DanF single rotor

[Treehouse]

Hi DanF I resently seen a post with your single rotor turbine on you antenna tower and would like to build one just like it. I don't have the money for a duel rotor

I tryed to build Hughs 4' and I messed it up lol.. So I am going to dismantel it buy 4 more neos and build one like yours. Do you have any more info or can you give me all the details for yours? if you don't mind, I realise you spent lots of time working on it and don't want to steal your work.  I too have an old tv tower on the side of my house and would like to put this new one up there. Any help you could give me would be great!  

Thanks, Dennis Saunders

 

[DanB]

Hi Dennis - with the magnets you have I think it may work well with perhaps a 6' blade set.  We used larger magnets on danF's and it really was too resistive for an 8' blade.  The best we saw from it was around 400 watts (which was no surprise).  You might try winding the stator like we did, put it together and then see what your cutin speed is.  You could improve it by running a blank rotor on one side.  We've only made one like that so far so its hard to give really good info here.  We are building another one almost just like it with plans to put a 7' blade on it.  We're using round magnets - and there has been a touch of debate about the coil shape/cancellation and the possibility of generating heat in the coils (see my last Monday Jan 23 posting) - but I'm doubtful that heat is being generated in the coils due to that.   I tend to think we're not building an inefficient machine there (it just wont be terribly powerful).  But - if you use the 1" x 2" magnets then you can have fairly proper coil shape and I expect it'll work out OK so long as you're not worried about real high power in high winds.  It should make a decent low wind 6 or 7' dia machine I think.

[Flux]

Dennis

What did you mess up on the 4ft machine. If you built it right it is a super little mill.

I agree with Dan about running a blank disc if you can't afford magnets.

I have just modified one of the Hugh 4 ft machines to take a 5'6" prop in a low wind area just by adding a blank rotor, but I did start out with a different mechanical arrangement as this was the intention from the start.

With different coils and a higher tsr it should manage a 6' prop with the blank rotor & the 8 magnets.

You will need 12 magnets to equal that with a single rotor, so if you are short of money it may be cheaper to buy another disc than more magnets.

As always it depends on what you have, what you can do and what you can scrounge as to which way works out cheaper, but if magnet is your main cost an un-backed single rotor is not very cost effective.

Flux

[Treehouse]

I messed up Hughs 4' by using 170 turns instead of the 85 it called for, for the 12V machine. So it's stalling real bad. The hub I used is no good, the back race spun and it's sloppy the hole mill shakes worse than I do lol! So I am going to get a new one. Third It's in a really bad spot 6' above my garage. Forth I'm itching to build a new  one worthy enough to put on the top of my TV tower. The one I have up now Hughs 4', I've never seen more than 1.7amps.I can afford 4 more NEOs(the wife said i could). I also had a thought about the blank rotor, I have 12 ceramic magnets almost the same size as the neos, there a pinch smaller. Could I put those to use? I know they are in no way the strength of the neos but would it help more than just a blank rotor?

[DanB]

Ive got some magnet rotors here with the same mags youve got treehouse.  If I have the time tomorrow Ill experiment with a stator with 1 rotor only - and then 1 mag rotor with a blank rotor on the other side.  Should be fun to get some numbers - if we have the time!

Im sure if you get 12 of those magnets on a 12" rotor, we can find a good match if its wound up correctly.

[willib]

That is an interesting thought ..

Would one  12 pole neo rotor , with 12 ceramic mags on the other rotor , work better than a blank second rotor?

i would say yeah  ..but i have been wrong before.lol

[Flux]

Yes winding it for 24v would make it useless at 12v. If you can get at the connections you could connect it with one coil in series and use 2 rectifiers but if potted it would be difficult and you have other problems.

I bet the vibration has more to do with balance or turbulence than the race but that is not good.

Watch it using ceramics with neos, yes it can work but you must keep the flux density less than Br for the ceramic and unless you really know what you are doing you would be better not doing it. Done properly you could gain but you would have to work with large gaps and low flux and gain from the increased winding space.

Flux

[jlt]

i built one with 12 neo .s and 12 ceramic mags and it has worked reaiy well for me .started out to be an all ceramic machine.after i started building it .i got plans for a 8ft machine by hugh piggot . i was for a 5 phaze set up.after getting it built i was not getting charging voltage until about 10 to 12 mph. so i orderd 12 2x1 half neo inch mags for it.it doubled the voltage at the same rpm.. the machine is 7 1/2 ft an i have seen as much as 50 amps. from it

[willib]

Nice looking machine !

Are those flywheels as rotors ? i was talking to a guy online who sells them .

They can be had pretty cheap.

Details ?, details ?

[jlt]

yes those are chevy flex plates. 13inch and allready have 12 flats on them. but are too thin . i am losing a lot of flux. dont know how much that hurts out put but it works. i found somewone to cut discs out using a water jet cutter. it does the whole thing including holes for mounting. and is much better.this picture is of 15 inch duel roter i am working on now .it has a steel band around the outside edge. that was made from half inch strap .made about a quarter inch too small and then heated up with a torch and driven on .like a ring gear on a flywheel.when it cools it was very tight.

[willib]

That looks really really nice!

How thick are those rotors , looks like a half inch? if you dont mind my asking how much did they charge ?

what is the steel band for?

[jlt]

i think it was about 70 bucks including the metal .the band around the outside edge it to help keep the mags in place .may not be needed but it makes placing the mags easy.eigth inch lip to rest against.