Personally, Flux has been very patient and most helpful with me on a couple of fairly basic generator concepts recently via email.

Please don't upset the guy - he is one of the most knowledgable people here, it would be a massive shame to loose him, for all of us..

I agree, wading through masses of questionable internet documents/pdfs is boring but Flux really does know what he is talking about.

All of the otherpower documents are rock solid also, maybe set aside an hour or so per day to read them is my best advise Ralph.

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

I too consider myself as  a 'newbie', even after 5 years on this wonderful forum.

Ben.

     Ralph, nothing in any of these posts was talking down to anyone. The point Flux made was very true and in no way condescending. Thats what this forum is for, folks like Flux helping us learn because first hand knowledge coming from patient (and free) teachers is better than trying to figure things out from, as Flux put it, a list.

The question about air cored and air gap terminology was a valid one and I can see that there is a confusion.

There is even more confusion about the term cogging and that was not even questioned.

From the start of the electrical industry the term cog has referred to the preferential attraction of magnets to a non uniform iron core. If there is no iron in the stator it can't cog. Torque pulsation of a machine delivering current can have a similar effect and many here seem to regard it as cogging. Again I can see the confusion and I have tried to correct this idea previously. On that basis all single machines cog, but they don't on the normal definition of cogging.

If your concept of a term is wrong then confusion is inevitable.

I don't take offence at your remark and perhaps I should have not included that last line, we do all indeed have to start somewhere. Pre internet you had to get to basics to do anything. Now you can find anything you want and it is wonderful and lets people do things they would never have done before, but not all information is correct and none of it is helpful if you don't get the basic concepts right.

There is wonderful information on this site, but it is scattered all over the place and some of it is buried in amongst discussion where there is often wrong information and sometimes confusion will occur.

Don't think it is all easy for me, I have had an engineering background, but 90% of the stuff here is as new to me as the rest of you. Air cored machines were rejected pre 1900 and only recently made a comeback with the invention of decent magnetic materials. Much of this comeback has been from people in the small wind turbine business and outside this site and a few similar wind power related ones I suspect they are still unknown. Large industry and the Universities seem to have caught the idea now but I am not sure that they are not following the early wind pioneers at Marlec and Hugh Piggott and DanB here.

I really don't know what you do about this single rotor thing, that is always going to be a problem. The true air gap is the length of flux path from one magnet to the next. The longest route is via infinity and the shortest is the minimum distance between magnets. Most of it lies somewhere between these limits. Restricting the discussion to the gap between rotor and stator is not going to be very helpful.

It really is not a very good form of construction but it does fill a need to use bigger standard magnets in a simple configuration where convenience is more important than cost effectiveness or efficiency. Within reasonable design limits the air gap can probably be considered as being close to the stator thickness, but with thicker or thinner stators this again could be way off.

Some things don't seem to have easy answers.