Composite alloys are ideal materials for manufacturing military weapons such as aircraft, rockets, and spacecraft due to their lightweight, high specific strength and modulus, good ductility, corrosion resistance, thermal conductivity, heat insulation, sound insulation, vibration damping, high (low) temperature resistance, ablation resistance, electromagnetic wave transmission, wave absorption and concealment, design flexibility, manufacturing flexibility, and ease of processing. Advanced composite alloys are used to process primary and secondary load-bearing structures, exhibiting stiffness and strength properties comparable to or exceeding those of aluminum alloys. They are currently widely used in aircraft fuselage structure manufacturing and the overall structure manufacturing of small unmanned aerial vehicles (UAVs).
After nearly 40 years of development, aircraft composite alloys have evolved from their initial use in non-load-bearing components to their application in secondary and primary load-bearing components, achieving a significant weight reduction of (20-30)%. They have now entered a mature application phase, and their contribution to improving aircraft's technical and tactical capabilities, reliability, durability, and maintainability is undeniable. Experience in their design, manufacturing, and use has become increasingly rich. To date, composite materials account for approximately 30% of the total materials used in fighter jets, and this figure is expected to reach 40% in next-generation fighters. The proportion of composite materials used in helicopters and small aircraft will reach approximately 70-80%, with some even being entirely composite material aircraft. The Comanche helicopter has a fuselage 70% made of composite materials, but plans are underway to further reduce its weight by 15% by reducing the weight of the lower front fuselage and expanding composite materials into components and bearings. The Apache will use composite materials instead of a metal fuselage to reduce weight.
In the past decade, composite alloys have also been increasingly used in domestically produced aircraft. For example, a composite material vertical tail panel for a fighter jet, developed collaboratively by three domestic research institutions, is 21 kg lighter than the original aluminum alloy structure, representing a 30% weight reduction. The QY8911/HT3 bismaleimide unidirectional carbon fiber prepreg and its composite materials have been used in aircraft components such as the forward fuselage section, vertical tail stabilizer, wings, drag plates, and fairing panels. The PEEK/AS4C thermoplastic resin unidirectional carbon fiber prepreg and its composite materials developed by the Beijing Institute of Aeronautical Materials have excellent fracture toughness, water resistance, aging resistance, flame retardancy and fatigue resistance. They are suitable for manufacturing main load-bearing components of aircraft and can work for a long time at 120°C. They have been used in the front skin of the aircraft landing gear bay liner.
