The IV-series big submarines were designed to serve as an underwater support to groups of battleships during their long-range operations. They had to follow battle groups at high speed (22-23 knots) surfaced and to engage attacking hostiles submerged. IV type submarines had a high-speed adapted external hull and rather heavy artillery. The concept was ready in October 1930.

The attempt to meet this technical requirements cannot be recognized successful. Small crush depth, very long time of coming underwater, bad manoeuvrability submerged at low speeds together with torpedo tubes usage limitations prevented treating these subs to be real battle ships.

Pravda, Zvezda and Iskra were used as training boats before the war but, nevertheless, all three were used in WWII operations as transport boats.