Su-4
An upgraded version, originally intended for the Urmin M-90 engine with 1,565 kW (2,100 hp), but later fitted with a Shvetsov M-82 (some Su-2s were also fitted with M-82). Due to a shortage of duralumin, the structural elements of the wings were made of wood with plywood skin. Wing armament was changed from four 7.62 mm ShKAS machine guns to two 12.7 mm Berezin UB machine guns.[1] One prototype was built and tested, but this improved version was not placed into production.
SU- 6
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Guns:
- 2 × 37 mm (1.46 in) Nudelman-Suranov NS-37 autocannon in the wings (90 rounds per gun, 180 rounds total)
- 2 × 7.62 mm (0.30 in) ShKAS machine guns in the wings (1,400 rounds per gun, 2,800 rounds total)
- 1 × 12.7 mm (0.50 in) Berezin UBT machine gun in rear turret with 196 rounds
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Rockets: 10x RS-132 rockets
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Bombs: Up to 400 kg (880 lb) of bombs