Planform Variations and Aerodynamic Efficiency of Movable Tip Strakes

摘要

The movable tip strake represents a novel use of the renowned concept believed to be important to the design of future airplanes. An experimental study has been conducted to explore the effects of varying strake planform on the performance of a rectangular wing. Four strake configurations, including two delta types, then one modified delta having a portion of the leading edge curved, and one cropped double delta, have been tested in a low-speed wind tunnel. The strakes were held at a constant setting relative to the main wing. The results showed noticeable advantages of the configurations employing strakes over the baseline wing. All strakes produced higher lift and drag coefficients than the clean wing. The highest lift-to-drag ratio was obtained when the cropped double-delta strake was used at moderate angles of attack, yielding improvements of up to 26%. It is believed that the minimal weight penalty associated with the actual implementation of the strake would further accentuate the attractiveness of this concept, which represents an innovative use of a traditionally very successful model. Further studies of additional planforms and settings appear warranted. Future plans include extensive use of flow visualization to aid in better understanding the flow phenomena associated with these types of configurations. Effects on wake vortex attenuation and possible use in roll control should also be addressed.