Merged DDWFTTW in a “Real” Wind

[humber]

This is irrelevant, at worst that would show up as an instantaneous spike, in the calculated results. But it doesn't because it is instantaneous.

Wrong again. You will note that the difference is 360 degrees, showing that the vane has passed through the null.

Then it was a dumb response, that's what happened while the CV was sitting still.

It suited the question, yet more than betters your responses.

This is just, flat, wrong.

According to you, the Global Positioning System produces random errors for a stationary receiver? That would make their use in surveying rather limited.
There is scatter, but not like that. So, wrong again.

What can one say, but...doh?

And the almost perfect mirroring of cart speed and wind direction

 

[Llyricist]

Wrong again. You will note that the difference is 360 degrees, showing that the vane has passed through the null.

and? You should note no anomalies happen in the calculated Wind vectors as a result.

According to you, the Global Positioning System produces random errors for a stationary receiver? That would make their use in surveying rather limited.
There is scatter, but not like that. So, wrong again.

What can one say, but...doh?
[qimg]http://www.internationalskeptics.com/forums/attachment.php?attachmentid=22119&stc=1&d=1305114178[/qimg]
[qimg]http://www.internationalskeptics.com/forums/attachment.php?attachmentid=22133&stc=1&d=1305182536[/qimg]


And the almost perfect mirroring of cart speed and wind direction
[qimg] http://www.internationalskeptics.com/forums/attachment.php?attachmentid=22132&stc=1&d=1305179438[/qimg]

D'oh indeed


Yeah as the wind gets closer to DDW the speed goes up.

 

[drewid]

I believe it to be an exact or at least relevant analogy.



If my hand is securely gripping the handle of the briefcase (in other words, no relative motion), why would the above be any more interesting?

JB

Because the mechanism (the hinge) is the same mechanism as is in a drive chain (say a bicycle chain), where the accounting gets a bit more interesting.

 

[humber]

and? You should note no anomalies happen in the calculated Wind vectors as a result.

Sure they don't.

D'oh indeed

Figured it out yet? The GPS does what?

Yeah as the wind gets closer to DDW the speed goes up.

The blue line is what?

and this contradiction...

 

[ThinAirDesigns]

Because the mechanism (the hinge) is the same mechanism as is in a drive chain (say a bicycle chain), where the accounting gets a bit more interesting.

Not unless the hinge is active of course (something not stated in the original suggestion).

For sure, a LOT more would have to be defined about the problem before it becomes intersting IMO.

JB

 

[humber]

Not unless the hinge is active of course (something not stated in the original suggestion).

For sure, a LOT more would have to be defined about the problem before it becomes intersting IMO.

JB

Holder of the 60 degree ddw record.

 

[69dodge]

Actually, if you're doing the analysis in the "ground's frame", it is force X distance over the ground.

What he is doing is mixing up energy required to do the work with energy balance. These are two separate issues.

In the first case I have 920 J/s KE loss of the air, plus 483 J/s of effective power spinning the perfect prop = 156 N X 9 m/s

I had lots of trouble understanding this, but now I've come up with an analogy that helps me. Can you tell me if it's truly analogous?

Consider a gas-electric hybrid car with regenerative braking. Imagine that, in addition to the gasoline engine, it has both a motor and a separate generator. Pressing the accelerator connects the front wheels to the motor, which discharges the battery as it drives these two wheels. Pressing the brake pedal connects the rear wheels to the generator, which charges the battery as it is driven by these two wheels.

Suppose the car is moving along at constant speed, and the gasoline engine is providing the power to overcome friction, with both the motor and generator inactive.

Now, the driver presses hard on both the accelerator and the brake pedal at the same time, engaging both motor and generator. Except for relatively small losses in the motor and generator, which are made up for by a correspondingly small input of energy from the engine, nothing happens. The car continues at constant speed.

If we focus on the front wheels, it looks like lots of work is being done on the car, because the car is moving forward and the front wheels are pushing the car forward with great force. Where does all this energy come from? The engine is only providing a small amount.

The answer is that it comes from the battery, which is getting it from the generator, the work to drive which is the very work whose energy source we're looking for. The energy doesn't need to come from anywhere else, like the gasoline engine.

Getting back now to the wind-powered cart, the moving air corresponds to the car's gasoline engine, which can provide some extra energy. The propeller, which drives the cart forward, corresponds to the car's front wheels and motor, which drive the car forward. The wheels of the cart, which are driven by the cart's motion, correspond to the car's rear wheels and generator, which are driven by the car's motion. The cart's drive chain, which transfers power from the wheels to the propeller, corresponds to the car's battery, which transfers power from the generator to the motor.

In conclusion, part of the power needed to do the (156 N)(9 m/s) of work per second which is being done on the cart can indeed come from the propeller, just as part of the power needed to run the car's motor can come from the generator. It doesn't all have to come from the wind. So, it is in fact correct to add the energy loss of the wind to the power provided by the propeller, to get the total work done on the cart by the 156 N of force on the propeller.

 

[windgrins]

Thanks BowlofRed!

I enjoy reading the thread, but I think I'll leave any of the big questions for others. I felt confident addressing the specific points raised in that one post.

Given that I don't have the skills (or desire) to do a full mathematical analysis, I doubt that anything I could say on the subject would be different than what is already said.

But yes, I agree that the treadmill works fine as an analog.

Thanks very much for your reply!

PS, I assumed from your Identity image that your handle is indeed "Bowl of Red". Hence my caps. Good name!

Regards,

WindGrins

 

[69dodge]

Here's another way to look at what I discussed in my last post.

Opposing the forward force of 156 N on the cart, via the propeller, is a backward force on the cart, via the wheels. Instead of considering the work done only by the 156-N force, consider the net work done on the cart by the difference of these two forces. It is this lesser amount of work that actually needs to be accounted for, and the energy from the wind then suffices.

This is somewhat too simple, because it glosses over the difference between the effective power of the propeller and the total power driving the propeller, the latter of which is what appears at the wheels.

So, in more detail:

Not all of the (156 N)(9 m/s) of power is wasted overcoming friction, and therefore needs to "come from" somewhere (namely, the wind). Some of it is indeed wasted overcoming air resistance and rolling resistance and friction in the chain and inefficiencies in the propeller. Some of it accelerates the cart, and this part too needs to come from the wind. But some of it (equal to the effective power of the propeller) is used, losslessly, to spin the propeller, generating thrust and providing part of the (156 N)(9 m/s) of power that we started with. This portion doesn't need to come from the wind, because it doesn't go anywhere. It just runs itself, in the same way that the generator runs the motor which runs the generator, in my example of the hybrid car.

There's one point that still confuses me a bit. Can we really separate the 156-N force between the air and propeller into a part due to the air and another part due to the propeller, as the above suggests? I'm not sure how to make sense of that.

 

[fttw]

This seems wrong to me. Can you elaborate? What thought experiments?

Actually I am wrong.

The thought experiment involved replacing the friction force with an elastic string, anchored to the train in one case, and to the track in the other case. I was going to suggest that the work done in slowing the block and stretching the elastic was the same in both cases but the track-anchored elastic has stretched further so the force it exerts must be lower. However - the track-anchored elastic has work done on it by the train and the train-anchored elastic doesn't.

I think that's the answer to the "riddle" if there is one; forces come in pairs. If you want to view one end of a force in a different frame of reference (moving at 50ms-1 say) and claim that it's generating energy because the point of application of that force is moving - you must view the point of application of the equal&opposite force in the same moving frame. The apparent gain (by moving frames) at one end is cancelled by the loss at the other.

 

[windgrins]

Definitive and Sarcastic Nonsense!

According to you, the Global Positioning System produces random errors for a stationary receiver? That would make their use in surveying rather limited.
There is scatter, but not like that. So, wrong again.

Humber, Once again you start talking like you are an expert in an area that you seem to know almost nothing about.

Most commercial GPS receivers compute a direction of motion by comparing one position fix to the next and displaying the difference in positions as a vector for direction and given the time between fixes computes the speed by distance/time.

So Llyricist is absolutely correct and you, as usual, are wrong. The small random differences for a GPS position produces random changes in motion direction for a fixed GPS at a very low velocity as stated.

This is why surveyors or anyone wanting a precise fix will use both the differential signal capabilities and the average mode in the GPS to average out the noise in the fix.

You are extremely good at making authoritative incorrect definitive statements about things you seem to know very little about. I can barely wait until you post a website claiming it proves your point, when in fact, it actually shows you are wrong.

WindGrins

 

[A.T.]

Most commercial GPS receivers compute a direction of motion by comparing one position fix to the next and displaying the difference in positions as a vector for direction and given the time between fixes computes the speed by distance/time.

So Llyricist is absolutely correct and you, as usual, are wrong. The small random differences for a GPS position produces random changes in motion direction for a fixed GPS at a very low velocity as stated.

We already knew that humber cannot differentiate between velocity & acceleration. But now he even fails to understand the difference between position & velocity.

He never fails to fail.

 

[Llyricist]

Sure they don't.


Figured it out yet? The GPS does what?

[qimg]http://www.internationalskeptics.com/forums/attachment.php?attachmentid=22134&stc=1&d=1305183971[/qimg]

Give the time range for that graph and I'll tell you.

The blue line is what?
[qimg]http://www.internationalskeptics.com/forums/attachment.php?attachmentid=22135&stc=1&d=1305184119[/qimg]

I don't know what you are trying to show here, but all it actually says is that the speed increased while the wind trended toward DDW, and decreased while the wind trended away from DDW. Which pretty much undercuts your position.

Of course there is no actual cause and effect relationship going on. But here's some data you left out for that same time period:

and this contradiction...

[qimg]http://www.internationalskeptics.com/forums/attachment.php?attachmentid=22117&stc=1&d=1305107294[/qimg]

I'm 95% sure that happened while they were towing the BB back in to position.... In fact, you should have used that in your reply to jduffy before.

 

[CORed]

Humber, Once again you start talking like you are an expert in an area that you seem to know almost nothing about.

Most commercial GPS receivers compute a direction of motion by comparing one position fix to the next and displaying the difference in positions as a vector for direction and given the time between fixes computes the speed by distance/time.

So Llyricist is absolutely correct and you, as usual, are wrong. The small random differences for a GPS position produces random changes in motion direction for a fixed GPS at a very low velocity as stated.

This is why surveyors or anyone wanting a precise fix will use both the differential signal capabilities and the average mode in the GPS to average out the noise in the fix.

You are extremely good at making authoritative incorrect definitive statements about things you seem to know very little about. I can barely wait until you post a website claiming it proves your point, when in fact, it actually shows you are wrong.

WindGrins

A little anecdote about GPS: My phone has a GPS unit in it, and Google Maps. In satellite view, at maximum scale, Google Maps shows my house quite clearly. It is amusing to lie in bed, and watch as my position moves about from the front yard, to the back yard, to my neighbor's house, and eventually (usually) settles down to my bedroom.

 

[humber]

Give the time range for that graph and I'll tell you.


I don't know what you are trying to show here, but all it actually says is that the speed increased while the wind trended toward DDW, and decreased while the wind trended away from DDW. Which pretty much undercuts your position.

Is that what you think? good

 

[CORed]

Give the time range for that graph and I'll tell you.


I don't know what you are trying to show here, but all it actually says is that the speed increased while the wind trended toward DDW, and decreased while the wind trended away from DDW. Which pretty much undercuts your position.

Of course there is no actual cause and effect relationship going on. But here's some data you left out for that same time period:

[qimg]http://www.internationalskeptics.com/forums/attachment.php?attachmentid=22141&stc=1&d=1305213226[/qimg]



I'm 95% sure that happened while they were towing the BB back in to position.... In fact, you should have used that in your reply to jduffy before.

One of the amusing features of humberscience is that an experiment can be invalidated by events that happened before and after the experiment, and probably even by events that happened during the experiment thousands of miles away.

 

[humber]

A little anecdote about GPS: My phone has a GPS unit in it, and Google Maps. In satellite view, at maximum scale, Google Maps shows my house quite clearly. It is amusing to lie in bed, and watch as my position moves about from the front yard, to the back yard, to my neighbor's house, and eventually (usually) settles down to my bedroom.

Err...+/- 100m is not uncommon for cheap units. I doubt the NALSA would like to be put in that group.

 

[Dr. Keith]

The chart show you such a device.

That is your claim and I am intensely interested in that claim.

Another is a windvane. The power to move that, comes from wind direction change, and vanes too have a lift/drag ratio.

I agree that a wind vane moves in response to a change in wind direction, but I have never seen a device that extracts useful power from a wind vane. Wind vanes are commonly used to align power extraction devices, such as windmills, but I have never seen a wind vane pump water or drive a turbine.

Your claim is that the cart is being driven to a speed over average wind speed by the variation in wind direction. A wind vane could not do that, could it? If so, how?

Finally, what parts of the BB achieve this result?

But cart supporter Steve Smith of NASA says:

One other possibility is worth discussing — that it could be the time-variation of the wind direction, rather than simply the fact that the wind is not (also..my edit) DDW. There are examples of similar effects in nature that would give some reason to consider this. For example, what is called “dynamic soaring” -- the maneuvering in a wind gradient field (regions where there is a consistent pattern of different wind speed) that allows birds (and gliders) to soar by extracting energy out of the wind gradient field."

Not small, but big changes, as seen in the chart.

Do you think the BB is using something similar to Dynamic Soaring?

If so, can you explain how?

Really, this fascinates me because if it is using something similar to dynamic soaring they have hidden that quite well. Maybe you could be the one to expose it . . .

 

[humber]

Humber, Once again you start talking like you are an expert in an area that you seem to know almost nothing about.

Most commercial GPS receivers compute a direction of motion by comparing one position fix to the next and displaying the difference in positions as a vector for direction and given the time between fixes computes the speed by distance/time.

So Llyricist is absolutely correct and you, as usual, are wrong. The small random differences for a GPS position produces random changes in motion direction for a fixed GPS at a very low velocity as stated.

This is why surveyors or anyone wanting a precise fix will use both the differential signal capabilities and the average mode in the GPS to average out the noise in the fix.

You are extremely good at making authoritative incorrect definitive statements about things you seem to know very little about. I can barely wait until you post a website claiming it proves your point, when in fact, it actually shows you are wrong.

WindGrins

The scale is in degrees....GPS output 1/sec. Still don't see the cause?

It's the willingness to see the face of Jesus in a tomato leads to believing in a magic cart, and then that 60 degree wind changes could even begin to be called ddw, hence the above post in support of that.

 

[Dr. Keith]

A simple device made from aluminum strip, and some parts from a construction set, is laughing at you.

Is that what your imaginary cart will be made of? When?

Despite my intense interest in your logic, this imaginary cart of yours is dead. Stop talking about it. We have debunked it and it will never recover. It only serves to embarrass you and those who would argue alongside of you.