Structural Adequacy Study of the XM27 Fin for Cartridge, 60 MM: HE, XM720.

The purpose of this investigation was to determine the structural adequacy of the XM27 fin used with Cartridge, 60 mm: HE, XM720 for the Lightweight Company Mortar System. Stress analyses were conducted on several fins which tested three aluminum alloys (6061T6, 6070T6, and 7075T6) as well as dual material designs using a steel insert inside the aluminum fin boom. Fin sections were subjected to tensile tests to determine the mechanical properties of the fin stock (6061T6 and 6070T6) and to determine the actual properties of the fin extrusion. It is noted that the actual tensile strengths were approximately 10.7% higher than the minimum specified. Static testing was conducted to verify analytical predictions and to establish the physical strength of XM27 fin, which is manufactured from 6070T6 aluminum alloy. The results showed that the XM27 fin's structural safety factor is approximately 1.9 at 70 F (21.1 C).