SUMMARY OF AVT-161, LESSONS LEARNED AND THE WAY AHEAD

Abstract

The NATO RTO AVT-161 Task Group was established to determine the ability of computational methods to accurately predict both static and dynamic stability of air and sea vehicles. The overall approach is to identify major synergy in terms of physical modeling, fluid vertical structures, or transition effects. The Task Group joins three major avenues of interest: the experimental part to provide highly accurate static and dynamic validation data; the CFD community who, is trying to predict the steady state and dynamic behavior of the target configurations; and the controls group which is analyzing the experimental and numerical data. The objective of the group is to provide best practice procedures to predict the static and dynamic behavior especially for configurations with vortex-dominated flow fields where non-linear effects have a significant impact. These non-linear regimes are the areas where typical linear prediction methods fail, or where wind tunnel data are only available for non-full-scale flight flow regimes. The AVT-161 Air Vehicle Task Group pursued a comprehensive research program designed to investigate the ability of computational methods to predict stability and control characteristics of a generic unmanned combat air vehicle and the X-31 experimental aircraft has been undertaken. The integrated approach to simulating static and dynamic stability characteristics was performed by the Air Vehicle Task Group AVT-161. The UCAV, named SACCON (Stability and Control Configuration), and the X-31 configuration was the subject of an intensive computational and experimental study. The stability characteristics of the vehicles were evaluated via a highly integrated approach, where CFD and experimental results were used in a parallel and collaborative fashion. The results show that computational methods have made great strides in predicting static and dynamic stability characteristics, but several key issues need to be resolved before efficient, affordable, and reliable predictions are available. The AVT-161 Sea Vehicle Task Group compiled and documented extensive model test data for validation of computational tools, i.e. the prediction capabilities of Systems-Based (SB), Potential Flow (PF), and URANS CFD ship maneuvering simulation methods were investigated through systematic quantitative comparisons and validation against experimental data for course keeping in calm water and waves for 5415M and maneuvering in shallow calm water for low-speed (KVLCC2) and high-speed (Delft Catamaran). The activities of the AVT-161 Sea Vehicle Task Group led to a Specialists’ Meeting, AVT-189, and a new Exploratory Team proposal, ET-118. Also the fundamental issues were used to help form foundation of AVT-183. Tremendous knowledge is achieved due to expertise sharing among participating Nations. The overall results of the AVT-161 Sea Vehicle Task Group are documented in over 12 journal articles and 38 conference papers along with the present RTO final report.