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Title: Integrated Modeling and Simulation for Shipboard Aircraft Operations

Author(s): Colin Wilkinson

Abstract: This presentation is based on Chapter 7 of the NATO AVT-217 Task Group Report on “Modeling and Simulation of the Effects of Ship Design on Helicopter Launch and Recovery”. Ships have traditionally been designed with few if any requirements relating to the flying aircraft. Instead of designing the ship to maximize the ship-aircraft operating envelope, the ship is built and whatever wind and ship motion limits are encountered in subsequent at-sea testing are accepted as the boundary of operation. A primary reason for not specifying the envelope prior to the ship being built is the lack of analysis capability to estimate the likely impact of the ship design on aircraft performance. The ability to apply integrated ship-aircraft simulation, both computational and experimental, to confidently predict the boundary of safe operations would provide a valuable risk reduction tool for the ship designer and potentially facilitate ships to be designed to maximize the operational envelope. Such a capability would also help reduce the amount of flight testing required to develop the envelope, as well as contribute to aircraft design in the realm of gust rejection and flight control technology development. The presentation will include the following key points: 1. Ship-aircraft operating envelopes delineate the boundaries of safe launch and recovery in terms of wind condition and ship motion. 2. Currently, the envelopes are determined during at-sea testing, which is expensive and potentially dangerous. 3. Integrated modeling and simulation, where the aircraft is immersed in a representative shipboard environment, can estimate the operating envelope prior to the ship being built. 4. Estimating the envelope during the ship (or aircraft) design phase could reduce the potential for costly redesigns and help maximize the operational capability of the aircraft. 5. Flight simulation methods and experimental methods are available for this purpose. 6. Flight simulation methods include real-time piloted simulation, as well as non-real-time desktop simulation and simulation of Unmanned Air Vehicles. Experimental methods include installing aircraft models in wind and water tunnels, as well as land-based flight testing. 7. Additional validation is necessary to provide confidence that the envelopes predicted by the simulation methods are sufficiently accurate to be accepted by the test community. The presentation will include descriptions of the various flight simulation and experimental methods, including limitations and their current status of validation. Conclusions and recommendations will include: 1. Integrated modeling and simulation provides the ship designer with the potential capability to evaluate a new ship design in terms of its impact on the aircraft and pilot workload, including the effects of airwake and ship motion. 2. Many different types of modeling and simulation exist. These methods are at varying stages of development and validation. 3. Although the current simulation capabilities are not presently validated to the extent that they can be used to confidently predict operating envelopes, the lessons learned during their development contribute valuable information to the overall understanding of what metrics and design features are most important for aircraft operations 4. Integrated modeling and simulation can be used as a risk reduction tool for ship design by identifying potential airwake problems prior to ship build. Currently, comparative analysis of a new platform compared to an existing platform can be used to estimate whether an improvement to the airwake has been achieved with a certain design change. 5. Currently, the available tools can inform the design process when used as part of an iterative design cycle. No general design guidance that can be applied universally to ship design is currently available.