Experimental and theoretical determination of forces and moments on a store and on a store-pylon combination mounted on a 45 degree swept-wing-fuselage configuration at a Mach number of 1.61

Morris, Odell A Carlson, Harry W Geier, Douglas J
January 30, 1958

An investigation of store-pylon forces and moments has been conducted in the Langley 4- by 4-foot supersonic pressure tunnel at a Mach number of 1.61. Separate forces and moments were measured simultaneously on a store and on a store-pylon combination for a number of pylon-mounted store locations below the wing of a 45 degrees swept-wing-fuselage combination. Tests were made through an angle-of-attack range of -4 degrees to 12 degrees and an angle-of-sideslip range of -12 degrees to 12 degrees. The basic model configuration, which was almost identical to the model used in NACA RM L55A13a, simulated a heavy-bomber-type airplane with a large ogive cylinder store. The results of the investigation indicate that the most important source of store-pylon side forces is the pylon itself. When immersed in a strong sidewash field, the pylon can assume a large load and also produce a large incremental load upon the store. Both tend to increase rapidly with increasing angle of attack or angle of sideslip. Location of the store-pylon combination in a sidewash field of strong intensity may also result in powerful secondary effects on the normal force and axial force of the store. The large unstable pitching moments obtained for the sweptforward store-pylon installations at moderate angles of attack indicate that release of an unfinned store from a forward store location could be hazardous. Tests with two stores mounted on the same wing panel show that the presence of the inboard store-pylon combination causes significant decreases in the outboard store and store-pylon side forces produced by angle of attack. The theory as used here provides a useful estimation of the angle-of-attack-induced store or store-pylon side force. However, the side force is underestimated at the inboard wing positions and is overestimated at the outboard positions.

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