Simulations for the Test Flight of an Experimental HALE Aircraft

Recent events, such as the crash of NASAs Helios aircraft during a test flight, show that more must be known about the nonlinear control of HALE aircraft. Shearer, Cesnik and their co-workers have developed a code that is a practical solution to the coupled nonlinear aeroelasticity and flight dynamics of very flexible aircraft called the University of Michigans Nonlinear Aeroelastic Simulation Toolbox UMNAST. They are also in the process of developing a model HALE aircraft called X-HALE which will be used to validate this code experimentally. This research performs flight simulations with UMNAST so as to make predictions about X-HALEs future test flights and subsequently uncover the strengths and weaknesses of UMNAST when X-HALE is finally flown. These simulations include simulations of straight and level flight and rolling flight. Rolling simulations involve periodic changes in the angle of the ailerons. Both the 6 meter and the 8 meter models of X-HALE are studied. Two control models are compared. These include the linear and non-linear models of UMNAST.