{HEAD ~ Each propulsor} is driven and configured by {TAIL ~ computer controlled actuators} so that the control surface undulates in various wave forms 
{ HEAD ~ Each propulsor } is driven and configured by { TAIL ~ computer controlled actuators } so that the control surface undulates in various wave forms
HEAD HEAD HEAD HEAD HEAD HEAD REL OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH