FABRICATION AND FUNCTIONAL TEST OF FLIGHTWORTHY FLUIDIC YAW DAMPER

The objective of the program was to design, fabricate, and perform acceptance tests on a flightworthy fluidic yaw damper system and to provide support during flight evaluation of the system. Control-system characteristics were optimized for the UH-1 series helicopters. This program incorporated significant improvements in the areas of component design, high-pass circuit simplification, noise reduction, and fabrication techniques. Temperature compensation studies illustrated a technique for maintaining a relatively constant rate-sensor scale factor over a wide range of fluid temperatures. Flightworthiness testing demonstrated that the system provided the required transfer function and was suitable for flight test. The flight test not reported in this document confirmed that the system was suitable for the helicopter environments and that it would increase the vehicle directional damping ratio from 0.3 to 0.6. Post-flight tests in the laboratory determined the bench performance of the system under several special conditions to which the system had been adjusted during the flight test. The program demonstrated that fluidic systems operating with hydraulic fluid can accurately provide simple control functions. Consistent and trouble-free performance obtained during this development indicates that fluidic systems should be considered for applications which require similar functions.