I would like information on the mounting of the OP-1 gunsight to early I-16s. The drawings I have of these aircraft in “Polikarpov I-16, The History of a Revolutionary Aircraft”, show a curved bracket at the front of the gunsight and what appears to be a cord running along the gunsight’s bottom to the canopy. Was this bracket the mounting? If so, it seems to be a vibration prone mounting. Was the cord used to open the cover of the gunsight or a means to pull the forward opening canopy forward? How and where did this cord terminat in the cockpit?