5
   

I don't understand how this car works.

 
 
Cycloptichorn
 
  1  
Reply Mon 7 Jun, 2010 01:07 pm
@DrewDad,
Hah! I just figured it out completely.

Half the speed is coming from the wind. The other half is coming from the ground. For the purposes of the device, the car might as well be standing perfectly still w/respect to the ground, and the ground is moving, turning the propeller, just like a wind power plant in reverse. That + gearing = speed more then double what the wind is itself.

innovative stuff!

Cycloptichorn
0 Replies
 
BillRM
 
  1  
Reply Mon 7 Jun, 2010 01:11 pm
@ebrown p,
Quote:
3) Spinning wheels can be connected to a propeller causing the propeller to spin. There is no law of physics being broken here.


You are taking energy away from the car to spin the blades to push the car so it is the same as if you was recharging a battery by using the energy in the battery.

Losing energy all over the place not gaining it.

How the hell can our school not teach basic science any better then this????
Cycloptichorn
 
  1  
Reply Mon 7 Jun, 2010 01:12 pm
@BillRM,
BillRM wrote:

Quote:
3) Spinning wheels can be connected to a propeller causing the propeller to spin. There is no law of physics being broken here.


You are taking energy away from the car to spin the blades


Bzzt! Wrong! You aren't taking energy from the car, but from the Earth. For the intents and purposes of the propeller, the car is standing still. The wind has nothing to do with the propeller at all.

Quote:
How the hell can our school not teach basic science any better then this????


Reading your posts in this thread, I keep asking myself the same question.

Cycloptichorn
BillRM
 
  1  
Reply Mon 7 Jun, 2010 01:15 pm
@DrewDad,
Quote:
You seem to be the more close-minded one, since you refuse to acknowledge the possibility that the experiment was genuine.


Lord this is the same kind of claims that had been proven false a millions times in the past.

If it was true then we would need to tear up every bit of our science going back to before Newton.

I would cheerfully bet my life let alone my wealth that this is a nonsense hoax.n

What background do you have in science/
0 Replies
 
DrewDad
 
  2  
Reply Mon 7 Jun, 2010 01:15 pm
@BillRM,
With a static sail: Wind pushes the sail, sail pushes on the car, car accelerates. Car accelerates until force from the wind equals friction from the wheels. Yes?


With a propeller sail: Wind pushes the sail, sail pushes the car, car linear velocity accelerates and sail rotational velocity accelerates. Car accelerates until force from the wind + thrust from the sail equals friction from the wheels plus friction from the spinning sail. Yes?
BillRM
 
  1  
Reply Mon 7 Jun, 2010 01:21 pm
@DrewDad,
Quote:
Car accelerates until force from the wind equals friction from the wheels. Yes?


Yes with the understanding that the force of the wind is decreasing with the square of the speed of the car along the wind vector.

If you have a wind of 14 MPH the force on the car at the start would be 4 times what it is as the car reach 7 MPH in the direction of the wind for example.
BillRM
 
  1  
Reply Mon 7 Jun, 2010 01:29 pm
@Cycloptichorn,
Quote:
Bzzt! Wrong! You aren't taking energy from the car, but from the Earth. For the intents and purposes of the propeller, the car is standing still. The wind has nothing to do with the propeller at all.


If you are unlucky enough to run into the wrong con-man you are going to lose every dime you ever own.

Taking energy from the earth indeed.
DrewDad
 
  1  
Reply Mon 7 Jun, 2010 01:30 pm
@BillRM,
BillRM wrote:
If you have a wind of 14 MPH the force on the car at the start would be 4 times what it is as the car reach 7 MPH in the direction of the wind for example.

That would affect acceleration, but it would not affect top speed. Basically, you're saying that as you approach top speed your acceleration falls off asymptotically.
ebrown p
 
  1  
Reply Mon 7 Jun, 2010 01:33 pm
@BillRM,
Quote:


Yes with the understanding that the force of the wind is decreasing with the square of the speed of the car along the wind vector.



This is not a sail. It is a propeller. This means the force of the propeller adds to the tailwind.

As the cars speed increases, the speed of the propeller increases, meaning more force and faster acceleration (of course there is also increased friction but on net there is a positive acceleration).

The propeller is being driven by the ground. The faster the car goes relative to the ground, the faster the propeller goes and the greater the backwards thrust is and the faster the car goes... and you get the idea.

All of the time the energy is coming from the wind. Air molecules are losing kinetic energy which is being transferred to the car.

There is no law of physics being broken.


0 Replies
 
Cycloptichorn
 
  1  
Reply Mon 7 Jun, 2010 01:37 pm
@BillRM,
Quote:
Taking energy from the earth indeed.


The wheels are doing exactly this. You don't really understand much about physics and force, do you?

You really are making yourself look foolish here, Bill. I suggest you rethink the situation and the Vectors of force involved.

Cycloptichorn
0 Replies
 
DrewDad
 
  1  
Reply Mon 7 Jun, 2010 01:39 pm
@DrewDad,
Bill,

I think you are saying that force in has to equal force out. That is not true. Work in has to equal work out.

Attach a rope to a skateboard. Attach the rope to a pully, stand next to the skateboard. Pull the rope, and the skateboard accelerates.

Now stand on the skateboard. Pull the rope. The rope pulls the skateboard and your feet push the skateboard. It doubles your force (almost). The trade-off is that you end up pulling twice as much rope to move the skateboard the same distance as before.

Same work, different amounts of force applied.

That's mechanical advantage.


With the sail cars, you are not getting more work out of the wind. You are getting the same amount of work. Same force over the same distance.
BillRM
 
  1  
Reply Mon 7 Jun, 2010 01:56 pm
@DrewDad,
Sorry they are all related.

F=M*A or A=F/M

Vfinal=Vstart +A*T*T/2 Assuming Vstart =0 then

Vfinal=A*T*T/2 =F*T*T/2*M

As force or acceleration is not a constant you need to integrates the above from T=0 to T when force equal 0.

Sorry that I do not have the ability to place the integration sign in this posting.

BillRM
 
  1  
Reply Mon 7 Jun, 2010 02:00 pm
@DrewDad,
Work is equal to force time distance.

As in Work=Force*distance and once more as force is not a constant here you need to intergrate in relation to Dx. can

Oh you indeed play games by increasing the D to decrease the force as in pulleys however the total work is the same and if you are moving a mass up into the air x feet you would still need to provide an energy equal to Mass*height*9.81 in mks units
0 Replies
 
DrewDad
 
  1  
Reply Mon 7 Jun, 2010 02:08 pm
@BillRM,
Yeah, it's apparent from the video that acceleration is lower than in a traditional sail car.

So lower acceleration over a longer time results in....?

Also, your equations are the classic "frictionless plane" format.

You need to write it out in force vectors at each point, including friction.
BillRM
 
  1  
Reply Mon 7 Jun, 2010 02:19 pm
@DrewDad,
DrewDad it is a hoax of the same class and for the same reasons as any Perpetual motion machine s in fact those who wish to sell such always try to confused one with the different between work and force.

You are not going to go faster then the wind driving a wind power car unless you stored up energy and used it to briefly go faster and your average speed will then be less then if you did not do so.
DrewDad
 
  1  
Reply Mon 7 Jun, 2010 02:25 pm
@BillRM,
No, you're not going to go faster than the wind unless you are still drawing power from the wind.

At the point at which the vehicle's speed equals wind speed, the wind is still encountering resistance because the propeller is creating a higher-pressure area behind it. The molecules in the air are slowed, and the car takes that momentum and adds it to its own.

Basically, the propeller is a method to gain mechanical advantage over the wind.
BillRM
 
  1  
Reply Mon 7 Jun, 2010 02:26 pm
@DrewDad,
Quote:
Also, your equations are the classic "frictionless plane" format.



Sorry not so as the F is the total force acting on the car second by second.
0 Replies
 
engineer
 
  1  
Reply Mon 7 Jun, 2010 02:29 pm
It seems to me that if you are counting on getting energy from the wind, then the amount of energy you could obtain comes from the delta velocity between yourself and the wind (in the direction the wind is blowing) times the surface area the wind impinges upon. I don't see how you can possibly take energy from the wind if you are running faster than the wind. In that case, you have to fight air resistance to move forward and in the absence of any other external energy supply, you will have to slow down. I'm with DrewDad on this one... I can't see it.
BillRM
 
  1  
Reply Mon 7 Jun, 2010 02:32 pm
@DrewDad,
Quote:
No, you're not going to go faster than the wind unless you are still drawing power from the wind.


Sure you can store up energy from the wind and then expend it when the wind force had reach zero to go faster for a short time then the wind.

A nice heavy fly wheel with gearings that you connected to the propeller or wheels at the proper moment would do that.

You spin it up at below maximum wind speed and then cut it out until you need it energy to go over the wind speed.
0 Replies
 
ebrown p
 
  1  
Reply Mon 7 Jun, 2010 02:39 pm
@engineer,
Quote:
It seems to me that if you are counting on getting energy from the wind, then the amount of energy you could obtain comes from the delta velocity between yourself and the wind (in the direction the wind is blowing) times the surface area the wind impinges upon. I don't see how you can possibly take energy from the wind if you are running faster than the wind. In that case, you have to fight air resistance to move forward and in the absence of any other external energy supply, you will have to slow down. I'm with DrewDad on this one... I can't see it.


Engineer. Think propeller.

The propeller pushing backwards acting in concert with a tailwind is the way you "take energy" from the wind if you are running faster then the wind. Also consider that the propeller is being driven by the road.

I would also ask the question again... I get that you don't see it... but what law of physics is being broken?
 

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