Aerodynamic Characteristics Of Several Airfoils Of Low Aspect Ratio

An investigation has been made to determine the effect of ground proximity on the aerodynamic characteristics of aspect-ratio-1 airfoils. The investigation was made with the model moving over the water in a towing tank in order to eliminate the effects of wind-tunnel walls and of boundary layer on ground boards at small ground clearances. The results indicated that, as the ground was approached, the airfoils experienced an increase in lift-curve slope and a reduction in induced drag thus, lift-drag ratio was increased. As the ground was approached, the profile drag remained essentially constant for each airfoil. Near the ground, the addition of end plates to the airfoil resulted in a large increase in lift-drag ratio. The lift characteristics of the airfoils indicated stability of height at positive angles of attack and instability of height at negative angles; therefore, the operating range of angles of attack would be limited to positive values. At positive angles of attack, the static longitudinal stability was increased as the height above the ground was reduced. Comparison of the experimental data with Wieselsberger's ground-effect theory (NACA Technical Memorandum 77) indicated generally good agreement between experiment and theory for the airfoils without end plates.

This paper presents the results of the investigation of a wing-alone and wing-fuselage configuration employing a wing with the quarter-chord line swept back 45 degrees, with aspect ratio 4, taper ratio 0.3, and an NACA 65A006 airfoil section. Lift, drag, pitching moment, and root bending moment were obtained for these configurations. In addition, effective downwash angles and dynamic-pressure characteristics in the region of a probable tail location were also obtained for these configurations and are presented for a range of tail heights at one tail length. In order to expedite the publishing of these data, only a brief analysis is included.

This paper presents the results of the investigation of wing-alone and wing-fuselage combination employing a delta wing having 45 degree sweepback of the leading edge, aspect ratio 4, and an NACA 65A006 airfoil section. Lift, drag, pitching moment, and root bending moment were obtained for these configurations. In addition, effective downwash angles and dynamic-pressure characteristics in the region of a probable tail location also were obtained for these configurations, and are presented for a range of tail heights at one tail length. In order to expedite publishing of these data, only a brief analysis is included.