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Experimental Studies of Roll Damping Coefficient for Basic Finner Model
Ionut Bunescu

Last modified: 2023-06-29


The aerodynamic roll damping coefficient is a critical parameter in the design of aerospace vehicles, such as airplanes and rockets, as it affects the stability and control of these vehicles during atmospheric flight. Experimental studies of the aerodynamic roll damping involve the measurement of the aerodynamic forces acting on a model aircraft undergoing roll motion in a wind tunnel or other controlled environment. The aerodynamic roll damping coefficient is a complex function of various physical parameters, including the shape and size of the aircraft, the speed and density of the air, the angle of attack, the angular speed of the model, and the characteristics of the airflow around the vehicle. The measurement (identification) of this coefficient requires careful control of these parameters, as well as accurate instrumentation to capture the relevant data. This paper presents the experimental studies performed at INCAS trisonic wind tunnel using the calibration model Basic Finner Model at different Mach numbers, angles of attack and angular velocities.

One commonly used approach to measure the aerodynamic roll damping coefficient involves the use of a forced rotation method, in which the model is spun with constant velocity, measuring the roll moment generated by the model. Another approach involves the use of a free rotation method, in which the aircraft is initially spun at an angular velocity and then it is allowed to roll freely under the aerodynamic loads. The aerodynamic roll damping coefficient is then determined by analyzing the decay of the roll angle over time, which is influenced by the damping forces acting on the aircraft. Herein, both methods will be used to compare their accuracy and complexity related to the obtained results, respectively to the data acquisition process.

The accuracy and reliability of aerodynamic experimental tests rely heavily on the use of corrections. These are applied to experimental data to account for the effects of various environmental and experimental factors that can influence the results of the test. Failure to apply appropriate corrections can result in erroneous data, which can lead to inaccurate conclusions and potentially dangerous design decisions. Applying corrections to experimental data is a critical step in the aerodynamic testing process, as it ensures that the data accurately represents the physical phenomena being studied. In this paper, will be presented the effect of the tare correction and the effect of the geometry deviation correction.

This paper concludes by summarizing the findings of the study and discussing the data obtained related to the effects of the Mach number, angle of attack and angular velocity over the roll damping coefficient.