Coupled CFD/CSD predictions of semi-span XV-15

This work focuses on a number of aspects which are progress toward the goal of tightly coupled CFD/CSD analysis for whirl-flutter prediction. First, the Rotorcraft Comprehensive Analysis System (RCAS) analysis is used to carry out traditional linear stability analysis. Next, a method of using trim springs to artificially increase the stability of the model during the RCAS trim procedure is presented. Finally, this method is used to complete time integrated transient analysis to identify the dominant modes and associated damping at a sweep of wind speeds. Differences between linear stability analysis and time domain analysis are presented. Finally, new capabilities introduced to the CREATEAV software Helios are used to present a first fully-elastic semi-span model of the XV-15 using the high-fidelity aerodynamics in Helios coupled to RCAS. Baseline loose coupled results are given. A focus is placed on developing modeling procedures which will allow for CFD/CSD tight-coupling for whirl-flutter predictions rather than correlating against previous results.