 On 28 December 2012 , Sukhoi delivered a batch of six serial production Su @-@ 35S fighters to the VVS . Defence Ministry officials accepted the aircraft at KnAAPO 's manufacturing plant in Komsomolsk @-@ on @-@ Amur , Russia . Five of the six Su @-@ 35S delivered in December went to the Gromov Flight Research Institute , where in February 2013 an eighteen @-@ month programme began to test the Su @-@ 35 's ability to conduct highly maneuverable short @-@ range combat . The programme consists of three components , which are dogfights ; the use of weapons and the ability to evade enemy fire ; and the ability to destroy helicopters and unmanned aerial vehicles . State @-@ acceptance trials would conclude in 2015 , by which time a second 48 @-@ aircraft order is expected to have been signed with the VVS . Another 12 Su @-@ 35S fighters were delivered in 2013 . 
