Experimental Investigation of a Generic Light Aircraft Model with Dual External Stores

The paper discusses the effect of dual external stores attached beneath the wing of a generic subsonic light aircraft model. An experimental investigation is conducted in UTM Low Speed Wind Tunnel to determine the aircraft model's aerodynamic characteristics and flow distribution. The interest in installing external stores on light aircraft has not been discussed in detail to date. Few light aircraft have recently been installed with external stores available in the market. In this experiment, the aircraft model was tested at three configurations: the model with clean wing, the model with single, and finally, the model with dual external stores. These configurations were tested at the same Reynolds number of 0.46 × 106 with angle of attacks ranging from −4 to 15° while the yaw angles ranging from −10 to 10°. Measurement techniques were performed on the model; the first was the external balance measurement, and the final was the surface distribution measurement. The results showed that the installation of dual external stores had reduced the lift coefficient by 13% compared to the clean wing configuration. Similar to the drag, it reduces because the induced drag is increased. The longitudinal static stability is reduced when the external stores are installed. Another observation is that the trim angle of the dual external stores configuration is greater than the clean wing configuration. In contrast, the rolling stability is improved, when the stores is installed. However, the effect of external stores is not significant in directional static stability. For pressure distribution, the external stores have delayed the flow separation to occur at a higher angle of attack.