MDR-3 (TsKB-11) by I.V.Chetverikov

16k b/w drawings from "History of aircraft construction in the USSR" by V.B.Shavrov, Vol.1 p.454

his large flying boat was included into plan of the TsKB naval section (Morskoj Otdel) under No11. Designers decided to use wing and some other parts from the TB-5 heavy bomber. In January 1931 the first in the country hydrochannel trials were performed on the MDR-3 scale maquette. Shape of the hull was found successful, what was proved lated during aircraft trials.
Assembly started in Spring 1931 and aircraft was ready in December same year. It was large shoulder-wing monoplane (with struts) and balance floats (3m3 each) placed relatively close to the hull. Four liquid-cooling engines were arranged in two tandems and installed on struts above the wing. Each pair had common water radiator under the front engine. Installation was very convenient for service purposes. Upper surface of central wing section was made of corrugated aluminum to allow to access engines. Hull was similar to that of ROM-2, but with additional step and external stringers.
Equipment of pilot's and navigator's cockpit, gun installations were same as on TB-5, with addition of specific naval equipment (anchor, rafts). Two 250kg bombs could be installed on fuselage hardpoints (between the wing struts).
In January 1932 aircraft was transported to Sevastopol Naval Base. Test flights started on January 13 by B.L.Bukhgolts and finished on March 25 same year. Aircraft was rejected...
MDR-3 had good seaworthiness, short takeoff run and decent for its class speed, but climb rate and ceiling were unacceptably poor. Partially it could be blamed on tandem installation of engines, but main trouble was poor aircraft airdynamic. Engine tandems were too close to the wing (specially the radiators). Numerous rivets with semi-spherical heads, other 'spiky' parts in the air flow, missing fairings on struts, external elements of the hull frame all together contributed to poor performance.
MDR-3 was transferred to A.N.Tupolev, who transformed it into MDR-4.

TB-5 TsKB-8


  • "History of aircraft construction in the USSR" by V.B.Shavrov, Vol.1 p.454-455;
  • ....
  • Technical data
    Type MDR-3, '11'
    Function Naval Reconnaissater
    Year 1932
    Crew 5?
    Engines 4*500/680hp BMW VI
    Length 21.9m
    Height ?m
    Wingspan 32.2m
    Wing area 153.0m2
    Empty weight 8928kg
    Loaded weight 13973kg
    Wing load 91.5kg/m2
    Power load 5.1kg/hp
    Speed at 0m 210km/h
    Landing Speed 110km/h
    Takeoff Roll 36sec
    Range 1600km
    Flight Endurance 8h
    Ceiling 2200m
    Fuel 3300kg
    Guns 8*7.63mm PV-1
    Bombs 2*250kg
    Created June 29, 1999
    by Alexandre Savine
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