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