Hi,
I just joined up today and my ultimate goal is to make direct drive motors for a telescope (no gearing). I've been doing a lot of reading and it seems axial and radial flux motors are a good possibility but I need to know a hell of a lot more before I even know if I can attempt it. For a telescope drive I'd need very low speeds (less than 1 rev per day - think comets or the moon) but with very smooth movement. Max speed would be perhaps 2 RPM for fast moves between targets.
While looking at all the material I ran across axial flux generators and realized I have a simpler application for axial flux that would be a great starter project - a wind genny for when I'm boon docking and using aforementioned telescope. I have a solar setup (200 watt with PWM controller) that's nearly sufficient (I run a couple laptops, two scopes, astro-video camera, DSLR with battery eliminator (hours of exposures each night) and a handicap scooter. On cloudy days and even some busy sunny days I have to run a gas generator under pretty specific and limiting rules. A quiet wind turbine could run 24 hours a day.
Most of the year I'm just doing a couple of days camping in various places where wind simply won't work. One week each year I attend a star party on top of a plateau at around 4000 feet where there's 10+ MPH wind almost all the time and for about 6-8 hours a day it exceeds 20 MPH. A few times I've seen porta-potties flip and tents go flying.
So I'm thinking if I could build a small genny, say 200-300 watts @15 mph, I'd be swimming in electrons and I'd be a lot further along in understanding enough to build (or know not to build) an axial flux very low speed motor.
So I'm looking for some starting hints helpful to a newb. I do have some mechanical and electrical background (navy marine engineer, presently a power engineer) and I make electronics for a hobby. I've done dataloggers, urinal flushers (not kidding!), HVAC diagnostic dataloggers (dual temp & hum), a talking keyboard for a fellow that was mute, autistic, and had MS (long before tablets), a swimming pool chemistry controller (ORP, PH, Temp), and lots of experimenting with micro controllers (Atmel, Arm, Parallax).
I also have a small CNC router for wood/plastic and a separate spindle for making circuit boards (using 5 and 10 mil end mills). I was thinking PCB stators since I can make them so easily but I'll save the decision for when I know more.
Anyway, I know generally how much power I want so I'm guessing the first decision is type and size for the turbine/props. What would you folks suggest as a portable, occasional use setup? Most likely I'll be welding a mount to my trailer frame and using a pole to get the blades above the trailer roof and out of range of people's heads/hands (it gets REALLY dark during new moon).
I realize I'll need some way to control the genny speed on those really windy days but thats a topic for later.
Thanks for any feedback.
P.S. I tried reading some of the faqs about building gennys but I keep getting errors and can't view them.