Determination of dynamic stability derivatives using forced oscillation technique

Abstract

The subject of the experimental investigation presented in this paper is to measure the dynamic stability derivatives of an oscillating generic combat aircraft model in the Ankara Wind Tunnel by using a direct forced oscillation technique. The model, which is used for the oscillatory tests is known as the AGARD, Standard Dynamic Model and is manufactured as a generic combat aircraft model to verify different measurement techniques in various wind tunnels of NATO countries. The aerodynamic forces and moments are measured with a five-component internal strain gauge balance placed inside the oscillating model. The paper presents the test rig used to perform the oscillatory tests in the pitch plane for the model, the motion control and the data acquisition unit which are interfaced to test rig to measure the aerodynamic loads, A brief review of the theory of dynamic derivatives is given and the results of the measurements are discussed. NOMENCLATUREk: Reduced oscillation frequency (CO 1/2 V^ ) 1: Reference length (m)

Linear Frequency Domain and Harmonic Balance Predictions of Dynamic Derivatives

“…The experimental data 28 The pitch damping derivatives were measured in the low speed, closed circuit Ankara wind tunnel. 27 The time-domain damping derivatives agree well with the experimental values. Because of the broad frequency content of the force and moment coefficient, deviations are expected in the predicted values of dynamic derivative for solutions using 1 and 2 modes.…”

Linear Frequency Domain and Harmonic Balance Predictions of Dynamic Derivatives

“…28 The pitch damping derivatives were measured in the low speed, closed circuit Ankara wind tunnel. 27 The time-domain damping derivatives agree well with the experimental values. Because of the broad frequency content of the force and moment coefficient, deviations are expected in the predicted values of dynamic derivative for solutions using 1 and 2 modes.…”

“…This geometry has been used at various wind tunnel facilities to collect data using different measurement techniques. [25][26][27][28] Further details on the geometry can be found in Huang. 29 This model has been used for two previous studies related to dynamic derivatives.…”

Computation and Evaluation of Dynamic Derivatives using CFD

“…37 The pitch damping derivatives were measured in the low speed, closed circuit Ankara wind tunnel. 36 Reasonable agreement is obtained between the two grids. The solutions using 40 and 80 steps per cycle yield very similar results.…”