Mortar weapons systems have existed for more than five hundred years. Though modern tube-launched rounds are far more advanced than the cannon balls used in the 15th century, the parabolic trajectory and inability to steer the object after launch remains the same. Equipping the shell with extending aerodynamic surfaces transforms the unguided round into a maneuverable munition with increased range [1] and precision [2]. The subject of this work is the experimental analysis of transient aerodynamic behavior of a transforming tube-launched unmanned aerial vehicle (UAV) during transition from a ballistic trajectory to winged flight.
Data was gathered using a series of wind tunnel experiments to determine the lift, drag, and pitching moment exerted on the prototype in various stages of wing deployment. Flight models of the design were broken down into three configurations: “round”, “transforming”, and “UAV”. Geometrically static tests which consisted of the round and UAV models were used to determine preand post-transformation aerodynamics. Post-processing of dynamic transformation tests employed spectral analysis and appropriate signal filtering to identify and characterize the aerodynamics of the transition between static model configurations. Results indicated that complete transformation occurred within 1/3 of a second and that the prototype maintained aerodynamic stability during the entire geometric transition.
