Growing military interest in this new technology caused GIRD to be merged with the Gas Dynamics Laboratory (GDL) at Leningrad in 1933 to create the Jet Propulsion Research Institute (RNII), headed up by the military engineer Ivan Kleimenov and containing a number of enthusiastic proponents of space travel, including Valentin Glushko. In 1932 Korolev began working on GRID-6, experimenting on the idea of Jet Fighters. The earliest models were made in the same year, only to be fully operational and doing its first manned flight in year 1940. Korolev became the Deputy Chief of the institute, where he supervised development of cruise missiles and a crewed rocket-powered glider. "Rocket Flight in Stratosphere" was published by Korolev in 1934.