THEORETICAL AND EXPERIMENTAL INVESTIGATION OF GROUND-INDUCED EFFECTS FOR A LOW-ASPECT-RATIO HIGHLY SWEPT ARROW-WING CONFIGURATION

摘要

An investigation has been conducted in the Langley V/STOL tunnel to determine the influence of ground proximity on the aerodynamic characteristics of a low-aspectratio highly swept arrow-wing configuration. The experimental results showed that as the height above the ground decreases, the configuration experiences substantial increases in lift and reductions in induced drag. Although a significant percentage of these ground-induced performance improvements are lost due to trim requirements, the net performance improvement remains quite favorable. The tests also showed that decreasing ground height results in a substantial increase in the horizontal-tail contribution to longitudinal stability.nComparison of the experimental results with results predicted by a planar vortex lattice theoretical model shows that the theoretical model provides a good estimate of the ground-induced effect on lift, drag, and longitudinal stability for the wing-body combination. However, the theoretical model does not adequately predict either the zero lift pitching moment or the horizontal-tail downwash characteristics.