I am designing a runner for a low head fixed propeller using: herehydro.weebly.com/uploads/9/3/9/1/93913/pico_propeller... and the spread sheets on Picohydro.org.uk With the flows that I have, the rpm can range with the design within a fairly wide range. I am planning to build an axial flux alternator similar to what I have read about in the homebrew wind turbine book. I could easily build for an rpm a wind turbines over speed. Any advice?
Kent