Parametric aeroelastic modeling, maneuver loads analysis using CFD methods and structural design of a fighter aircraft

Abstract

The DLR Future Fighter Demonstrator (FFD) is a highly agile, two-seated aircraft with twin-engines equipped, a reheat and a design flight speed extending into the supersonic regime (up to Ma=2.0). Based on a given conceptual design, the presented work focuses on the aeroelastic modeling, including structures, masses and aerodynamics. Using the models, a comprehensive loads analysis with 688 maneuver load cases, covering the whole flight envelope, is performed. Comparing the results obtained from aerodynamic panel methods (VLM and ZONA51) with higher fidelity results obtained from CFD, the necessity of CFD based maneuver loads analysis in preliminary design of such fighter configuration is shown, as it leads to physically different as well as higher loads. The rigorous application of CFD is a heavy burden during the preliminary design, but this work demonstrates that it is doable as of today. Finally, the model is subject to structural optimization, demonstrating that the differences in loads result in a heavier primary structural net mass with ≈ 3.3t for the approach based on aerodynamic panel methods and ≈ 4.1t for the CFD based approach. Because all remaining models are unchanged, this difference in mass can be clearly attributed to the physical differences in the flow solutions obtained from the panel methods and CFD.