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Design Basics to a Tilt-Up Guyed Tower

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Guyed TowerA guyed tower has a center mast (pole) with guy wires supporting and holding it in place. These towers are typically the easiest and cheapest to build and the most popular by home wind turbine builders. The mast takes all the vertical force of the wind turbine, mainly the weight of mast itself plus the wind turbine. The guy wires support all the horizontal force that the wind is applying to the turbine and tower.

The Mast

Mast are typically be made out of steel, commonly water pipe or tube is used because of its accessibility. Steel tubing that is used for water pipe is easy to find, work with, light, easy to cut, drill, and weld. Using hollow tubing also allows you to run the cables from the wind turbine inside the tower. Dumps, recycling centers, salvage yards, and scrap yards are a good source of steel pipe. Pipe that has been threaded has been weakened, I recommend welding the pipes together verse threading them. I personally have used the threads of 1 3/4 in pipe before on smaller 4 FT rotor turbine with no trouble, but I am not going to recommended it.

Here is a chart that is for general information only, giving you an idea of the smallest pipe size to use.

Turbine Rotor Size

Steel Pipe Size

3 FT

1 ½”

6 FT

2”

9 FT

4”

12 FT

6”

If you are going to use something else than steel tubing, then review the strength of the material and ensure it will support the weight of the tower and be easy to work with. The tower will also have a torsion force on it between the ground and each individual level that the guyed wires attach to. That force can be calculated with a little physics and basic geometry.

Tower Hinge

A hinge for tilt-up tower is an important part. It must be able to withstand the day to day force and put up with the abuse of rising and lower the entire weight of the tower and turbine. I always recommend a concrete foundation and either embedded part of your hinge in the concrete foundation or properly bolting it to the foundation.

The hinge does not have to complex in design, it can be as simple as two base plates and two tower plates with center holes drilled that a locking pin fits into that can support the entire weight of the tower and also allow it to pivot.

Do not be shy on the size of mounting bolts and the Locking Pin. Use ½” or larger 1” bolt embedded at least 5” in the reinforced concert, using undersized bolts could be catastrophic. The same goes for the Locking Pin, use ½” steel or larger, you can use a partially treaded bolt or a real locking pin, I do not recommend rod stock unless you can rivet the ends.

Gin PoleTilt-up Tower

Some tilt up towers have what is known as gin pole, which is perpendicular of the main mast. This arm is used to help lift the tower off the ground. Usually it is a steel pipe of the same diameter as the tubular tower pipe. The longer the gin pole, the easier it is to lift the tower. A gin pole makes it much easier to raise the tower but not completely necessary.

Guy Wires

Guy wires will support the stresses from the wind pressing on the turbine and any other horizontal force the tower or turbine receives. Guy wires are typically stranded metal cables. You can purchase 3/16” galvanized wire rope from most hardware stores which will work excellent for most towers. If you are installing the turbine in a temporary position then standard rope can be acceptable instead of metal cables.

You should put three or four guy wires per layer evenly spaced around the tower. Each layer should not be any further than 18ft between each layer or 18ft from top or bottom of the tower. If your tower is twenty feet tall, you would want one layer of guy wires at 18ft, if your tower was thirty feet tall, you would want one layer at 12ft and another layer at 25ft.

The distance of the guy wire anchors should be at least half the distance from the base as it is the distance up the tower. Example: Your first set of guy wires is attached to the tower at 18 FT and then you would want your anchor to be placed at least 9ft from the base of the tower.
Anchors

Concrete blocks
The best anchor is a large block of reinforced concrete in the ground, it also looks very professional. You can use ready mix and some pieces of rebar. You should calculate how much weight you want for the support of your turbine. Eye bolts should be embedded to attach the guy wires to.

A Dead Man
A dead man is a deep buried object and is an excellent cheap anchor. Rope or any other corrodible material should not be used below the ground. You will need some kind of riser, a stainless steel bolt or chains are good options. Dig a hole and bury a piece of steel pipe, treated lumber, or anything you can find that will not degrade over time. The depth will depend on the forces involved, the type of ground you have, and the size of the dead man, but at least two feet down. You need to give time for the ground to settle before using it as anchor. Please also note it is not a good idea to use an actual dead person as the anchor, they will degrade to fast, and prison time might interfere with your wind turbine project.

Posts and stakes
For small wind turbines you can get away with posts or large stakes to use as guides. You must have good soil for holding the stakes in. Stakes must be driven at a perpendicular angle from the path of the guy wire.

Yawing

The most common yaw ‘bearing’ is by slipping a larger size of tube over the end of the tower tube or the other way around. They must be snug to each other but still be able to move freely. Depending on your design, you might have to weld a plate on the top of or the bottom of the mount to keep the two tubes in together. The cable can hang down the middle of the tube of the tower.

There are more ways to build your yawing bearing than the two tube method, however, I do find it simple, easy, effective, and cheap. There are a variety of off the shelf items that can be purchased to work as well.

Also creativity can really come into play here. My first yaw mount that I made was using a pipe unioner. I unscrewed one of the sides from the unioner and applied thick waterproof grease to the inside on the flange of the other side. Loosely tighten the side that was previously removed, this should allow the opposite side to still spin freely. Apply JB Weld around the screwed side and allow to harden. Once finished you should have a perfect yaw mount. This unit will not last forever but should have many years of life, depending on condition.

Last Updated on Monday, 27 February 2012 02:22  

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