Have you ever wondered during your flight what those aircraft are made of, and what materials are used in constructing their structures? In this article, we provide you with a detailed explanation of the types of materials that have been used in aircraft construction since their invention.
Types of Materials Used in Aircraft Manufacturing
Various materials can be used in the construction of primary aircraft structures, such as wings, fuselage, or landing gear, for different types of aircraft.
Wood was used in most early aircraft and is now primarily used in home-built aircraft. Wood is lightweight and strong, but it also produces a lot of splinters and requires significant maintenance.
Aluminum (alloyed with small amounts of other metals) is used in most types of aircraft because it is lightweight and strong. Aluminum alloys do not corrode easily like steel. However, they lose their strength at high temperatures, making them unsuitable for aircraft surfaces that become very hot, especially for aircraft flying faster than twice the speed of sound.
Steel can be four times stronger and harder than aluminum but is also three times heavier. It is used for specific parts such as landing gear, where strength and toughness are crucial. It has also been used for the outer skin of some high-speed aircraft as it retains its strength at higher temperatures better than aluminum.
This is one of several types of composite materials that have become widely used for many aircraft structures and components. These materials typically consist of strong fibers embedded in resin (in this case, graphite fibers embedded in epoxy). Thin layers of the material can be stacked in different ways to meet specific strength or stiffness requirements. Graphite-epoxy is as strong as aluminum but weighs about half as much.
Titanium is as strong as steel and weighs less, although it is not as lightweight as aluminum. It maintains its strength at high temperatures and has better corrosion resistance than steel or aluminum. Despite being expensive, these properties have led to increased usage of titanium in modern aircraft.
Aircraft wings are made from a specific type of aluminum alloy, providing a blend of hardness and strength similar to steel, making them conducive to easy flight. However, scientists from North Carolina State University are exploring what could be a superior material, composed of a mixture of epoxy resin and a compound metallic foam known as CMF.
Use of Composite Materials in Aircraft Structure Manufacturing
The use of composite materials, which have similarly aided in both design and application through computer utilization, has evolved from non-structural applications (such as cabin luggage doors) to the creation of complete aerial structures.
These materials have an added advantage in military technology due to their low observability (stealth) qualities to radar detection.
Some aircraft constructed from composite materials began to emerge in the late 1930s and 1940s. Typically, these materials were plastic-impregnated wood, with the most famous and largest being the construction of Duramold for the Hughes H-4 Hercules (Spruce Goose), an eight-engine aircraft. Some production aircraft used Duramold materials and construction techniques.
During the late 1940s, interest in fiberglass-reinforced materials grew. By the 1960s, sufficient materials and techniques were developed to make widespread use possible.
The term “composite” in this construction method refers to the use of different materials that provide points of strength, lightweight, or other functional advantages when used in a combination that couldn’t be achieved individually.
They usually consist of a resin matrix reinforced with fibers. The resin could be phenolic, epoxy, or polyester, while reinforcement could be a variety of fibers, ranging from glass to carbon and boron, among others.
Additional strength is sometimes added by incorporating a core material, making the structural construction effective. The core could consist of various materials, such as plastic foam (polyester or polyurethane), wood, or honeycomb (multi-cell structures) made from paper, plastic, fabric, metal, and other materials.
The desired final shape, both in terms of external appearance and required internal structure for sufficient strength, can be achieved through various means for composite materials. The simplest involves layering fiberglass sheets, as seen in boat construction, and saturating the sheets with resin.
More advanced techniques involve shaping materials into specific forms using precision machinery. Some techniques require molds, either male, female, or both, while others use vacuum bags that apply atmospheric pressure to shape parts.
The utilization of composite materials opened entirely new avenues for construction, enabling engineers to create parts that are more cost-effective, lighter, and stronger than the previously possible forms made from wood or metal. Similar to the computer, the use of composite materials quickly spread across the industry and will continue to be further developed in the future.
The impact of new technology in computers and composite materials on commercial aviation has been substantial. Larger aircraft like the Boeing 747 and faster aircraft like the Concorde became not only feasible but inevitable. In the field of commercial aircraft, new techniques have led to a range of executive aircraft with more modern features.
These include the uniquely configured Beech Starship, almost entirely made from composite materials, and the Piaggio Avanti, which has a radical configuration, primarily employing metallic construction but incorporating a significant amount of composite materials.
Commercial aviation operations are increasingly using composite materials, following a pattern similar to military services, where large aircraft such as the Northrop B-2 are constructed almost entirely from advanced composite materials.
The legal considerations mentioned earlier have been reviewed alongside developments in computers and vehicles.
The Role of Completely Home-Built Aircraft
Although home-built aircraft have always been a part of the aviation scene (the Wright Flyer was, in fact, a “home-built” aircraft), designs were entirely traditional for many years, often utilizing components from existing aircraft.
Since the emergence of the Experimental Aircraft Association (established in 1953) in the United States, the home-built movement preceded the aviation industry. It pioneered the use of computers and vehicles, especially radical configurations. While many practitioners exist in this field, one man, American designer Burt Rutan, epitomized this transition from backyard tinkering to a leading role. Rutan, from Mojave, California, created a long series of successful designs, reaching the pinnacle of acclaim with the Voyager aircraft, in which his brother Dick Rutan and Jeana Yeager completed an unforgettable non-stop flight around the world in 1986.
Three other areas of civil aviation significantly benefited from these technological advancements. The first is vertical takeoff and landing aircraft, including helicopters. The second is glider aircraft, which reached new levels of sophistication.
The third involves a wide range of gliders, light aircraft, as well as smaller, more advanced human-powered or solar-powered aircraft. Each has been greatly improved through contemporary advancements in design and construction, and each holds great promise for the future.