The Flap Turbine (FT) is a novel type of vertical axis turbine (VAWT) where the blades are made of movable flaps. These movable flaps, when combined together, act as a sail or blade for the VAWT. This type of turbine is also known as a check valve turbine because of the check valve like the behavior of the moving flaps. When the sail is moving in the downwind direction, the flaps are closed and will not allow air (water if the turbine operates in the water) to pass through the sail. However, when the sail is moving in the upwind direction the flaps will be in the open position and allow air (or water) pass through the sail.

The most important characteristics of the FT, which is self-starting and omnidirectional, is that the flaps are operated by the wind (or water) and not with complex mechanisms.

I know that there are a lot of interesting ideas about vertical axis wind turbines (VAWT) out there and none of them compete with more traditional three-blade horizontal axis wind turbines (HAWT). These traditional three-bladed HAWT have many advantages compared with VAWT. Admittedly, these advantages seem hard to beat. However, they have also disadvantages which will be discussed on this site. There has been and continues to be a lot of investments in the research and development of three-bladed HAWT. It is hard to convince people that there is a future for the VAWT for large-scale energy production. Ignoring the existence of a limited number of VAWTs, all the large-scale energy production is dominated by three bladed HAWT. VAWTs are limited to small-scale (1kw-5kw range) energy production application because they are easier to manufacture.

Is there a future for large-scale energy production by using a VAWT? Yes there is and on this site, I will try to demonstrate these concepts by using the flap turbine principles to prove this point. Since there are no actual turbines which work with the FT principle, other than my crude prototypes, all the explanations will be conceptual. I will try to demonstrate why this turbine has a future. Only time will tell whether this is a good idea or another dead end in the VAWT lineage. My hope is that in the future large-scale flap turbines will produce energy for generations to come.

This video is of the worlds first flap turbine. Initially smaller versions of this turbine were built to test the idea, after being convinced that the idea was working this turbine was built in less than three (3) hours. Actually, most of the time was spent cutting the paper flaps and securing them on the wire mesh, which for this prototype is made from a clothes organizer. In the real application, the flaps should be built from a light plastic material which will allow for the turbine to work under wet conditions. Considering its simplicity this is the most efficient, versatile, scalable and cheap ACTION type VAWT one can build. This VAWT:

1. Is efficient because the sails moving in the upwind direction have open flaps which result in minimum drag
2. Is versatile because there are no mechanisms to move the flaps
3. Is scalable because you can build in many sizes
4. Is cheap because sails are made from smaller parts which reduce transportation costs
5. Can work under low wind conditions where HAWTs are unable to

The video below shows a 9 ft high turbine wich flaps made of tent fabric. The previous model was 1 ft tall and flaps were made of paper. Next model will have flaps made of plastics.

Below is a video of the flap-turbine with plastic flaps. These rigid flaps eliminate waving and give better performance with respect to flexible flaps made of cloth.

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