With the departure of Richard, KB MOS was transferred to TsKB (Tsentrahl'noye konstrooktorskoye byuro - central construction bureau) TsAGI (Tsentrahl'nyy Aerodinamicheskiy i Ghidrodinamicheskiy Institoot- central aerodynamics and hydrodynamics institute) in the name of N. Ye.
In 1931 Chyetverikov had given a proposal for a submarine-launched folding flying boat to the head of TsKB (Tsentrahl'noye Konstrooktorskoye byuro - central construction bureau) but nothing was heard for two years until the NII (Naoochno-Issledovatel'skiy Institoot – scientific test institute) placed an order for two prototypes of the SPL.
Polikarpov and the others were moved to Central Design Bureau 39 (TsKB-39) to complete the I-5 project.