The Su-57 airframe isn't based on any Soviet era airframe.Has Russian air force developed any newer aircraft that weren't based on the flanker, fulcrum, or foxbat airframes? Is there any reason why all their new designs are based on these platforms?
The Su-25 has an empty weight of 10 tons and max takeoff weight of 19 tons. Engine power of 88 kN. The Yak-130 has an empty weight of 5 tons and a max takeoff weight of 7 tons. Engine power of 48 kN. It is simply not possible to replace the Su-25 with the Yak-130.Wasn't the plan the replace the Su-25 with a Yak-130 variant scrapped several years ago?