The following information is copied from a patent from US Patent Office
Patent number:US 7,344,353 B2
Mar. 18, 2008
Helical wind turbine features:
[1] The turbine contains 2 or 3 blades
[2] Commonly used number of blades 2-10
[3] Preferable number of blades 3-5
[4] Non-linear portion is in the form of helix
[5] Each blade and/or the rotor section as a whole is rotationally balanced so minimal vibration is encountered
[6] In a preferred embodiment the helical blades overlap the central vertical axis so as to prevent wind from passing through the center of the rotor
[7] Non-linear portion provides lifting force to the rotor
[8] Each non-linear blade portion is preferably oriented so that the wind will impact the blade on the radially inward and downwards facing
[9] This non-linear configuration reduces the effective rotation weight
[10] Also the rotor section rotation direction and the lift direction can be adjusted by reversing the blade construction or orientation
The following information is from my point of view:
From my point of view at constant wind speed and for profile rotation of 180 or 360 degrees compared with Savonius:
[1] I think also this turbine will rotate with constant angular speed without the need of inertia [kinetic energy storage].
[2] Bending stress on the shaft cross section will be extremely reduced
[3] Fatigue on the shaft will be eliminated due to uniform torque
[4] Power output will be uniform [at least this is useful in testing]
