 By 1943, the La-5 had become a mainstay of the Soviet Air Forces, yet both its head designer, Semyon Lavochkin, as well as the engineers at the Central Aerohydrodynamics Institute (Russian: TsAGI), felt that it could be improved upon. TsAGI refined earlier studies of aerodynamic improvements to the La-5 airframe in mid-1943 and modified La-5FN c / n 39210206 to evaluate the changes. These included complete sealing of the engine cowling, rearrangement of the wing center section to accommodate the oil cooler and the relocation of the engine air intake from the top of the cowling to the bottom to improve the pilot's view.
