
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.

The propellers of a cargo aircraft Hercules. ❐ 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. source