Build Your Own Wind Generator!

Building Your Own Wind Generation System

Credit to the author (including the built in link if this page is posted elsewhere on the internet), copyright notice and warnings & disclaimers are included.
You make no profit from the redistribution of this page. I don't mind you covering your reproduction costs, but it's not fair that you make money off of my hard work.

Warnings, disclaimers, yada yada,...

I have made every effort to make this information accurate, however it is based on my own personal designs & innovations which I cannot gaurantee will work and not infringe on any patents, copyrights, etc... It is placed on this web page in an "as is" fashion meaning errors may or may not be in it. I cannot gaurantee the structural integrity of this design either for reasons both already stated as well as lack of control of the constructor's methods. Use this information at your own risk.
DANGER! This particular windmill (and most others) can produce incredible force in even a moderate wind. As stated in the construction overview, the propeller itself should be able to spin freely and never come closer than 8 feet from the ground - IT CAN DECAPITATE, INJURE, OR OTHERWISE KILL YOU! As stated per instructions, a remotely operated brake is strongly advised. The direction and strength of the wind is completely unpredictable and therefore the direction and speed of the blades are also unpredictable. I cannot and will not be held resposible in any way for damage to property, injury or death caused by the use of this information. Those using this information do so at their own risk!
The tower upon which this windmill is mounted must be strong enough to take incredible pressure from ALL directions. I cannot control what tower you use nor how you mount and anchor it, therefore you are completely responsible for the safety of the tower installation and its conformation to the local building code of your area.

Construction overview:

    This is a fun little project I actually built when I was about 16 and was recently requested by a teacher down in Ottawa (Have fun with it guys!), so I decided to post what little information about the project I could.
    It is essentially just a simple twin bladed wind mill. I used flatstock aluminum from the local building materials store (available in your favourite colours too!) to construct the entire blade assembly. Depending on your access to both funds and/or materials, you may be able to substitute some parts with different materials for efficiency. I will make a few suggestions.
    The blade is a single piece twin blade, with non-adjustable pitch (unless you build that in - you're on your own there!). The blades can be built with a twist in them as I will show to account for the difference in speed of the blade at different radii from the rotation center; that is the tip of the blade moves considerably faster than the root of the blade, only 1 or 2 feet from the center of rotation.
    The blade is constructed around a very strong but simple and lightweight box beam you make out of flatstock aluminum and pop rivets, overlaid as shown by flatstock folded over in an airfoil shape.

This drawing shows the basic concept of how to construct the airfoil: Simply fold the aluminum over and pop rivet the trailing edge together frequently. A straight blade will work but a twisted blade (even a crudely made one) is considerably more efficient. Without the twist, the tip of the blade will attempt to move far faster than the wind is pushing it, thus it will actually act as a speed brake - the faster it turns, the harder the air pushes to slow down the propeller.
To get the twist in the blade, form your blade and pop rivet only one end (You may need to put in a few pop rivets for strength until you actually get the blade built):

This is an end view of the twisted airfoil. The box beam is already shown mounted on the inside of the airfoil. The dashed line along the trailing edge of the airfoil shows an approximation of where the overlap of the two edges of flatstock will wind up because of the twisting action. Just pop rivet along where the edge winds up, then trim the two edges flush with each other.

It's best to build the box beam first (oh no, are you one of those people who builds as they read? No, no, you're supposed to read the instructions first, then you build! Get it?). If you can afford it or have some tubing around already, you can substitute the box beam for a strong piece of aluminum or steel tubing. Tubing is actually better than a box beam because it is easier to pop rivet the airfoil to the spar then (Your tubing or box beam that runs down the middle is the main spar). However, for those of you like me who have teensy-weensy budgets, flatstock box beams may be the answer. Bend half-boxes in your brake as shown, as long as you can get away with. Remember: A propeller with ten foot blades means the box beam needs to be somewhere around 22 feet or more long! Ten feet for each blade plus two feet or so for the center mount where there is no blade.

Innevetibly, you will need to make several halves to make the full length so stagger the joints as shown in order to create strength of the beam. Pop riveting the optional spacer reinforcements every six inches to two feet greatly increases the strength of the beam.
Important!: Rivet / bolt / screw a tight fitting piece of wood into the inside of the beam at its center, at least 1 foot long ( i.e., the center of the wood is located at the center of the beam). This will serve as your mounting point reinforcement: You will actually drill holes right through the aluminum and wood and bolt the beam to a large pulley to mount the whole propeller on a bearing.

Your final box beam will look something like this:

Pop rivet the whole assembly together. The rivets should penetrate both halves and the center reinforcements.

Once you have made your box beam, start at one end with a ten foot long piece of flatstock laid lengthwise up the beam (assuming you're making a ten foot long blade) and fold it over to create the airfoil. Pop rivet the trailing edge together on the outside end to hold it while you apply your twist.
You will need to make a jig or angle measuring system of some kind that will enable you to at least fairly accurately match the twist and angles of the two blades to each other - that is more important than getting the angle to the wind correct. It could be as simple as a small rack that holds the box beam from the other end and a piece of cardboard mounted on the workbench with a line drawn on it.
Determine which edge will be the front of the box beam. This is the direction the wind will be coming from and it's important. The outer tip of the blade is travelling the fastest and is therefore the flatest to the wind. It should only be at about ten degrees or so, as in the drawing we already saw:

The very top of the picture is the direction the wind comes from. You are looking at the very tip of the blade, the part of the blade that achieves the greatest speed, therefore it has the greatest angle of attack relative to the wind. The root of the blade has the smallest angle relative to the wind and travels the slowest.

Once you have made your blade and riveted it to the center beam or tube make the other blade and mount it as well.

Find the center of the beam and bolt the blade assembly exactly centered on a large pulley. Canadian Tire's a good place to hit. The pulley makes a nice mounting face with a pre-made mount for mounting on a bearing assembly shaft (which you also need). Clamp the pulley to the beam so it is exactly centered and the clamp will hold it all together while you drill holes through them all. Bolt them together with some fairly sturdy bolts - at least 1/4 inch or larger. Use nylon insert nuts 'cause you hate this blade coming off the pulley when it's spinning full tilt! (My lawn has never been the same since that incident - nor my neighbours! :-)

Now you can mount the entire blade on a bearing block which in turn can be mounted on a bracket or even a board - whatever works. This whole assembly will sit atop your tower with the wind vane mounted on the back, able to turn to face any direction.. You need a fairly large vane to counteract the gyroscopic effect of the blades and turn the whole assembly into the wind.

This is basically what the final assembly will look like. It is important that the entire unit be able to spin around horizontally easily. Some counterweights on the vane end of the assembly may be neccessary to counteract the weight of the blades. What you do with the drive shaft is up to you. Remember though, if you use an automotive alternator you NEED A BATTERY. Alternators take current from the car battery and the energy provided spinning the pulley to create a whole wack more of current. There are plenty of places on the 'net showing how to hook up car alternators as portable generators driven by motors, etc...

The tower I used was a standard TV aerial tower (the exact same kind you get at Radio Shack). It's not the strongest in the world but it seemed strong enough for this. Guy wire it as high as you can get away with and as frequently as you can. Remember that the blade will spin all around the tower so be sure the blade won't clip the guy wires.

Download this entire page in a ZIP format. (Obviously you will need Winzip or something of the like to open it up!)

Hope you enjoyed this and get something out of it.