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This paper presents the results of an investigation to improve design/analysis techniques for aircraft hydraulic systems. A design/analysis tool was developed by integrating control-surface commands and loads obtained from Aircraft Dynamic Simulator Software (ADSS) with an enhanced version of the HYdraulic TRansient ANalysis (HYTRAN) program. Control-surface commands and loads from an ADSS simulation of a selected maneuver were used as dynamic input to the HYTRAN program so that the hydraulic system response could be predicted throughout the maneuver. Predicted hydraulic system pressures and control-surface positions from the HYTRAN simulation of the maneuver were compared to flight-test data and were found to be in excellent agreement. The successful coalescence of the two independent software programs gives engineers a concurrent design/analysis tool that can be used to optimize hydraulic system designs during the very early stages of design.

An F-16 Environmental Control System (ECS) computer model was developed to assist engineers with the design and development of ECS control algorithms. This model consists of many dynamic component modules (ducts, valves, heat exchangers, compressor, etc.). The accuracy of this analysis tool was verified by comparing model results to F-16 ECS test-stand and test-aircraft data - the verification results are in excellent agreement. Presented in this paper are modeling techniques, model descriptions, verification results, discussion of test-stand data reduction and comparison, and discussion of the comparison with flight-test data. Our F-16 ECS model is a viable and accurate simulation tool for concurrent analysis and design of environmental control systems.

The HYdraulic TRansient ANalysis (HYTRAN) program has under gone extensive revisions that correct and enhance the program to meet the needs of those analyzing and/or designing aerospace hydraulic systems. Presented in this paper are a discussion of the revisions, a detailed explanation for the changes, and evidence from flight-test data that the improved HYTRAN program can meet the needs of the aerospace industry. The revisions affect all aspects of the HYTRAN program: steady-state analysis, transient analyses, hydraulic component models, and overall program improvements. The effects of these revisions on hydraulic analyses have been to 1) correct previous steady-state and transient solution errors, 2) reduce user handling time, 3) increase computational efficiency, and 4) improve HYTRAN's hydraulic component library.