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Trisafe Single Axis Flight Control System

Report Number: AFFDL TR 65-89
Author(s): H. L. Ehlers, R. D. Blosser and H. O. Williams
Corporate Author: Autonetics Division of North American Aviation
Laboratory: Air Force Flight Dynamics Laboratory
Date of Publication: 1965-09
Pages: 132
Contract: AF 33(615)-1479
Project: 8225
Task: 822504
AD Number: AD0474100

The TRISAFE Single Axis Flight Control System developed for the Research and Technology Division of the Air Force consists of a deliverable controller and simulator with associated recorder. This equipment is to be used primarily as a laboratory demonstration model of a triple redundant, self-adaptive flight control system. The controller incorporates the Autonetics developed triple redundant, analog circuit technique called TRISAFE that represents nearly optimum in redundancy, efficiency and reliability. To compensate for the normal increase in size and weight due to the triple redundancy, the use of a square wave 400 cps carrier has been employed to reduce the number of components, and molecular integrated circuits are used to reduce the size of the components. A multi-layer circuit board is used to further reduce the weight and volume of the controller. The controller measures 3 x 9.7 x 12 inches and weighs approximately 6 pounds. Plug-in modular packaging is used for maintainability. The controller is based on the dynamics of a high performance tactical aircraft and provides stability augmentation for the pitch axis. To provide for optimum gain throughout the performance range of the aircraft, a self-adaptive system is used. Known as the dither-adaptive technique, it employs a low level test signal to measure the response of the airframe and adjusts the gain accordingly.

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