 The Su @-@ 27M ( T @-@ 10S @-@ 70 ) prototype first flew on 28 June 1988 piloted by Sukhoi chief test pilot Oleg Tsoi . The first prototype differed slightly from later examples in : retaining standard Su @-@ 27 vertical stabilizers without the cropped top ; lacking a fire @-@ control system ; having a three @-@ tone grey / blue camouflage scheme , along with minor differences . Designated T10M @-@ 1 to T10M @-@ 10 , the first ten prototypes were built by Komsomolsk @-@ on @-@ Amur Aircraft Production Association ( KnAAPO ) in conjunction with Sukhoi ( as the Soviet military @-@ industrial structure separated the aircraft designer and manufacturer ) . They differed slightly , as four were converted from Su @-@ 27s , and the others were new @-@ builds . The second prototype started flying in January 1989 , while the third followed in mid @-@ 1992 . The prototypes were used to validate the canards and new flight @-@ control system . 
