NACA-RM-L56K22

Abstract

INTRODUCTION <br>At transonic and supersonic speeds a significant part of the total drag of aircraft or missiles is associated with reduced pressures along the afterbody of the fuselage or nacelles. The problem of designing an afterbody to fair from a fixed diameter of a fuselage or nacelle to a fixed diameter of the base so that minimum drag would be obtained for both supersonic and subsonic flight has received considerable attention. Calculation of afterbody drag can be readily accomplished at supersonic speeds and the literature contains numerous experimental investigations at these speeds. At the higher subsonic speeds of current interest for cruise operation, theoretical determination of the drag is not readily accomplished, and at low supersonic speeds the theory is restricted to thin bodies. Experimental data at transonic speeds are reported in references 1 to 6 and elsewhere, but for the most part consist of results from specific configurations or from afterbodies with stabilizing fins. <br>The investigation reported herein is part of a general program in progress in the Internal Aerodynamics Branch of the Langley Compressibility Research Division to study the drag of afterbodies through the transonic range. The present work concerns the drag of a series of conical and circular-arc afterbodies without an issuing Jet. The boattail angle of the conical and circular-arc afterbodies tested ranged from 0 &#176; to 45 &#176; and the ratio of base diameter to maximum diameter varied from 0 to 1.0. These 1-inch-diameter afterbodies were attached to a cylindrical sting which extended upstream into the tunnel entrance bell. The tunnel test section was slotted and data were obtained over a Mach number range from 0.6 to 1.3. The corresponding Reynolds number range was 3.3 &#215; 10⁶ to 4.4 &#215; 10⁶ per foot.