My New Wind Turbine

[DanB]

Way too much fun this weekend!  I'm working on new machine.. maybe to be installed here, or maybe I'll save it to power the shop I'm hoping to build come spring time.

I spent yesterday cutting out metal parts.  All the work was done with a bandsaw and a hole saw on the drill press.  Of course.. it's a dual rotor machine.  The rotors are 16" diameter, from half inch thick steel.  There will be 16 magnets on each rotor, the magnets are 1.5" wide, 3" tall, and 3/4" thick.  The stator will be 20" diameter, and 5/8" thick.  Im hoping for about 2.5 - 3KW @ 200 rpm.  I figure it'll be good for a 17' prop (give or take 1').... but that's just a guess untill I test a completed alternator.

The hub I got from a trailer supply store, it's much larger than a Volvo, although I'm allready wishing I'd gone with a larger one.  I'm also wishing now that I'd gone with larger rotors.  AT 16" diameter, the magnets will be fairly crowded on theire inner diameter so there will be some cancellation in the coils.  It should work OK anyhow.  The main reason I went with 16" is that it's the biggest diameter I can work with on my drill press should I need to work on the center.  As it turned out though - it was much cheaper and easier to have this done and it would've been quite easy to have larger rotors made.  The rotors were made at 'Colorado Iron and Metal' - they have a CNC water  jet cutter.  They came out really nicely...  The rotors cost me about $75 ea (I had 4 made) - that included materials, setup, and the cost of cutting.  They cut all the holes in the middle and everything came out to a very high tolerance.  

The Yaw bearing is 3" pipe and it's 16" long(allready wishing I'd gone bigger! - but it's twice as big as my current 14' machine).  The tail pivot is about 1.8" OD thick walled tubing, and it's attached to the yaw bearing with a bracket cut from 1/2" steel.  The tail bearing will be from 2" diameter pipe.

That's about where I got at 11PM last night.  I think the only reason I made it to bed at all last night was.... I ran out of diesel fuel!  Sometimes I get into something like this and go til the wee hours.  I suspect it'll move along quickly - hopefully in a week or so I'll have some prelimary information on the completed alternator.  I've not decided yet if I should dare try to build a machine this big for 12 volts (thats what my system is now but I intend to upgrade someday).  I think I could - if I widen the airgap, run a slightly smaller prop and have it furl early, but the temptation is to go straight for 48 volts with it.  At 12 volts I think I'd be dealing with unreasonably thick wire.  Im guessing that, for cutin between 60 and 70 rpm - I'll want about 15 - 20 turns per coil for the 12 volt machine.  Lots of fun... most of the fun for me is in the building - who knows when I'll actually get this one up.

[RobC]

You know Dan your just an endless inspiration to the rest of us. Keep it up. RobC

[Dave B]

Dan,

  How heavy do you estimate the completed mill to be  less blades ? What will you use for the yaw bearing ? Mine is pipe over pipe with grease fittings and a  1/2 thick steel washer / welded on top as the bushing, the inner pipe is thick walled with very little slop and the unit is very nearly balanced and so far it is very smooth operating. I am using a rear tapered wheel bearing hub from a mini van that is plenty heavy enough for my 12' rotor but it is really hard starting in cold weather with regular wheel bearing grease, are you using different lubricant ? Also, what do you use if anything to help keep the blades from icing up ? Sorry for all the questions but you have extreme conditions there (as do we here in Western NY) and when this goes way up later this Spring it's going to be a little tougher to mess with than 10' off the ground as is now. Great stuff, thank you. Dave B.

[DanB]

Hi Dave -

"How heavy do you estimate the completed mill to be  less blades ? "

I expect upwards of 200 pounds - just guessing.  heavy - well have to hoist it, or assemble it on the tower top.

"What will you use for the yaw bearing ? Mine is pipe over pipe with grease fittings and a  1/2 thick steel washer / welded on top as the bushing, the inner pipe is thick walled with very little slop and the unit is very nearly balanced and so far it is very smooth operating. "

Ill probably use a thrust bearing of some kind.  The steel washer like you've done would probably work OK too.  On matts we put in a throwout bearing from a clutch - that worked nicely.  I'll probalby look for something like that.

"I am using a rear tapered wheel bearing hub from a mini van that is plenty heavy enough for my 12' rotor but it is really hard starting in cold weather with regular wheel bearing grease, are you using different lubricant ?"

Ive heard complaints of that before - I've never noticed any problem with it personally.  I wonder if part of the problem is the fact that you have a single rotor machine, the bearing is allready under a fair load from the magnets attracting the stator.  You probably have some (though it may be minor) drag due to iron losses as well.  Just a little bit of drag like that will make it much slower to start - even if it does turn in a light wind, it will take much more time to come up to speed.  I question if it's the grease though - I've not noticed any affect from that in cold weather.

 "Also, what do you use if anything to help keep the blades from icing up ? Sorry for all the questions but you have extreme conditions there (as do we here in Western NY) and when this goes way up later this Spring it's going to be a little tougher to mess with than 10' off the ground as is now. "

I dont use anything to preven icing up.  Its happened a few times to me though - the machine usually sheds it pretty quick, and once it comes off 1 blade it seems to come off the other two almost at the same time, but it is one of those things I wonder about.

[Dave B]

Thanks Dan,

  Now that I think about it I'll bet part of the problem is the grease seal. When I rebuilt the bearing I installed a new grease seal also. I balanced the blades and hub together with the new bearing before grease and the seal and marked everything so I knew after greasing it all up and reinstalling the rotor and blades it would be very well balanced, and it is. I was never happy with the amount of resistance the rubber from the seal added to the drag but after swinging that 12' prop it didn't seem to matter much and certainly  on a car or van you wouldn't care or notice it at all. But, that was in warmer weather and as is the case it swings much easier when it's above freezing. Cold grease, cold rubber on the seal, single rotor I think it all adds up in the extreme weather. Changes will be made come Spring but I still like the single rotor with silicon laminates (thanks Ed.) Keep us informed Dan, your photos and reports help us all to learn much.  Dave B.

[monte350c]

Hi Dan,

Looks interesting as most of your machines!

If you know the water jet guy you could have him make some cutouts in the rotors so you end up with sort of like 4 spoke mag wheels. With half inch plate there's lots of meat strength wise and you could probably knock about 30% off the weight of each rotor.

Ted.

[RP]

Dan,

You spoke of 12V versus 48V.  I wonder if you could wind your stator with three strands of wire kind of like using dual 14gauge to get close to 11g wire.  If you wire it with three strands and keep track of the ends you could switch it later to 48 volt by re-wiring the strands in series on each coil.

I suppose if you were a glutton for punishment you could even do this remotely with a host of relays.  At the very least when you're ready to switch to 48volt you wouldn't have to replace the stator, just re-configure the starts and stops.

rp

[farmerfrank]

What are you using for blade material?

[iFred]

Very Cool, you never fail to inspire us all! Please keep us informed on the stats of this monster, it should be good!

P.S. when you get into the groove of building, everything else fades away, all cares, worries and doubt. What is left, is mind and thought and concentration. time stands still, nothing matters but what you do best. This is where inspiration, will power and ideas flow without time. energy is conserved. Hope you are having this type of fun, because there is nothing else like it! it is what we strive for. The best you can be.

Good Luck and thanks for the share!

[johnlm]

IFred,

You are turning into quite the philosiphor.  Did I speel that right?

John

[Gary D]

Can't wait for you to get this one proven out! Then hopefully off to ebay to sell a spare one(or forget ebay and offer em here under products)? Realizing it will probably be at least a year away tho... finances should be vastly improved here by then... Gary D.

[nothing to lose]

16" WOW!

Okay, a few question about how are you building the stator and other things.

Since your getting into such a large size are you using your standard type magnets and coil sizes? Not wire size or number of turns but diameter or heigth/width sizes.

Are you planing to cast the stator solid as normal.

I am thinking since noramally the dual rotor systems I seen the stator has to be mounted from outside the diameter of the rotor, then if you leave the inner 10" or so void you save alot of resins and some weight. Not needed to fill that unless it adds strength.

Also if your gennie is basically just using the outer 3" of that 16" diameter, could you build a second gennie using the inner 12" diameter that would basically be unused, sorta 2 gennies in one. Perhaps skew the inner gennie just a bit to offset the cogging.

Not have both inner and outer cogging at same time, don't now if it would have any offset to reduce each gennies coggin also, but at least they would not both cog at the same time.

Would take more mags and coils and add to weight, but you only need one of set everything else, rotor plates, blades, tower, tail, ect...

I think getting into really large diameter rotor and stators using the space from center to edge for several gennies in one might be an option to produce more power at less total cost.

[DanB]

"16" WOW!"

well... it's not that big!  Not compared to a few other projects that have been popping up around here lately.

"Since your getting into such a large size are you using your standard type magnets and coil sizes? Not wire size or number of turns but diameter or heigth/width sizes."

yes...

Im using a more standard shape here simply because rectangular magnets are less than half the cost of 'wedge' shaped magnets it seems.

"Are you planing to cast the stator solid as normal."

Yes - I considered making it in two pieces, so I wouldn't ever need to jack the rotors apart, but I've decided to make it solid.  It should be a bit more rigid than past once since it will be 5/8" thick.

"I am thinking since noramally the dual rotor systems I seen the stator has to be mounted from outside the diameter of the rotor, then if you leave the inner 10" or so void you save alot of resins and some weight. Not needed to fill that unless it adds strength."

Well - in this case my magnets are 3" tall, so the ID of the magnet rotor (the actual part with magnets on it) is 10".  The ID of the insides of the coils will be about 7" I figure.  So there's not much room to save here, as usual - the coils will barely clear the studs that hold it all together.

A"lso if your gennie is basically just using the outer 3" of that 16" diameter, could you build a second gennie using the inner 12" diameter that would basically be unused, sorta 2 gennies in one."

My rotors are 16" diameter, the magnets are 3" tall - so the ID is 10" - not 12".  The ID of the coil ring will be more like 7".  No room for anything like that...

 "Perhaps skew the inner gennie just a bit to offset the cogging."

This type of alternator doesn't cog since there is no iron in the stator.

There may be some minor vibration - but being a 3 phase machine it should be pretty smooth.

[DanB]

I thought about that... it would've cost a bit more.

No way I'd save 30% though...

The hub is 7" dia I think, the inside dia of the magnets is 10" - so there really isn't much space there to work with.

[monte350c]

Sorry Dan - didn't think about the dimensions before I posted that. I guess this is one of those problems as things get larger in the wind business - they also get a lot heavier!

Ted.

[jacquesm]

cool Dan !

that's going to be a pretty awesome machine, I'm very curious about the power curve of that thing.

Are you going to 'bench test' it somehow ?

[DanB]

Hi Jaquesm -

Hopefully once its together I can 'truck' test it!

I'll bolt it to the rear axel of my model A - it works nicely, you can adjust the throttle from outside the truck and control the speed pretty well.  Should be fun!