Air Screws

By Xah Lee. Date:
The propeller of a anti-submarine warfare airplane the EP-3E Orion. Note the blade's attack angles are variable, and in this case turned flat.
800px-Hercules propeller
The propellers of a cargo aircraft Hercules. 1800×1322 Note the blade's attack angle are variable, and in this case turned very sharp.
A contra-rotating propellers of a modified P-51 Mustang fitted with a Rolls-Royce Griffon. Photo by Eric Gideon. image source

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