A High Performance Aircraft Wind Tunnel Test Using Response Surface Methodologies

Abstract

A Response Surface Methodology (RSM) approach to wind tunnel testing of high performance aircraft is being investigated at the Langley Full-Scale Tunnel (LFST). In an effort to better characterize an aircraft's aerodynamic behavior as a function of attitude and control inputs, and also decrease testing time required, an exploratory study was completed using RSM on a 19 percent scale modified X-31 model. The X-31 model was chosen based on its non-linear aerodynamic behavior at high angle of attack that is representative of modern fighter design and a substantial pre-esisting data base. A five-level nested fractional factorial design, augmented with center points and axial points, produced regression models including pure cubic terms for the characteristic aerodynamic forces and moments over a cuboidal design space as a function of model attitude and control surface inputs. Model adequacy and uncertainty levels were described using robust statistical methods inherent to RSM practice. Comparisons to baseline data and sample lateral-directional and longitudinal aerodynamic characteristic are given.