When you are streaking through the sky at 800 kph, high up at 33000 feet, the temperature outside is -33 degrees centigrade, and the atmospheric pressure is just 2 kg compared to 6.66 kg per square inch on the ground. Yet you are able to pick up a magazine and relax comfortably on your seat in the aeroplane. The skin and structure of the tube that ensures your safety and comfort are made of none other than humble aluminium. The aircraft you regularly travel with is estimated to contain up to 80% aluminium.
Aluminium is the saviour of the aerospace industry. It’s a chemical element in the boron group and is characterized by a silver-white colour and soft and ductile texture. It’s strong, lightweight, and inexpensive. Its high resistance to corrosion and good weight-to-strength-to-cost ratio makes it the perfect material for aircraft construction. Apart from these advantages, the one property that makes aluminium the ideal metal for aircraft construction is its resistance to damage by UV rays.
Steel is stronger than aluminium, but the problem with steel is that it is three times heavier than aluminium. Weight is all important in the manufacture of aircraft. Too much weight restricts an airplane’s ability to take-off and fly. And heavier a plane is, it lessens its carrying capacity and increases fuel consumption.
Historically, aluminium was used for flying even before it was used in the manufacture of aircraft. In the later part of the 19th century, Count Ferdinand Zeppelin used aluminium to make the frames of the famous Zeppelin airships.
When aeroplanes were invented, the Wright brothers built a special engine in which the cylinder block and other parts were made from aluminium, as the existing engines were made with iron and were too heavy.
During World War I and after that, lightweight aluminium began to replace wood as the major component for aircraft manufacture. The German aircraft designer Hugo Junkers built the world’s first full metal aircraft, the Junkers J 1 monoplane, in 1915. Its fuselage was made from an aluminium alloy that included copper, magnesium and manganese.
Interest in aeroplane racing developed in the early 20th century. Racing required more aerodynamic and lightweight machines, which led to the development of the monoplane and all-metal bodies made of aluminium.
Demand for aluminium skyrocketed during World War 2 for manufacturing the thousands of aircraft required waging war. The demand was so high that radio shows were broadcast to encourage Americans to save and contribute scrap aluminium to the war effort in America. Recycling was encouraged and public drives for ‘aluminium foil balls’ offered free movie tickets in exchange.
Since World War 2, aluminium has become integral to aircraft manufacture. The composition of aluminium alloys has vastly improved. Now, aluminium allows designers to build a plane that is as light as possible, can carry heavy loads, uses the least fuel, and is entirely rust-resistant. In the manufacture of modern aircraft, aluminium is used everywhere. Today’s planes use aluminium in the fuselage, the wing panes, the rudder, the exhaust pipes, the door and floors, the seats, the engine turbines, and the cockpit instrumentation. The world’s largest-selling commercial jet, Boeing 737, is roughly made up of 80% aluminium.
With the rising fuel prices, aircraft weight became an even more critical consideration. Reducing weight by one kg saves ~ 0.02 to 0.03 kg of fuel per 1000 km. Now imagine the millions of kilometres travelled by jets across the world in a year and how much fuel can be saved by reducing the weight of planes.
Different types of aluminium with varying alloy compositions are used for manufacturing aircraft-grade aluminium, considering durability and corrosion resistance, strength vs weight ratio and thermal properties. Some aluminium alloys of today:
2024 aluminium alloy:
The most extensively used heat treatable Aluminium alloy, 2024, has good strength and fatigue properties making it suitable for use in aircraft structures and components.
7075 aluminium alloy:
This aluminium has a high strength-to-weight ratio and is used to manufacture fuselages, wings and other structural parts.
6061 aluminium alloy:
This alloy is the most commonly used in aircraft construction. It has good formability, weldability, excellent corrosion resistance, and strength. It is used in many aircraft components, such as engine mounts, landing gear and wheel assemblies.
5083 aluminium alloy:
This alloy is primarily used for constructing fuselages and other structural components due to its high strength and good formability. It also offers excellent corrosion resistance and weldability.
Conclusion
Aluminium is indispensable in manufacturing aircraft that provide mobility, turning the wheels of today’s commerce and business. Apart from aircraft, from humble kitchen utensils to space crafts, the multifarious use of this wonder metal never ceases to amaze.
Anindya Ray: A creative professional from the field of advertising who has worked with Ogilvy One, McCann, Rediffusion and the international digital marketer Wunderman. He made his maiden foray into writing as the author of ‘A Jukebox of Stories’, a compilation of short stories. Dabbles in photography, digital art and is a certified gearhead.