Flight dynamics modeling and analysis of high aspect ratio UAV based on flexible beam model

The high aspect ratio wing of the High Altitude Long Endurance(HALE) UAV is flexible, causing the UAV to have large structural deformation. Adopting the spatial beam assumption of the high aspect ratio wing, this paper studies the flight dynamics of the UAV uses Hodges intrinsic beam dynamics model combined with aerodynamic strip theory and quasi-steady assumption, uses this method, computes the static deformation in trim state, analyzes the stability in different thrust distribution, calculates the flying qualities in different altitudes, structural rigidities and payload distributions. The results and their analysis show preliminarily that: (1) the flexible high aspect ratio wing changes the longitudinal static stability and the pitch inertia of the UAV, resulting in decreased short cycle frequency and increased damping; (2) the phugoid motion couples with structure bending motion.