Carbon Fiber/Thermoplastic Overwrapped Gun Tube

The emphasis on lightweight large-caliber weapons systems has placed the focus on the use of advanced composite materials. Using composite materials not only directly removes weight from the gun tube but, by better balancing the tube, allows the use of smaller gun stabilization drive systems, thus further enhancing system weight loss. Additionally, the use of high stiffness composites helps with pointing accuracy and alleviating the dynamic strain phenomenon encountered with high-velocity projectiles. Traditionally though, using composites has been difficult because of the coefficient of thermal expansion mismatch between the steel substrate and the composite jacket, which causes a gap after manufacturing. Dealing with this mismatch has greatly complicated the manufacturing process in the past to the point where mass-producing the barrels would be problematic at best. By using a thermoplastic resin and a cure on the fly process, the manufacturability of the barrels has been greatly improved and the gap has been eliminated. This is the first time that this approach has been applied to a large-caliber gun tube. A $120mm$ barrel has been manufactured using this process with IM7 fibers in a polyetheretherketone matrix and successfully test fired. This paper will present the design, manufacturing, and test firing of this barrel.