Research, design and development, and manufacture of Soviet aircraft are performed by administratively separate organizations all under the central authority of the Ministry of Aviation Industry. Information flows link the separate organizations. Research institutes, which control the test facilities, provide design bureaus with handbooks of approved aerodynamic forms and structures. For the manufacturing plants, they list approved materials and manufacturing techniques. Requests for information are sent to the research institutes. The design process for a proposed new aircraft is competitive. Several design bureaus are asked to submit preprojects — paper designs turned out rather rapidly by small groups of experienced designers. Depending on the degree of advanced technology involved, one or more pre-projects are chosen for continued development. After flight tests, one prototype is selected for production. The emphasis on speed, competition, production, and the use of handbooks constrains the designers to work within a common, proven technical code and to rely on simplicity, commonality, and inheritance of design.