The electric Orbiter

Abstract

An electromechanical actuator (EMA) system is described and compared to the baseline hydraulic system for the Shuttle. Employment of the EMA depends on minimal changes in the avionics and software, no change in the vehicle configuration, and satisfaction of performance requirements. There are 13 actuators on the Shuttle, all subject to the standard four (redundant) command channels. The actuator control units, motor control units, mechanical actuators, and motors are discussed, and system and sizing requirements are outlined. The effects on the displays and controls, the environmental control system, electrical power and distribution, and software are mentioned, and projected to be minimal. It is noted that although the EMA total systems' costs have not been calculated, substantial weight, turnaround time, and power savings are available by use of EMA.