Book excerpt: Aviation historians often dismiss the Polyikarpov I-16 because it did not fare well against its more modern adversaries in WWII. It was often referred to in the West by the disparaging nickname of Rata, the Russian word for rat! Nikolay Polyikarpov's I-16 was nevertheless an outstanding fighter in its day--among other things, because it was the world's first monoplane fighter with a retractable undercarriage. Its capabilities were demonstrated effectively during the Spanish Civil War and it was still in front line service when the German armed forces fell on the Soviet Union in 1941. This book details every variant of this diminutive fighter, including development aircraft and unbuilt projects. An account is also given of Polyikarpov's early monoplane fighters that presaged the I-16 and of the later designs that evolved from it. Details are given of all surviving examples including the six aircraft that were restored to airworthy condition in Russia in the 1990s.