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Idea to reduce tower guy wire footprint


By mbeland, Section Mechanical
Posted on Sat May 10th, 2008 at 09:42:44 AM MST
A frame tower


What bothers me the most about the idea of having a wind turbine on a tilting tower is the space occupied by guy wires. If I aim for a tower 80 ft high (which I consider necessary considering the nearby obstacles, i.e. trees), the conventional footprint would be 40 ft on each side plus the space to lower the tower. That is equivalent to 4800 ft2.

My idea would be to make the foot print more linear by removing the side guy wires and making the tower in the form of an « A » with web gussets. Assuming the A frame has a 20 ft base, the foot print would be 1200 ft2 i.e. 4 times less than conventional tilt up tower.

Here is a drawing of the concept:


I haven't designed nor calculated loads and pipe sizing and I understand piping is usually more expensive than guy wires but I may have found some cheap pipes that shall be handy (will post later about this potential finding). The pivot bases will need to be quite beefy too.

Anyone has any experience with this type of tower? Is it a good idea?

Martin

Idea to reduce tower guy wire footprint | 9 comments (9 topical, 0 editorial)

Re: Idea to reduce tower guy wire footprint (3.00 / 0) (#1)
by wpowokal on Sat May 10th, 2008 at 06:07:16 AM MST
(User Info)

Martin, such towers have been around for probally 100 years, albiet probally not 80', also google Rohn towers.

allan down under
A life lived in fear is a life half lived.



Re: Idea to reduce tower guy wire footprint (3.00 / 0) (#2)
by BruceDownunder (brucedownunder@hibis.wbs.net.au) on Sat May 10th, 2008 at 05:44:04 PM MST
(User Info)

  a 80 foot tower is more than the DIY  can do ,,especially if it~s non guyed .. mine is 60 feet  and guyed..
Thinking of you and looking at mine ,,makes me say --give it a miss--

 If you haven~t the space ,,then, sorry ,,for safety ,,re-think position

Bruce



Re: Idea to reduce tower guy wire footprint (3.00 / 0) (#3)
by zinguvok (gmail.com is where zinguvok is at) on Sat May 10th, 2008 at 06:22:27 PM MST
(User Info)

Martin, I read this and wrote it off -- but something felt hinky, so I came back and reread it. I would very strongly suggest you include a side view -- as I believe the previous two posters thought this tower was fully self-supporting since there are no visible guy wires. I think it might be a workable design, and I have to admit my curiosity is piqued. Folks, I'm pretty sure what Martin is giving us is a face view -- and the side view would appear to be one vertical pipe guyed from the top and maybe one other point. I think he's showing us a tower where there are no guy wires perpendicular to the tilt plane, only lattice framing -- which gives the tower a much narrower footprint. Interesting.



Re: Idea to reduce tower guy wire footprint (3.00 / 0) (#4)
by wpowokal on Sun May 11th, 2008 at 12:03:21 AM MST
(User Info)

Zinguvok, my 40' 3 leg self supporting comercial tower has a footprint of around 6' between legs, therefore if one extrapilated this out, 20' is possibly feasable for 80'.

But! at 80' a 10' turbine has great bending force, this is realy (as usual for towers) a matter for a structual professional.

I suspect the diagram posted was a simplified diagram only, which to me conveyed the posters intent.

If one does not have room for guy wires for an 80' tower, I suspect one does not have room for an 80' tower. People/buildings/dogs etc should at all times reside well away from a tower's reach.

allan down under
A life lived in fear is a life half lived.
[ Parent ]



Re: Idea to reduce tower guy wire footprint (3.00 / 0) (#5)
by zinguvok (gmail.com is where zinguvok is at) on Sun May 11th, 2008 at 07:36:08 PM MST
(User Info)

Very salient comment about fall zone. I would be inclined to use the space amongst the guy wires for farming or something similar which would not be seriously harmed were the tower/mill to fall on it. While it's unlikely that such an A-frame tower would fall towards one of its un-guyed sides, it is a serious matter.

Even in light of this consideration, though, A-frame towers would still be worth thinking about for sites where locating the side guys is unfeasible. Ridge tops come to mind, if they aren't too turbulent.

Does anyone actually know what kind of forces turbines of given sizes apply to their towers under given wind loads? This would be handy information to have...

[ Parent ]



Re: Idea to reduce tower guy wire footprint (3.00 / 0) (#7)
by Ungrounded Lightning Rod on Mon May 12th, 2008 at 08:50:51 PM MST
(User Info)

A mill comes close to putting the same wind load on a tower as a solid wind-facing wall the size and shape of the swept area.

So treat it like a sign mounted on a tall pole or tower.  B-)

[ Parent ]



Re: Idea to reduce tower guy wire footprint (3.00 / 0) (#8)
by SparWeb (sparweb at ANTISPAM_hotmail_com) on Mon May 12th, 2008 at 09:16:54 PM MST
(User Info)

...Plus a couple of other forces... gyroscopic forces... vibration...
Steven Fahey
[ Parent ]


Re: Idea to reduce tower guy wire footprint (3.00 / 0) (#6)
by mbeland on Sun May 11th, 2008 at 08:55:36 PM MST
(User Info)

Hi Zinguvok,

Thanks for your reply. Yes the figure I posted was a face view. As you suggested, side view would be just like any tilt-up tower, guyed in both direction at the top and probably at two other points. So I thought no use to post that. Sorry if there was confusion in my post. I may have to guy the side of the A frame too...??

Must I understand that the towers that another poster sead were around for decades are totally freestanding? It is not what I wanted since I want something easy to access for maintenance and I don't want to have to climb although I think it might be fun the first time but not if I had to do it every year.

I understand 80 ft is high and I would have to make sure everything is calculated to withstand the loads. 80 ft is not totally set in stone yet. Our lot is 2 ha and is sloping towards incoming dominant winds. Trees are not as high as 60 ft yet but will be in a few years. I Just wanted to know if anyone had tried this. So, has any of you?

Martin
Eau, soleil, le vent
[ Parent ]



Re: Idea to reduce tower guy wire footprint (3.00 / 0) (#9)
by SparWeb (sparweb at ANTISPAM_hotmail_com) on Mon May 12th, 2008 at 09:42:24 PM MST
(User Info)

In one plane, it is rigid, but in the other plane, it rotates and must be supported with guy wires.  I think you're asking for "the best of both worlds", when you can only get one (easily).  There's nothing technically wrong with your idea, but don't you want to be the guy who can prove it will work, if you're the one to do it?

I work for a company that has designed and built a couple of unique towers for a customer with very specific needs.  The towers, once raised, worked very well and they were very pleased.  Once the towers got into the field, the process of lowering and raising them overwhelmed the abilities of the people using them.  People with university degrees.  Both were dropped at least once (fortunately without any injuries).  The customer has abandoned the project.  (Sort of an oversimplification - they didn't drop the project because of the towers, their other equipment was self-destructing with no human intervention at all!  But the towers didn't help, either).  The lesson is that, while your solution may be a good one, the more skill required to do it right, the greater the risk.

When designing one for my own back yard, I set out to make my tower as simple and quick to lower and raise as possible.  I succeeded: it can go down and back up again in one half hour.  I do it alone, and I need only one wrench.  I pull with the tractor.  It has been raised and lowered over 2 dozen times since finished last July.  If I decide to install a winch, I can eliminate the tractor part, too.

I mean to warn, not to discourage you.  The base of my 45-foot tower is a 40x40 diamond, so it takes up a lot of space.  What you propose is a tower twice as high, with only 150% the footprint.  If you don't have the skill to design it yourself, then you need to buy that skill.

Advice on a web forum is worth what you pay for it :^)

Steven Fahey



Idea to reduce tower guy wire footprint | 9 comments (9 topical, 0 editorial)
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