  a fin is a thin component or appendage attached to a larger body or structure. fins typically function as foils that produce lift or thrust, or provide the ability to steer or stabilize motion while traveling in water, air, or other fluid media. fins are also used to increase surface areas for heat transfer purposes, or simply as ornamentation.fin oxford dictionary. retrieved 24 november 2012.fin merriam-webster dictionary. retrieved 24 november 2012. fins first evolved on fish as a means of locomotion. fish fins are used to generate thrust and control the subsequent motion. fish, and other aquatic animals such as cetaceans, actively propel and steer themselves with pectoral and tail fins. as they swim, they use other fins, such as dorsal and anal fins to achieve stability and refine their maneuvering.helfman g, collette bb, facey de and bowen bw (2009) "functional morphology of locomotion and feeding" chapter 8, pp. 101â116. in:the diversity of fishes: biology, john wiley & sons. isbn 9781444311907. ==generating thrust== foil shaped fins generate thrust when moved, the lift of the fin sets water or air in motion and pushes the fin in the opposite direction. aquatic animals get significant thrust by moving fins back and forth in water. often the tail fin is used, but some aquatic animals generate thrust from pectoral fins. fins can also generate thrust if they are rotated in air or water. turbines and propellers (and sometimes fans and pumps) use a number of rotating fins, also called foils, wings, arms or blades. propellers use the fins to translate torquing force to lateral thrust, thus propelling an aircraft or ship.carlton, john (2007) marine propellers and propulsion pages 1â28, butterworth-heinemann. isbn 9780750681506. turbines work in reverse, using the lift of the blades to generate torque and power from moving gases or water.soares, claire (2008) [http://books.google.co.nz/books?id=rtpzp1ycqbkc&printsec=frontcover&dq=rotating+turbine|turbines+propeller|propellers+fan|fans++pump|pumps+fin|fins+blade|blades&hl=en&sa=x&ei=-fywu
Animal_anatomy Rocketry Watercraft_components