Question on towers/ couplings

[freejuice]

Hi Folks,

 I have found a good deal on some 4 inch schedule 40 pipe. I was wondering if I make the tower about 55 ft tall and later want to "upgrade" to a larger windmill other than my 10 ft....what would you folks think it could be capable of handling later? Maybe 14 ft or so?

 Also you folks have any coupling ideas for 4 inch pipe?

 At 55 ft I think I will use 1/4 inch cable everywhere for guy wire, however I'm thinking of staking it down with some 2 inch, 6ft pipe into this South Carolina clay-like, hard pan soil and attaching my guy wires to each stake ( 4 stakes with two guy wires at nintey degrees around the perimeter.

[SparWeb]

Well it will depend on the class of wind your site experiences and whether you're talking about an otherpower 10' or something else.  The first red flag is the 1/4" cable.  It might be okay, but it might not, again, depending on what weather is coming your way.  I'd say that an 8' windmill is about the maximum for 1/4" cable, then go up to 3/8".  Of couse the intermediate cables can usually be smaller than the uppermost cable.  Another question is why you aren't going to use a concrete anchor for the wires.  You will probably need a concrete base for the tower itself, so why not?...  anyway there are many many questions so a lot of research is necessary to figure it out.

If you're building the tower yourself, it can be a project to dwarf building the wind turbine!

[freejuice]

Hi Steven,

 Thanks for the reply,

 Yes it is a 10 ft machine from this site. The winds around here will not reach 40-50 mmph unless a hurrincane blows inland and by the time it gets here it has broken up pretty good...the only one that was abnormal was HUGO in 89...it was tearing stuff up inland for 200-250 miles

I thought about a concrete base, but was hoping to use some 2 inch sch 40 for stakes...this red clay soil we have around here is tough going...it usually takes a pick-axe ( mattock) to do anything with it after a few inches.  So digging holes is tough going.

 I would consider concrete, but I simply dont have any idea as to how much to pour...is there any calculations out there for that kind of stuff vs the 4 inch 55 ft tower I want to build?

 Living out here in the country I have plenty of room out here in the "backyard" for a very safe area, fall zone, etc in case anything happens and I believe in extras to keep everything rigid....so I will bump the 1/4 cable up to your 3/8 cable advice.

[Volvo farmer]

You will probably need a concrete base for the tower itself, so why not?..

Having just gone through this... Concrete needs to be buried down a ways, doesn't it? We also have very dense clay soil at my location, and I chose some 6" aluminum arrowhead anchors that are driven into the ground 40" deep. Holding power is supposed to be 5000 lbs in this soil. I bought these back before I had a tractor with a hoe because I couldn't easily dig deep enough to make a good concrete anchor.

Now, I have no actual bad-weather experience with these yet, as I am a week or two out on my project's completion. But if these anchors work out, they are pretty easy to install with an electric jackhammer, and require no digging. I installed all 4 of my anchors in about 1.5 hours, and the whole kit ran about $200 I think.

Keep in mind that my anchors are untested so far, but the common-sense engineer in me says that 5000 lbs of holding force is enough. Heck I think my 5/8" turnbuckles are only rated for 3500 lbs.

[freejuice]

VolvoFarmer,

 Indeed I have thought of those too! Either the duckbill or or arrowhead anchors...I've seen them on ebay for sale....can I ask you what cable size are your anchors? All the ones I have seen are 3/16 diameter cable attached to the arrowhead anchors. I wave wondered if they would be enough?

 Another question: Are you, or have you, attached the upper guy wire and lower guy wire to together at each anchor point or did each guy wire have its own anchor?

[SparWeb]

Have a look at this:

My website's tower stuff

I've written a few things down that should help give you the "big picture".  As for the smaller picture, have you looked through the Otherpower website and found the 40' tower plans?

Duckbills, arrowheads, screw-ins, they all anchor into the soil but are dependent on the moisture, granularity, packing, etc of your soil.  Your soil sounds okay but it never hurts to bury one anchor just to test, and deliberately pulling it out.  If you can't budge it with a small tractor then you have some confidence.

At the base of the tower pole, the weight of the windmill, tower, and the sum of the guy wire tension is all pressing down on the earth.  What's distributing that load enough for the earth to support it?  It is possible to have too little base area, allowing the tower to "sink" as you crank the guy wires tight.

The other, and MORE IMPORTANT reason for a solid tower base is that it must resist the forces of raising the tower up.  When pulling the tower up, a fraction of the force is pulling the tower along the ground.  It must not slide!

The otherpower website shows that is possible to make a 4-legged base for the tower and stake down those legs.  This is probably a good alternative if the soil is impossible to dig, but otherwise concrete is more sound.

If you don't know where to start with the numbers, then you are really in for a tough go.  Working safely with a tower is a combination of understanding, adequate materials, and cautious practices.  The understanding usually comes from math, and this is where an engineer can help you if you get a bit lost.

[SparWeb]

Here's a picture of my system.  Click and you will see the photo full size.  The tower is more prominent than the windmill!

[Volvo farmer]

Mine are 1/4" cable. I got them from American Earth Anchors. The aluminum ones are available up to 10". I will say that it was no walk in the park driving these things in. I literally had to stand on a ladder and put all my weight on the electric jackhammer, just for the 6" ones. I used a large shackle and connected both turnbuckles to the same anchor. it's my understanding that the majority of the forces in high winds are on the top guy.