doing this for some time.

Yes, this appears to be the first device that can outrun the wind, straight downwind. And, I'll admit that I thought it was some kind of trickery when I started reading the OP. But, even I (who is an not expert on anything) can grasp the concept. I can understand that it's not a question about whether the idea can overcome the forces against it (friction), but understand that the question is "What is the minimum wind speed you'd need to make it work?" Is 5 mph enough? Or would 100 mph be needed? Of course, me not being the skeptic that you are, I take the videos on the treadmill to be demonstrations that normal wind speeds will suffice.

Humber, I'd like to know if you believe it's possible to construct a device that will travel directly into the wind, using only the wind as power?

It is becoming ridiculous, because I still find that I am being held to things that I never actually said, while the things I have said, are ignored.

1. I do not say anything is faked

2. The cart in the wind may look fast, but is it? How fast would a cart without gearing, or with sail appear to move? The wind and cart speeds are unknown. The wind is invisible, so I have no idea how fast it is local to the cart. Not evidence that it isn't traveling at windspeed, but also not evidence that it is. I am surprised that so much is taken at face value. Is that overly skeptical of me?

3. I think that to reach windspeed directly down wind, and exceed the normally expected drag barrier, would require more energy than is available to the propeller. No additional energy is available from the ground.

4. Movement up the treadmill is explicable. I understand the idea of "equivalence" that supports the treadmill, and the way that the belt is used to model the wind. The motor is the power source, and a model of the same from the wind. I disagree that the treadmill/cart is the equivalent of a cart in wind.

I am not sure what you mean when you mention the different speeds, Screenshot. The absolute speed is not important. The cart will always achieve a terminal velocity less than the wind. Wind is nebulous, so lets say a constant velocity airflow. The cart cannot extract enough energy from the airflow, to drive it to the same velocity. I am aware of the ground energy idea, but say that is notional.

Boats don't fly, and sailboats are not carts. There are all manner of ways in which a sailboat may beat the wind. They are complete systems that may change their shape, and be steered by intelligence to take maximum advantage of the available resources. Under these conditions, I think that I may need to redefine windspeed, and start looking at the energy budget of the boat locally to it, rather than at some remote point.
I can turn a cat into I rat, if I look for the similarities, and ignore the differences. All manner of contraptions, all unproven, are used to support the cart, yet there is still something new?

I doubt that a simple direct wind craft can even reach windspeed. The drag will win. "A device", certainly.

As I have said, I plan to put this all together in one post. I do have good reasons. I do understand what I am being told.

 

[humber]

It's probably pointless responding, but your numbers seemed to add up, which had me confused for a bit, so I couldn't help but think it over until I realised where you went wrong.

The amount of force gear 1 is using to to turn gear 2 is identical to the force gear 2 is being turned by gear 1.

So... Top wheel to Gear 1 (x2). Gear 1 to Gear 2 (x1). Gear 2 to Wheel 2 (x1/4) Answer = 1/2, Ft = Fc/2.

My drawings are another way of looking at the gears, to show that if I am consistent in my thinking of the ratios, I will arrive at 1:1 ratio for V:F. I have a better idea in mind, but have not had the time to post it. If that fails, you win.

 

[screensnot]

I think you misread my last Q, Humber.

Do you think it's possible to construct a device that will travel directly into the wind, using only the wind as power?

 

[humber]

I think you misread my last Q, Humber.

Do you think it's possible to construct a device that will travel directly into the wind, using only the wind as power?

Sorry, yes. If currents can contraflow, I don't see why that would disqualify an object. The 'against bit' is no problem. That treadmill cart is an example of how the force acting against a device, can be 'reflected' to hold it in place. Additional energy could be gathered to provide thrust.

 

[humber]

No, the tether will move freely on the post. It's only there to keep the cart from moving off the turntable.

Would the cart outpacing bubbles from a bubble-making machine on a level outdoor road satisfy tou for this bet?

Brain_M,
Real wind is a real problem. Difficult to measure. If the wind is steady enough, then I would think bubbles would be OK. In a controlled airflow, yes, but direct measurement would probably be easier.
Actually, I think it must be indoors. There are a number of ways in which the cart could gain some advantage if the conditions are not controlled. Outdoors is not ruled out, but so many variables and uncertainty of repeatability.

I know the cart is tethered as you say. There is a second reactive path for the wheels and propeller. Two force return paths would be a problem. Not so much of a problem for the air driven case, I think.

 

[Dan O.]

1. I do not say anything is faked

If you accept that Jack Goodman's video in post 1 is not faked then we already have our evidence that the cart performs as claimed. Jack was thoughtful enough to have provided a wind indicator on the cart so we can see the relative velocity between the cart and the wind.

We can see in the opening frames that the windsock is mounted to place it on the left side of the cart.



The windsock is clearly long enough to extend in front of the propeller so it must be far enough to the left to not get caught by the propeller. That means that the windsock is in clear air and not in the propeller backwash.

There are long sections in the video where the cart is traveling faster than the wind as evident by the wind sock. We can measure the speed of the cart by measuring the travel relative to markings in on the road. If the cart gains speed during any period while the cart is continuously traveling faster than the wind this would prove the claim.

 

[ThinAirDesigns]

Spork and I just had a really fun conversation with one of the engineers that worked with Andy Bauer or the original DDWFTTW cart in the '60s.

Turns out it wasn't any of their own ideas but they found the idea buried in some long forgotten midwestern students job application/resume in the '50s. They have no idea if it was his original idea or if one of his professors gave it as a problem, or something else.

Spork will have more details as he was keeping notes.

ynot will be particularly interested in this little tidbit:

We asked if they build a smaller version or just the large ride-along one in the picture and he said that they built a model, tethered and ran it on a large turntable to tweak and test it. Ynot, you are in some very good pioneer company with your idea.

Very cool speaking with that guy.

JB

 

[humber]

If you accept that Jack Goodman's video in post 1 is not faked then we already have our evidence that the cart performs as claimed. Jack was thoughtful enough to have provided a wind indicator on the cart so we can see the relative velocity between the cart and the wind.

Not that easily, Dan O.
I covered this oh-so-many posts ago. This device works by gathering momentum. Wind bursts will help, but are not mandatory. Without describing how that works, I can still take issue with the evidence.

We can see in the opening frames that the windsock is mounted to place it on the left side of the cart.

[qimg]http://www.internationalskeptics.com/forums/imagehosting/151444939f1ef9ef2b.jpg[/qimg]
The windsock is clearly long enough to extend in front of the propeller so it must be far enough to the left to not get caught by the propeller. That means that the windsock is in clear air and not in the propeller backwash.

1. The wind is variable, and means of measurement unknown.

2. I wonder what the windsock is telling me. Why not another out in the
breeze as a reference? Why not on the front away from the propeller, so I am sure that it is not in the backwash?
Also the sock's rather vague and variable behaviour, suddenly acquires precision, becoming a binary indicator of windspeed or not windspeed.
The most important parameter is indicated in the most lax way. Anemometers are cheap.
ETA:
If the sock is an accurate indicator, then the cart is capable of phenomenal acceleration.

There are long sections in the video where the cart is traveling faster than the wind as evident by the wind sock. We can measure the speed of the cart by measuring the travel relative to markings in on the road. If the cart gains speed during any period while the cart is continuously traveling faster than the wind this would prove the claim.

[/QUOTE]

Aren't there just. The average velocity is not considered. With a long enough period of acceleration to accumulate velocity and momentum
( in the enormous and massive propeller), that momentum can then be used to drive the cart over the finish line at the point declared to be windspeed, and the point at which filming is stopped. Neat. How many takes failed?

Faked, no. Fraud, no. Bad science, yes

 

[Dan O.]

Anemometers are cheap.

A piece of cloth is adequate to show the critical fact of whether the cart is traveling faster or slower than the wind that can be seen directly in the video if you can believe your own eyes.

The average velocity is not considered. With a long enough period of acceleration to accumulate velocity and momentum
( in the enormous and massive propeller), that momentum can then be used to drive the cart over the finish line at the point declared to be windspeed, and the point at which filming is stopped. Neat. How many takes failed?

Faked, no. Fraud, no. Bad science, yes

You tell me how the cart accelerates or accumulates momentum while traveling faster than the wind.