Windmill Blades

Hello and welcome to the windmill blades blog. I have made this blog to help answer your questions regarding how to design your wind turbine blade, how your generator should work, your windmill tower design and any other questions you might have. All the information you find here is thanks to this renewable energy website so have a look for yourself.


What is the best windmill blade design

The design of your blades depends on a few different factors which are:

• Wind velocity
• Rotor size
• Generator size

Wind Velocity

The speed of the wind will determine firstly the number of blades that your windmill will have. If there is:

• a low wind speed of 7-10 mph then I would recommend more than 3 blades with a smaller diameter. Make sure the blades are made out of light material such as balsa wood or thin PVC with a twist to them. Also attach the blades to the rotor at quite an angle to allow for more efficiency.

• a high wind speed will require 3 blades with a bigger diameter and also with more length to them as well. You can still use wood and I also recommend acrylic or light weight sheet metal. These materials allow to design more of a twist to the blades and also to sand the edges to a bit of a point. Still attach them to the rotor at an angle to allow for increased efficiency.

Rotor Size

The size of the rotor will determine how quickly it will rotate, therefore the bigger the rotor the longer the blades should be. You generally want to make the rotor as big as you can, depending on the wind velocity, because this allows for a higher ratio for your generator turbine. The rotor is linked to the generator turbine at a higher ratio to increase the energy generated per revolution.


This is the simplest example I can give where the rotor would be the white gear and the turbine would be attached to the red gear. The ratio would be determined by the generators size and voltage capacity.





Generator size

This generally relates to a bigger generator because then you need to increase the ratio and revolutions of the turbine in order to get enough energy to generate the energy you are after. You would only go for a bigger generator if there is high wind speed, therefore a longer and wider blade.

More Homemade Windmill Instructions

If you want to get a complete instruction kit that will show you how to make a homemade windmill from scratch have a look at the renewable energy website link at the top/right of this blog for access to a great source.

Windmill Tower

The tower of your homemade windmill is very important because it determines how efficient your wind turbine will be. The main reason is that you do not want obstruction from the wind by other factors so it is wise to have your tower up to 30 feet above ground but remember I am saying "up to 30 feet", it is dependant on your location.

Other factors to consider

Does your location have flat land, is it uneven and are there many trees in the immediate area. It is fine if you need to place your windmill away from your home but I would not recommend any further than a 300 foot radius.

Tower base

Make sure that the base is very solid and grounded, generally it is wise to dig into the ground a few feet and have a concrete base. If you do not want to use concrete I recommend stainless steel or very hard wood. In terms of your hole cover the base of the hole with sand, pebbles, sand again and then place the tower base on top of this.

Tower materials

The best thing to make your tower out of is steel piping so that you can run your wiring down through the middle of it, this prevents wear and tear on your wires. Have 3-4 straps or metal cables attached to the top of your tower and secure them into the ground with pegs or sand/water/concrete weights.

Final tips

Remember your tower is facing the elements so paint it for rust prevention if need be, make sure the straps (metal cables) are a few feet below the complete top of the tower and all your wiring is securely strapped or screwed down.

Savonius windmill opposed to a common windmill

A savonius windmill is a vertical axis windmill that converts wind into torque on a rotating shaft.

These types of windmill are actually less efficient than your common windmill however they are much cheaper to make so if you where planning to go in this direction I would probably advise making a lot of them. In all seriousness do not make a homemade savonius because it will not deliver the energy results you need.

Common places that you will see these vertical axis windmills are on the top of buses to provide cooling and at an event like the football or at the beach where promotional banners are placed on each of the sides.

If you do want to make a savonius then I recommend using plastic buckets or bins cut in half as the blades/sails. This is the easiest option but if you are looking to get a little more technical and also gain a bit more efficiency I recommend some light sheet metal or acrylic with a twist to each blade (refer to picture).

How does a Windmill generate Electricty/Power

So you have heard about windmill electricity or power generation which is probably why you are interested in building one for yourself but you need to understand how it actually works. No problem let me explain how.

Battery or energy storage device

So if you are using a homemade windmill then you will be generating electrical power through a battery system. Usually if you want to charge a battery you plug it into the wall socket and allow electrical current to run from the grid into the battery (energy storage device) and then use this power for what ever reason you see fit. So what you will do is generate this electrical power from the generator on your windmill which is attached to your battery. Now you are asking how does the generator create electricity?

How does wind generate electricity?

I will explain how a basic magnetic generator works and then it will become quite clear. A magnetic generator has a large magnet in the middle and a large turbine around it covered in copper. When the turbine rotates around the magnet, energy is generated and directed through a copper wire into whatever power storage device is connected (battery).

So with a windmill the turbine is connected to the rotor which has the windmill blades attached. The wind blows and causes rotation of the blades/rotor and turbine therefore creating wind power. The faster the rotation the more electricity that will be generated etc...

What size generator should you use?

This is dependant on the wind speed in your area, the size of your windmill and what you need to power. I would recommend looking at a more detailed source so if you follow the link at the top/right it will take you to a homemade windmills website that links to a professional source. (It's worth checking out).