EXTRACTOR variable pitch hub

Here is a photo of our variable pitch hub mechanism which provides continuous control of blade pitch angle

Click here> for a more detailed explanation of variable pitch operation and advantages


[click here to enlarge]

Otherwise, the simple car transmission analogy below can illustrate variable pitch advantages.            

Single gear vs Automatic

Imagine you had a car with only a single low gear. Acceleration from a standing start would be exhilarating, but maximum engine speed would be reached very quickly, only to find you were not going very fastÖ.every time.

Imagine instead, you had a car with only a single high gear.  After a stumbling start in that high gear, you would eventually achieve a comfortable smooth cruising speed, but the stumble at the start would happen....every time.

Now, consider someone provided your car with a six speed automatic transmission.  The transformation would be miraculous.  Without even having to think about it, you would enjoy exhilarating starts, smooth acceleration, and effortless cruising at maximum efficiency, always.

Fixed pitch vs Variable pitch

Variable pitch wind turbines act just like the above automatic transmission  by automatically adjusting their variable pitch blades to optimize blade efficiency over a broad range of wind speeds.

Fixed pitch turbines, on the other hand, share the same shortcomings as single speed  transmissions. Their blades can only be set for one pitch angle setting, either for low speed winds or high, but not for both. Think about that difference, it matters a lot

The reality is, in the present small turbine marketplace, only fixed pitch wind turbines are offered.  We are changing that with our EXTRACTOR, the first true variable pitch wind turbine to compete at a comparative price.  It offers unrivaled efficiency over an extremely wide range of wind speeds, including prevalent lower speed winds, largely missed by fixed pitch turbines.  And, it completely solves overspeed control.

 Comparison of output curves

The following curves illustrate the comparison of variable pitch and fixed pitch turbine outputs. The wide output range of the variable pitch turbine is obvious.  But, letís look at that more practically and carefully.

Considering normal winds are usually less than 30 mph, you can see very clearly that variable pitch performance provides a consistent advantage over fixed pitch turbines under 30 mph. 

The surprise comes when the wind speed is greater than 30 mph. Variable pitch turbines do much better still by offering continuous output and control, no matter what the wind speed.  Neither gusts nor sustained winds pose any threat for the variable pitch wind turbine. The same can not be said for fixed pitch turbines.  Simply, they must shut down to avoid self destruction, thereby losing significant power, as shown. 

composite graph - W vs mph - merged - final

Comparison of output curves


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