Dynamic Modeling and Flight Test Validation of an In-House Design UAS Built for Polar Research

Abstract

An in-house unmanned aerial system (UAS) is designed, analyzed and manufactured to support high-sensitivity and low-frequency ice penetrating radars to be used for research in the polar region. A 55 MHz antenna will be secured onto the wings. The UAS, called Astrid, is designed based on previous research experience that provided information on the significant effects of the polar atmospheric conditions (e.g. wind shear, gusts, etc.) on UAS performance. In addition to the adverse weather conditions, post flight test analysis showed that pusher engines on UASs cause significant changes to the aerodynamic forces and moments generated by the horizontal tail. This is primarily due to the turbulent nature of the propwash slipstreams flowing over the empennage and variation of their turbulency with changes in engine RPM. Based on this information, a wing configuration with a stabilizing polyhedral is selected. Astrid UAS also features a pusher engine with a twin boom, high-horizontal tail offset from the zero-lift plane. A dynamic model for Astrid UAS is developed using Advanced Aircraft Analysis (AAA), a program used to estimate aircraft stability and control derivatives. These derivatives are used to create a linear time-invariant system used for modal analysis. The dynamic model of the aircraft was used to investigate its handling qualities. Astrid's maiden flight test was successfully conducted in October 2019 and the longitudinal dynamic model is validated in subsequent flight tests.