The general theory of blade screws including propellers, fans, helicopter screws, helicoidal pumps, turbo-motors, and different kinds of helicoidal blades
A 1920 technical treatise on blade screws, covering propellers, fans, helicopter rotors and helicoidal pumps, issued by a government aeronautical research body for engineers and designers. Its pictures are dense engineering drawings: grid-ruled graph sheets of blade geometry, a set of smooth curved charts, and side-on and plan views of helicoidal blade surfaces with reference lines and dimension marks, offering a designer precise technical linework and a sense of how screw blades were drafted.
