Contrarotating propellers are two propellers rotating in opposite directions about the same shaft axis and usually driven by the same engine. Do not confuse them with counterrotating propellers which are propellers rotating in opposite directions, but on different shaft axes.
counterdirectional heterodirectional contradirectional corotating countermoving counterflowing antimetric cross counteroppositional contrariant
vortices twin screws rings propellers propeller ring beams vortex cells
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