This is Russian build engine for control line speed.
In English you would pronounce the name similar like Z-AST- CUM 2.5 cubic cm.
Produced not far from Moscow ( Ivanovo?). Very popular in Russia for those who don’t have ability build their own or buy ‘Rossi’ or ‘Nelson’.
Build to run on FAI fuel (no nitro). Produced for over 20 years. Pretty close to ‘Rossi’.
I had my first of them in 1982, I think. Yours looks a bit lighter ( less aluminum around exhaust) , but almost the same.