DALLAS — The 1903 Wright Flyer bore a wooden frame and muslin fabric wings. While these materials served the world’s first airplane well, modern aircraft need something a little more reliable.
Today, high-strength composites and alloys of titanium, aluminum, and steel are some of the most common materials used in aerospace design. Additionally, engineers are hard at work on innovative new products, and they could change human flight as people know it.
How Modern Materials Help the Aerospace Industry
Space exploration and commercial aviation have changed considerably since their inception. The materials used in aerospace have advanced the industry in many ways, including the following.
In the 1980s, American Airlines (AA) famously removed one olive from its in-flight salads, saving $40,000 a year in both food and fuel costs — and passengers did not seem to notice or care. Along the same lines, lighter building materials make for lighter aircraft, saving fuel and allowing planes to carry more passengers and cargo.
Improving Passenger Comfort and Safety
Better materials reduce airplane cabin noise and vibration levels, leading to a smoother, more comfortable ride for everyone on board. Improved insulation keeps the cabin warm even at 35,000 feet. New materials that strengthen aircraft can also make them safer for passengers and crew.
Withstanding Harsh Conditions
Better corrosion resistance and higher thermal protection give modern aircraft an edge over their predecessors. Probes can reach farther into space, and planes can fly higher than ever. New materials, like silicon carbide, could also coat the interior of rocket engines to allow them to reach higher temperatures without melting.
Factors for Choosing Materials
Many historic aerospace materials no longer have a use in the industry. For example, wood has fallen out of favor due to its ability to rot, inconsistent weight, and susceptibility to insect damage. Instead, engineers look for strong, human-made materials, evaluating each one based on factors such as:
- Function: How and where will the material be used?
- Production: How easy is it to manufacture the material? Is it consistently available and easy to acquire?
- Properties: A material’s corrosion resistance, reaction to environmental heating, strength-to-weight ratio, toughness, and stiffness all influence how it performs under pressure.
One of the most important material properties is lightness. Reducing a component’s density leads to a more fuel-efficient plane with better climb rates and G-force loading. Studies have found reducing weight is three to five times more effective than increasing stiffness or strength.
The Most Common Materials Used in Aerospace
Today, a handful of materials dominate the aerospace industry.
Composites combine two or more materials to reap the benefits of each one. The most common composite materials used in aerospace are aramid, carbon fiber, and composite glass, and they have countless uses.
For example, G10, an epoxy-glass composite, is resistant to chemicals, UV light, and heat below 140°C, making it useful for aircraft panels and wiring. Aramid is a class of synthetic polymers that can reduce accidental damage to engine pylons. Carbon fiber composites are up to 60 times stronger than steel and make up much of an aircraft’s fuselage, wings, and tail.
Other applications for composites include propellors, single-aisle wings, wide-body wings, brackets, interiors, nacelles, and engine blades.
- Aluminum Alloys
Pure aluminum was once widely used in aerospace. Today, it is more common for engineers to combine aluminum with another metal to create a versatile alloy, although elemental aluminum still finds many uses. Common aluminum alloys and their applications include:
- 2024: Aircraft skins, repair and restoration
- 3003: Cowls and baffle plating
- 5052: Fuel tanks
- 6061: Aircraft landing mats and other structures that stay on the ground
- Steel Alloys
Stainless steel alloys are the most common use for aerospace-grade steel. The material is extremely tough and resistant to corrosion, high temperatures, and wear while still being lightweight. It is cost-effective and can withstand large impacts and high stress for years. Typical applications for steel alloys include fuel tanks, exhaust ducts, engines, and landing gear.
- Titanium Alloys
Another common alloy is titanium, which boasts an excellent strength-to-weight ratio and holds up well in outer space. It is highly corrosion resistant and can operate from sub-zero to over 600°C temperatures.
The most commonly used titanium alloy in aerospace is Ti-6Al-4 V, which is so popular that it accounts for over 40% of the world’s titanium alloy market share. It is critical for building landing gear, hydraulic systems, firewalls, airframes, and helicopter exhaust ducts, among many other applications. Titanium alloys are also useful for engine parts such as blades, plug and nozzle assemblies, shafts, discs, and casings.
Materials of the Future
Advances in engineering have led to breakthroughs in material design. New materials that show promise for the aerospace industry include the following.
- Metallic Microlattices
Researchers from HRL Laboratories, the University of California, Irvine, and Caltech announced their creation of this material in 2011. A metallic microlattice is a springy, ultra-lightweight foam made from metal and is one of the lightest structural materials in existence.
A metallic micro lattice is extremely strong and has potential uses in battery electrodes and catalyst support, vibration insulators, and thermal insulators. Engineers built the prototype from a nickel-phosphorus alloy, but they could potentially make microlattices from other metals.
- Silicon Carbide
Rocket engines already get hot enough to melt steel, but they need to be even hotter to power advanced spacecraft. Scientists from the NASA Glenn Research Center and Rice University have invented fuzzy silicon carbide fibers that look similar to wool.
The fibers are much stronger than straight threads, helping them resist damage under high heat and pressure. Someday, these silicon carbide fibers could line the inside of aircraft engines to allow greater combustion temperatures.
Another material that shows promise in the aerospace industry is graphene — the same material used to make pencils. This compound is composed of thin sheets of carbon atoms that sit on top of one another.
Graphene’s shape makes it a great electrical conductor, and it is lightweight, strong, and flexible. It can be used in de-icing systems, as a component of paint, and in aircraft fuel systems to remove water from fuel tanks. Although it is expensive, many engineers are looking to graphene as a promising material to build lighter aircraft.
The Sky Is the Limit
Advances in engineering have allowed the aerospace industry to take off in recent years. The materials used in aerospace continue to evolve, creating new opportunities for space exploration, shipping, and travel. Future aircraft may look much the same as they do now, but they will be miles ahead of their modern counterparts.
Featured image: Boeing