DESIGN, IMPLEMENTATION AND FLIGHT TESTING OF A SUBSCALE DEMONSTRATOR FOR ASSESSING THE STALL BEHAVIOUR OF A LARGE SWEPT-WING RESEARCH UAV

The flying demonstrator T-FLEX for the assessment of active flutter suppression and load alleviation technologies is developed and flight tested during the projects FLEXOP and FLiPASED. In order to assess the stall behavior of the demonstrator without conducting the respective tests on itself, the scaled demonstrator DeFStaR was developed during a project work and Master’s Thesis [1] in order to conduct respective flight tests. The scaling focused on aerodynamic scaling in terms of aerodynamic coefficients CLα and Cmα as well as dynamic scaling in terms of center of gravity as well as mass moments of inertia. The scaling factor was finally determined to be 0.53. The design relied on commercial-off-the-shelf components whenever possible, while the wing was manufactured in- house in order to assure close geometric similitude. After implementation, ground and flight tests were conducted in order to assure dynamic and aerodynamic similitude, using bifilar pendulum tests for determining the mass moments of inertia as well as system identification techniques to verify the relevant aerodynamic derivatives of the demonstrator. Following stall tests showed a wide range of different behaviors from a "plunging" flight state, that allowed the pilot to maintain attitude, to a flat spin causing considerable loss of altitude.     «

The flying demonstrator T-FLEX for the assessment of active flutter suppression and load alleviation technologies is developed and flight tested during the projects FLEXOP and FLiPASED. In order to assess the stall behavior of the demonstrator without conducting the respective tests on itself, the scaled demonstrator DeFStaR was developed during a project work and Master’s Thesis [1] in order to conduct respective flight tests. The scaling focused on aerodynamic scaling in terms of aerodynam...     »