By the mid-1940s the limitations of piston aero engines were becoming apparent. Every possible scheme to squeeze the last bit of power from the internal combustion engine was tried. One of the most successful innovations was the contra-rotating propeller arrangement whereby two sets of propellers driven by one engine and sharing a common axis are contra-rotated (with one set travelling clockwise and the other anticlockwise). (hushkit.net) 更多...
