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The objective of this program was to investigate means by which the reliability of flight control stability augmentation sensors could be improved by the use of redundancy, preferably at an elemental level. The investigation did not uncover any approach involving redundant elements that promised a significant reliability improvement. Rate gyro failures, as opposed to catastrophic failures, are largely of a drift nature. The use of suspension spring stress rather than gimbal position as an output is suggested as a means of reducing null shift errors. Further, sensors should be applied in redundant sets and the median signal selected by means of any of several voter circuits to accomplish that end. A production rate gyro was modified to include semiconductor strain gages on the suspension spring. Evaluation data taken on this gyro and recommended design features for a new gyro are included. (Author)

The objective of this program was to develop means to improve the reliability of flight control nonelectronic components with a minimum weight penalty. A survey of the published field failure data was accomplished and the flight control servo actuator was selected as the component for detailed study. A number of approaches to the mechanical were evaluated and the principle of Hammock netting was selected as the best means of providing redundancy at the element level in this class of actuators. A breadboard model incorporating four specially designed single stage servo valves and a non-redundant ram was designed and evaluated under normal conditions and with simulated faults. With the ram at rest, a hardover fault in one valve causes a transient ram excursion of about 2 percent of full travel. A valve failure to null reduces the actuator bandwidth to about 50 percent of the degraded bandwidth. The design will tolerate one fault in any valve and 40 percent of the combinations of two faulted valves. (Author)

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This archival material has been provided for educational purposes. Ball State University Libraries recognizes that some historic items may include offensive content. Our statement regarding objectionable content is available at: https://dmr.bsu.edu/digital/about