Author Topic: 18 in diam disc  (Read 5013 times)

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Jason Wilkinson

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18 in diam disc
« on: September 09, 2014, 08:31:30 PM »
 Hi to all. Got myself two 18 in diam rotors and am thinking of putting 20 magnets (2*1*1/2)  on each disc i want to wind for 24 volts .  As i still have a bit of #14 magnet wire, was wondering about the no. of turns.  I have 6ft long blades (don't want to go longer/larger)  but am thinking of using a wide air gap .In  Piggott's 2009 edition  his 18'' disc calls for a 14' blade , would a 6' blade be enough to turn those disc for 24 volts?
  Jason

gww

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Re: 18 in diam disc
« Reply #1 on: September 09, 2014, 10:42:15 PM »
Why build such a heavy turbine and only have 6' blade.  My 8' blade turbine only has 12 inch rotors and I can't lift it high enough to put on a test stand by myself.  I had both my rotors cut including the holes for the trailer hub bolts for 50 bucks.  (I did feel that was cheep so bought two more and built two turbines).

Not saying it couldn't be done.  Wish I had a 14' turbine.  It is on my might do list.
gww

hiker

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Re: 18 in diam disc
« Reply #2 on: September 10, 2014, 01:06:36 PM »
just build a smaller mill--youll get the same amount of power.. weather on a big mill or small--plus it would take more wind to get the dang thing going -more mass and load !
WILD in ALASKA

hiker

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WILD in ALASKA

Mary B

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Re: 18 in diam disc
« Reply #4 on: September 10, 2014, 06:27:03 PM »
I have an xcel spreadsheet that calculates the rough number of turn to get you in the ballpark. I can email it if you want it.

Jason Wilkinson

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Re: 18 in diam disc
« Reply #5 on: September 10, 2014, 09:03:43 PM »
Thanks Maryalana (  Jason_wilkie@hotmail.com )
 Gww  two turbines means two towers
 Those 18'' disc were once on a 14 ft turbine that was destroyed in a huricane  I just want to use the disc again  with something different
Jason

kitestrings

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Re: 18 in diam disc
« Reply #6 on: September 10, 2014, 10:11:31 PM »
I also have a turns calculator I put together from bits and pieces of things presented here.  Curious if this comes anywhere near yours.  More of a back of the napkin without knowing more.  I'm guessing cut-in near ~130 rpm?

Assumptions:               
magnet size -   2.5   dia (in)         
               
volts:   24.0            
#poles:   20            
rpm:   130            
rps:   2.17            
telsa   0.55            
#coils / ph:   5            
average emf:   4.0   (phi)f volts / turn         
sine wave form factor:               
   1.1            
rms volts / ph:   4.4            
         sq in  =      
Surface Area of Magnets:         4.9284      
      x   =   sq cm  =      
      6.4516   31.80      
               
Total Flux / Pole:      telsa x area (sq cm/10)      mWb   
      0.55      1.75   
               
line volts = rms volts/ph x 1.732, and               
DC volts = rms volts/ph x 1.732 x 1.4, therefore:               
               
rms volts/ph = DC Volts / 1.73 / 1.4 =            RMS Volts / ph   
24   1.732050808   1.414213562      9.80   
            line volts   
            16.97   
Speed is:   130   rpm         
   2.17   rps         
frequency = pn / 2  (where p = #poles, n = rps)               
rps   x  #poles      /   =      freq (Hz)   
2.17   20   2      21.67   
               
               
line Volts  /   rms/ph  /    (tot flux / pole /   1,000 / )   freq  =   #turns/ph
9.80   4.40   1.75   1,000   21.67   59
               
      #turns/ph /      coils/ph    = turns/coil
      59.0      5   11.8

gww

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Re: 18 in diam disc
« Reply #7 on: September 10, 2014, 10:46:29 PM »
Kitestring
With 6 foot blade wouldn't cut in neet to be closer to 220 to 250?
gww

ps jason sorry for your loss during the huricane.  I would still cut down the rotors with six foot blades but no matter what you build I hope to see some photos and hope it works for you
« Last Edit: September 10, 2014, 10:51:08 PM by gww »

kitestrings

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Re: 18 in diam disc
« Reply #8 on: September 11, 2014, 10:42:39 AM »
gww,

Maybe I misunderstood.  I assumed he meant 6' blades; 12' diameter, otherwise those discs are huge.  I'd looked at one with a 12' dia. in one of Hugh's recipe build/books.

By quick calcs; 12' dia. at a TSR of 7, with a cut-in at say 8 mph it works out to 130 rpm.  I've never built this size, but does that sound close.

~ks

gww

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Re: 18 in diam disc
« Reply #9 on: September 11, 2014, 10:53:04 AM »
ks
Perhaps I misunderstood and you have it correct.  Maybe it will get clairified for us.
cheers
gww

Flux

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Re: 18 in diam disc
« Reply #10 on: September 11, 2014, 11:39:46 AM »
I think it has to be 12ft diameter to make sense.

18" seems a fairly large diameter for 20 of the 2 x 1 magnets but should work fine.

I got about twice as many turns as Kitestrings but he used 2" dia magnets. Looks as though it will be about 3 in hand for #14 wire.

Flux

Jason Wilkinson

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Re: 18 in diam disc
« Reply #11 on: September 11, 2014, 12:06:11 PM »
Oops  don't know where that post has gone to
 Glad to see you guys working on it, That 18 in diam was on a 14 ft turbine already but didn't last long  i want to "do it again"  this time "bigger"
 (just can't get attachments to work)
At present my working turbine is a 12ft  16in diam rotor/32 mag 60 turns of #15 , 2 in hand  , about 50 ft high.  works well but i need a bit more power
  Jason

kitestrings

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Re: 18 in diam disc
« Reply #12 on: September 12, 2014, 10:39:19 AM »
Quote
I got about twice as many turns as Kitestrings but he used 2" dia magnets.

Yes, I actually used 2.5" dia.  I see now that it was intended to be 1" x 2" x 1/2".  Reducing the area, I come up with about 29 turns.

kitestrings

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Re: 18 in diam disc
« Reply #13 on: September 12, 2014, 11:32:40 AM »
Jason,

I probably should clarify that I understood that you had these magnets and rotors and was responding to the original question of "about how many turns" for, in this case a 20-pole, 12', 24V alt.  I didn't get into the prop design or matching aspect of it to know whether 12' is the right fit for this.  Re-plugging the inputs, I get:
Assumptions:               
magnet size -               
length:   2.0   inputs in blue         
width:   1.0            
               
volts:   24.0            
#poles:   20            
rpm:   130            
rps:   2.17            
telsa   0.55            
#coils / ph:   5            
average emf:   4.0   (phi)f volts / turn         
sine wave form factor:               
   1.1            
rms volts / ph:   4.4            
               
Surface Area of Magnets:               
   l  x   w  =   sq in  =      
   2.0   1.0   2      
      x   =   sq cm  =      
      6.4516   12.90      
               
Total Flux / Pole:      telsa x area (sq cm/10)      mWb   
      0.55      0.71   
               
line volts = rms volts/ph x 1.732, and               
DC volts = rms volts/ph x 1.732 x 1.4, therefore:               
               
rms volts/ph = DC Volts / 1.73 / 1.4 =            RMS Volts / ph   
24   1.732050808   1.414213562      9.80   
            line volts   
            16.97   
Speed is:   130   rpm         
   2.17   rps         
frequency = pn / 2  (where p = #poles, n = rps)               
rps   x  #poles      /   =      freq (Hz)   
2.17   20   2      21.67   
               
line Volts  /   rms/ph  /    (tot flux / pole /   1,000 / )   freq  =   #turns/ph
9.80   4.40   0.71   1,000   21.67   145
               
      #turns/ph /      coils/ph    = turns/coil
      145.0      5   29.0

Jason Wilkinson

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Re: 18 in diam disc
« Reply #14 on: September 12, 2014, 02:37:05 PM »
Thanks to all u guys, as soon as my 2 spools of wire arrive  i'll start 30 turns  (in hand ?)  will take pictures and try to post results
  Thanks, Jason

gww

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Re: 18 in diam disc
« Reply #15 on: September 12, 2014, 04:32:00 PM »
Jason
Looking forward to seeing you build and getting reports.  I really want to build hughs 12' or 14' turbine.  If I take one of the 8' apart, I will have twenty mags per rotor to work with.  I have 8 mags on differant turbine.  I first want to figure out how to get anouther tower put together.  I have 9 twenty foot sectons of a latice tower. I thought of cutting the legs off the towers and just making anouther pole tower cause I know how to do that.  Either way, If I get the tower figured out, your reports on your soon to be new turbine may really have some bearing on my thought prossesses.  I wouldn't mind hearing more about the one That didn't last long.  What was the problim and what do I need to avoid from having the same experiance?
Thanks
gww

kitestrings

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Re: 18 in diam disc
« Reply #16 on: September 12, 2014, 06:10:53 PM »
Quote
i'll start 30 turns  (in hand ?)

I believe Flux was suggesting 3 in-hand with 14#CU

The number of turns will depend in part on what the magnets are and how close your gap is.  I assumed a telsa of .55T which is probably conservative with 1/2" neos.

Once you wind one test coil you can mount it between the magnet rotors and spin it by hand to see if you have the correct number of turns.  You may have done/know this, but for anyone who hasn't seen it here's some examples (mine & one of, I think, Dan's).





Best of luck,  ~ks

Jason Wilkinson

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Re: 18 in diam disc
« Reply #17 on: September 15, 2014, 11:47:13 AM »
This may not go down well with some of you, but until my wire arrive  i plan to "destroy" one of my "12 footer" stator  to salvage the coils they are 60 turns  2 in hand, i've done that before ,unravel the coil,straiten it by passing with tension over plastic pipe and you're good to go
  btw i can't get pictures down to the correct size  for posting
  Jason

gww

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Re: 18 in diam disc
« Reply #18 on: September 15, 2014, 01:47:39 PM »
I built a turbine with wire I salvaged from ten microwave ovens.  The turbine didn't work very well due to a stiff bearing and being to many turns for a 12 volt battery.  There was nothing wrong with the coils though.  No short and it would put out power in a good enough wind.  I salvage the coils twice once out of a stator I wasn't happy with.
It is a lot of work/labor but when you have more time then money, go for it.

I also have a terrible time with pictures.  Normally I send them to email, then drag them from my email to my desk top and then post.  Some time I have to do this twice to get the picture data to be low enough to post here.  Some time it only comes up to a link to the picture but most time it shows the picture here.
gww

Jason Wilkinson

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Re: 18 in diam disc
« Reply #19 on: September 16, 2014, 04:01:00 PM »
Gww  thanks for that pic posting tip  will try it
Jason

Bruce S

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Re: 18 in diam disc
« Reply #20 on: September 16, 2014, 05:15:17 PM »
Jason;
There are plenty of free photo resizers available.
One that I've been using lately is FastStone photo resizer. It is not very large, but does do what it says.
I normally resize a pic from my cell phone that I've sent to my email address to something of a normal size (320x240) that can be found in their advanced options let it convert to a new image check the properties and then set it for posting here. I hardly ever have it automatically change the original (that way I have it in original format).
When at home I use GIMP that comes standard on Linux computers.
hope that helps, if you're still having issues let us know , the MODs & GMs are here to help :-).
Cheers
Bruce S
« Last Edit: September 17, 2014, 12:45:42 PM by Bruce S »
A kind word often goes unsaid BUT never goes unheard

Mary B

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Re: 18 in diam disc
« Reply #21 on: September 16, 2014, 06:14:07 PM »
Upload to photobucket then select direct link there to post here. Automatically resizes pics to fit.