![]() ![]() ![]() Later, Leonardo da Vinci adopted the screw principle to drive his theoretical helicopter, sketches of which involved a large canvas screw overhead. A flying toy, the bamboo-copter, was enjoyed in China beginning around 320 AD. It was probably an application of spiral movement in space (spirals were a special study of Archimedes) to a hollow segmented water-wheel used for irrigation by Egyptians for centuries. The origin of the screw propeller starts at least as early as Archimedes (c. 287 – c. 212 BC), who used a screw to lift water for irrigation and bailing boats, so famously that it became known as Archimedes' screw. ![]() Propellers can have a single blade, but in practice there are nearly always more than one so as to balance the forces involved. The innovation introduced with the screw propeller was the extension of that arc through more than 360° by attaching the blade to a rotating shaft. In sculling, a single blade is moved through an arc, from side to side taking care to keep presenting the blade to the water at the effective angle. The principle employed in using a screw propeller is derived from sculling.
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