Project Alpha: Joined Wings

A basic comparative aerodynamic analysis of Joined Wings & Conventional Wings.

Results and Discussions

Pressure Distribution Plots

Pressure distribution was plotted using CFX-Post for each of the surfaces of both main wing and tail wing for all four configurations. The Red and Blue curves represent upper and lower surface of the main wing respectively and green and pink represent the upper and lower surface of the tail wing respectively.

Figure below shows the pressure distribution over the surfaces of main wing and tail wing for all the configurations follow the elliptical pressure distribution and hence follow the Prandtl’s theory of minimum induced drag theory. With the pressure distribution plots, all the lift curve slopes, drag curve slopes can be verified. The pressure in Pascal (Pa) is observed and the pressure differential will yield in similar results as it did in the slopes of lift and drag, i.e. on comparing first two charts, it can be observed that for conventional wing and joined wing at 70% semispan joint, the later has lower pressure on the Upper surface of the main wing when compared with the conventional wing, and has higher pressure on the lower surface of the main wing and therefore producing more lift.

For the tail wing, the lower surface (pink curve) and upper surface (green curve) of the joined wing configuration at 70% span is experiencing variable pressure as the chart count is increased i.e. from wing root to wing tip when compared with the conventional wing.

On the other hand, the two remaining joined wing configurations with respective tail airfoils, the pressure distribution can easily be observed on main wing caused by the change. It is observed that the pressure at lower surface of the main wing (blue curve) is now greater for the joined wing configuration at 100% i.e. with high lift tail airfoil. This change reflects the effect of induced downwash and up-wash caused be the close interaction of airfoils quite similar to biplanes.