Posted by bealiba on September 17, 2007, 10:40 pm
> beal...@gmail.com wrote:
> > Okay. Take a motorcycle drum brake.
> Yes, we considered a centrifugal clutch (eg chainsaw), which is similar
> to your suggestion. Motorcycle parts are too bulky, alas.
> > A chain type governer.
> Not sure what that is, but we're trying to avoid chains, belts, etc if
> possible!
> > As seems the case you are talking savonius, they are generally self
> > regulating and by tuning the angle of the blades can be speed limited.
> Sounds like serious engineering - could blow the budget.
Nah, preset at assembly, don't have to look at it again.
Posted by Jordan on September 17, 2007, 11:28 pm
bealiba@gmail.com wrote:
>>> As seems the case you are talking savonius, they are generally self
>>> regulating and by tuning the angle of the blades can be speed limited.
>> Sounds like serious engineering - could blow the budget.
>
> Nah, preset at assembly, don't have to look at it again.
>
The "blades" will be, for the artistic requirement of these
installations, nothing but four flat panels ("canvasses") with a lip on
the outer edges. Not much room there for interfering with engineering
shapes!
Posted by bealiba on September 18, 2007, 12:49 am
> beal...@gmail.com wrote:
> >>> As seems the case you are talking savonius, they are generally self
> >>> regulating and by tuning the angle of the blades can be speed limited.
> >> Sounds like serious engineering - could blow the budget.
> > Nah, preset at assembly, don't have to look at it again.
> The "blades" will be, for the artistic requirement of these
> installations, nothing but four flat panels ("canvasses") with a lip on
> the outer edges. Not much room there for interfering with engineering
> shapes!
My point exactly. You are not dealing with a high speed device.
Posted by danny on September 19, 2007, 11:27 am
>-> > Why not just make it strong enough that it can spin as fast as a
>strong
> -> > wind will make it turn without flying apart?
> -> > Brakes just add complexity. Heat has to be dissipated, etc.. There's
> no
> -> > need for them.
> -> But, would it turn in a slight breeze?
> -> Re: heat - Wouldn't the wind tend to keep things cool?
> Having no brakes on it would presumably allow it to turn more easily,
> so a lighter wind could move it.
> Sure. Wind can carry away heat. But you'll still have to arrange for
> the wind to be able to reach the parts that get hot.
> dow
///////////
This is where the Greek wind turbine is at it's best.
The triangular sails are self regulating as it speeds up the sail flattens
out, slowing the tubine down by changing the angle to the wind.
Posted by tallex on September 20, 2007, 2:22 am
> I've volunteered to help an artist, who wants to place a number of small
> vertical rotor windmills in a seaside park, on top of picnic sheds. (He
> has permission!)
> The rotors will be about 6 ft diameter, 3 ft high, and free-spinning -
> won't drive anything.
> The challenge is how to control the things so they don't spin too fast,
> but still be able to start in a light breeze.
> Of course, cost matters.
> Ideas so far:
Several years ago I was testing some prop designs over extended
periods. I set up a mounting rig with a permanent mag motor from a
photocopier. I wired a 50mfd electrolytic across the output with an
ne2 neon light. The cap charged up, flashes the neon and applies the
braking action with increasing wind..the back emf works like a charm
to shunt down the speed of the props totally automatically. Different
caps will give you different braking action at differing wind speeds,
so experiment and find one that works best for you. This was a real
life saver for me and prevented me from getting a few good wacks from
over speeding props. Two parts and the motor, coudn't be simpler and
very reliable.
regards
tallex
> 1. Centrifugal-operated "air brake".
> 2. Permanent-magnet motor, with speed-sensing switch to short out for
> back-emf braking.
> 3. Sails attached with Velcro, to rip out in big wind.
> All comments and suggestions welcome.
> Jordan
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> > Okay. Take a motorcycle drum brake.
> Yes, we considered a centrifugal clutch (eg chainsaw), which is similar
> to your suggestion. Motorcycle parts are too bulky, alas.
> > A chain type governer.
> Not sure what that is, but we're trying to avoid chains, belts, etc if
> possible!
> > As seems the case you are talking savonius, they are generally self
> > regulating and by tuning the angle of the blades can be speed limited.
> Sounds like serious engineering - could blow the budget.