 The first variant was designed during the 1980s , when Sukhoi sought to upgrade its high @-@ performance Su @-@ 27 , and was initially known as the Su @-@ 27M . Later re @-@ designated Su @-@ 35 , this derivative incorporated aerodynamic refinements with increased manoeuvrability , enhanced avionics , longer range , and more powerful engines . The first Su @-@ 35 prototype , converted from a Su @-@ 27 , made its maiden flight in June 1988 . More than a dozen of these were built , some of which were used by the Russian Knights aerobatic demonstration team . The first Su @-@ 35 design was later modified into the Su @-@ 37 , which possessed thrust vectoring engines and was used as a technology demonstrator . A sole Su @-@ 35UB two @-@ seat trainer was built in the late 1990s that strongly resembled the Su @-@ 30MK family . 
