Dynamic Modeling and Controllability Analysis of a Moderately Damaged Unmanned Aerial System

This research presents dynamic modeling and controllability analysis of a moderately damaged Viking-400 unmanned aerial system. In absence of flight test data, changes in longitudinal and lateral-directional dynamic modes of this aircraft due to asymmetric damage are investigated using Athena Vortex Lattice. Dynamic modeling of damaged aircraft has not been studied extensively. The majority of existing works are based on research conducted at NASA Langley, which used wind tunnel experiments on a 5.5%-scale model of generic transport aircraft. Only a few studies have examined onboard adverse impacts on the dynamic model of damaged UASs and most of these studies used extremely simple approaches to reflect changes in the UAS dynamic by manipulating stability and control derivatives based on perceived impact of damage. In this work, two major cases with different extents of damage are considered. Main scenarios are: (1) wing tip loss with partial aileron loss (2) damage to the horizontal tail and elevator. Damages are assumed to be asymmetric, inflicted by man-portable air defense systems. Uniquely, a methodology is created to document the changes in moment of inertia and aircraft geometry. Utilizing AVL, stability and control derivatives were developed at the aircraft's cruise velocity of 60 knots for each damage condition. Modal analyses are conducted for each scenario. Using linear time-invariant system representation of the UAS, a controllability analysis is also conducted for each scenario. The results of this analysis show that the aircraft is controllable for all damage scenario.