In order to tackle short fuel range, the MiG-21SMT (Sapfir Modernizirovannyy Toplivo, "Sapphire Modernized, Fuel Increased") version featured several upgrades including updated Sapfir radar and respective fire control system and most notably a large saddle tank. The "Hunchback" was awkward to fly and so unpopular with Soviet pilots that all MiG-21SMTs were rebuilt into the MiG-21ST variant starting from 1972, featuring the smaller and lighter saddle tank from the MiG-21bis

This Fishbed-K is easily recognised due to its enlarged spine hump. This made it harder fo fly and so this variant was unpopular with its pilots. Thus example is on display at this very friendly museum.