United States Contra-rotating propellers

xb-35 flying wing shown quartet of pusher contra-rotating propellers. option later discarded due severe vibration in flight , later changed traditional single rotating propeller.



douglas xb-42 mixmaster



general motors p-75 eagle

the u.s. worked several prototypes, including northrop xb-35, xb-42 mixmaster, douglas xtb2d skypirate, curtiss xbtc, a2j super savage, boeing xf8b, xp-56 black bullet, fisher p-75 eagle , tail-sitting convair xfy pogo , lockheed xfv salmon vtol fighters , hughes xf-11 reconnaissance plane. however, both piston-engined , turboprop-powered propeller-driven aircraft reaching zenith , new technological developments such advent of pure turbojet , turbofan engines, both without propellers, meant designs eclipsed.