High Quality Content by WIKIPEDIA articles! A propeller is a type of fan that transmits power by converting rotational motion into thrust. A pressure difference is produced between the forward and rear surfaces of the airfoil-shaped blade, and a fluid (such as air or water) is accelerated behind the blade. Propeller dynamics can be modelled by both Bernoulli`s principle and Newton`s third law. A propeller is sometimes colloquially known as a screw.