Vladimir Panfilovich Yatsenko worked on Polikarpov’s team, then replaced Kochyerigin on DI-6 programme. His own effort was I-28 fighter (about 1 May 1939), many good features, including tight group of 2 x 20-mm and 2 x 7.7-mm; eventually accepted for production, halted February 1940 with 5 delivered.