The Sh-90 (Shturmovik, Attack Aircraft) project intended to develop an attack aircraft to replace the Su-25. The main entries consisted of modified trainer designs from MiG and Yakovlev, and an unusual two-cockpit design from Sukhoi. The project was later cancelled due to the emergence of modernized Su-25 variants, such as the Su-25T, Su-25TM (Su-39) and Su-25KM.
Read more about this topic: Post-PFI Soviet/Russian Aircraft Projects