New to this please, I need just a little help!

[ghurd]

I keep getting stuck on this whole Cubic Feet thing.

About the time I am getting over that, you hit me with the off set being relative, then back to swept area.

Where did you get this idea of Cubic Feet being relative to wind power?

It seems like you are confusing issues in the cube square law and Betz.

If a 4' x 8.66' VAWT can beat a 16' HAWT, based on 'volume',

then a 2' x 4' VAWT (12.56^3') can beat a 34" diameter HAWT (11.9^3')?

A decent 34" dia HAWT should make 100W easy enough.

Show us a 2' x 4' helix VAWT that makes 100W.  Just one.

The helix video shows nothing.  

A 5:09 video commercial, with the thing first turning at 3:04?  

It's 5 minutes and time typing it lost from my life.

"Performance data available at" their website.  Where?  Load, RPM, wind speed, something solid?  Maybe something about the 2500W part?

The best number I found in the entire video is 59%.

Not about Betz, but the % of video BEFORE they show it turning.

I find that % thing funny.

G-

[ghurd]

BTW, I gave you the square foot advantage by 25%.

G-

[Todd a]

No it does not work like that.  Like I said there are disadvantages to a VAWT, but do to larger surface area (without having to massively increase the size) it pretty much makes up for it.  There are things to take into advantage when comparing surface area though.  On a HAWT the blades are always providing thrust under wind, but a VAWT might provide thrust on say between 1/4 and 1/2 of the rotation and part of the rotation on a single blade is drag.  Also some have better high wind performance and some better low wind as there are many types of VAWT (pretty much one type of HAWT).

There are drag and lift type wind turbines and even these come on very different types, from Lenz, Darrieus, Giromill, Cycloturbine, and Savonius.  On top of that the blades can be twisted (Helical) on most of these types to decrease thrust pulsing.  You can also combine a thrust and lift type together.  For HAWT you have number of blades, upwind or downwind, TSR, and type of furrowing.  Most of these are also done on VAWT (and more)... like variable pitch, number of blades, mechanical breaking, height to width rations, blade thickness...

Say you take a Savonius type. and Helix it like that HelixWind turbine.  The surface profile (not counting the twisted surface) you are looking at a massive wind profile of 4'x8.5' or 34 square feet, but do to the limited arc that the air pushes on and the drag you are actually having about 25% of that are as being productive at any one time, so say 8.5 square feet.  Now take a 12' HAWT and the 3 blades are say 9" wide (5 feet of blade plus the hub) then you have a nice 11.5 square feet of blade surface area producing thrust.  This is very vague but gives you a rough idea.  The big thing is that the HAWT does cover a much larger area, the blades spin much faster at the tips, and there are much more thing to mechanically go wrong.  It is just weaker.  .  It is just larger, noisier, and harder to maintain, but likely easier to build.

Now it is not strait forward like this and there are Soooooooo many variables to effect this.  Simple blade geometry, balance, and how well the turbine fits to the generator along with tower height and wind conditions and blade material...  The whole thing is coming up with a combination of everything that works the best.  Hughs has a good design and many people copy that.  VAWT are a bit different and unless you want to just make a basic Lenz or Savonius, then there are a lot of things you need to figure out.  There is just not too much information out there on how to make a VAWT.  This is the biggest advantage of HAWT.  There are tons of web sites and book on how to make a HAWT.  I think with a good design and the right materials you could make a VAWT as efficient as a HAWT and likely have it tougher.... but it would require a lot of work.  I think some are getting closer.

[Todd a]

Oh and yes they do give specs and power ranges and junk if you dig far enough.  The start-up speed is high at 8mph and the rated speed is not achieved until 13, which is higher than most HAWT (but actually about the same as that SkyStream 3.7).  It is not by any means perfect, but it is very tough and can take an environment like the top of a sky scraper and thrive in that environment.  I have seen some VAWT with only a 5MPH start-up (lower with variable geometry).  I have seen some with a 2MPH that spin slow with very high toque.  They need a pulley system to get usable RPMs for a generator, but they have enough toque to handle this and can actually start making power in VERY low wind speeds.

I am not saying VAWT are perfect, but they are not as bad as many people make them out to be.

[ghurd]

Check what fungus and Betz said.

[TomW]

Mister a;

Might I enquire as to your "qualifications" to make these statements?

You have pretty much hijacked this thread to make your "points". I don't see anything but words with no backup beyond our being expected to accept your word or the claims of the manufacturers. One could be forgiven for wondering how much they pay you to drop their names on a popular RE board?

Extraordinary claims require extraordinary proof.

I actually like VAWTs but until they see service and produce they are just toys and hooks to snag the unwary. Pimping them as any kind of "solution" to immediate, useful energy production is ludicrous. Playing and experimenting is another story, of course.

This board is about useful energy production for the DIY crowd and not for pimping commercial crap.

Tom

[Todd a]

Personally I just like VAWT.  I have been working on one for a while.  Lack of time and money has sidelined things a bit and my first attempt had several issues (wood rotors sucked and I messed up the stator ring... bad).  I have seen a lot of bad VAWT, but I have seen a lot of really cool looking ones.  I think HAWT are just boring... and a bit dangerous.  I started looking at VAWT as a way to get around the very restrictive local zoning of a 5' diameter wind turbine.  A VAWT is a way to cheat... Make it 5'x5'.  

I messed up the wiring on the stator and after chipping into the epoxy I was only able to get one phase working.  The blades were too heavy and not the best design.  Before I could rework them they massively warped... but I was able to at least test it a little bit and it did spin up a bit and the single phase did make power, but I had no wind almost all the week and ripped the generator apart after that.  I do have a new stator ring, but still really not what I want it to be, but I do not have the money for another spool of wire.

As for hi-jacking the thread... sorry, when people talk down VAWT I get a bit defensive.  Maybe I will ultimately fail and convert my generator to a HAWT, but not be able to put it up at my house.  I have a few ideas for a hybrid version of this if the regular blades do not allow low speed start-up.

[valterra]

Oh, what the hell did Betz know!!  Scientists obviously have no taste in art!

These things LOOK REALLY NEATO.  And they will spin no matter which direction the wind is blowing!

And they look really neato.

I had really crappy blades that "didn't spin as fast" as my newer, better ones.  I take it from the argument above that my old blades had an advantage?

Did I mention that they look really neato?

My grandpa used to make little cars out of old Coke cans.  When the wind would blow, the wheels would spin around.

Those looked REALLY neato.

Just like to see one that actually worked.  The Dans don't have Datasheets or Whitepapers.  They have pictures and meters.  You know - science stuff.  

Oh - The Dans Blades look really neato, too.

[valterra]

Sounds like more "form over function."  

Reminds me of someone who built a giant fancy tent with really neato solar panels ALL THE WAY AROUND.  Sure, by definition, over 50% of them were facing the wrong direction.  But we can't let facts get in the way.  It LOOKED REALLY COOL.

Also reminds me of how Honda stopped making hybrid Civics.  Why?  People weren't buying them because they didn't LOOK like a hybrid.  

(SIGH)  www.evalbum.com/">EV Album is filled with all kinds of ugly, piece of crap-looking cars that are 100% electric.  They're actually DOING something innovative...  how unromantic.

[wdyasq]

I went to a site linked by Todd_a ... there was a Savonius turbine with a helix. They advertise a 3.19 swept meter design and claim 6000kWh/year output in places with average wind-speed of 10m/s or 36km/hr. That is about 22.5mph. This works out to ~.68kWh per hour - 24/365 ...

The handy calculator on the IRC channel says a HAWT MIGHT do 309 Watts in a constant 10m/s breeze. And HVATs are more efficient than Savonius rotors on every test I have seen.

Yes, overunity exists in a sales brochure.

On another note, as I see it, one of the ways to avoid the torque ripple Sandia Labs had so much trouble with is to use a Helix design. I think the Gorlov will make a more practical device then the Savonius but, that is my opinion.

BUT.... the thing is rated at 2.5kW ...

Now, if you are being paid for 'carbon credits' at some inflated price ... and are able to use the fictional numbers, hey, it's a great unit! But, if one is depending on the thing for power it is another.

I must remember, it is not my money that will be wasted on one of these projects. Unless, of course, it has been taken away by the government and given to a shyster to test one of these, IMO, foolish things.

Reality is not a kind lady. The opinions are my own and not influenced by drug enhanced fantasy .....

Ron

[Todd a]

I also read an article a while ago stating that the drawbacks of VAWT were mastly because of the materials used for making the turbine, but with newer materials and designs that VAWT could likely match HAWT in efficiencies.  Weither this turns out to be true I do not know.  Others that tested VAWT were only testing one design and usually just a reproduction of the original Darrieus wind turbine and had made changes and admitted that better results were likely possible.  Plus the fact they tried one out of a dozen basic designs available now.

Like I said I like Helix designs, but they are hard to make for the DIY, but hybrid lift/drag are not that hard.

The big question is... What is this efficiency comparison based on?  Blade surface area, sweep, cost to build, weight?  I always assumed blade surface area, but I could be wrong.  I was looking at a 5' HAWT or a 5'x5' VAWT.  The 4 blades on my VAWT have a surface area of about 12 square feet, while a HAWT with 3 blades would only have about 3 square feet (figuring 2 feet of blade beyond the hub, 6" wide, and 3 blades...)  Even if a VAWT was 1/2 as efficient I was figuring I was making about the equivalent of say a 8-9 foot HAWT, which I can not have do to local zoning.  I just need about $200 for all the aluminum and wire and I need a better jig for making the coils.  I'm hoping to get around 750w with my VAWT at around 12m/s, but I think the generator could actually make quite a bit more if the wind was really strong, like 16 m/s.  It would be nice if I could hit say 1.5kw in higher winds (I just don't think my VAWT can normally spin fast enough and I do not have a pulley system set up for it).

Plus I'm bored...  I am on a week of layoff (I work in the doomed Michigan automotive industry making parts for car interiors)...  No money, lots of time, and the kids at school. :p

[ghurd]

"What is this efficiency comparison based on?"

Output power / Available power.

http://www.windstuffnow.com/main/wind.htm

"I always assumed blade surface area, but I could be wrong."

Wrong.  And the basis of most of your problems.  Swept area.  Did you read Betz Law? A 5' HAWT is 19.6^2 feet.  A 5x5' VAWT is 25^2 feet.

Most of what you think about HAWT blades is way off base.  And I am not good with blades.

Get a wind gauge.  12m/s is a lot of wind at 6' or ground level, more than I ever measured at my home or the mall parking lot when the forcast called for 22m/s. 16m/s at ground level in a housing development with any trees around, and the VAWT is the least of the problems.

Sorry T Wood.  I'm done now.

G-

[wdyasq]

Come on now Glen,

We are being introduced to the new way of thinking of things. I'm sure Todd will have new methods of calculating known physics soon.

16m/s is 'only 36 mph' ... well, 16 (meters / second) = 35.7909807 mph according to Google. With that kind of wind on a continual basis you won't be chasing your cap down the street, you will be needing to glue your hair on. (IF you have any left after pulling it out trying to get a handle on this new method of calculation.) I doubt you will need to worry about trees growing over a few feet tall in that kind of continual wind either.

"I also read an article a while ago stating that the drawbacks of VAWT were mastly because of the materials used for making the turbine, but with newer materials and designs that VAWT could likely match HAWT in efficiencies.  Weither this turns out to be true I do not know.  Others that tested VAWT were only testing one design and usually just a reproduction of the original Darrieus wind turbine and had made changes and admitted that better results were likely possible.  Plus the fact they tried one out of a dozen basic designs available now."

Well Todd, you need to read another article ... Perhaps you should try and read the data paid for by tax dollars taken by force from those who produce. I've read several thousand pages by Sandia Labs on VAWTs. I've read several thousand pages on HAWTs also. I have helped build VAWTs and HAWTs.

HAWT machines can have a lot of problems. Fortunately, they have been developed to a great extent and plans are available that are continually improved.

VAWTs are, IMO, still experimental at this time. I have never seen a successful VAWT except of the ones WindstuffEd posts. There was one from Australia Gizmo directed me to as a success ... but the wind data from a station only a short distance from the supposed working turbine and the output didn't match. I couldn't figure out how the wind-turbine could put out near maximum power when the weather station said there was very little wind. I have not learned the revolutionary new physics of wind soon to be introduced.

Ron

[Todd a]

There seem to be plenty of VAWT that do work from small ones generating 300w or less all the way up into the tens of thousands on kw.  I do agree 100% that VAWT is still in the experimental stage and has lots of room to grow.  Also all these studies that I have seen deal with the standard Darrieus wind turbines.  I did see one study talking about different blade thicknesses and variable pitch to improve start-up speeds.

How about start-up speeds for this hybrid Darrieus/Savonius...

http://www.ganwind.de/download/datenblatt_2.5_engl.pdf

This is a bit bigger at a 10x5' VAWT, but is a nice 2Kw and has a 1m/s start-up and the rated speed is only 11.  Not too bad.  This is a retail product.  Too bad it is out of Germany.  I wonder if a smaller version would work OK.

[wdyasq]

Todd,

There is only a certain amount of energy in an area of wind on the 'old' method of physics. In some new method, folks may find more.

The handy calculator on the IRC forum states - "5143.7 watts possible from 2.9 m dia prop (6.6 m^2) in 39 km/Hr wind (density of 1.225000) 823.0 watts output assuming generator is 80% efficient and Cp of 0.20"

Now, that is very close to the "GanWind_what_take_your_money_2.5" in size. Note they get about 2-1/2 times the efficiency the highly developed HVATs get.

I guess it is time for me to get a copy of the "new physics text" and go to an over-unity forum to freshen up on what is possible now.

After all, the president elect ran on 'change' and is expected to be coronated  in about a month. I guess the laws of physics will be changed also.

Ron

[valterra]

Coronated?  You mean take his place sitting on the right hand?

He IS the one who said "the sea levels will stop rising..."

Anyhow.  Tens of KW from a VAWT.

Where?

[ncblue]

i liked the post. i live in an area where hawt's arent feasible in any manner but no-one would notice a vawt. right now i have two experimentals running and i cant get into all that engineering technical stuff too much. i have a natural wind tunnel right behind my place thats almost always running 15 mph day and night. the biggest one i have is a 2x3 unit based on the sandia design and this baby sings in a decent breeze, the smaller unit i 6" x 12" and i use it to run my windspeed meter through a pcm circut. as for the generator i havent really decided on what to use yet. i havent gotten into the lenz style yet as i am a diehard savonius fan nor will i ever use more than two blades. the next one is based on the helical design to see how that fares.