Bratukhin G-4
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The first Soviet helicopter with the engines purposely designed, with cooling fan and front gearbox giving vertical and lateral outputs for the rotor and for transverse coupling shaft. The transmission was provided with centrifugal clutch; overall drive ratio 0.27 (540 rotor rpm). The main rotor had an inbuilt twist of 6 deg 45 min along the blade, and blade spar were extruded instead of folded sheet. Two prototypes were built, the first flown in October 1947 by M.K.Baikalov and second a month later. In January 1948 the first G-4 was damaged in the course of autorotational descents and deadstick landings typically at 12 m/s descent along 15.5-16 deg glide path.
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