Editing Contra-rotating (section)

==Aircraft propulsion and lift==

{{Main|Contra-rotating propellers}}
While several nations experimented with contra-rotating propellers in aircraft, only the United Kingdom and Soviet Union produced them in large numbers. The U.S. worked with several prototypes, including the [[tailsitter|tail-sitting]] [[Convair XFY]] and [[Lockheed XFV]] "Pogo" [[vertical takeoff and landing|VTOL]] fighters, but [[jet engine]] technology was advancing rapidly and the designs were deemed unnecessary.

Some helicopters use contra-rotating [[coaxial rotors]] mounted one above the other.  The [[H-43 Huskie]] helicopter uses non-coaxial [[intermeshing rotors]] turning in opposite directions.

The [[F-35 Lightning II#F-35B|F-35B]] variant of the [[F-35 Lightning II]] strike fighter uses a lift fan with contra-rotating blades.