Validation of Methodology for Estimating Aircraft Unsteady Aerodynamic Parameters from Dynamic Wind Tunnel Tests

TLDR

Flight dynamics requires accurate aerodynamic models, and although a wide‑band input methodology for estimating unsteady aircraft aerodynamics was previously developed, advanced test facilities were lacking for full validation. The study aims to develop a general nonlinear unsteady aerodynamic model and to validate it using advanced testing techniques at NASA Langley. The model retains static and rotary dynamic terms while replacing acceleration terms with general indicial functions, and the validation employed advanced wind‑tunnel tests with wide‑band, forced oscillation, coning, and ramp inputs. The validation experiments produced results from static, conventional forced oscillation, wide‑band forced oscillation, oscillatory coning, and ramp tests, demonstrating the feasibility of the methodology.

Abstract

A basic problem in flight dynamics is the mathematical formulation of the aerodynamic model for aircraft. This study is part of an ongoing effort at NASA Langley to develop a more general formulation of the aerodynamic model for aircraft that includes nonlinear unsteady aerodynamics and to develop appropriate test techniques that facilitate identification of these models. A methodology for modeling and testing using wide-band inputs to estimate the unsteady form of the aircraft aerodynamic model was developed previously but advanced test facilities were not available at that time to allow complete validation of the methodology. The new model formulation retained the conventional static and rotary dynamic terms but replaced conventional acceleration terms with more general indicial functions. In this study advanced testing techniques were utilized to validate the new methodology for modeling. Results of static, conventional forced oscillation, wide-band forced oscillation, oscillatory coning, and ramp tests are presented.