NASA NACA-RM-L56D03

Abstract

INTRODUCTION <br>Previous investigations (refs. 1 t o 4) have shown that large increments of trim lift coefficient can be obtained on delta-wing airplanes by use of double slotted flaps and that static longitudinal stability can be maintained up through the stall by the use of a properly located horizontal tail. The large increments of lift coefficient were limited to the low and moderate angle-of-attack range and only relatively small gains in maximum lift coefficient were obtained because of the reduction in flap effectiveness at angles of attack near the stall. Shifting the hinge line of the double slotted flaps to the delta-wing trailing edge (extended double slotted flaps) resulted in a configuration in which the flap effectiveness held to angles of attack near the sta1l (ref. 5). The present investigation was made to determine whether the attainment of flap effectiveness through the angle-of-attack range such as that of reference 5 might be obtained on an aspect-ratio-1.85 pointed-wing plan form with double slotted flaps. Less rearward movement of the flap would be necessary for this configuration than for that of reference 5, and thus less mechanical complication and less diving moment for a given lift-coefficient result. The hinge line of the swept forward trailing-edge double slotted flap of the present investigation was along the 83 percent chord line which has sweep of -3.4⁰. The hinge line of the constant-chord extended double slotted flap of reference 5 was unswept. Results of high-speed investigations made a pointed wing with flap controls having an unswept hinge line are presented in reference 6. <br>Included in the investigation were the effects of a delta of and a straight horizontal tail on the longitudinal stability and control characteristics of the pointed wing with double slotted flaps. Both tails had approximately the same variation of lift with angle of attack. <br>In order to make a preliminary evaluation of the static lateral stability of the model, a few tests were made with and without a delta vertical tail at angles of sideslip of <u>+</u>5⁰ through the lift-coefficient range.