Modeling, design, and testing of a barrel-launched adaptive munition

Structural and aerodynamic models for a 10 degree half-angle, articulated, conical, barrel-launched adaptive munition (BLAM) are presented. The forward half of the test BLAM was gimballed and actuated by two orthogonal pairs of piezoceramic tendons. Laminated plate theory models showed that piezoceramic actuators could survive hard-launch conditions if they were properly precompressed by using an elevated temperature cure cycle and a high, favorable mismatch in coefficient of thermal expansion between the substrate and the piezoceramic. Aerodynamic models based on supersonic pressure distributions over cones were used to predict free-flight trim angles and normal force range. A series of bench tests on a 13.4 cm (5.28 in) long BLAM showed plus or minus 0.12 degree steady articulation angles and a first natural frequency of 198 Hz with close agreement between theory and experiment. A series of wind tunnel tests at Mach 3.26 demonstrated a steady deflection increase with field, producing untrimmed normal force coefficient changes of plus or minus 0.0019. Extrapolation of the data to a 105 mm (4.13 in) caliber PGU-28 shaped round fired at 610 m/s (2,000 ft/s) showed that effective range increases by more than a factor of 15 over the conventional PGU-28.