 In 2003 , Sukhoi embarked on a second modernization of the Su @-@ 27 to produce what the company calls a 4 + + generation fighter that would bridge the gap between legacy fighters and the upcoming fifth @-@ generation Sukhoi PAK FA . This derivative , while omitting the canards and air brake , incorporates a reinforced airframe , improved avionics and radar , thrust @-@ vectoring engines , and a reduced frontal radar signature . In 2008 the revamped variant , erroneously named the Su @-@ 35BM in the media , began its flight test programme that would involve four prototypes , one of which was lost in 2009 . 
