WING OF ASPECT RATIO 8

The incremental l i f t and pitching moments produced by 20-percent-chord s p l i t f l a p s of various spans at various spanwise posit ions on two 45 ' sweptback wings of aspect ra t io 8.02 have been obtained by pressure-d i s t r ibu t ion t e s t s in the Iangley 19-foot pressure tunnel. These data of 4,000,000 and a Mach number of 0.19. were obtained in the linear angle-of-attack range a t a Reynolds number- The experimental data indicated that inboard f laps were far more effect ive in prducing l i f t than outboard flaps (a 20-percent-span f n b m d f l a p produced approximately twice the increment i n lift produced by a 40-percent-span outbmrd flap). Furthermore it was found that, in con-trast t o the case f o r straight wings, the f lap l i f t effectiveness (%) and the chordwise center of pressure of the incremental loads produced by full-span flaps on sweptback wings vary along the flap span. C o m p a r i s o n with the experimental data indicated that the procedure of NACA Technical Note 2278 can be used t o predict the integrated incre-ments i n lift and wing-root bending moment produced by flaps on high-aspect-ratio, highly sweptback wings w i t h fair accuracy. Probable causes of the deviations of the calculated loadings froan the experlmental have been discussed. For these wings the accuracy of the incremental pitching moment corn-puted by the method outlined in NACA Wartime Report L-164 is dependent primarily upon the accurate prediction of the spanwise load distribution. The spanwise variation of the chordwise center of pressure of the load produced by the longer span flaps could, by a simple modificatfon of the method, be closely approximated