{HEAD ~ A propulsor system} is an assembly of individual propulsors that act in concert to form {TAIL ~ a substantially continuous control surface} that undulates in a working fluid 
{ HEAD ~ A propulsor system } is an assembly of individual propulsors that act in concert to form { TAIL ~ a substantially continuous control surface } that undulates in a working fluid
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH