Using groups of {HEAD ~ helicoids} which alternately turn clockwise and {TAIL ~ counter clockwise} all gyroscopic forces, which appear when the structures are turned to follow changes in the direction of the flow, are internally balanced 
alternately turn
Using groups of { HEAD ~ helicoids } which alternately turn clockwise and { TAIL ~ counter clockwise } all gyroscopic forces , which appear when the structures are turned to follow changes in the direction of the flow , are internally balanced
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH REL REL OTH OTH TAIL 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