Investigation at Low Speed of a Six-Percent Thick Symmetrical Circular-Arc Airfoil with Leading Edge Retraction in Combination with Nose Slot

Citation

Birdwell, Carl (1955) Investigation at Low Speed of a Six-Percent Thick Symmetrical Circular-Arc Airfoil with Leading Edge Retraction in Combination with Nose Slot. Engineer's thesis, California Institute of Technology. doi:10.7907/B8SG-Y069. https://resolver.caltech.edu/CaltechETD:etd-12022003-154259

Abstract

The effectiveness of leading-edge retraction as a possible high-lift device for thin, sharp-nosed airfoils was investigated. Experimental results are presented for a symmetrical, 6%-thick, circular-arc airfoil configuration, such that the forward 9.5% section of the chord is retractable up to a distance of 20% chord into the wing. The results include direct force measurements, limited surface pressure surveys and limited single-tuft surveys. Tests were made with varying amounts of retraction in combination with variable stagger between leading edges of upper and lower surfaces and with several upper surface slot configurations. One retracted configuration was tested with a 20% chord, split-flap. The results show that retraction is ineffective in increasing maximum lift. In general the effect on maximum lift was as follows: (1) Retracting up to approximately 9%, decreased maximum lift in proportion to the loss in wing area, (2) With exactly 9.06% retraction and with certain configurations of stagger and/or slots, the stalling angle of attack was increased 2[degrees] and the maximum lift was equal to that of the unaltered airfoil, (3) Retracting more than 9.06% resulted in a disproportionate loss of maximum lift, approximately 20% less than the unaltered airfoil.

Thesis Files