In the first nine hours of the German invasion of Russia on June 22, 1941, the Soviet Union admittedly lost over 1,200 aircraft. After a week, 90% of Soviet front line air power had been wiped out. But in the next five years, the Soviet Union secretly developed a massive air force, literally moving its factories on trains out of the path of charging German soldiers. So secrative were the Soviets that it wasn't until the 1960's that details about the Soviet aircraft from WW2 were actually learned. Much information about old Soviet fighters is still unknown to the world today.
Selected Soviet Aircraft