Study on the relative motion of parafoil-load-systems

Abstract

Based on the experimental vehicle ALEX the relative motion between parafoil canopy and payload is surveyed. This motion results from the flexible textile linkage of parafoil and load. Specific movement patterns are excited by maneuvers or gusts. The study characterizes the different types of relative motions and their impact on the flight qualities of the vehicle. For modeling purposes, these additional degrees of freedom are taken into consideration. A sensor system is designed and implemented for recording the relative motion during flight tests. Flight data is acquired with a customized video-measurement system combined with image processing algorithms (tracking). In a further step, the parafoil-load-system is modeled with respect to the multi-body-problem and the aerodynamic effects in a computer simulation environment. By means of system identification techniques the parameters of the models are estimated and then validated using additional flight test data. These computer models are used for simulation studies to analyze the effects and impacts of relative motion. Also, with this extra knowledge both measurement improvements and deeper insights to the nature of flight mechanics are obtained. This leads to the concluding discussion of the applicability of the proposed methods for future projects.