. . . "1"^^ . "Polikarpov DI-1 (also known as 2I-N1, Russian: \u041F\u043E\u043B\u0438\u043A\u0430\u0440\u043F\u043E\u0432 \u0414\u0418-1 (2\u0418-\u041D1)) was a prototype Soviet two-seat fighter designed during the 1920s. The sole prototype built crashed on its ninth flight, due to manufacturing defects, and the program was cancelled."@en .