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Post Info TOPIC: Micro Vawt #2
crazyguy


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Date:
RE: Micro Vawt #2
 

Where's Jeff? Come on I really like your design.  



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PASVAWT


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Date:
RE: Micro Vawt #2
 

Hi JeffD, That looks like a Sharp VAWT to me.  

It is possible to combine the Sharp VAWT arrangement of the blade unit parts and the Sicard/Bayly-Kentfield VAWT arrangement of the blade unit parts.

Both VAWT use the same principle. The main difference between the two VAWTs is whether or not the blade's mass is used as part of the bob of the centrifugal pendulum. The Sharp VAWT uses the blade as part of the pendulum bob. The S/B-K VAWT does not.

A different approach that I invented long ago is to use blade with counterweights in front of the leading edge of the blade, and place the pivot point of the blade near the leading edge of the blade. Then mount two horizontal pendulums inboard of the blade, each with its own pivot axis, and one on each side of the central axis of the VAWT. The blade provides the aerodynamic pitch force, and the two horizontal pendulums provide the centrifugal restoring force.  Connect the pendulums to the blade using cords. The advantag of this system is that it is dynamically balanced, so it can't produce any vibration and also it can be operated with the central shaft horizontal because gravity can't affect the pitching of the blade. This is for a 2-bladed VAWT arranged in a stacked configuration. From a theoretical perspective, this type of pitch control is a variation of the S/B-K VAWT.

For a 3-bladed VAWT, use 3 horizontal pendulums for each blade. A central star mounted on the VAWT shaft can coordinate the pendulums for each blade.  However, this gets a bit complicated, and that detracts from the simplicity of the basic concept.

Also, I later discovered that the single-blade Bird Windmill can operate with its blade horizontal, and going around in vertical circles. That is far simpler.

The C-blade and the V-blade used for a single-blade Bird Windmill simplify further because the usual rocking arms used with straight blades are eliminated; the inward curve of the C-blade and the inward bend of the V-blade both create their own rocking arms (effective rocking arm). Yet the entire mass of the blade in each case is part of the centrifugal pendulum bob, so the blade unit is still a Sharp VAWT type blade unit.



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Peter A. Sharp
itsandbits1


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Date:
RE: Micro Vawt #2
 

go with it then. I really don't care.

whatever you imagine it to be, that is what you will be happy with.

end of discussion from my end.



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I will only try to build the best. If it ends up looking like yours, take it as a compliment. I am always in the developement stage
crazyguy


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Date:
RE: Micro Vawt #2
 

looks like  a 1/4" long rocking arm.

arm.gif



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"I have not failed. I've just found 10,000 ways that won't work."
Thomas A. Edison
itsandbits1


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Date:
RE: Micro Vawt #2
 

as to whether it is a hybird of different ideas; which it appears to be, there is no rocking arm....... there is a pivot point which is more akin to the baley sicard kentfeild and you have simply moved the weight and pivot point. I am simply giving the credit down line to some of the original thinkers of the concept

If you look at the first page of this forum there is a description of the system you are accrediting and by giving it a v blade you introduce a rocking arm but it has no pivot point in that case as the rocking arm and the pivot point become one so I think one is being traded on the other and I am just keeping it clear.

baley sicard kentfeild postulated the pivot point being anywhere from the leading edge to the 33% point of chord but did not put the weight forward of the leading edge so as I say, what you are making is a hybyrd system and if it works thats great. Just want to give kudos to the people that did a lot of the groundwork on the self pitching blade, that others have built on. 



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I will only try to build the best. If it ends up looking like yours, take it as a compliment. I am always in the developement stage
crazyguy


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Date:
RE: Micro Vawt #2
 

Sure looks like a SHARP to me. remember an earlier post that said it didn't matter where the arm was attached or it's shape, just where the axle (pivot) was. Looks like the arm is 1/4" long, and the pivot is right at the leading edge where Peter said it should be. [Great integration of two components.]

JEFF..... how are you gluing the counterweight arm/rocking arm on  to the blade ?....this is driving me nuts cause I'm being a copy cat and building one also (different size) but I like your arm-counter weight design.

 

 

 

 

 

 

 

Copying a design is the best form of flattery



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"I have not failed. I've just found 10,000 ways that won't work."
Thomas A. Edison
JeffD


Veteran Member

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Posts: 51
Date:
Micro Vawt #2
 

Yes several builds used that configuration.  But I trialed several configurations to see what the difference would be.  As long as I balanced the wing so that the 1/4 chord point was tangent or very close to the blade path then I would get good performance.

sharpvawt_build7.jpg

sharpvawtfishline.jpg

sharpvawtpainted.jpg

sharpvawtcounterweight.jpg

I'm not going to argue if this is a Sharp VAWT or not.  If Peter chimes in and states that it meets his criteria then cool.  If not then well I don't think it matters in the long run,  its just another VAWT.

I will just show what I am building and what has worked for me.



-- Edited by JeffD on Thursday 20th of December 2012 12:17:07 AM

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sjh7132


Guru

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Date:
RE: Micro Vawt #2
 

I think that's a SHARP Vawt except normally I believe the blade would be pointing right down the yellow line.  Did your other VAWTs have the weight set in like that?



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Steve
JeffD


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Date:
Micro Vawt #2
 

pivotarm.png

So that we are all on the same wave length I labeled a top down view diagram showing what I am calling the pivot arm and pivot point.  The pivot arm is the line in blue.  If that is not the pivot arm then I am very confused.  As far as I can tell the pivot point is not at the leading edge of the blade.



-- Edited by JeffD on Wednesday 19th of December 2012 11:47:00 PM

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JeffD


Veteran Member

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Date:
RE: Micro Vawt #2
 

Not sure why you say there is no pivot arm but maybe I misunderstand what a pivot arm is.  For me this configuration has worked really well on 9 builds as can be seen in the vids about the popsicle stick vawts.  I am only making a material change and not a design change so I don't see this build operating any differently.

If I have errored in calling this a Sharp VAWT then I apologize.  I will just call it a VAWT, I should be safe with that.



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