Aerospace Instrument-Making Annotation << Back To the problem of determining optimal time of a turn of a spacecraft controled by powered gyroscopes Levskii М.V. The questions of the correct choosing the time of optimal spacecraft turn from any initial position into prescribed final angular position are investigated. The case, when a turn is executed with minimum magnitude of spacecraft angular momentum, is considered. Optimal control is in the class of regular motions. It is supposed that dynamics of spacecraft rotation during a turn corresponds to the known method of control [1] which includes as much as possible fast acceleration of a spacecraft, rotation with the constant module of angular momentum and as much as possible fast cancellation of angular mo-mentum. The formalized equations are presented, and computational expressions for de-termination of optimal duration of reorientation maneuver are obtained for known mass-inertial characteristics of a spacecraft if attitude control is carried out using inertial actuators (by system of control moment gyroscopes, gyrodynes). The condition for definition of the moment of the beginning of the braking which uses current parametres of motion (information on angular position of a spacecraft and measurements of angular velocity) was given, it considerably increases accuracy of spacecraft move into a required position. This paper adds the researches [1, 2]. Key words: spacecraft, optimality, control, attitude, powered gyroscopes. Contacts: E-mail: dp940@mail.ru Pp. 21-30.