 The improved variant , the development of which began in the early 1980s , featured a host of changes in aerodynamics , avionics , powerplants , and construction methods , as well as increasing payload capacity . High @-@ strength composites and Aluminium @-@ lithium alloys were used to reduce weight and boost internal fuel volume . One of the distinguishing features of this early design were the canards , which improved airflow over the wings , eliminating buffeting and allowing the aircraft to fly at an angle of attack of 120 ° . These canards were governed by a new digital fly @-@ by @-@ wire flight @-@ control system . The aircraft was fitted with the Luylka AL @-@ 31FM ( AL @-@ 35F ) turbofan engine which is larger , more reliable and , with a thrust of 125 kN ( 28 @,@ 200 lbf ) , more powerful than those found on the Su @-@ 27 . 
