Stability and Performance of a Light Unmanned Airplane in Ground Effect

Abstract

The objective of the present work is to understand the effect of ground proximity on the aerodynamic performance and stability of a light unmanned aerial vehicle. The flowfield around the airplane was computed by PAN AIR and Athena Vortex Lattice. The ground effect was simulated using the method of images. The stability coefficients and other aerodynamic characteristics were obtained at different heights above ground and in free flight. The results demonstrate that the airplane is lateral-directional statically stable, longitudinal statically stable in free flight and longitudinal statically unstable in ground effect. The dynamic stability characteristics of the airplane were obtained at different heights above ground. The phugoid mode is considerable influenced by ground effect and a divergent and non-oscillatory mode appears when the airplane is near to the ground. This is called non-dimensional height mode. The short-period, the Dutch roll, the roll and the spiral modes are slightly affected by ground effect. Significant differences were obtained when the z derivatives were neglected in the dynamic analysis for longitudinal motion. The present work demonstrates that the performance and stability of the unmanned airplane are considerably influenced by ground effect.

Dynamic Ground Effect on the Aerodynamic Coefficients of a Wing using a Panel Method

“…This is a straight wing form with a NACA4415 airfoil section and it has an aspect ratio of 8.5877, taper ratio of one, and a wingspan of 5.187 m. Figures 12 and 13 show the drag reduction factor and lift ground-effect influence ratio as a function of H/b, respectively, for this wing estimated in subsonic flow with the present code compared to the results of Eqs. (2)-(4), and to those obtained by PANAIR, 20 AVL, 20 and CMARC. 13 The results accomplished with the panel codes that model the wing with thickness (PANAIR and CMARC) present a difference in the analytical result of less than 10%, and for H/b≥0.16667, of less than 4.6%.…”

“…These are common findings in static ground effect studies. 1,[5][6][7][8]12,13,20,21 Traub 21 explains that ground effect causes reduced downwash over the wing's bound-vortex system, and this increases the lift-curve slope and diminishes the induced (or vortex) drag. In addition, it is observed that the larger the wing's aspect ratio, the greater the increase of the lift and pitching moment coefficients and the reduction of induced drag coefficient would be.…”

“…In order to compare the capabilities of the code respect to the panel codes capable of modeling three-dimensional arbitrary configurations, a wing previously studied by Boschetti et al 20 and Boschetti and Cárdenas 13 was simulated. This is a straight wing form with a NACA4415 airfoil section and it has an aspect ratio of 8.5877, taper ratio of one, and a wingspan of 5.187 m. Figures 12 and 13 show the drag reduction factor and lift ground-effect influence ratio as a function of H/b, respectively, for this wing estimated in subsonic flow with the present code compared to the results of Eqs.…”

Application of smart flap for race car wings

“…Park et al (2009) have presented the optimisation of airfoil under the ground effect. The effect of ground proximity on the aerodynamic performance and stability of a light unmanned aerial vehicle has been carried out by Boschetti et al (2010). The shape optimisation using the multi-objective genetic algorithm and the analysis of the three-dimensional wings in ground effect have been offered by Lee et al (2010).…”

Three-Dimensional Investigation of Smart Flap Aerodynamics for a WIG Vehicle

“…Park et al 11) presented optimization of an airfoil under the ground effect and considered NACA0015 as a baseline model. A study on the effect of ground proximity on the aerodynamic performance and stability of a light unmanned aerial vehicle was performed by Boschetti et al 12) Lee et al 13) carried out shape optimization using a multi-objective genetic algorithm and analysis of the 3D WIG effect. Conventional wings have been used in e most WIG vehicles.…”