Wind-Tunnel Investigation of a General Aviation Airplane Equipped With a High Aspect-Ratio, Natural-Laminar-Flow Wing 871019

An investigation has been conducted in the Langley 30- by 60-Foot Wind Tunnel to evaluate the performance and stability and control characteristics of a full-scale general aviation airplane equipped with a natural-laminar-flow wing. The study focused on the effects of natural laminar flow and boundary layer transition, and on the effects of several wing leading-edge modifications designed to improve the stall resistance of the configuration. Force and moment data were measured over wide angle-of-attack and sideslip ranges and at Reynolds numbers from 1.4 × 10⁶ to 2.1 × 10⁶ based on the mean aerodynamic chord. Additional measurements were made using hot-film and sublimating-chemical techniques to determine the condition of the wing boundary layer, and wool tufts were used to study the wing stalling characteristics.

The investigation showed that large regions of natural laminar flow existed on the wing which would significantly enhance the cruise performance of the configuration. Also, because of the characteristics of the airfoil section, artificially tripping the boundary layer did not significantly affect the lift, stability, and control characteristics. The leading-edge modifications were found to be effective in improving the stall resistance of the configuration, and resulted in only minor penalties in calculated cruise performance,