Light aircraft flight tests: performances, stability and flying qualities measurement

The present paper deals with flight test activities performed on light aircraft at University of Naples, Dipartimento di Progettazione Aeronautica (DPA) by the ADAG (Aircraft Design and Aeroflightdynamics Group) research group. Flight tests performed on a Brasilian light aircraft called Curumin and on G97 Spotter ultralight aircraft (ULM) will be presented. An accurate and complete flight test equipment and instrumentation has been designed and assembled by the research group. A complete set of sensors and instruments (pressure transducers, inertial platform, GPS, pitot probe used for angle of attack and sideslip measurement etc.) has been integrated and used to measure flight data and an accurate A/D converter and a flight data logger system has been set up for flight data acquisition. The complete on-board system is light and compact since it is also used for model aircraft (RPV or UAV) flight tests. The flight data are stored on board and sent to the ground where a ground control station is used for real-time monitoring. The ground station allows real-time ground visualization of all flight data parameters and aircraft position and attitude. In the paper all the advantages (i.e. fast evaluation of dynamic stability characteristics of the aircraft) in using a telemetry system for flight test activities will be highlighted. The complete instrumentation constitutes a valid tool for light aircraft flight tests and is also extensively used at our University for teaching purposes. The paper presents some flight test procedures and results concerning light aircraft aerodynamics and performances estimation. The paper will also present our current methodology based on Maximum Likelihood Method (MLM) for aerodynamic and dynamic parameter estimation. This allows the build-up of the complete aircraft aerodynamic data-base to be used for flight simulation. For the prediction of performances and dynamic behaviour of the airplane in flight, specific and detailed maneuvers have been designed and executed in order to excite dynamics modes. Comparison between simulated and measured maneuvers will be performed. Examples of linear and non-linear flight parameters estimation such as longitudinal non-linear aerodynamics from stall maneuver will be presented