60 ft tower

[freejuice]

Hi Everyone,

  As usual, I have another question.

 In the Dan's book they have a "favorite tower" lissted as 12 gage 6 inch tubing.

 I essentially will have alost the same however it is 4 inch sch 40 with three guys in the typical noth, south east, west setup. Does anyone know how much concrete they used at each guy loaction?

(I had found their old posting about building this tower but I didnt seem to find the amout of concrete they used at each guy location....groan)

My tower base will sit on a concrete/rebar slab that is 4 feet by four feet by 2 feet deep. The tower hinge is a piece of solid 3-1/4 cold rolled barstock about 9 inches long very well welded to an I-beam post about one foot tall on each side. These I-beam posts have a 1/2 steel plate welded to the bottom of them, these plates about 1 foot square with four 3/4 bolt holes on each corner, to eventually be fastened to the concrete. ( Happy boss man let me have them, they were making some room for new equipment at work and he let me do some "dumpster diving" with a cutting tourch )

 The pipe that hinges over the 3-1/4 barstock is schedule 80 4 inch pipe...that stuff has about a 3/8ths wall thickness... everything so far is very robust.

 All my steel guy cables are 1/4

I have very hard South Carolina red clay soil, its very hard to push a shovel with your foot through this stuff, often I use a pickax or mattock to bust through this stuff and then scoop it out with a shovel.

 However I have a tractor with a post hole digger, It will auger a hole PDQ; about 9 inches in diameter and about 4 feet deep.

 Do any of you folks think one hole would do the trick for each anchor point, if I used a well made lattice work of rebar and concrete setup for each hole? Or would multiple holes be best for each anchor point, such as two side by side or three hole close together in a clover leaf fashion but interconnecting?

 Thanks for any and all advice,

 Gavin

[bzrqmy]

I don't remember how big your turbine was.  I hope no larger than 10 footer for 4" sched 40.  The base concrete slab at 4 x 4 x 2 deep is probably a bit overkill especially if you have that hard clay.  The slab will do nothing more than hold the weight of the tower.  It will however take some stress while lifting the tower. 1/4" guys sound good as long as you have three sets, 20', 40' and short of the blade tips. I have seen all kinds of anchor schemes from 55 gallon barrels filled with concrete to anchors epoxied in rock.  For my 40' tower, I used some screw in anchors that are about 36" and 2 1/2 large bags of concrete.  I used more on the anchor that I use to pull my gin pole.  I probably should have used more concrete. The anchors have rebar weled in T shape perpendicular to the anchor shaft.  There is another guy that used a similar method, but added an old brake rotor at the bottom of the anchor.  I forgot what my turnbuckles are rated for, but it was about 1/4 of the guy wire.  My turnbuckles are certainly the weakest link, so ran a cable through the anchor loop, through the turnbuckle and through the cable thimble and back onto itself as a seafey measure.

Make sure your anchor points are at a higher elevation than your tower pivot point or your cables will become very tight while lowering the tower.

It really helps if you can have your tower lifted a bit before pulling it up, the higher the tower angle, the less force there will be on the pulling cable until it becomes 0 when the tower is at 90 degrees.

I have a spreadsheet that will calculate the pulling force required to pull up your tower based on height, turbine weight, gin pole length, and such.  E-mail me and I will send you a copy.

Good Luck!

[birdhouse]

gavin-

ARE wind turbines has a engineered plan set here that is almost exactly what you are looking to do.  

http://www.abundantre.com/REFERENCE%20-106%20ft%204%20in%20Tower%20Appendix%20Ver.%201.2.pdf

i've studied these plans and think they are pretty good and would like to use them for my tower.  the one change i would make is to lengthen the guy termination to tower base measurement.  i think you can skimp on concrete some if the guy footing were further from the tower.  ARE over designs the concrete work to obtain a guy radius less than 1/2 the tower height.  to get this they have a heavy re-bar cage and over 1 yard per footing.  i'm no engineer, but think you could get by with 1/2 yard per footing so long as the footing is deep and there is lots of earth backfilled above it, and the portion of steel connecting the footing to the guy is very thick and of the correct angle.  

biggest question is sch. 40 = to 1/8" wall?  that's the pipe ARE specs.  

good luck!  let me know how it goes/ steel pricing as this is exactly what i want to do!

[freejuice]

Hi Everyone,

 Thanks for the information,

 The turbine is a 10 footer... well  its about 11 feet...might end up sawing the length of the blades a bit.

 However I would like to eventually put something like a 14-15 footer on it, closely following the Dan's or Hugh's arraignment, nothing weird in design but something that closely mimics a tried and true plan.

That's the reason for some of the overkill, I see where the Dans once buit a tower with the outside lattice work to support the main post/beam. I'm wondering if I could upgrade the 4 inch sch 40 to that situation eventually to accomdate the larger turbine at a later date...if not I could simply spend a few extra bucks and make up a larger diameter tower.

The steel cables will be at 3 junctions, except for the top. which will be slightly lower by a few feet to clear the swing of the blades.

 Thanks for the heads up on the side guys needing to be higher than the hinge point.

 I will get some of that cardborad concrete tube, they sell at home improvement stores and cap the concrete pour to slighty above the hinge point...say 2-3 inches?

I will also explore that web site too!

 Thanks guys abd all the best,

 Gavin

[Beowulf]

Interesting info:  could you email me the spreadsheet?

Send to: beowulf_seeks@yahoo.com

Thanks

[wooferhound]

> Make sure your anchor points are at a higher elevation than your tower

> pivot point or your cables will become very tight while lowering the tower.

I have given this a lot of thought and I believe that you are incorrect about this point. If the Guy Anchors are higher than the tower Pivot. Having the tower laying down with tight guy wires tight guy wires, when you raise the tower the wires will loosen up. Then if you tighten the wires again and lower it they will tighten up.

It will be the reverse if the Guy Anchors are lower than the Pivot. Then they will be loose when the tower is down and will tighten when you try to raise it.

[wooferhound]

I have more time now to expand on this . . .

Think about it this way, using a tower set-up with 4 guy wires in a North/South/East/West arrangement.

Imagine using an extreme and unrealistic situation where the Guy Anchors are raised to half as high as the tower. If you released the North/South set of wires the tower would still have enough support to stay standing because the two remaining wires will tighten with any movement.

If the guy wire anchors were in a deep ditch circling the tower and you released the North/South set of guy wires, then the tower would easily fall as the two wires still working would get more slack as it's falling.