Ideas welcomed

[afcs]

From previous post, I am somewhat stuck.  I am able to locate some rotors and the draft specs are :

-2x1x.5 N40 mags

34. -winds per coil
    
12. v-system
    
12. -coils per stator
    
16. -mags per rotor
    
3. -phase
   
2. -strands # 14 guage to wind coils
   
   

I am looking (if they are made) for a shaft the will be able to go inside the rotors as pictured above. Also is there a posibility that bearings are made the size to fit a shaft that size. The picture would probably explain my craziness.

Any ideas of how to connect the rotors to the shaft will be more than appreciated. Was thinking  about a PVC shaft but something tells me no

[coldspot]

PVC prop/blade maybe

Shaft, heck NO

Metal, shaft and bearings

"Johnstone supply"

cat # 195

P. 196 shafts

P. 198 pillow block bearings

P. 191 interchangable hubs

My

$0.02

[coldspot]

$0.02
More
A large PVC to enclose the magnet rotors and stator
would help weather issues
My Ametek mini mill has a half a pc
around the top side to help
cover it, (don't know why it's enclosed anyway,
but did mainly for looks).
You could use this as a weather cover easly.
Maybe even put a small fan blade at rear
of unit on shaft to draw air thru for cooling
a computer fan could also be used, either just
the fan blades or the whole unit hooked into
the power out. So when it's running, it's cooling.

[tecker]

  I thought of something along those lines in conjunction with a auto alternator .

 I was looking to a hub at each stator, shaft with keyway and locking hub at each rotor large enough to support the rotor atraction.

[oztules]

if you are going to use the 12 mags the least diam i would consider is around 12inch diam tube, more like 16" tube. The large three phase motor may get up to that kind of diameter.

If you can only find smaller, then multiple stators may have to be looked at. You will have to get the laminates out of the motor, and press the rotor off the shaft.

This could give you a solid carcass with which to begin. You would have the shaft, bearings, casing (now lighter than original,ie only wall and shaft.) and hopefully mounting feet.

The rotor could be normal 1/4 or 5/16 steel with a solid steel boss welded onto it and  keyed to the  shaft. If you make the boss the right length, it will act as the gap setting. Brackets will have to be made to carry the stator/s.  These could be bronze threaded ferrules bedded into the stator, which could then be screwed into from the outside. This design could then accomodate as many rotor/stator assemblies as you could fit to get your voltage and current requirements. messy but doable.

You would really need a lathe to do any of this. However, it would bring to life that which you are trying to do. It would be robust, weather proof, exactly the design above.

..........oztules

[afcs]

Please excuse my stupidity. Are shafts made the size to accomodate the rotor(2005 mustang) if not I am assuming you are referring to use the interchangable hubs if I am correct.  I noticed a "boss" was mentioned. Could you please elaborate on the description.  

[kitno455]

you might want to re-think some of this thing. that tower must be 2 feet in diameter? that is not exactly an off-the-shelf yaw bearing. how are you going to yaw without a tail, etc.

build something small first, and learn the ropes. i think you will find this thing difficult to assemble with all those alternating mag plates and stators, and with such a massive shaft.

once you go to the point of building all of this, the couple hundred bucks you save using car rotors will pale in comparison to the cost of the tower. so, you may as well use fewer, larger plates.

allan

[Birdmanjack]

Coldspot is that a 90 volt ametek you are running there? If not what is it?

[afcs]

Thankyou all for replying.  I was considering after looking at all the interesting designs, why not build it generally the same way but with more rotors and stators. I do see your concerns about size and complexity of the system. But I was not considering the tower with a diameter of 2 feet, although it might end up that large. I was under the impression that if I move the rotors and stators on top of a basically flat tower inside of a "cage", it would relieve pressure and force off the propeller, there by reducing friction and drag.  Also, the hubs/bearings would be eliminated by securing the stator to the same "cage", reducing more weight. In my stupidity I did not add on the tail in the pic. Sorry for the inaccurate data. The rotors would be secured to the shaft((still have'nt firgured that out yet, maybe welded, but needs to be adjustable,possible threaded shaft if any exists)) without any hubs/bearings. Again thank you and any other ideas are much appreciated.

[kitno455]

hmm- you will get some additional vertical load carrying capacity from the large flat top, but that wont help much with the lateral prop thrust load.

if i understand correctly, your design is: the rotors get fixed to the shaft, and the stators are keyed to a housing. the housing has two end caps with bearings mounted in them for the shaft. the shaft protrudes beyond the cap on one end for prop mounting. the housing is attached to the yaw bearing and tail somehow. boy- sounds an awful lot like a big motor casing

you might need a fan in one of the end bells, and leave holes near the center of the rotors and spaced along the housing for radial airflow. it would be nearly impossible to assemble or adjust the airgap unless the housing was split along its length with a removable top?

seems like an awful lot of work, just to use smaller mag rotors?

allan

[afcs]

kitno455 from your description, it sounds like you have my basic idea.  I definitely agree it may be a large project to undertake, tis the reason why I value all the vast knowledge from individuals such as yourself.  My ultimate question is if with more stators and rotors, will the benifits outweight the disadvantages? (i.e. possible more power, less bearing/hub weight, 1 prop instead of more)I definitely agree that more research needs to be done, but my theory and idea behind it all is if I could consolidate several rotors and stators in 1 unit while keeping weight and definitely price to a minimum.

[kitno455]

i would not say i have 'vast knowlege', i just took some engineering classes many moons ago, and i have fixed alot of broken things since then. so i offer another comment, complete with grain of salt...

i dont think you will see any weight savings, you have a heavy shaft you have added. maybe the bearings get a little smaller, but that weight savings will probably be offset by all those mag rotor centers you just added. i think a pair of 24 inch diam .75 inch thick plates with generous lightening holes (or all-aluminum centers) would weigh less, and the general consensus here seems to be that large surface area mags should give better performance than a high pole count. seems to make better use of the magnetic material.

how about a big pipe butt flange or a heavy truck clutch ring, and some used aircraft wheel's center section?

if you like the idea of the enclosed housing, why not move to a radial configuration? should be easier to build...

allan

[oztules]

No afcs not knowing the answer is not stupid,

You would have to fabricate the rotors from plate steel and solid steel for the boss.  eg. If the rotor was made from 12inch round plate steel, 5/16"thick. You would then weld a 2inch piece of solid round steel 3/8 inch thick front and back. Then you would turn out the hole in the center to the shaft diam and machine keyways into both the shaft and the rotor. The rotor would now have a thickness at the inner hole area of 3/8 + 5/16 + 3/8 inches. from the 2"radius out to the perimeter, the rotor would be 5/16 inch. With two of these rotors on the shaft, pressed up against each other, they would have a gap between them of 3/4 inch for the stator to fit into. If the stator is thicker then spacers between the boss's would increase air gap, if you needed smaller, then you would machine the boss down to less than the 3/4 inch.

Like I said, a lathe would be necessary, but the project would be possible.

Without machine tools, perhaps better to use the piggot design ..tried and true.

The design you are talking about is nice, but is the kind of thing you would build because "you can ", not because it is better than the usual design.

It must be remembered that the reason most people build the piggot design, is that is has proved to be very doable for the average person, and very successful. If you wish to go against popular practice then that is perfectly fine, but it is the path that should only be trodden by those prepared for a failure or two. If you need instant success, then do it the way most people do. They do it that way for a reason.

I'm happy to do things differently, but I have a pretty fair workshop, and couldn't care less if I fail, I can just keep modifying till it works...coz I can.. Sometimes thats more important than the best..... ask any vawt practitioner, they are clearly behind the eight ball, but they are prepared to keep trying new things...oneday they will get one to work very well, instead of barely adequately, but the fun is in trying.

If you need power not amusement, I would urge you to build the normal design. If you crave amusement, and power is a bonus, then feel free to experiment. I choose the second path myself, but everyone has different needs.

........oztules

[pepa]

see if this will work

[afcs]

Did'nt see the pic

[kitno455]

cause its not a pic- its a pdf. pepa- if you want to post pictures, make sure to save it as jpg or gif, not pdf.

allan

[whatsnext]

Have you thought first about defining your needs and then designing a suitable mill to fill them? I reread all your posts and have yet to see even a guestimate of the projected output of this thing. I kind of like the idea of a stacked rotors set over an ever larger diameter rotor pair but there's no need to even consider it unless you're starting out with the idea of some sort of very large machine. Do you really want a very large 12VDC mill because that's what it looks like you're proposing?

John...

[paradigmdesign]

I agree with allan 100%  The problem with using multiple rotors (over 2) is you are dividing up the magnets and then only passing them over a portion of the coils.  Wouldn't it be better to have all of the magnets pass over all of the coils every revolution?  It does get more costly, as you go up in diameter, shafts, bearings, etc, but it is still better than trying to build 5 smaller gennys and put them in one box.

I found a 2" case hardened solid steel shaft and a dual row, angular conact bearing for it for 80$ online, I will have to find out where I went.  Ill get back here with that info.

[ghurd]

Me too, I agree with allan 100%.  Substitute 10 millennia for many moons.

Do not forget about voltage being induced by the speed at which the flux changes.

More magnets in a circle means the flux is changing faster.

Someone did a nice test of the idea a while back. It didn't turn out so well.

G-

[pepa]

i have a lot of trouble posting. look at my photo uploads under multible stators. sorry about the blank reply. with allen's reply, i'll be able to do better next time. i am old and the computer is new and that dont mix well to start. if i can help, let me know. thanks allan, for your comment. pepa

[kitno455]

i am not 100% sure about the benefits of larger rotors from a power generation perspective. yes, the mags linear speed will go up, increasing the rate of change of flux.

but the coils will spend less time with mags under them, unless you increase the size of the mags. i suppose larger mags give more flux, but they also slow the rate of change?

increasing the number of poles will increase the rate of change, but the flux wont be any greater?

i think you gain, but not by as much as i first thougt. previous threads on this only increased diameter, but did not increase pole count or surface area to match.

allan

[ghurd]

Very interesting you mentioned that!

Relates to something about the Jerry Rigged and Flux's testing I am having trouble comprehending.

The flux won't be greater, but it will be changing faster, needing less turns meaning lower resistance.  (right?)

And the top/bottom (or inner/outter) areas of the coil are sometimes shorter with more magnets, meaning lower resistance.

Like a 24 / 18 with the same magnets as a 12 / 9 will need less turns and have a lower resistance

Probably that means lower turns of larger wire and a bigger faster prop to use the alternator?

Jerry Rigged gets double the voltage (2X) instead of star voltage (1.73X), but Jerry Rigged can get more power at lower RPMs.  Know what I mean...?

But star amps last longer (right?).  Maybe like 1/2 of 1.73x?  So star could be better for low wind.  And part of the resistance is divided by another leg. Just like star is better than delta at low rpms (right?).

Still, it seems like someone did a 3 rotor 2 stator and the results were not as good as the same parts in a 2 rotor 1 stator.

G-

[kitno455]

"And the top/bottom (or inner/outter) areas of the coil are sometimes shorter with more magnets, meaning lower resistance."

i dont think so, cause you will have more coils, so you have more short pieces of dead winding. i think that comes out in the wash.

i need to think about this some more. if you had a 12 inch triple rotor with mags on both sides of the center rotor, every mag pair will cover ~38 inches per rotation. if you make a larger dual rotor with the same mags and spacing, you would need a 24 inch rotor, and it would only have to make half a rotation at the same shaft rpms to make the same power?

but the prop has got to be able to handle the increased torque, assuming the original unit had exactly the right prop, you would have to increase the prop size by 1.4? all while using the same amount of mags and wire? wow, thats better than i thought. i must be wrong

allan

[ghurd]

I believe it could use more discussion.

""And the top/bottom (or inner/outter) areas of the coil are sometimes shorter with more magnets, meaning lower resistance."

i dont think so, cause you will have more coils, so you have more short pieces of dead winding. i think that comes out in the wash.""

Not correct.  

(Jeeze, I hope you ARE right, it'd make my project easier)

With more magnets and the same total magnet area, the turns stay the same total number. Meaning less per coil, and less per turn of dead wire.

Figure the wire and magnets of an 8/6 with 1" square magnets, and how many turns it takes.

Figure a 16/12 the same magnets. The dead wire and resistance is less.  Don't forget the first turn in 4", but the last turn is around the first turn so it is about 8" long.  The last turn is 2x the length and resistance as the first.

Willib math.  And he probably thought no one was paying attention.

I don't see the prop as important for this.  Bigger gens need bigger props.

And Allan, Don't confuse my logic by introducing any facts.  It confuses me.

G-

[kitno455]

ok, not facts, just a dumb approximation:

two 1x1 mags have a total perimeter of 8 inches. a single 1.4x1.4 inch mag is 5.6 inches around but the same surface area.

assuming coil leg size to be half of mag width, your coils go out to 2x2 and 2.8x2.8 respectively.

this makes the outer wrap 16 inches total for the two small mags and 11.2 inches for the big one.

i dont know if its correct to use the average, but i will just to be easy. the small mags are avg turn length is 12 inches. big mag is avg 8.4

there is less copper in the single larger coil.

the flux is also going to be higher (cause the one big mag is stronger that two smalls even with equal surface area), but it will be moving slower.

allan

[ghurd]

Now I see what you are saying.

I'll have to go down and see what other size magnets I have that fit.

G-

[kitno455]

i left one thing out, my original point- on the two smaller mags, fully 4 inches of each 'turn' passes over the mags, or 1/3 of the total length. on the single larger mag, 2.8 inches of each turn, for 1/3 of total length

so you see, if you keep the mag shape the same, the winding ratio of dead space to active should stay the same, no matter the number of poles, as long as total mag surface area stays constant.

now- that is a purely mathematical phenomenon, that may have no bearing on actual power production. though i would not be surprised to find that the flux density rate of change is lower, but the max flux density is higher, so that comes out in the wash too.

allan

[paradigmdesign]

Yes, but you need to increase the number of poles AND coils when upgrading the genny dia.  Also, when you get larger diameter genny, with same sized coils, and if you keep the same space between the mags, the wasted copper on the coil actually drops due to the smaller angle difference from the top to the bottom of the coil.  

As a general rule of thumb, the larger the genny is, the more efficent they are, I read that in my basic electronics book.

P.S. I'm working on a 32" dia. genny right now, so soon (few weeks) we will get to see if they are any more, or less efficent.  

[coldspot]

Birdmanjack-

Ametek

30VDC