Therefore, with the lateral articulated joints of blade 2 following a circular path, and {HEAD ~ its rear section} articulated {TAIL ~ joint} following an elliptical path, the desired effect is obtained in the form of cyclical changes in the blades pitch angle as it travels in the closed cylindrical path 
Therefore , with the lateral articulated joints of blade 2 following a circular path , and { HEAD ~ its rear section } articulated { TAIL ~ joint } following an elliptical path , the desired effect is obtained in the form of cyclical changes in the blades pitch angle as it travels in the closed cylindrical path
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH