Browsing by Author "Araujo-Estrada, Sergio A."

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    Evaluation of Aircraft Model Upset Behaviour Using Wind Tunnel Manoeuvre Rig
    (AIAA Atmospheric Flight Mechanics Conference, 2015-01) Araujo-Estrada, Sergio A.; Lowenberg, M. H.; Neild, Simon; Goman, M. (Mikhail G.)
    This paper discusses the development of a novel multi-degree-of-freedom dynamic manoeuvre rig aimed at investigation of aircraft upset/LOC-related behaviour in the wind tunnel. The motivation behind the development and characteristics of the rig are first described, along with example behaviour of an aircraft model exhibiting nonlinear time-dependent aerodynamics in an open-jet low-speed wind tunnel. Test objectives for assessment of upset onset scenarios - both for parameter estimation purposes and to 'physiccally simulate' the behaviour - are then described, as is the design of the upgraded instrumentation system to facilitate experimental investigation. Finally, examples of relevant behaviour involving real-time control of the rig to explore nonlinear conditions leading to upset are presented; these are evaluated in terms of prospects for such testing in aircraft development and analysis projects.
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    Experimental investigation of aerodynamic hysteresis using a 5-DoF wind tunnel manoeuvre rig
    (AIAA, 2019-01-11) Gong, Z.; Araujo-Estrada, Sergio A.; Lowenberg, M. H.; Neild, Simon; Goman, M. (Mikhail G.)
    The high-incidence aerodynamics of a lightweight jet trainer aircraft model has been investigated using a novel five-degree-of-freedom (DOF) dynamic maneuver rig, recently updated with improved actuation and data acquisition systems, in the 7 × 5 ft closed-section low-speed wind tunnel at the University of Bristol. The major focus was to identify the nonlinear and unsteady aerodynamic characteristics specific to the stall region and which affect free-to-move aircraft-model behavior. First, the unstable equilibrium states in the limit-cycle regions were stabilized, and so observed, over a wide range of angles of attack using a simple elevator feedback control lawbased on pitch angle and pitch-rate sensor measurements. Tests with two DOF, namely, the aircraft model and rig-arm pitch angles, revealed the existence of static hysteresis in the normal force acting on the aircraft model in the stall region. Unlocking the aircraft model in roll and yaw accompanied by feedback stabilization of the lateral–directional modes of motion demonstrated the onset of asymmetric aerodynamic rolling and yawing moments in this four-DOF configuration. This observation implicitly indicates a link between the static hystereses in the normal aerodynamic force with an onset of aerodynamic asymmetry. The experimental results show the efficiency of the updated multi-DOF actively controlled maneuver rig in providing insight into complicated aerodynamic effects within the stall region.
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    Wind Tunnel Manoeuvre Rig: A Multi-DOF Test Platform for Model Aircraft
    (54th AIAA Aerospace Sciences Meeting, AIAA SciTech, 2016, 2016-01) Araujo-Estrada, Sergio A.; Gong, Zheng; Lowenberg, M. H.; Neild, Simon; Goman, M. (Mikhail G.)
    This paper presents recent progress in the development of a novel multi-degree-of-freedom dynamic manoeuvre rig aimed at investigation of aircraft model nonlinear and time dependent aerodynamics in the wind tunnel. The purpose and characteristics of the rig are first described, along with a description of the data acquisition, processing and presentation system. The dynamic manoeuvre rig capabilities are demonstrated via a series of experiments involving a wind tunnel model aircraft in a closed section low-speed wind tunnel. First, an experiment illustrating low-speed wind tunnel aerodynamic model identification is presented. Then, examples of experiments involving real-time control of the rig/aircraft model are shown; these are evaluated in terms of testing productivity with a focus on the development and design of aircraft control laws.