tower vibration [RE-wrenches]

[Peter Duchon]

Couldn't it be, being in a high wind area, that the guy wires themselves
have gotten "stretchy" over time -- appearing taut in low winds because
there is  normal deflection -- but when they kick up, that big weight at the
top starts a-spinnin' and a-tweakin the vibration control that the guy wires
were assisting right outa-there.  Next really high winds could snap a
fatigued guy wire set pretty good I would think, maybe two at once even.
The force and moment of that situation, at hub height no less, could pull a
whiplashed tower down maybe.  Maybe also, just a contributing factor at this
time?  I would replace the guy wires, maybe re-anchor em too if needed, and
see what happens with a nice fresh and tight pull on the tower.

PD
-----Original Message-----
From: Matt Tritt [mailto:solarone at charter.net]
Sent: Tuesday, April 25, 2006 8:31 PM
To: RE-wrenches at topica.com
Subject: Re: tower vibration [RE-wrenches]



Are the blades wood? Even if they aren't, you might have some warpage
occurring, or maybe water intrusion in one of the blades. Either of
these things can cause the blades to go out of balance with each other.

Matt T

Kirk Herander wrote:

>Hello,
>
>I have an old World Power H1500 (1500 watt) machine on an 80’ homebrew
>sectional steel pipe tower. It’s in a high wind area, and has flown with
>no complaints for 7 + years. Several months ago, the tower started to
>vibrate in high winds, maybe 15 + MPH, when the machine really starts
>cooking. I lowered the tower expecting to find something obvious – but
>no luck. The blades are on tight, the tail boom pivot bolt/bearings look
>fine, all bolts are tight, no problems with the machine that I can see.
>When the tower is up and brake on, there is the normal several inches of
>deflection on all guys. But at those higher wind speeds the front and
>rear middle and top guys develop at least a foot of “up and down”
>deflection – it really looks scary – and the tower shakes big time. What
>am I missing?
>Could the guys be too tight? Or too loose? Thanks.
>
>Kirk Herander
>Vermont Solar Engineering
>802.863.1202
>fax 802.863-7908
>NABCEP(tm) Certified Solar PV Installer
>Xantrex Certified Dealer Charter Member
>NYSERDA-eligible installer
>VT Solar and Wind Partner
>
>
>
>
>
>


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