It is easy to admire an aircraft in flight, gliding across the sky, but far harder to imagine the furnace within—jet engines, where fire and metal coexist under extreme conditions, held together by precision and control. More than just a component, the jet engine is one of engineering’s most complex feats, operating at the limits of science and design.
At its core, the idea is simple: to generate thrust. Unlike propellers that push air back with blades, jet engines accelerate air to high speeds and expel it rearwards, creating forward motion through Newton’s third law of motion—every force pushing air back drives the aircraft ahead.
The machination
Most modern jet engines are gas turbines operating on the Brayton cycle, where air is continuously compressed, heated and expanded to generate thrust. The process unfolds in four stages: intake, compression, combustion and exhaust.
Air enters through the intake and is compressed by rotating blades, then is directed into the combustion chamber, where fuel is ignited to produce high-energy gases. These gases expand, spin the turbine and are expelled at high speed to generate thrust, while the turbine powers the compressor to sustain the cycle.
A large share of the turbine’s energy drives the compressor, making efficiency critical. Inside the turbine, temperatures exceed 1,500°C, exposing components to extreme heat, pressure and stress. To withstand this, turbine blades are made from single-crystal superalloys, coated with thermal barriers and designed with internal cooling channels, making them among the most advanced metal components ever engineered.
Evolution
The development of jet engines mirrors the growth of modern aviation, driven by the pursuit of speed, altitude and control. From early turbojets of World War II to today’s systems with digital controls, stealth features, thrust vectoring and supercruise, each generation pushes the boundaries further.
Independently developed in the 1930s by Frank Whittle and Hans von Ohain, jet engines replace piston-propeller systems that struggle at higher speeds. This shift allows aircraft to fly higher and faster.
In commercial aviation, aircraft such as the de Havilland Comet and later the Boeing 707 make long-distance travel faster and more accessible. However, early turbojets suffer from high fuel consumption, noise and heat. These limitations lead to turbofan engines, which improve efficiency by routing additional air around the engine core.
Modern fighter jets rely on low-bypass turbofans that balance speed and efficiency, often equipped with afterburners for short bursts of thrust. More specialised technologies, including ramjets and scramjets, are designed for supersonic and hypersonic speeds.
Harder than it looks
Despite steady progress, jet engine development remains one of the most demanding tasks in engineering. It requires the integration of multiple disciplines into a system that must perform reliably under extreme temperatures, pressures and speeds, where even minor deviations can lead to failure.
Brahmini, CEO of GMach, a company working on indigenous micro turbojet engines for UAVs and target drones, says a jet engine is a highly integrated system. The compressor, combustor, turbine and nozzle are deeply interdependent.
“These are not independent units but tightly interlinked components, where the behaviour of one directly influences the performance of the others. Even a minor deviation in one section can cascade through the system, affecting efficiency, stability and safety. The real challenge, therefore, is not just designing individual components, but ensuring that all of them function seamlessly as an integrated whole,” she says.
Metallurgical challenges
At the heart of this complexity lies the interaction between materials and extreme environments.
According to Dr G.D. Janaki Ram, Professor of Materials Science and Metallurgical Engineering at IIT Hyderabad, turbine blades represent the pinnacle of materials engineering, made from single-crystal superalloys through sophisticated processes.
Jet engines use thousands of specialised components tailored to different conditions—nickel-based superalloys in the turbine for heat resistance, titanium alloys in the compressor for strength and weight, and aluminium and composites in intake and fan sections. Temperatures can reach 1,500–1,600°C, while pressure peaks in the compressor, requiring precise material selection. The combustion chamber must resist oxidation and corrosion, while the turbine endures the highest thermal and mechanical loads.
Single-crystal technology improves durability by eliminating grain boundaries, but producing these components is complex, requiring precise processes such as the Bridgman technique to control solidification.
Testing infrastructure is equally important, says Brahmini. “Every component must undergo rigorous validation under simulated operating conditions, often multiple times, before it is approved for integration into the engine.” She notes that countries leading in jet engine technology build expertise over decades through repeated testing and failure cycles. India, which starts later, lacks this depth of data but is progressing through expanded testing programmes and improved instrumentation.
Testing remains a major challenge, as engines must be validated under extreme conditions to meet strict safety standards. Strengthening this ecosystem is crucial, and India is investing in it.
India’s long journey
For India, the development of jet engines remains an unfinished effort. While the country advances in space, missiles and aircraft manufacturing, engine technology continues to lag due to the need for a complex ecosystem of suppliers, research, metallurgy and testing.
The Kaveri engine, developed by GTRE under DRDO, is sanctioned in 1989 with a 1996 deadline, later extended to 2009.
As noted by then Defence Minister Manohar Parrikar in a 2015 Rajya Sabha reply, delays are caused by technological complexity, lack of critical materials, limited infrastructure, shortage of skilled manpower and an expanded project scope. The programme costs about `2,700–2,900 crore but fails to achieve the required afterburner thrust of 81–82 kN for the Light Combat Aircraft Tejas. A derivative “dry” engine is now planned for unmanned systems.
Certification adds further complexity, as components must meet strict airworthiness standards. Coordination also remains a challenge, with expertise spread across institutions.
Unistring Tech Solutions MD Nagendra Babu Samineni says early challenges stem from limited access to advanced materials and an underdeveloped precision engineering ecosystem. Despite multiple prototypes and extensive testing, a thrust shortfall of about 10–12% means the engine is not selected for the LCA programme. He also points to the lack of critical infrastructure, such as high-altitude test facilities and flying test beds, which forces reliance on foreign facilities.
Strategic importance
Dependence on foreign engine manufacturers creates strategic vulnerabilities, as supply delays and geopolitical factors affect access to components, upgrades and maintenance.
Nagendra Babu says, “We should not depend on foreign partnerships to develop core technologies. Companies will always protect their commercial interests.” He calls for an indigenous ecosystem involving public sector units, private industry and global Indian talent, adding, “India has brilliant engineers and scientists. We should create a national consortium, attract top talent even from abroad and give them the resources, funding and time needed.”
The implications extend beyond technology. A country that cannot build its own jet engine cannot fully control its fighter aircraft programme, as engines determine performance and remain subject to supplier restrictions. This capability remains concentrated among a few countries, including the United States, the United Kingdom, France, Russia and increasingly China, with manufacturing dominated by firms such as General Electric, Pratt & Whitney, Rolls-Royce, Safran, Klimov and Saturn.
And in the end, the story of jet engines is not just about the machine, but a test of patience, precision and persistence. For India, the challenge is less about catching up and more about building from within, piece by piece, until the gap between ambition and capability finally disappears.