JoeF,

My understanding is that pizo cells do have some internal movement relative to the positions of the molecules in the crystal. So I assume that the distortion of the cells can be measured externally, although the amount of external change is very small.

So I agree that if pizo cell were infinitely rigid, it would not be able to generate electricity. But, pizo cells are not infinitely rigid.

An infinitely rigid blade on a VAWT would have very little effect on the efficiency of a VAWT. And it is not relevant pizo cells or Active Lift.

Likewise, it would have very little relevance to the Betz limit.

I presented an argument for understanding Active Lift. I said using the pizo cells as I described would increase the power. Not much, but a little.

So I can’t make sense of your argument that pizo cells can’t beat Betz. That is because I didn’t claim that they could. You are arguing against something that I didn’t say. That is not a valid argument with respect to what I did say.

Then, your last line seems to agree with what I said, and seems to imply that you accept that Active Lift can generate additional power for a VAWT.

Am I missing something about what you said?

PeterS

DaveS,

Please define DS and then show precisely why DS is relevant to the Cyclo-Kite.

PeterS

DaveS,

“Cyclokite DS Pattern: Low swooping at the surface, where wind is slowest.”

I have already explained why the lower wind speed near the ground is disadvantageous for the Cyclo-Kite, not advantageous as it would be for DS.

You are the ignoring evidence that contradicts your claim.

PeterS

Hi Pierre,

You are assuming that the pressure of the blades against pizo cells that produces electricity must leave the total power of the VAWT constant, with no increase. You are assuming that the power of a VAWT will remain the same, regardless of whether pizo cells are added or not. That argument depends upon seeing the problem as a conservation of energy problem. But it isn’t.

Please keep in mind that the blades are already applying pressure pulses to their blade mounts, so adding pizo cells has no way to extract energy from the normal way that the VAWT produces power. The pizo cells can only add to the total power.

The additional power has always been available, but nobody knew how to tap it efficiently. Lecanu describes what happens as converting potential energy (wind pressure on the blades) into kinetic energy (torque).

A normal fixed-blade VAWT does not convert wind pressure on the blades into additional torque and power. Nor do most cycloturbines. However, the Sharp Cycloturbine does, because the blades move downwind a short distance when they pitch (which forces the support arms forward faster and farther than the blades). But the ALT is much more efficient at using Active Lift.

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If I understand Lecanu correctly (and I have my doubts about that), he is saying that additional energy can be produced without slowing down the wind any more than usual for a fixed-blade VAWT. He is saying that converting wind pressure on the blades is a separate and additional source of energy in the wind – but only if you have an efficient way to do it.

If that is true, then the normal “Betz” limit for VAWT (Cp max. = .61) can be equaled or even exceeded by a real ALT.

PeterS

Hi PierreB,

Yes. The word “without” in the first sentence is a typo. It should be “with”.

PeterS

DaveS,

You simply repeated your claim. You once again ignored what I said about how a normal wind gradient is disadvantageous to a Cyclo-Kite near the ground, not advantageous as would be the case for DS. You failed to define DS and show precisely why it is relevant to the Cyclo-Kite. Your manner of discussing this issue is illegitimate for a discussion of technical matters.

JoeF,

DaveS is falsely describing the operation of the Cyclo-Kite and misleading people about how it functions. Please do your job as moderator. Please require people who make claims to provide convincing evidence for them. If you believe that DaveS has provided that evidence, then please define DS and then show precisely why DS is relevant to the Cyclo-Kite. If you can’t do that, it means that he has not provided convincing evidence to support his claim.

PeterS

Hi PierreB,

Thank you for your good advice and accurate description of Dave’s technique.

PeterS

Hi JoeF,

I am not aware that their literature includes the claim that an Active Lift Turbine could beat Betz using pizo cells. You might wish to double check.

PeterS

Hi JoeF,

I already sent you an email that went into the effect of a positive wind gradient, a negative wind gradient, and no wind gradient, and compared them as to their effects on the Cyclo-Kite. I also explained that it depends upon what you are comparing and why that is so. So we seem to be starting over again.

You are correct that if the wind near the ground is taken as the ambient wind speed, then a wind gradient with higher wind speeds above will increase the average wind speed and there will be more total energy in the wind, and the Cyclo-Kite will produce more power. More wind energy, more power. That is the usual connection. But it has nothing to do with DS.

However, you seem to also be suggesting that the higher wind speed acting on the upper part of the blade’s orbit (quadrants 2 and 3) will benefit the lower quadrants (4 and 1), although you don’t say in what way they would benefit. So since your point seems unclear to me, I can’t agree or disagree.

Consequently, I don’t see any reason to conclude that the Cyclo-Kite is using dynamic soaring (DS).

Did I miss something?

Peter

Hi JoeF,

To paraphrase you, the available energy that can be obtained by slowing the wind, no matter what form of energy is produced by the wind turbine, cannot exceed the Betz limit. That is correct as far as I know.

But what Lecanu is saying is that his system does not slow the wind any more than usual. Instead, he is able to convert the normal wind pressure acting downwind on the blades into additional torque. The usual resistance of the blades to wind pressure acting in the downwind direction is converted into torque by way of his unique mechanism. So it is energy that was already there as potential energy. He is just converting it to kinetic energy. And he is doing it much more efficiently than pizo cells could.

His math is presumably correct and his mechanism does look like it would significantly increase the Cp. But as you say, it makes sense to be skeptical until the concept is tested and verified.

PeterS

DaveS,

“PeterS thinks the gradient effect is the negative in his case”.

You are incorrectly stating what I said. What I said was that the effect of a wind gradient on a Cyclo-Kite depends upon what wind speed you use as ambient. If you use the wind speed near the ground as the ambient wind speed, then a normal wind gradient will increase the average wind speed and that will increase the energy in the wind and that will increase the power of the Cyclo-Kite. Conversely, if you use the higher wind speed in the wind gradient as the ambient wind speed, then the average wind speed will be lower, the energy in the wind will be lower, and the power of the Cyclo-Kite will be reduced; it will have a negative effect.

I most definitely did not say that a normal wind gradient has a negative effect on the Cyclo-Kite. To claim that I did is to ignore what I actually said and to misrepresent what I said.

The effects of the wind gradient, no matter what they are, do not cause the Cyclo-Kite to function like a DS glider.

As far as I can tell, since you won’t provide any further evidence, you are concluding that because the kite and the glider both do loops, and they can both operate in a steep wind gradient, they must function the same, so therefore the Cyclo-Kite employs DS. But that is quite wrong. There are major difference between the way that they function. A Cyclo-Kite can function normally when there is no wind gradient. A DS glider cannot. So they cannot be based on the same fundamental principle of operation.

PeterS

No, Dave. To interpret what he said literally is to deliberate distort its meaning.

What you did demonstrate is an inability to distinguish between a simple declarative statement and a metaphor.

PeterS

Hi PierreB,

Sorry, I’m not sure what you are saying. What statement is it that you are referring to?

PeterS

No, Dave. Wrong again. The definition in Wikipedia of DS does not reveal how the Cyclo-Kite employs DS.

You are claiming a connection without showing one. You are just trying to bluff you way out.

PeterS

Hi JoeF,

I don’t see anything in that article about pizo cells. Please quote what you wish to refer to.

PeterS