In this blog post, we’ll explore how advancements in materials science have contributed to improvements in aircraft design and performance, examining the properties of various materials and their applications.
Airplanes are a symbol that vividly illustrates humanity’s scientific and technological progress. Since the Wright brothers obtained a patent for their aircraft design in 1906, aviation technology has undergone remarkable advancements over more than a century, and today it serves as a vital mode of transportation connecting the entire world. Since the Wright brothers obtained a patent for their aircraft design in 1906, aviation technology has undergone remarkable advancements over the past century, establishing itself as a key mode of transportation connecting the world and a catalyst for economic and cultural exchange. Today, airplanes are no longer the product of cutting-edge technology; they have become such a familiar part of our daily lives that we see them crisscrossing the sky whenever we look up. Yet, the sight of a massive aircraft carrying dozens or even hundreds of people across the sky remains awe-inspiring. Countries around the world are actively conducting various technological research efforts to create faster, safer, and more eco-friendly aircraft. So, from the perspective of materials engineering, what materials are these giant flying machines made of, and what physical properties are required?
Before delving into aircraft materials in detail, we must first examine what physical properties are required of them. Above all, strength is paramount. To support the weight of the aircraft itself, dozens of passengers, cargo, and cabin pressure, high structural strength is essential. However, simply using strong materials is not the solution. If heavy materials are used solely for strength, flight efficiency drops significantly, requiring larger engines and more fuel, which reduces economic viability and practicality. Therefore, materials with high “strength per unit weight,” or specific strength, are suitable for aircraft.
Additionally, since aircraft are subjected to continuous vibrations and repeated loads during flight, they must have a long fatigue life. Wear resistance against air friction and corrosion resistance against humidity and salt are also important. In particular, for supersonic aircraft or high-altitude aircraft, which are exposed to high temperatures, heat resistance—the ability to maintain structural stability even at high temperatures—is also essential. In addition, machinability—including machinability, weldability, and formability—is considered very important from an industrial perspective, as it affects production costs and process efficiency.
Early aircraft were primarily constructed using wood and fabric. While wood had the advantages of being lightweight and easy to work with, it was limited in terms of strength and durability. To overcome these limitations, Duralumin—developed by the German metallurgist Alfred Wilm in the early 20th century—began to be introduced as an aircraft material. Duralumin is an alloy of aluminum with added copper, manganese, and magnesium; it boasts high strength while weighing only about one-third as much as steel. It is also easy to machine, making it advantageous for reducing aircraft manufacturing costs.
To this day, duralumin and its improved variants, super-duralumin and ultra-super-duralumin, are still widely used as primary structural materials in aircraft. It can be found in long-haul commercial aircraft such as the Boeing 737 series and the 747-400. However, duralumin has the drawbacks of losing strength at high temperatures and corroding when exposed to salt or humidity for extended periods. To compensate for these limitations, titanium alloys are used in high-speed aircraft or in areas requiring heat resistance.
Titanium offers excellent specific strength, fatigue resistance, and corrosion resistance, and remains stable even at high temperatures; however, because it is difficult to machine and expensive, its use is limited to specific areas such as the outer skin and firewalls. In addition, high-strength special steels are used in components subjected to heavy loads, such as bolts, gears, and landing gear.
The hottest topic in the aviation industry today is carbon fiber-reinforced polymer (CFRP). Composite materials are created by combining two or more materials to maximize their respective advantages; typically, a low-stiffness matrix material is combined with a high-strength reinforcement, such as fibers. Carbon fiber is gaining attention as a key material for aircraft lightweighting due to its exceptional strength-to-weight and stiffness-to-weight ratios, while weighing only about one-sixth as much as steel. In particular, carbon fiber prevents load concentration when internal cracks occur and blocks crack propagation, making it superior in terms of fracture resistance. Since it is not a metal, it also offers excellent corrosion resistance.
Applying CFRP to aircraft structural components can significantly reduce weight, thereby lowering fuel consumption and, consequently, contributing to reduced carbon dioxide emissions. The Boeing 787 Dreamliner consists of approximately 50% composite materials, with about 43% of those being carbon fiber composites. As a result, it achieved a fuel savings of about 20% compared to previous models and reduced the aircraft’s total weight by more than 5 tons. Airbus’s A350 XWB is another prime example, with more than half of its structure composed of composite materials, thereby achieving improvements in fuel efficiency and reduced carbon emissions.
In addition, research is actively underway on next-generation aircraft materials such as ceramic matrix composites (CMCs), conductive-coated composites, and nanoparticle-reinforced composites. For example, technologies are being advanced to improve heat resistance and wear resistance by adding silica nanoparticles, as well as to apply conductive coatings for lightning protection. These new material technologies also hold great potential for application in supersonic aircraft, high-altitude unmanned aerial vehicles (UAVs), and personal eVTOL aircraft.
Beyond the aviation sector, high-strength, lightweight composite material technology is already expanding into various fields such as the automotive, railway, aerospace, and defense industries. Recently, global automakers such as BMW, Tesla, and Lucid Motors have been designing the bodies of their premium electric vehicles using carbon fiber composites to simultaneously achieve weight reduction and increased driving range. In the aerospace sector, space agencies worldwide—including NASA, ESA, and Japan’s JAXA—are increasingly adopting CFRP-based materials for rockets, satellites, and spacesuit components.
Furthermore, as next-generation eco-friendly aircraft—such as electric and hydrogen-fueled aircraft—become a reality starting in the mid-2020s, research into the ultra-lightweight, high-performance materials that make them possible is becoming even more active.
Demand for air transportation is expected to continue growing in various forms, including passenger, cargo, military, unmanned aerial vehicles (UAVs), and eVTOLs. Consequently, aircraft materials will also evolve to be lighter, stronger, safer, and more environmentally friendly. Next-generation aircraft materials, including carbon fiber-reinforced composites, are emerging as key elements driving a sustainable future for the aviation industry, going beyond their role as mere structural components. These advancements in material technology hold the potential to not only improve aircraft performance but also provide solutions to humanity’s mobility challenges and environmental issues.
