It may not be a missile, fighter aircraft or drone, but India's next major defence achievement could be in the form of a new engine. It could be a sheet of glass.Defence Research and Development Organisation and CSIR-Central Glass and Ceramic Research Institute are working on a ₹50-crore programme to develop an indigenous transparent armour system which could cut down the thickness and weight of conventional bullet resistant glass by 30-50 per cent. The four-year programme is in advanced stage and is in collaboration with DRDO's Terminal Ballistics Research Laboratory and Naval Materials Research Laboratory.

That's no mere cosmetic cut. One of the harshest limitations of an armoured vehicle is weight. Each extra kilogram put into protecting the vehicle has an impact on its acceleration, range, fuel usage, suspension, weapons, ammunition, and electronic-warfare equipment and sensors.

Transparent armour is a particularly tricky engineering challenge. A typical armoured hull can use opaque steel, ceramics and composites. The rest of the crew, however, still have to look out. Windows therefore must be transparent and able to absorb huge amounts of impact energy without letting projectiles or dangerous fragments penetrate the protected area.

The Indian programme tackles that issue by using nanometer-sized crystals embedded in a designed glass matrix form a material known as glass-ceramic. Controlled crystallisation is used to develop a product that would be transparent yet have significantly higher strength and toughness than normal glass.

First ballistic tests are an important proof of concept. The material prevented rounds fired from a Tricky Assault Rifle with ballistic characteristics similar to an AK pattern rifle from penetrating the material at DRDO's TBRL facility at Chandigarh. The bullets have been reportedly shot from 10 metres at about 695 metres per second. Protection ultimately to be aimed for is at BIS Level V and VI including specified rifle threats.

The most important part is multi-hit testing. Battlefield protection should continue to be of value following the initial impact where cracking and structural damage may make a transparent armour panel much more susceptible to the next round. Scientists are thus required to show not only hardness, but also to show damage that can be controlled and crack resistance as well as ongoing protection after repeated impacts.

The international research has been going on on the weight issue for years. ALON (aluminium oxynitride), magnesium aluminate spinel and sapphire are transparent ceramics that have proven to offer significant benefits over conventional glass laminates. There is published material research suggesting that advanced transparent ceramic architectures could lead to a potential reduction in armour weight, or thickness, of approximately 30 to 60 per cent as a function of the threat and configuration. Other experimental systems have demonstrated similar ballistic protection densities at densities less than half that of traditional glass systems.

India is thus not coming up with a unique idea of lightweight transparent armour. Its strategic opportunity is the development, domestication, qualification against Indian standards, the mastery of repeatable manufacturing and eventually the ability to produce large panels economically at scale.

With twice the capability and often better quality, advanced ceramics can prove very impressive in the lab but can be costlier and very hard to make consistently. There are many critical requirements for the production of large, transparent panels, such as composition, crystallisation, optical quality, internal defects, bonding and finishing. An imperfection in the manufacture of the glass that is too small to notice when using a pair of glasses can be deadly serious if required to take gunfire when on a rifle.

DRDO, therefore, plans to include an industrial partner in the programme for mass production. The choice of material may be as important as the actual choice of a decision. Defence self-reliance is not realised through the survival of a prototype. This is accomplished when Indian industry can produce hundreds or thousands of identical units, guarantee their quality, rapidly and easily repair and replace them on deployed platforms, without relying on an overseas supplier.

The economics of the programme has also undergone a complete overhaul. India's defence production for FY25-26 stood at a record ₹1.78 lakh crore, a 15.6 per cent rise from the previous year's ₹1.54 lakh crore. About 24 per cent (around ₹42,000 crore) came from private companies. Defence exports also hit a new high of ₹38,424 crore, up 62.66 per cent from a year ago.

Armoured land vehicles are the first application, but there are more technological possibilities. Possible applications include protection for critical-security installations, transparent protection for aircraft and naval platforms, and protection for observation systems. The requirements will vary significantly across platforms, and the vehicle armour cannot be directly applied to an aircraft window, but a good grasp of the materials science gives scope for further development.

Materials that are seldom publicized, but play a vital part in modern military power, are in the form of specialised alloys, ceramics, semiconductors, energetic compounds, carbon composites, optical materials and high-temperature coatings. A country may build complex platforms and yet still be externally dependent, due to the fact that the platform's critical materials are imported.

This is merely the beginning and not the end for India's defence-industrial ambition, which is to replace foreign finished weapons with Indian finished weapons. The more profound goal must be mastery of the materials, manufacturing processes and IP rights of which those weapons are made.

The amount of ₹50 crore spent on the bulletproof glass programme is small compared to that of combat aircraft, submarine or missile programmes. But, strategically, it is all the reason it should be paid attention to.