Among several government projects of 1930s, most important aircraft to fly was Pionir monoplane for prone-pilot research, with 2 x 55-hp Mikron III, designed by Major Dragoljub at Beslin 1940. This was scaled up into Type 451, 2 x 160-hp Minor 6-III, built by Ikarus and flown 1951. This again modified into 451M light twin-jet. Resurrected industry 1946-60 wholly nationalized undertaking, though using facilities of former Ikarus, Rogozarsky and Zmaj, most important type being S-49 fighter based on Yak-3. Other types 213 and 522 piston-engined advanced trainers, 214 crew-trainer/transport and 452 baby twin-jet.