Beginning in 1928, he worked at the Soviet Gas Dynamics Laboratory along with several other notable Soviet rocket scientists, and they developed rocket projectiles that used smokeless powder. This group was later merged with another rocketry organization to become the Jet Propulsion Research Institute (RNII). Langemak became the deputy director of the RNII. In 1936 this group completed the technical specifications for a rocket-glider.
By 1937, during the Great Purge, he was fired and arrested by the Soviet government, along with the RNII director Ivan Kleymenov and the engine designer Valentin Glushko, on trumped up charges.
Both Langemak and Kleimenov were tortured, sentenced to die in a mock trial, then executed. He is chiefly remembered for being the co-designer and directing the development of the unguided rockets which were to be used with such success in the Katyusha rocket launchers of World World War World War II The crater Langemak on the Moon is named in his honor.