Application of a Pendulum Support Test Rig for Aircraft Stability Derivative Estimation

Abstract

This paper presents a novel technique for extracting longitudinal stability derivative information from an actively controlled wind-tunnel test model. The technique, designated as the pendulum support rig, uses a test model mounted inverted and suspended from the wind-tunnel roof via a supporting strut and a single-degree-of-freedom gimbal providing model motion in heave and forward translation. An additional single-degree-of-freedom gimbal connecting the model to the support strut was also used to allow model rotation in pitch. Overall, the technique was found to perform well at predicting the dominant longitudinal stability and control derivatives. This was assessed primarily against the results from an existing established technique obtained by an independent source and from results obtained by the author in a previous investigation, using a different technique.