Fidelity Off Helicoptter Real-Time Simulatiion Models

GARTEUR (Group for Aeronautical Research and Technology in Europe) has engaged the rotorcraft industry and research laboratories on the topic of helicopter modelling for flight mechanics and handling qualities for a number of years, with a focus chiefly on developing an improved understanding of the fidelity requirements in research, design and development. The most recent of these initiatives, GARTEUR Action Group HC-AG12, has refocussed on real-time simulation models for flight simulators. This Group is addressing several questions. For example, what is the sensitivity of fidelity to modelling errors? Are the tolerances set in the (JAR-STD) standard fine enough that they lead to only minor changes in (ADS-33) handling qualities? If the physical models do not satisfy the tolerances, what tuning is acceptable and what is the tuning process? What is the effect of modelling fidelity on the overall pilot control strategy? The work of the AG in addressing these questions is described in this paper with examples given from recent Industry experience of qualifying a flight simulator to the JAR-STD, together with various sensitivity studies into the suitability of the JAR tolerances. While it is accepted that the new standard provides a substantial basis for quantifying fidelity, the work has exposed many gaps due to lack of supporting data on the one hand and limited qualification experience on the other, and new measures for overall system fidelity need to be included to support the pilot assessments.