5
   

I don't understand how this car works.

 
 
ThinAirDesigns
 
  1  
Reply Tue 8 Jun, 2010 04:28 pm
@georgeob1,
georgeob1 wrote:
I'll add one qualification. Assuming the propeller has a controllable, reversible pitch, it might be possible, after a long enough vehicle acceleration to a speed nearly equal to that of the wind (during which the propeller too is extracting energy from the wind - and adding drag in the process), to reverse the pitch of the propellers and to use the stored rotational energy in the propeller to accelerate the vehicle further through the clutch & gearing to the wheels. However, that is not a sustainable thing, in that the rotational energy will soon be dissapated and the vehicle will quickly slow down to speeds well below the wind speed due to friction.


George, to use the kinetic energy of the rotating propeller to speed up the vehicle momentarily, the vehicle would need to be equipped with either a clutch (as you mention) or a variable speed transmission. Our vehicle has neither -- the drive axle is hard geared to the prop axle, running only through a ratchet to allow the pilot to brake quickly without need to stop the mass of the propeller.

Additionally, our prop blades were built intentionally light and store very little energy in pratice. Here is a video of our device on the dyno where I shut off power while the prop is at full speed -- notice that the prop stops completely in only about 6 revs. That's not going to get you far.

0 Replies
 
Chumly
 
  1  
Reply Tue 8 Jun, 2010 04:31 pm
@rosborne979,
rosborne979 wrote:
Yes. And that's exactly why I posted the information on sailing vectors several pages back. Unfortunately, nobody seemed to read them.
I read them!
georgeob1
 
  1  
Reply Tue 8 Jun, 2010 04:47 pm
I also note some discussion here of sailing vessels that use an airfoil (the sail) to produce the driving force. Visualize for a moment the plan view of a sailing vessel tacking with the main boom displaced (say ) 30 degrees from the axis of the ship. The wind generated force on the sail (transmitted to the mast) is roughly perpindicular to the main boom, and proportional to the square of the relative wind speed. That means it is able to extract energy from the wind in some cases at ship speeds greater than that of the relative wind. However, if you look carefully at the geometry, even in this situation it won't generate any sustainable thrust after the ship's speed increases to equal the wind velocity, mostly because the forward component of the force on the mast with the boom correctly positioned will decrease too fast.

In the vehicle pictured there is no sail, and, in effect no boom to position an airfoil advantageously. It is equivalent to a square-rigged sailing vessel, and on such a vessel the sails luff when there is little or no relative wind (i.e. when the ship approaches wind speed).
ebrown p
 
  1  
Reply Tue 8 Jun, 2010 04:55 pm
@georgeob1,
Quote:

Well if the energy source is, as you say, the speed of the wind relative to the ground, then, when the vehicle reaches a speed relative to the ground equal to that of the wind, what is the mechanism by which the wind transfers additional energy to the vehicle to accelerate it further?


Sigh.... I feel like I am repeating my self.

1) The wheels drive the propeller (I think everyone gets this).

2) The propeller pushes the car forwards which causes the wheels to turn. (I think everyone gets this). If it helps... think about how you don't need a propeller for steps one and 2. You can reach equilibrium at pretty damn close to wind speed with just a sail (and sails don't actively push back on the air).

3) Since the propeller is pushing air backwards into the tailwind, the tailwind interacts with the propeller (even though the propeller is going faster then the the tailwind). It is this interaction between the wind and the propeller that allows the wind to transfer energy to the car even when the car is going faster then the wind. The faster the tail wind the faster the car will go.

The car will go faster then the tailwind simply by getting the propeller to spin at all.
0 Replies
 
ThinAirDesigns
 
  1  
Reply Tue 8 Jun, 2010 04:56 pm
@georgeob1,
gerogeob1 wrote:
In the vehicle pictured there is no sail, ...


Not only is there a sail on the vehicle -- there are two. Both are behaving identically to a properly trimmed sail on a broad reach.

Cycloptichorn
 
  1  
Reply Tue 8 Jun, 2010 04:57 pm
@ThinAirDesigns,
There's your money video for explaining this thing

Cycloptichorn
BillRM
 
  1  
Reply Tue 8 Jun, 2010 04:59 pm
@Cycloptichorn,
Economic factors is not the only reason to find something wonderful and second there is something a little strange as this device is being promoted all over the internet by people who claimed to be involved with it.

Given the history of perpetual motion machines the people involved always had have some plans to turn their claims into money so the other shoe may not had been drop yet.

0 Replies
 
BillRM
 
  1  
Reply Tue 8 Jun, 2010 05:02 pm
@Cycloptichorn,
We back to the ice boats once more even those one of the people who claimed to be involved in this device/car agree that an ice boat can not go faster then the wind downwind to the wind.
ThinAirDesigns
 
  1  
Reply Tue 8 Jun, 2010 05:03 pm
@Cycloptichorn,
cycloptichorn wrote:
There's your money video for explaining this thing


LOL -- that's a good one for those who realized that a sailboat can have a downwind VMG of greater than windspeed while on a reach. Unfortunately there is a lot of ignorance around regarding something that has been being done by traditional sailing rigs for near a century now.

JB
Cycloptichorn
 
  1  
Reply Tue 8 Jun, 2010 05:05 pm
@BillRM,
BillRM wrote:

We back to the ice boats once more even those one of the people who claimed to be involved in this device/car agree that an ice boat can not go faster then the wind downwind to the wind.


It doesn't matter whether it is going down-wind or not; if what you said earlier is true (that no vehicle can accelerate to a velocity faster then the component vectors of a windstream that is pushing it) how is it possible for tacking ships and ice boats to reach velocities which are far higher then that of ANY of the vectors of the windspeed?

I think the obvious answer is that the claim that they cannot is incorrect.

Cycloptichorn
Cycloptichorn
 
  1  
Reply Tue 8 Jun, 2010 05:06 pm
@ThinAirDesigns,
ThinAirDesigns wrote:

cycloptichorn wrote:
There's your money video for explaining this thing


LOL -- that's a good one for those who realized that a sailboat can have a downwind VMG of greater than windspeed while on a reach. Unfortunately there is a lot of ignorance around regarding something that has been being done by traditional sailing rigs for near a century now.

JB


And it clearly explains the physics as to why the prop accomplishes the same effect. So surely you are less of a skeptic now?

Cycloptichorn
0 Replies
 
BillRM
 
  1  
Reply Tue 8 Jun, 2010 05:07 pm
@georgeob1,
A flywheel would do a similar thing as I had pointed out many pages ago or any other numbers of energy storage devices including changing the pitch however this would not be a steady state ability.
ossobuco
 
  1  
Reply Tue 8 Jun, 2010 05:09 pm
I'm enjoying this thread, learning a lot. I got a D in physics/uni, overwhelmed when I sat in class for the first time as a graduating senior when I needed the class - and when the prof was talking vectors, me, not having had high school physics, was totally confused, what the hell were they talking about, and never caught up, got the D since I went to all the lab hours. Later wished I had settled down and figured out at least the basics.

Welcome to a2k, thinairdesigns. (I'm on the rosbourne/cyclo/thinair point of view, but my view is not statistically valid...)
0 Replies
 
ThinAirDesigns
 
  1  
Reply Tue 8 Jun, 2010 05:10 pm
@BillRM,
BillRM wrote:
A flywheel would do a similar thing as I had pointed out many pages ago or any other numbers of energy storage devices including changing the pitch however this would not be a steady state ability.


That is correct Bill, there are countless ways to store energy and momentarily exceed the speed of the wind while DDW. There are quite a few less ways that it can be done steady state.



JB

0 Replies
 
BillRM
 
  1  
Reply Tue 8 Jun, 2010 05:19 pm
@Cycloptichorn,
As long as you have a relative wind force at the sail you have force from that wind, and speed is not repeat not a vector, vel. is a vector however.

Zero relative wind on the sail equal zero force.

With wind directly behind your sails there is zero force from that wind at the wind vel/speed.

Confusing speed and vel is a cute game however it does not get you anywhere for those of us who know vector math.

Z
Cycloptichorn
 
  3  
Reply Tue 8 Jun, 2010 05:41 pm
@BillRM,
Quote:
With wind directly behind your sails there is zero force from that wind at the wind vel/speed.


And due to the design of the props here, the wind is never directly behind the 'sails' - even when it is directly behind the vehicle. Do you not understand this?

Cycloptichorn
BillRM
 
  1  
Reply Tue 8 Jun, 2010 07:25 pm
@Cycloptichorn,
Quote:
And due to the design of the props here, the wind is never directly behind the 'sails' - even when it is directly behind the vehicle. Do you not understand this?


Yes, I understand it is the same kind of meaningless words games as had been used time after time in connection with other forms of perpetual motions machines.

Now my question is what is to be gain by trying, all over the net, to sell this concept and defend it from attacks.

After all it is not being wheel out as a power source or as a mean to do away with gas or electric driven cars.

No cold fusion with tens of millions in research grants within reach of the developers.

So what is the point of this hoax?


ebrown p
 
  2  
Reply Tue 8 Jun, 2010 07:49 pm
@BillRM,
Quote:
Yes, I understand it is the same kind of meaningless words games as had been used time after time in connection with other forms of perpetual motions machines.

Now my question is what is to be gain by trying, all over the net, to sell this concept and defend it from attacks.

After all it is not being wheel out as a power source or as a mean to do away with gas or electric driven cars.

No cold fusion with tens of millions in research grants within reach of the developers.

So what is the point of this hoax?


It is just fun to play with you people, BillRM. We have had GungaSnake going with our little "evolution" hoax for years.

0 Replies
 
maporsche
 
  1  
Reply Tue 8 Jun, 2010 08:05 pm
@ThinAirDesigns,
This actually helped a lot.
0 Replies
 
rosborne979
 
  1  
Reply Tue 8 Jun, 2010 08:16 pm
@Chumly,
Chumly wrote:

rosborne979 wrote:
Yes. And that's exactly why I posted the information on sailing vectors several pages back. Unfortunately, nobody seemed to read them.
I read them!

Thanks Chumly. You're like a tree falling the woods when nobody is around Wink
0 Replies
 
 

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