Modelling & Handling Qualities of High-Altitude Platform

As technology demonstration, CSIR - National Aerospace Laboratories (NAL) has developed a sub-scale version of low speed, long endurance high-altitude platform named as HAP. Long endurance with limited power from solar cells and batteries imposes stringent demands on the aircraft aerodynamic design. To achieve maximum efficiency, these aircraft often feature high aspect ratio wings, which are long and slender. Nevertheless, the combination of high aspect ratio wings and low structural weight results in a flexible structure. Hence, a mathematical model coupled with elastic effects is required to understand the interactions occurred due to flexible structure. A nonlinear, integrated flight dynamics model (FDM) for a flexible aircraft has been developed. The flight dynamic model discussed here is intended for application in flight dynamics, simulation, and control system design for light to moderate flexible aircraft. Low order linear model is derived from integrated FDM and further used to facilitate the control system design process. The effects of flexibility on the flight dynamics and Handling Qualities of an aircraft are presented.