Russian VKS is lagging behind in Su-57 production. The backbone of the Russian aviation Su-35 will be modernized to Su-35SM. Here's what the upgrade entails.| Bulgarian Military Industry Review
The first variant was developed in the Soviet Union as early as the 1980s. The version, initially referred to as the Su-27M, had a revised airframe, duck wings, an enlarged radome for the N-011 radar and improved avionics.| Bulgarian Military Industry Review