homebuilt alternator w brake discs

[youmanskids]

Im building a 10 foot axial flux machine according the the homebrew windpower book, but would like to use the 11 inch discs that came with the VW bug front strut axle.  should i use higer flux 2x1x1/2 inch magnets (N42 instead of the reccomended N30) to compensate for the smaller(slower)diameter discs (to get the same power output)?

has anyone done a 10 foot machine with 11 inch rotors? if so, your help/experience would be appreciated.  thanks in advance.

[Flux]

It will help. Reducing disc size limits your winding space and number of turns and makes things difficult all round.

You can compensate to some extent by using higher grade magnets so that you can use less turns without having to use thinner wire. You may need to go better than N42.

Everyone has their own ideas but personally I would far prefer decent plain discs over awkward brake discs and if buying then it may depend on your disc cost compared with the cost of higher grade magnets. I regard N30 as dead and probably now you can get N42 at the same cost but going to N48/50 may work out more than decent discs.

I think you are pushing things to build a 10ft machine with those rectangular magnets and try for smaller discs. You may have to accept a reduced output and make adjustments to the furling to keep it safe. As long as you are prepared for this it will be ok. You will have to go through the test coil thing to get your number of turns if you want best results.

Flux

[youmanskids]

thanks for the reply,  that is very helpful.  due to the issues you describe, I think it would be wise to just have 12 inch steel disks made so I dont reget it in the end.  thanks for the advice. Roger