Designation from Avtozhir (autogyro), decree by NII VVS 1932 for all-Soviet autogyro, and preparations for production organized forthwith for use as military trainer and observation machine. Design led by N.K.Skrzhinskii using known Cierva technology, regarded as minimal risk. Structure similar to 2-EA but single fin, more power, dual controls. First flight 6 Nov 1932, second flight three days later resulted in unexplained rotor vibration and loss of lift, with heavy impact on ground despite maximum power. Production had begun and frantic research with different rotors eventually yielded satisfactory machine, passing NII tests late 1933. Ten delivered 1934 (possibly a few more later) and served as trainers and in field manoeuvres.
Bill Gunston "The Osprey's Encyclopedia of Russian Aircraft", 2000
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Technical data for A-4
Engine: 1 x M-26, rotor diameter: 13.0m, span: 6.7m, length: 7.2m, weight empty: 1065kg, fuel+oil: 95+20kg, weight loaded: 1365kg, max speed: 176km/h, min speed: 50km/h, ceiling: 4100m, range: 185km, take-off run: 70-100m, landing run: 3-10m