NACA-TN-3481

Abstract

An investigation was made at a Mach number of 0.13 in the Langley stability tunnel in order to determine the effects of closed wing-root air ducts (horizontal) on the static longitudinal and static lateral stability characteristics of unswept-midwing models having wings of aspect ratio 2, 4, and 6. In addition, the effects of top and bottom fuselage ducts (vertical) on the static longitudinal and static lateral stability characteristics of model configurations employing the unswept wing of aspect ratio 2 were determined. <br>The results of the investigation have indicated that, in the low angle-of-attack range, the addition of and increase in size of the horizontal ducts on model configurations employing an unswept wing of aspect ratio 2 resulted in a large forward movement of the aerodynamic center regardless of the vertical location of the horizontal tail. When the aspect ratio of the wing was increased from 2 to 6, this effect became more pronounced. In contrast to this effect of the horizontal ducts, the addition of and increase in size of vertical ducts on model configurations employing the wing of aspect ratio 2 produced a slight rearward movement of the aerodynamic center. <br>Regardless of the aspect ratio of the wing, the addition of and increase in size of the horizontal ducts caused an increase in directional stability for complete models or a decrease in instability for tail-off configurations at low and moderate angles of attack. The addition of and increase in size of vertical ducts on the models with the wing of aspect ratio 2, however, resulted in large decreases in directional stability which were about constant for the angle-of-attack range investigated.