It is ironic that talks about HAL manufacturing Tejas MK2 shortly are floating around, even as HAL has defaulted on its scheduled delivery of Tejas MK1 and Tejas MK1A, not once but twice, despite the Final Operational Clearance (FoC) by the Indian Air Force (IAF). The prolonged delay might cost the state-owned defence firm dearly, thanks to the steep hike in the price of the composite materials required to manufacture the fighter jets.
Weary of the delay, the first time around, when the IAF decided to monitor the production line all by itself, the production of Tejas finally fell in line. However, there is yet another
delay now, but the reason is different– the escalating price of composite materials used to build the fighter jets.
What exactly is a composite?
A composite is a material made from two or more materials of dissimilar properties, that, when combined, make the resultant material stronger than the individual materials by themselves. Simply put, composites are a combination of components.
Most composites are made of just two materials. One is the matrix or binder. It surrounds and binds together fibres or fragments of the other material, called the reinforcement.
For instance, wood, a natural composite, is a combination of long fibres of cellulose (a very complex form of starch) held together by a much weaker substance called lignin. Although lignin is weak in itself, its binding capacity is very high and hence it acts as a natural glue that binds and stabilizes the cellulose fibres. Cellulose is also found in cotton and linen, but it is the binding power of the lignin that makes a piece of timber much stronger than a bundle of cotton fibres.
The bones in our body are also a composite. It is made from a hard but brittle material called hydroxyapatite (mainly, calcium phosphate), and a soft and flexible material called collagen (a protein). Collagen is also found in our hair and fingernails. On its own, it would not be of much use in the skeleton, but when combined with hydroxyapatite it gives the bones the properties that are needed to support the body
Composites are also developed by men in labs. An example of a man-made composite would be plywood. Another simple example of man-made composites is concrete. Here the aggregate (small stones or gravel) is bound together by cement. Concrete has good strength under compression, and it can be made stronger under tension by adding metal rods, wires, mesh or cables (i.e., creating reinforced concrete).
The first modern composite material was fibreglass. It is still widely used today in boat hulls, sports equipment, building panels and many car bodies. The matrix is plastic, and the reinforcement is glass shredded into fine threads and often woven into a sort of cloth. On its own, the glass is very strong but brittle, and it will break if bent sharply. The plastic matrix holds the glass fibres together and also protects them from damage by dispersing the forces acting on them.
Some advanced composites are now being made using carbon fibres instead of glass. These materials are lighter and stronger than fibreglass but more expensive to produce. They are used in aircraft and expensive sports equipment such as golf clubs.
The new Airbus A380, the world’s largest passenger airliner, incorporates modern composites in its design. More than 20 per cent of the A380 is made of composite materials, mainly plastic reinforced with carbon fibres. The design is the first large-scale use of glass-fibre-reinforced aluminium, a new composite that is 25 per cent stronger than conventional airframe aluminium and also 20 per cent lighter.
Why use composites?
The most significant advantage of modern composite materials is that they are light in weight yet strong. An optimal combination of matrix and reinforcement material can yield new materials to suit the requirements of a particular application. Composites also provide design flexibility because most of them can be moulded into complex shapes. The downside is often the cost. Although the resulting product is more efficient, the raw materials are quite expensive.
The DRDO laboratories in Pune, Hyderabad and Bengaluru have been working on creating composites for the last two decades. The aerospace-related product development by DRDO, CSIR and ISRO labs took the lead in establishing manufacturing industries and processes for product development. Some examples include carbon fibre reinforced bridges of different spans for the army that are 40 per cent lighter in comparison to their metallic counterparts. Besides, glass fibre-reinforced armoured vehicle hulls comprising integral ceramics armour have been developed. Composite materials are fast replacing traditional materials in design, and end products in the industrial sectors. Easily accessible and reliable, the composite elements are playing a pivotal role in the aerospace and defence sector.
Though composites are triggering a revolution, they have also become a bane to the defence manufacturing sector, thanks to the increase in import duty and the supply chain disruption of the specialised materials during the Covid 19 pandemic. Shipment costs rose sharply, besides, most composite raw materials need to be transported and stored in 20° C freezers. Moreover, composites come with an expiry date and if not used within the stipulated time, result in massive losses.
Indigenous development and manufacture of weapons, especially in Defence, is associated with high performance. And composites are being used to make our defence weaponry stronger. They are currently in use in many Indian weapons programmes. The airframe of the Light Combat Aircraft (LCA), superstructures of naval vessels, and components for various strategic and non-strategic missile systems are a few examples.
According to sources, 463 vendors in the LCA programme – supplying carbon wing skins, forward fuselage, flaperons, rudder, keel beam, front fairing, upper fuselage shells, crown and side panels – are already struggling with the increase in raw material costs, which has risen between 30-100 per cent. This will in turn increase the delivery time twofold. An additional challenge is that HAL’s LCA assembly line has still not matured enough. Since each aircraft is not a replica of the previous one, the components have a different iteration each time and it goes through the full operational capability stage.
The Light Combat Aircraft (LCA) uses 45 per cent of carbon composites which now is a matter of great distress as the first batch of the composites is expected to be delivered only by February 2024. Each LCA Mk1A uses 2.24 tons of composites; 23.1 tons for submarines, 945 kg for helicopters, and 640 kg for UAVs, according to a KPMG report on military materials. Multi-functional composites are used for armour application. Aerospace composites with functional features such as radar transparency, stealth, etc., are also being developed indigenously.
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