# Need design help to build my PMA



## quicksilver147 (Aug 7, 2015)

Everyone, I'm new here and looking for some help from those who've gone before.

Looking for good design for a PMA with dual rotors, single stator.
Specifically, I need help with designing the rotor and stator size, magnets, wire turns and gauge, that type of thing. New to building PMA's but eager to learn.

I have a Windy Nation 5-blade aluminum prop already purchased which is what I plan to use.

I would appreciate any good, sound help.


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## LincTex (Apr 1, 2011)

Everything I do for wind power is based on High Piggott's (http://www.scoraigwind.com/) "Axial Flux" design.

By far, the greatest source of online info comes from http://www.otherpower.com/otherpower_wind.html
The same website has a forum call "fieldlines" and it's a great source of info.

I built the 10 foot design with 1" x 2" x 1/2" "N42" magnets, but I don't have a tower for it yet. http://www.otherpower.com/turbineplans.html


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## readytogo (Apr 6, 2013)

pma;acronym for positive mental attitude right?.


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## LincTex (Apr 1, 2011)

PMA = Permanent Magnet Alternator


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## LincTex (Apr 1, 2011)




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## LincTex (Apr 1, 2011)




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## quicksilver147 (Aug 7, 2015)

Sorry, i was poking fun at the wise guy asking if PMA stood for "positive mental attitude" 

I guess it could, but a positive attitude wont (by itself) get my batteries charged....but its a start...


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## LincTex (Apr 1, 2011)

quicksilver147 said:


> I said: "any good, sound advice".......


Well..... I can't figure exactly what the heck you are wanting to know?

Make your questions more specific, please. 
If you ask generic questions, you get generic answers....

Here's some really "good, sound advice": don't get any part of your body between these magnets.


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## LincTex (Apr 1, 2011)

Additionally, I can't recall if I have ever heard of anyone here (Prepared Society) who has built an axial flux PMA other than me. If there are, they are pretty quiet about it.

There are folks here who have installed small wind turbines, but I can't think of one other person having ever built any axial flux designs resembling Hugh Piggott's work.

Furthermore, Most of what I know comes from reading Hugh's books & having studied the Otherpower.com website for years. My 10' mill design is a copy of theirs.

I'm afraid if you are looking for design help "above and beyond" what you can learn from Piggott's books & blogs, and from learning from the experiences of the "2 Dans" over at Otherpower, you will likely not receive any answers academically superior on this website, but I applaud you for trying.


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## quicksilver147 (Aug 7, 2015)

*misunderstanding*



LincTex said:


> Well..... I can't figure exactly what the heck you are wanting to know?
> 
> Make your questions more specific, please.
> If you ask generic questions, you get generic answers....
> ...


LINCTEX:
Wanted to let you know i appreciate the info.

Earlier i was being sarcastic to the guy responding to my post asking if PMA stood for "positive mental attitude"

Sorry if you thought I was talking you...


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## LincTex (Apr 1, 2011)

No worries.

What exactly was it you needed help with? 

Have you started buying materials yet?

Which "wind zone" are you in?


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## quicksilver147 (Aug 7, 2015)

LincTex said:


> No worries.
> 
> What exactly was it you needed help with?
> 
> ...


LINCTEX, 
I 'm good mechanically, but weak on electrical theory....been studying info though.
I really need good info on how to design the rotor and stator mechanisms so they
Work with my 5 blade, 78" dia. Windy Nation alum prop - only item purchased so far.

If I had good plans for yhe rotor & stator I can design and machine the rest just fine.
As for my wind zone, I'm in Steele county, Minnesota and we get alot of wind.

Thanks for your help sir !


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## quicksilver147 (Aug 7, 2015)

I 'm good mechanically, but weak on electrical theory....been studying info though.
I really need good info on how to design the rotor and stator mechanisms so they
Work with my 5 blade, 78" dia. Windy Nation alum prop - only item purchased so far.

If I had good plans for yhe rotor & stator I can design and machine the rest just fine.
As for my wind zone, I'm in Steele county, Minnesota and we get alot of wind.

Thanks.


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## LincTex (Apr 1, 2011)

Hmmm... thin aluminum design. Only 6' 6" in diameter; doesn't give a lot of "Disc area". (The bigger the disc, the more energy it captures).

I would build something very similar to the Otherpower 10' design, but everything "about half."... instead of 2"x1"x1/2" magnets, go with 1"x1/2"x1/4"

Concerning electrical, The number of windings is where you get your "cut in speed". If the generator "cuts in" (starts charging) too early, the generator will drag the prop down so it can't "get up to speed". It will turn, but will be "lugging", just like trying to take off in 4th gear in a car.

That small prop of yours will need RPM to work. It needs to get up to enough speed so that it has momentum and RPM once the generator starts to make electricity and "load down". 

I'm really wondering what to do about the hub. I think something from a small motorcycle would work. A bicycle hub would be too flimsy, and an automobile hub (like the Otherpower) will have way too much drag.

Was that prop designed to work with a 90 volt DC treadmill motor?


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## quicksilver147 (Aug 7, 2015)

LincTex;399501
Was that prop designed to work with a 90 volt DC treadmill motor?[/QUOTE said:


> Yes I believe it was designed to work with either a treadmill motor or small PMA that windy nation sells (for alot of $$).
> 
> I could buy one of those, but what I'm trying to accomplish is the DIY so I know how to repair it and understand how it works so I'm not dependent on purchasing parts from someone who may not be around in time of need.
> 
> ...


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## Caribou (Aug 18, 2012)

For a friend near GA here are some solar panels for salvage. This is about a week old add. Good luck.

http://www.otherpower.com


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## LincTex (Apr 1, 2011)

quicksilver147 said:


> I'll look up the "Otherpower 10' design" you mentioned...If I can find it.


Here you go....

http://www.otherpower.com/turbineplans.html

http://www.otherpower.com/windfarm1.html

http://www.otherpower.com/timsturbine.html

http://www.otherpower.com/davesmill.html

http://www.otherpower.com/trips1.html


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## LincTex (Apr 1, 2011)

So, I'm reading through those articles I posted. 
All of them have very interesting info....

One in particular: http://www.otherpower.com/timsturbine.html

has this little jewel of info:


> One of the machines we made last winter had some stall problems (the line was very short *and* the wire very heavy.. *and* the magnets too large) , so we decided to mount a wider, slower 11' diameter blade set to that machine. So.. we had a spare set of 10' blades. My thought was that they would be a good match for this machine since the magnets are a bit smaller.


Ok, so there are 4 design variables accounted for:
1) Length of wire from alternator to battery bank
2) size of the wire
3) magnet strength, and -
4) blade shape & size

Here's what's freakin' me out a little bit with your aluminum "Windy Nation" prop - designing a generator to fit your prop might be putting "the cart before the horse". You may have to build several generator designs (none are cheap at all) to fit your prop.

It may be much more economically feasible to build a good generator design (The stinkin' magnets are $300 a set already) and adjust blade shape/size/design to suit.


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## divemaster19631 (Dec 29, 2015)

I am new to thismforum but have been doing this for years. My shop 1000 feet from my house is total solar and wind. I do use a small generstor for my 5 hp radial arm saw. Only. I have built one but with my wind sourse i have been using ecm motors convereted into pm motors. I get between 4-600 watts with my wind load plus lower visablity. They are the simplist things to convert and I build a complete mill in a day and produce power. If you are wanting start generating power that would be where i would start to get a felling for wind gens without paying thru nose for rare earth mags.

John


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