Editing Contra-rotating propellers (section)

===United States===
[[File:YB-35 42-13603 on the ramp.jpg|thumb|[[XB-35]] Flying Wing showing its quartet of pusher contra-rotating propellers. The option was later discarded due to severe vibration in flight and later changed to traditional single rotating propellers.]]
[[File:B-42 Mixmaster.jpg|thumb|[[Douglas XB-42 Mixmaster]] ]][[File:General Motors P-75 Eagle.jpg|thumb|General Motors P-75 Eagle]]

The United States worked with several prototypes, including the [[Northrop XB-35]], [[XB-42 Mixmaster]], the [[Douglas XTB2D Skypirate]], the [[Curtiss XBTC]], the [[A2J Super Savage]], the [[Boeing XF8B]], the [[XP-56 Black Bullet]], the [[Fisher P-75 Eagle]] and the [[tailsitter|tail-sitting]] [[Convair XFY]] "Pogo" and [[Lockheed XFV]] "Salmon" [[vertical takeoff and landing|VTOL]] fighters and the [[Hughes XF-11]] reconnaissance plane. The [[Convair R3Y Tradewind]] flying boat entered service with contra-rotating propellers. However, both piston-engined and [[turboprop]]-powered propeller-driven aircraft were reaching their zenith and new technological developments such as the advent of the pure [[turbojet]] and [[turbofan]] engines, both without propellers, meant that the designs were quickly eclipsed.

The US propeller manufacturer, [[Hamilton Standard]], bought a [[Fairey Gannet]] in 1983 to study the effects of counter rotation on propeller noise and blade vibratory stresses. The Gannet was particularly suitable because the independently-driven propellers provided a comparison between counter and single rotation.<ref>{{cite conference |pages=708–717 |title=Single rotation and counter rotation prop-fan propulsion system technologies |url=http://www.icas.org/ICAS_ARCHIVE/ICAS1984/ICAS-84-5.6.2.pdf |given1=B. S. |surname1=Gatzen |given2=C. N. |surname2=Reynolds |conference=Congress of the International Council of the Aeronautical Sciences |date=September 9–14, 1984 |location=–Toulouse, France |edition=14th |conference-url=http://www.icas.org/ICAS_ARCHIVE/ICAS1984/1984.html}}</ref>