We already have a layout ready for PVC blades, they just need to be cut. We have acquired a second bike wheel, which is a rear wheel, so that we can drive it using a chain and motor on a second test rig. This will provide us with a constant rotation velocity for electrical testing.
We experimentally determined that alternating magnet polarities is advantageous because it reduces the stalling force on the magnets, which sacrifices power but reduces the torque required for start-up. We have prepared some coils and mounted a bracket for one of them; measuring the starting force for a few different spacing values, we found that reasonably low forces are necessary when the coil is just half an inch or so away from the magnets. As such we do not need to abandon our core or make any drastic design changes. We also built a rugged rectifier, and devised a method for supporting three evenly-spaced coils.
Thursday, October 14, 2010
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