is not centre supported in order to increase the efficiency of transversal turbines.
Transversal turbines are known to equip preferably three straight rotor blades, for example the H-rotor design having blades extending parallel to the axis of turbine rotation. It is further known that a centrifugal force arises due to the rotation, acting on the turbine mass and directed outwards at a right angle to the axis of rotation. Thus, the centrifugal force vector adds to the lifting force vector on the rotor blades; composing an additional radial force vector on the rotor blades at the downstream, leeward and upstream passages, but a reversed radial force vector windward. Thus, the resulting pulsating force vector reaches its maximum at leeward and minimum at windward; which difference increases the risk ofmaterial fatigue, critical vibration resonance modes and undesired noise from the turbine rotation. Rotors provided with straight rotor blades exhibit these design challenges which have to be overcome at the design of attachments to the rotor blades. It is further known that transversal turbines having three straight rotor blades cannot start by themselves at low fluid velocities, but by the generator; while helical rotor blades are easier to start. Rotor blades of helical shape are known, amongst other from CA 2674997 which describes a wind turbine having helical rotor blades arranged vertically and attached directly at multiple locations to the hub on the axis of the turbine. Also, in WO2120153813(A1) a water turbine is described in analogy with the said Darreus turbine NL19181 but provided with multiple rotor