Another Windcharger

[Junkaholic]

Hi all,

I had a treadmill motor handy and wanted to see how pathetic they really were on a windcharger.  I guess I found out!  At around a 28mph wind I was able to get 6 volts and 1.5 amps. It has a 4 foot blade and is direct drive to the motor.  I put a manual brake on it too.  If I ever try it again I may gear it up and see what happens.  For now I will just put a small light bulb or something on it for a load and do an endurance test on the bearings and brushes.  It will just be decoration

[DanB]

Can you describe some more detail about the blade you've got on there?

From the picture... it almost looks like it's no backwards, but I don't know what the other side of it looks like...

[Nil]

To sidetrack this some, I have a tower that from what I can tell looks exactly the same as yours. Did yours have a wind charger of some kind on it? I've only got the tower and it looks to be setup for some kind of a charger, but I have nothing to go off of to find out otherwise.

Thanks.

[Norm]

  Something don't seem right here I've yet to

put a prop on mine

http://www.fieldlines.com/story/2005/3/23/225230/317

  But it seems others may have got better results

at lower wind speeds.

                  ( :>) Norm.

   

[Flux]

I think the blades are the problem as well. A decent 4 ft 2 blade prop should hit 2000 rpm unloaded in a 28 mph wind.

Looks as though you have copied a wincharger blade and fitted it backwards.

Flux

[Junkaholic]

Yes, the blade is copied off a larger original.  I thought it was backwards too but this is how it was on the other one.  This blade has no twist, no tapers, and the back is flat!  The wind is usually 15-20 mph here so in a day or so I will check my data again.  It is a 90 volt motor.

What would a good two blade design be?  

Here is a picture of the tower and the original charger.  I am currently restoring it to working condition.  But that will be another story if anyone's interested?  I have many pictures of it.  I don't know what make it is?

[Countryboy]

Your blade is on backwards.  The back should not be flat.  You want the flat side of the blade facing the wind, and the curved part on the backside.

Flip the blade over so the flat part is facing the wind, and I believe you will see a vast improvement on output.

[Norm]

   Taking a real close look at the real Windcharger

...it appears to me that the rounded part of the

blades are to the back as they should be...

next...I'm venturing a theory...you see you

haven't made an exact copy only half....

the air brake is actually a shroud for those

short wide blades in the center....

  I would venture to guess that the Windcharger

also had field coils so it could produce

a larger current at a lower speed than a PM treadmill

motor....which wasn't really designed to be a

generator in the first place.

  The treadmill motor would probably work better

with 3 wide plastic blades and maybe a little

less diameter...should work very well in a

10  to 15mph wind.

  All of this is just speculating on my part...

I could be wwwroong !

                    (  :>) Norm.

   

[Junkaholic]

I will make a new blade and flip it then.  I guess I described that wrong.  The back of the blade is all in one plane.  Nothing was done to that side to change the shape or angle.  I hope I am clear enough.

Yes the blade on the original does appear to have the curve to the back but it isn't.  The dark rotting side looks like a shadow.  Some long splinters were broke off too.

I try and stay away from plastics.  At first I was going to use 3 PVC blades but went with the wood instead.  I don't know what fatigue would do to them?  But it's worth a try.

Thanks for the help guys, I appreciate it

[Countryboy]

The back of the blade is all in one plane.  Nothing was done to that side to change the shape or angle.

Let me get this straight.  You did nothing to the back side of the blade?  You took a flat board, and carved the rounded airfoil onto the front side of the blade, and then you mounted it on the shaft?

Read this page before you carve your next set of blades.  http://otherpower.com/blades.html

[Flux]

Take the existing prop, turn it over so the flat side is up , plane away the trailing edge of each blade so it is 3/16" lower than the leading edge and make a flat surface that joins the leading edge to trailing edge.

Leave the back side rounded, it doesn't look quite right but will be near enough for now.

Mount it with the flat driving face facing the wind and it will fly. That should give you a good idea what to change for your next attempt.

Flux

[Junkaholic]

I HAVE read that page.  I just wanted to copy an old blade for this one.

How would something like this work?

[Countryboy]

That design looks a lot better.  Just be sure the bottom of the blade in your diagram faces into the oncoming wind.

You probably don't want that aggressive of an angle at the tip of the blade.  The displayed cross section would be better back towards the root.

[Flux]

Agreed. The basic idea is ok.

Instead of starting at top left for the front face, start 1/4 the way up and run out to bottom right.

Keep the same basic shape on the back, but make the blade as if you had rotated your section to the left by about 10 deg.

This is silly try this.

Flux

[RogerAS]

Hi,

If one loks at the end of the turbine blade it should look something like this.

This is for upwind machines.

[willib]

Hey Norm ,

how did you get a digital readout of the RPM

what did you use

[Junkaholic]

That works much better with a new blade.  I still have alot to learn!

Thanks guys