Cogging solution via floating hub

[domwild]

Michael Lawley of ecoinnovations website (kiwi) used to sell or still sells F&P-based mills using a floating hub. This is my interpretation of a floating hub:

At best I have a 360 deg. free turn of the prop mounted on a pipe flange before the bolt hits the spring-loaded hinge and then turns the shaft of an F&P (Fisher and Pykel) PM washing machine motor.

The shaft of an F&P is 25.0 mm, the pipe's ID is 41.9 mm, which fits two 25x42 mm ball bearings after turning. This is the floating hub. At the pipe end sits a pipe flange, which is the prop hub. The photo shows two PVC blades mounted via two straps each.

A spring loading in general will take the shock of star/delta switching and soft/hard braking, where soft would be via resistors and hard via a short circuit. A short on an F&P is permissible as the windings are exposed.

Testing is by no means complete, there are only two blades instead of three, etc.

[TheCasualTraveler]

     Ingenous little solution. I imagine in winds too light to generate anything it just bounces back and forth. How much wind does it take to get it past the cogging? I saw in your files you tried it with 4 blades, how did that compare with 2 for startup? What are the size of the blades? Tell us about testing so far please.

[domwild]

Andy,

In light winds and if there is no separation because the spring has not wound the prop back, the prop just works against the spring until finally the spring turns the shaft. Sometimes, this becomes a turn/no turn situation until the wind picks up sufficiently to keep the shaft turning continuously.

You may be talking about gizmo (www.thebackshed.com), who uses four blades to get the torque or other contributors use even more blades as the F&P cogs badly. My blades are 1.5m radius or 3m in dia., which with better wooden blades would give you one kW but not with PVC blades. I am hoping for 200-300W at the most, the rule with F&Ps from memory is 1 W for 1 RPM. More with three capacitors paralleled to the three phases.

However, an F&P can have its poles rounded to reduce cogging at the expense of power OR a new rotor can be purchased, which does away with cogging altogether.

Testing so far: A friend gave me a 36V UPS and a stock standard F&P without rewiring gave me only 2 Amps. Since then I have paralleled 14 coils and made them into two parallel seven coils to better fit a 36V battery as per a suggestion by commanda. And that has not been tested yet.

A larger tower is under construction.

Sorry, no quantitative testing so far as the Picaxe-based V, Amp, wind speed and RPM electrickery is still being constructed.

Regards,