NUMERICAL ANALYSIS OF AN ECHELON FORMATION EXHIBITING POST-STALL BEHAVIOUR

A vortex-lattice based numerical scheme that uses a novel decambering technique to predict poststall aerodynamic characteristics is used to study the aerodynamics of tandem Cessna 172 aircrafts flying in echelon formation. The scheme requires 2D coefficients of lift and pitching moment vs angle of attack as input to predict 3D aerodynamic coefficients of single/multiple wings. Three such sets of 2D data are used for this purpose. Results like 3D coefficient of lift from the current method are compared with experiment. Additional results like section 2D coefficients of lift and pitching moment distributions over wing span, coefficients of pitching moment, rolling moment, induced drag vs angle of attack, effect of wing incidence, angle of attack and analysis for overlapping wings in the spanwise direction are reported. Post-stall numerical analysis, the effect of change in the chord-wise, span-wise and vertical offsets, i.e. dx, dy and dz on the aerodynamics of the formation are also reported.