Wind Tower Survey

[imsmooth]

I am curious what type of guyed wind towers people have.  I finally got a kit for $300 that included the hardware, cable and connectors for a 30' tower.  I am going to buy 2.875" (OD) tube.  The cable is 1/4".  The guy radius is suppose to be 20'.  I want to extend my tower up to 35' and was thinking about bringin the guy radius into 18'.  It will be teathered up 15' and at 30' with the remaining 5' for blade clearance.  I went through the tension loads and everything seemed fine.

I would like to know what type of towers others have here: height, radius of cable footing, cable thickness, pipe diameter.  Also, does everyone bury their augers/anchors in concrete or are some of you satisfied with the holding power of a heavy clay soil?

[MAXial dreamer]

raising the  the tower and narrowing the guy's both weaken the tower catasrophe threshhold.  I prefer to over build myself.  a dead man in dirt deep enough would work theoreticly but it would need to be tightned often as the guy's would loosen till they reach a strait line between the dead man and tower fasten point.  I personally would stick to the plans and use plenty of concrete and rock.  It also matters what your putting atop it.  Ask yourself am i feeling lucky?  Well are you punk.

[KEG]

I,m not going to be much help but I prefure the free standing tower myfelf as the foot print is much smaller, I wouldn,t push the desien of the tower you bought, the out come will be what you don,t want!





Thats 48' tall with a base leg spread of 10'

[mgtd]

I recently completed my 103' tilt up lattice tower.  It was a used tower that I purchased from the local hospital when they put in a new communications tower.  I hinged the base (5 feet across the 3 legs) and use a 34' gin pole.  Guys are not hooked up during raising/lowering.  4 way guy wires are attached at 40 and 78 feet.  I used 3/8" guy cable and 1/2" tilt cable.  Pulled it up with my compact Massey 4WD tractor.  Good luck on your tower construction--keep in mind, better to overbuild than rebuild.

[luv2weld]

We've got a 45 foot 4 inch black pipe tower. Guyed on 4 sides, with a

radius of 22 feet. The guys are set at 20 and 40 feet, and it's 1/4 inch

wire rope. The anchors are deadmen set 36 inches down, large rocks

concreted together on top of them. Then backfilled with broken rock and soil.

And tamped very well.

Ref: the holding power of a heavy clay soil?

I think it would depend on the diameter of the blade on the anchor/auger

and on the depth that it was in the ground. Heavy clay has good holding

power if you spread the stress out a little. To explain what I mean----

A 2 inch diameter auger blade set 8 inches in the ground ain't going

to hold very much.

Ralph

[TomW]

weld;

We have loamy black dirt to a depth of say 4 foot average before you hit the limestone up where my tilt ups are. Easy to dig but not very good at holding those screw in anchors unless they are the big ones up around 8" on the auger disk and long.

I opted for a method Volvo Farmer posted about doing. Where has he got off too, I wonder?

Anyway the nutshell version is you bore a post hole as deep as practical [below frost here so 4 feet is good] Then drive a T post [steel fence post] in at an angle that is in line with your guy points on the tower so the post is into the bottom or near bottom of this post hole. I made sure the "spade" on the post was in the center of the hole. backfill with concrete at least half full. Once the concrete is set you have an anchor that simple cannot be pulled sideways thru the soil to loosen or come out. I also put some long scrap iron into the hole between the spade on the T post and the tower side of the hole to lock it all together.

I like this because it creates an solid slug of concrete that would have to be pulled sideways through undisturbed soil in order to loosen. They have not been put into use yet here but I am confident they will be strong. You could use other steel or cable or chain in place of the T post but I had posts on hand.

Just another interesting way to do "deadman" type of anchor without digging big holes.

Tom

[TomW]

By the way, these will anchor guys for a 47 foot 6.75" tube mast with a 10 foot actual DanBuilt turbine. I put the guy anchors at 30 feet from the tower base to facilitate grafting on another 11 foot section of tube to get it up to 58 feet should I decide to do that.

That stuff is semi documented over here:

http://www.anotherpower.com/gallery/Tower-Site?page=1

I am not very good at ongoing project photos but try to get some after its a going concern.

Tom

[luv2weld]

Tom,

good idea.

Was it suitep that was going to use the "thread the needle" idea??

One hole intersecting the other, so they are locked together just

about like what you're doing.

You're right about the Farmer. Maybe he's on vacation.

Ralph

[suitep123]

Howdy folks:

    We were indeed talking about this very kind of thing.  We did get two sets of holes drilled with the auger on the tractor.  It was very time consuming and on unlevel ground one needed to be 5 feet while the other would need to be 7 feet.  We have full-size chevy (I think) truck tortion arm rods (1 1/4 inch X 4 foot solid) to thread through the welded on 3 inch eye on the botto of the two inch pipe.

Cattle and road issues delayed the finishing of the tower and guy anchors.  We had gotten there to do some leveling of the ground in order to finish drilling these holes and found a horse trailer that was sitting right next to where the generator will be raised, had been stolen.  This is the second theft of something in that area and we're a bit leary about putting the genny up at all right now.  Insurance?  We have farm liability but to add coverage for the few items of equipment out there, the premium is almost as much as the whole liability police with the standard deductible.  Problem is - the deductible is half of replacement costs on most of our equipment.  We don't live on the property...  

    In this dirt, we still believe this to be the best way to go.  We were concerned about the pipe wall buckling and possible breakage versus the strength of the solid rod which we believe would just bend.

    Still not dead in the water on this - it'll fly.  And we're already looking to try a homemade alternator.

    Y'all have a great day!

Bob and Pauline

[suitep123]

Forgot to say, we have broken MANY t-post type fence posts and seen some last a very short time in the ground, Seams to me they are very soft mild steel.

Bob

[SparWeb]

I often chime in on questions about towers, and this is no exception.  I've spent about 45 minutes re-writing this posting, because the more I think about it, I find some other reason it's a bad idea.

I don't know why you want to reduce the guy wire footprint.  In addition to this you want the tower to be 5 feet taller, but you don't say why.

These two changes alone will increase the tension loads on the guy wires by 70%.

You also come along and ask about a pipe size that is, in all probability, smaller than the kit maker's recommended size.

The pipe is a column, under a compressive load.  The weight of the windmill, and more importantly the tension in these guy wires (which you have cranked up extra tight, I might add) all put thousands of pounds of load on the column.  The thinner the column, the more likely it will buckle under the stress.

Column buckling strength is a squared power factor.  That means that 20% less pipe diameter translates into 2/3 the strength of the column.

I know you have been reading the tower-related threads for over 6 months because I've seen your comments in many of them.  You have also posted questions about some poor choices of materials in the past, and I want this to stop, now.

Towers are structures that are engineered for a reason.  Hire an engineer to provide you with a safe design and a contractor to build it safely for you.  

It must sound harsh.  Believe me, it's no fun writing this stuff either.

[imsmooth]

I know I asked about augers and clay, but I actually plan to do it a different way.  I have 5/8" galvanized 6" augers.  I have acquired steel rotors that have to be at least a foot in diameter.  I plan to use a post-hole digger to get 3+ feet down and 1.5-2' wide.  I will bury the auger and put the rotor over it so the auger has to lift the rotor out in order to get out of the hole.  Then I am going to bury the rotor in about a foot of concrete before putting the clay earth on top.  I figure this will hold quite a bit.

[imsmooth]

I truly appreciate the comments.  The kit calls for 2.875" OD schedule 40 which is what I plan to use.  Their 50' tower kit also uses the same diameter pipe, so my 35' designation should still withstand the compressive load.  I plan to go up 5' from the 30' height to clear some low-lying trees, and I didn't want to go up as high as 42 or 50' in my backyard. I will maintain the 20' guy radius, although it seems many have used guy wires that are set at 50% of the height.

[SparWeb]

"Their 50' tower kit also uses the same diameter pipe..."

That doesn't make it right.

The pipe will "dance".

I may have already told you to look at this in the past, but the Southwest Wind Power website has a tower construction and installation manual.  I am much more comfortable with their specifications than your kit's.  Please read that carefully, and decide for yourself if you are "picking and choosing" the information you want to use, and ignoring what contradicts what you want.

[imsmooth]

The kit is from Southwest wind power.