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Marcus20VT
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Joined: 02/09/2008
Location: Wales
Posts: 49

Posted: 06:35pm 19 Sep 2008

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Hi - just a quick question from a thicky!
Would model helicopter blades be suitable for driving a small motored wind turbine? Or is it all different pitch, etc.?
ThanksEdited by Marcus20VT 2008-09-21

Gizmo

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Joined: 05/06/2004
Location: Australia
Posts: 5117

Posted: 11:51pm 19 Sep 2008

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Helicopter blades are like aircraft propellers, they are designed to create lift as they rotator. Windmills work in another way, they use lift to make them rotate. Aircraft blades have the lumpy bit of the airfoil upwind, windmills have the lumpy bit downwind.
So, yes a aircraft propeller will sort of work as a windmill, but not very efficiently. A flat plank of wood would probally work better.

Glenn

The best time to plant a tree was twenty years ago, the second best time is right now.
JAQ

Gill

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Joined: 11/11/2006
Location: Australia
Posts: 669

Posted: 04:54am 20 Sep 2008

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Marcus,
Sorry to contradict you here Glenn but I looked at helicopter rotors some time ago and thought them suitable. The main problem I saw was that they had just one mounting hole at the blade root. I gather it relies on centrifugal force to get and keep them fully extended. Safety feature when crashing????? Any movement from that fully extended state is not such a problem when rotating in the horizontal but not so good in the vertical plane of our HAWTS. Perhaps an extra securing bolt could be fitted?

In flight they would have much the same characteristics as the Chinese fiberglass blades as they have no twist and no taper. They will need to be mounted upside-down to the helicopter mounting and will spin the opposite direction. The price was about $80 for a set of two and the length was about 800mm per blade for the ones I looked at.

Might suit a reduced coil F&P or perhaps DC motor but a bit pricey to be buying new?Edited by Gill 2008-09-21

was working fine... til the smoke got out.
Cheers Gill _Cairns, FNQ

GWatPE

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Joined: 01/09/2006
Location: Australia
Posts: 2127

Posted: 07:52am 20 Sep 2008

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Hi Gill,

are you sure on the length of the blade? I have and still do fly model heli. Fuel & also electric. A scale model may have this size, but the 3D style, up to 60 size, are much shorter. A lot of blades are symetrical sections. Most are long and thin and are designed for high rpm, > 1000. The single bolt, swivel mount reduces the fatigue and breakage caused by the torque as well. A lot are now hollow moulded carbon, with tip weights.

You could also make a cheap set of blades for a small windmill from wooden venetian blinds.

Gordon.

become more energy aware

Marcus20VT
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Joined: 02/09/2008
Location: Wales
Posts: 49

Posted: 08:41am 20 Sep 2008

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Thanks all for your replies.
I'm just being a bit lazy really - I know I should make my own blades, but I'm looking for a cheap&easy way out!!!!
There's no substitute for hard work as my mum always said!

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