I don't understand how this car works.

@ebrown p,

ebrown p wrote:

In this case you are forgetting the key part.... the propeller which (being driven by the wheels) is pushing the car forward (by pushing air backwards). This certainly provides an acceleration. The key to understanding this is that the thrust of the propeller adds to the tailwind (or to put it another way, it is measured relative to the tailwind).

And you're forgetting that the force to drive the propeller is coming from friction with the road, which is a force vector in the opposite direction.

ebrown p wrote:

If there was no tailwind (in your example) instead of the car moving at the "same speed as the wind"... the wind would be going against the motion of the car (from the cars perspective).

I'm describing a circumstance exactly like the video that was posted. If the car is moving at a speed equal to the wind, then to the driver of the car it appears like he's in a dead calm, and the road is rolling beneath him. How is the wind adding energy to the car at that point?

ebrown p wrote:

The point being, the tailwind certainly "helps" the car in any of these circumstances (i.e. the energy being added to the car is always greater with a tailwind then without).

But you can't describe how the tailwind "helps" the car in any of these circumstances.

I'm back to wanting the experiment independently verified. Every site that reports on this uses the same talking points from that one website.

3 Replies

@DrewDad,

Quote:

I'm describing a circumstance exactly like the video that was posted. If the car is moving at a speed equal to the wind, then to the driver of the car it appears like he's in a dead calm, and the road is rolling beneath him. How is the wind adding energy to the car at that point?

You are changing Frames of Reference on me Drew. In Physics it is often the case that the analysis is different depending on your Frame of Reference-- the answer, of course, must be equivalent no matter how you analyze it.

In the point of view of the driver the wind is not moving and the car is not moving. This means that from this perspective the wind has no kinetic energy and the car has no kinetic energy. However, if you look at it this way, the road is moving (and has kinetic energy). The road is using this energy to drive the propeller which is spinning.

You do accept the fact that a spinning propeller causes an acceleration even in a dead calm, right?

Of course, in the normal way of looking at it (i.e. the roads perspective). The wind is moving and the car is moving. And, of course, the road is not moving (and thus the road has no potential energy). In this case it is the wind that has the kinetic energy. The wind pushes the car which drives the wheels which drives the propeller which adds to the amount the wind is pushing the car.

The explanation on the website carefully talks about it being the difference of speeds between the road and the wind. They are being careful to encompass all frames of reference (i.e. ways of looking at the problem).

1 Reply

@DrewDad,

Quote:

I'm back to wanting the experiment independently verified. Every site that reports on this uses the same talking points from that one website.

The toy car didn't do it for you? This type of experiment is well known and is done in Physics classrooms around the country.

There are no serious physicists who challenge these results.

1 Reply

@ebrown p,

ebrown p wrote:

You do accept the fact that a spinning propeller causes an acceleration even in a dead calm, right?

You do accept that a system without outside input will eventually run down, right?

2 Replies

@maporsche,

maporsche wrote:

I'd really like to see some math on this.

http://upload.wikimedia.org/wikipedia/en/4/4f/Wiki_sailing_vector_downwind.png

This diagram pertains to boats, but the basic principles apply when you realize that the propeller being driven by the rotating wheels on the vehicle act as the angle-to-ground interface equivalent to the boat.

0 Replies

@ebrown p,

ebrown p wrote:

There are no serious physicists who challenge these results.

...if they were performed in a laboratory setting.

Extraordinary claims require extraordinary proof. I haven't seen that proof yet.

1 Reply

@DrewDad,

Quote:

You do accept that a system without outside input will eventually run down, right?

There are two significant forms outside input. There is a 13mph tailwind. And there is contact with the road.

0 Replies

@DrewDad,

Quote:

Extraordinary claims require extraordinary proof. I haven't seen that proof yet.

It is not an extraordinary claim. There are lots of things in Physics that are counter-intuitive. This does not mean that they break any laws of Physics.

This car is running on wind power. It is taking energy from the wind and transferring it to the kinetic energy of the car. The counter-intuitive part is that it is able to access the wind power even when it is going faster then the wind. However there is nothing about this that breaks any laws of Physics. This isn't even a particularly extraordinary claim.

This is cool... but it ain't magic.

1 Reply

@DrewDad,

You've really been eating into my spare time with this post.

Here's how I'm picturing it right now (which may be different than an hour from now.) At time zero, the car is running with the wind at almost the speed of the wind. There is a generator on the wheels making electricity. (I know this is not the case, but it helps me understand it.) The force generated by the wind is proportional to the wind speed and the size of the sail the wind is acting upon. The forces resisting motion are the drag from the generator on the wheels, the friction resistance in the wheels and bearings and the wind resistance which should be negligible since the car is air is moving about the same speed as the car. In this scenario, I can picture the car moving almost the same speed as the wind and also generating electricity. Given a big enough sail, I could generate a decent amount of electricity and still be moving almost the same speed as the wind. Now instead of electricity, I convert that energy into propulsion. I should be able to go faster.

I'm going to crush productivity at work today. I've forwarded the link to the physics and mech engineering guys. I'll let you know if they have any great insights.

1 Reply

@ebrown p,

It can not take a mill watts of power from the wind once it pass the vel. of the wind.

And no waving of anyone hands is going to change that fact.

Love to see someone try to place this nonsense into formulas as not even the hoaxers themselves had not try to do so.

At least the Dean Drive supporters try to back up their claims with math.

It is never never a good sign when someone claimed they had broken the laws of physics and do not even come up with any math to support their nonsense.

2 Replies

@DrewDad,

DrewDad wrote:

An iceboat's speed can be faster than the wind, but only when moving across the wind. But point the iceboat downwind, the speed drops off, and it can never average a speed downwind faster than the wind itself.

Correct. That's why sailboats never travel directly downwind to win a race. They can achieve higher speeds by impacting the wind at an angle.

DrewDad wrote:

These folks are claiming that the car can go downwind indefinitely at 2.85x the speed of the wind. I'm not seeing where the energy to do so is coming from.

It's not "energy" which is being added to the system, it's velocity. The system is exchanging torque (or power) for velocity.

Sailboats don't move "off the line" quickly by using the same sail angle that they will ultimately use when traveling. To start out with they use a shallow wind angle to generate more power for getting going, but once they are moving the efficiency of the sail at a sharper angle can be used to deflect the wind at a higher velocity and it's this velocity which is translated into speed.

The land vehicle is doing the same thing, but it is using a propeller (another type of airfoil, just like a sail) in conjunction with wheels geared to the ground, so create an effective "angle" to the wind even though it is traveling directly downwind.

DrewDad wrote:

That being said, I'm not seeing how that little car manages to climb up the incline of the treadmill. I suppose there could be a fan blowing on it, that's out of frame.

The car moves up the treadmill by the same principle. It replicates a situation in which the "real world" vehicle is already traveling with the wind and is essentially in "still wind" conditions.

It seems counter intuitive because you are equating "energy" with "speed" and they are not the same thing. No "Energy" is being created by the system any more than changing gears on your car makes it go faster.

Maybe that's the best way to think about it... if your car engine runs at a constant power output, but you change gears, the car will travel at different speeds, but the power being used to push it is always the same. The only difference is that you're exchanging torque for speed.

0 Replies

@BillRM,

Quote:

It can not take a mill watts of power from the wind once it pass the vel. of the wind.

What law of Physics says this? Can you prove this assertion? (because I can disprove it ).

2 Replies

@engineer,

Engineer I would not waste too must time as the hoaxes are likely to come out into the open shortly giving the finger to all those who fell for the nonsense.

0 Replies

@ebrown p,

Quote:

What law of Physics says this? Can you prove this assertion? (because I can disprove it ).

Zero wind in relationship to the car mean zero force cause by the wind on the car mean zero energy/work into the car as W=F*D with force at zero work is at zero.

Side note all of the above are vectors terms but I can not place the little arrow about the terms.

0 Replies

@ebrown p,

By the way had you ever in your life taken a college level course in physcis?

1 Reply

@BillRM,

BillRM wrote:

It is never never a good sign when someone claimed they had broken the laws of physics and do not even come up with any math to support their nonsense.

Nobody has claimed to have broken the laws of physics with this.

Bill, if we could convince you that ice boats travel faster than the wind, would you consider the idea that the prop on this vehicle is behaving like a sail which is impacting the wind at an angle?

Do you agree that ice boats can travel faster than the wind, even though they are not traveling directly downwind?

1 Reply

@DrewDad,

DrewDad wrote:

ebrown p wrote:
You do accept the fact that a spinning propeller causes an acceleration even in a dead calm, right?

You do accept that a system without outside input will eventually run down, right?

The system in question "does" have outside input. Just because the system is in equilibrium doesn't mean it has no input.

While in "calm" air the wheels are turning and the prop is exerting force on the air around it.

If the vehicle begins to slow, then the tailwind becomes apparent again and adds force to the system causing the wheels to turn and re-establishing equilibrium.

0 Replies

@rosborne979,

Ice boats can travel faster then the speed of the wind at an angle so there are still wind forces in relationship to the boat.

No repeat no ice boat can travel directly down wind at a speed greater then the wind powering it. No ice boat can travel faster in a direction then the wind component vector in that direction.

You not understanding this is a big red sign on the limit of your education on this subject.

2 Replies

@BillRM,

BillRM wrote:

No repeat no ice boat can travel directly down wind at a speed greater then the wind powering it.

We agree on this.

BillRM wrote:

You not understanding this is a big red sign on the limit of your education on this subject.

I'm trying to be nice Bill, but you're not doing yourself any favors at this point.

You seem to be closed minded on this. Are you giving reasonable consideration to the explanations we are giving, or are you just ignoring them?

1 Reply

@rosborne979,

When some hoaxers are claiming to had broken newton's laws I get very closed mind indeed.

And now that we agree that an ice boat can not move faster then the wind down wind would you care to drop that subject and give the math as how this hoax car can travel down wind at a vel. greater then the wind driving it!!!!!!!!!!!!

2 Replies

I don't understand how this car works.

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