By Deepak Mathur
Aviation World; March-April 21 Being lighter, yet stronger and offering high resistance to corrosion are the properties that make aluminium – metal of the past, present and future. In a world that is changing rapidly and turning many a leaf by using technology and working for a cleaner world of tomorrow.
As far as relationships go, aluminium and its usage in the aerospace industry is a bond that has aged. It dates back in time to the 19th century and is well-documented that the first use of aluminium in aerospace was in making frames by the famed Count Ferdinand Zeppelin in his ‘airships.’

An Old Historic Relationship

The historic relationship between aluminium and aerospace also finds a place in the Wright Brothers story. The cylinder block and some other parts of the Wright Flyer in 1903 are known to have been made with aluminium making it lighter yet stronger to achieve a successful take-off. Aluminium against a wooden frame that was in vogue during that time ensured that the aircraft design despite of the low wind-speed availability and limited aerodynamics lifted off with the intended weight. And it did.

Meeting the Demand

For another decade, the absorption of aluminium in aerospace was slow. It gathered pace between the two World Wars. Aluminium alloys became an ideal option as racing aircraft became a rage in Europe and America in 1920’s. In the absence of maintenance and care, they wouldn’t rot and cause splinters like wood. And just like that wood lost its charm and aluminium alloy began its journey by meeting the demand.
Replacing wood was easy. There was a significant and healthy weight loss in an aircraft on account of using aluminium alloys. Being one-third lighter metal than steel gave manufacturers the capability to carry more weight or improve fuel efficiency. Given aluminium’s strength, the reliability and manufacturing costs involved in an aircraft also increased.

New materials: Aluminium Alloys

The Boeing 737, popular narrow-body aircraft in use across the globe and in India, comprises of 80 per cent aluminium alloys in its making. It’s lighter, but strong and has high corrosion resistance. This remains the foundation of aluminium’s popularity despite the sophistication in modern-day aviation.
There are new materials of aluminium alloys that have contributed to changing the landscape over time. Aluminium alloys are being used in making the aircraft fuselage or body, wingspans, doors, flooring, and even the seats that we as passengers are seated on.
Having also made it to space through various exploration programmes, there is no doubt that the confidence in aluminium alloys will continue into the next generation of aircraft since performance characteristics have been established, costs of fabrication have been set along with modern production facilities capable of meeting the demand.

Aluminium alloys v/s Composite material

Today, aluminium’s usage in aerospace comes with its combination of various alloy elements. For instance, when the need calls for a high strength to weight ratio and the alloy has to be tough and yet offer workability it is combined with copper or zinc, which is the most common alloy used in aerospace today. These alloys are generally found in the wingspans and fuselage given the tension that these parts have to withstand.
Aluminium alloys form part of traditional while composite materials are a fairly new entrant so to speak. Both have their strengths but aluminium being the big brother is much more established in its advantages. The aluminium alloys offer a cheaper deal given the established manufacturing and pricing process, while composite material is prone to degradation from ultraviolet rays, unlike aluminium alloys which are not.

Aerospace: The future & use of aluminium alloys

Innovation holds the key to the future and the development of new generation aluminium alloys are not lagging. If zinc is the present for aluminium alloys, the future is also in the making using aluminium-lithium alloy. Some research reports indicate that aluminium-lithium alloy or Al-Li alloys offer a 10 per cent weight reduction in comparison to using composites in aircraft.
With the industry continuing to gain from using aluminium alloys in providing for a safer, reliable flight and keeping aircraft manufacturing low, the future and use of this versatile metal are poised for a long flight into the future.

(The author is Sr. Vice President – Sales and Marketing at Jindal Aluminium Limited. Views expressed are personal.)