Aleksei Isaev began work under Leonid Dushkin during World War II, on an experimental rocket-powered interceptor plane, the BI-1.

After abandoning the heavy, complex and undercooled German engine designs, Russia's principal engine designer Valentin Glushko turned to Isaev's innovations: thin-walled copper combustion chambers backed by steel support, anti-oscillation baffle to prevent chugging, and the flat injector plate with mixing-swirling injectors.

The latter was an enormous simplification of the "plumbing nightmare" of the V-2 engine, because it avoided the need for separate fuel lines to each sprayer.

Although his inventions influenced the design of Glushko's large engines, Isaev was better known for building efficient small rockets.

He designed a series of course-correction engines for Soviet planetary probes, including the KDU-414 used in Venera 1, Mars 1 up to Venera 8, the KTDU-425 used in later planetary probes, KTDU-5 used in the Soviet lunar landers Luna 4 to Luna 13.