Design and Test of a Hydra-Optic Flight Control Actuation System (HOFCAS) Concept

This report describes the development, testing and demonstration of a Hydra-Optic Flight Control Actuation System HOFCAS suitable for the actuation tasks of a Digital Fly-By-Wire flight control system. HOFCAS offers a realistic, cost effective approach to reducing the susceptibility of aircraft fly-by-wire systems to EMP, EMI, RFI, lightning, etc. By removing the conventional wiring to the actuation areas of an aircraft, the concept eliminates the opportunity for electromagnetic hazards to enter the system. The HOFCAS concept provides a direct drive, hydraulically powered surface actuation system that provides immunity to electromagnetic radiation. The direct drive actuator, developed in a previous multiphase Navy Advanced Flight Control Actuation System AFCAS program, uses an electrical torque motor to power a single stage hydraulic valve for control of the actuator. A hydraulically powered alternator supplies the electrical power needed to operate the torque motor. The actuator command signal is supplied by a fiber optic link. The HOFCAS was configured to operate the directional control system in a T-2C aircraft. The AFCAS program demonstrated direct digital control of a surface actuator, and the HOFCAS extends this technology to demonstrate that conventional interconnecting electrical wiring to the surface actuators can be eliminated.