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DaViD

Senior Member

Joined: 14/01/2009
Location: United States
Posts: 120

Posted: 09:16pm 21 Apr 2009

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Hi guys, would it stop my mast and my blades from making so much
vibration if I was to move the blades another foot away from the mast and
counter weight the tail for balance?

If your not living on the edge your taking up to much space!

Gizmo

Admin Group

Joined: 05/06/2004
Location: Australia
Posts: 5119

Posted: 10:56pm 21 Apr 2009

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Hi David

Do you mean tower wobble, where the tower wobbles as the turbine spins around. If so, thats caused by a out of ballance turbine, and moving the turbine further out could make it worse.

Tower vibration is just a noise thats really loud if you put your ear against the tower. This is fine unless your tower is mounted to the roof, a bad idea.

Glenn

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

DaViD

Senior Member

Joined: 14/01/2009
Location: United States
Posts: 120

Posted: 12:30am 22 Apr 2009

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Hi Glenn, It's a vibration that comes down through the mast then to the metal (yes roof) of my shop. So I guess i'll get a taller pole and mount it?

If your not living on the edge your taking up to much space!

KiwiJohn
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Joined: 01/12/2005
Location: New Zealand
Posts: 691

Posted: 08:59pm 25 Apr 2009

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David, if your machine is in balance and the vibration is just an annoying noise being transmitted into the building maybe you can cure the problem by isolation.

For example, and these are just ideas off the top of my head, put the foot of the mast loose fitting into a tall socket supposing you have a 3" mast you could use a couple of feet of 6" pipe as the foot and fill the space with well tamped sand, stand the mast on a rubber isolation foot a big engine or machine mount etc.

If you have a really strong roof and dont like the idea of isolation maybe you can damp the vibrations by mass, mounting the mast on a slab of concrete perhaps.

Just a couple of ideas which might all be worthless!

DaViD

Senior Member

Joined: 14/01/2009
Location: United States
Posts: 120

Posted: 03:12pm 29 Apr 2009

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Hi KikiJohn, The only problem with isolation is my roof is not all that strong. I was just trying to cheat and gain some extra air without the added length of mast.
It seems to pulse when the blades past the mast and the pulses increase to become a vibration when the rotor speeds up. I guess when I get the time I'll put it in the ground.

If your not living on the edge your taking up to much space!

robbo

Regular Member

Joined: 25/03/2007
Location: Australia
Posts: 71

Posted: 10:26pm 01 May 2009

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Hi there David,
I had the same problem with my mast, it was vibrating due to the blades running past the pole. Mine was about 6 inches from the pole I think.
I isolated the vibration from the house, by adding some thick rubber between the pole and the support that lead to my house. It worked really well.

I used an old thong for the filling. About 2cm think.Edited by robbo 2009-05-04

"the Earth was not given to us, by our fathers, rather, it is lent to us by our children".

DaViD

Senior Member

Joined: 14/01/2009
Location: United States
Posts: 120

Posted: 12:59pm 02 May 2009

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Hi robbo, I wish it was that simple for me. My mast is attached to the ridge on my roof with guy wires at each corner. I'm just to

lazy to take it down and mount it on a higher mast

If your not living on the edge your taking up to much space!

MacGyver

Guru

Joined: 12/05/2009
Location: United States
Posts: 1329

Posted: 05:44am 12 May 2009

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Hi, new to this forum. Over the years, I've encountered many "vibration"
problems and found that it's not always a question of balance, although
balance is critical especially with larger-diameter up-wind blades.

One thing that often gets overlooked is the fact that as each blade passes
in front of the tower, the airflow spilling off the airfoil is spoiled a little
bit by the fact that the tower is in the way. This will often times set up a
kind-of "harmonic" beat and it'll drive you crazy.

Down-wind blades suffer a similar problem as each blade passes through
the tower's shadow. An easy solution is to either extend the blades away
from the tower or elevate them using a single-post tower extension
(which still interferes, but not as much).

Hope that helps

Nothing difficult is ever easy!
Perhaps better stated in the words of Morgan Freeman,
"Where there is no struggle, there is no progress!"
Copeville, Texas

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