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Indigenous combat jets and Kaveri turbofan engine: All About IAF's new aerospace plan


Apr 28, 2011
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Indigenous combat jets and Kaveri turbofan engine: All About IAF's new aerospace plan​

As the deal to procure 114 foreign fighter jets (dubbed as MMRCA 2.0) progresses, simultaneous efforts are also being made towards acquisition of indigenous fighter aircrafts for filling up the gaps.​

Amartya Sinha
Amartya Sinha
New Delhi,UPDATED: May 16, 2023 23:13 IST

India’s future Twin-engine Medium Class Omni-Role Combat Aircraft (ORCA) fighter is also in the works. (File photo: AFP)

By Amartya Sinha: It is a widely endorsed fact that aerospace is the domain of the future and the one who controls it, will also control the planet. As of 2023, the Indian Air Force (IAF) has a combined strength of 31 squadrons. A total of three MiG-21 Bison squadrons will be retired by 2025.

With the addition of three Sukhoi-30MKI squadrons and two LCA-Tejas Mark-1 squadrons this year, the IAF will somehow be able to make up its strength for the retiring jets and maintain up to 33 combat jet squadrons.

An additional squadron of Jaguar deep penetration strike aircraft will also retire by 2027, thus bringing down the combined strength to 32 squadrons. So, there will be a total shortfall of 10 combat squadrons by 2030, if additional fighter jets are not ordered immediately.

Meanwhile, as the deal to procure 114 foreign fighter jets (dubbed as MMRCA 2.0) progresses, simultaneous efforts are also being made towards the acquisition of indigenous fighter aircraft for filling up the gaps. Technology-intensive air power requires faster replacement of assets due to quicker obsolescence.

While IAF has a Plan-B to fight with what it has, if forced into conflict, but numbers are clearly not adequate to fully execute an air campaign in a two-front war scenario. It is imperative of time that the IAF quickly rebuilds the squadron strength and acquires modern fighters that are as good or better than the adversaries.

Developing indigenous aircraft is critical for India to become a global power. China has already moved way ahead. The Light Combat Aircraft- Tejas and the Advanced Medium Combat Aircraft (AMCA) are the main two indigenous combat aircraft projects and it is important to continuously monitor their progress.


The LCA-Tejas was originally envisaged as a fourth-generation combat jet and the AMCA is meant to be a fifth-generation fighter. Fourth-generation fighters are mostly multi-role. These jets use ‘energy-manoeuvrability’ concept for performing ‘fast transients’- quick changes in speed, altitude, and direction- as opposed to just high speed; lightweight aircraft with higher thrust-to-weight ratio, and use digital Fly-By-Wire (FBW) flight controls which allow relaxed static stability flight and in turn agility.

These planes have electronically managed powerplants. Pulse-Doppler fire-control-radars give look-down/shoot-down capability. Head-up displays (HUD), hands-on-throttle-and-stick (HOTAS) controls, and multi-function displays (MFD) allow better situational awareness and quicker reactions. Composite materials help reduce aircraft weight. Improved maintenance design and procedures reduce the aircraft turnaround time between missions and generate more sorties. The F-16, F-18, MiG-29, SU-30 MKI and Mirage-2000 are all in this category.

A sub-generation called the 4.5th generation fighters evolved in the last two decades, which saw advanced digital avionics, newer aerospace materials, modest signature reduction, and highly integrated systems and weapons. These fighters operate in a network-centric environment. Key technologies introduced include a multi-function active electronically scanned array (AESA) radars; longer range BVR AAMs; GPS-guided weapons, solid-state phased-array radars, helmet-mounted display sights (HMDS), and improved secure, jamming-resistant data links.

A degree of supercruise ability (supersonic without afterburner) was introduced. Stealth characteristics focused on front-aspect radar cross section (RCS) reduction through limited shaping techniques. Eurofighter Typhoon, Dassault Rafale and Saab JAS 39 Gripen were in this category. Many 4th generation aircraft were also upgraded with new technologies. Su-30MKI and Su-35 featured thrust vectoring engine nozzles to enhance manoeuvring.

The fifth generation was ushered in by the Lockheed Martin/Boeing F-22 Raptor in late 2005. These aircraft are designed from the start to operate in a network-centric combat environment and to feature extremely low, all-aspect, multi-spectral signatures employing advanced materials and shaping techniques. AESA radars are with high-bandwidth low-probability of intercept. IRST and other sensors are fused in for situational awareness and to constantly track all targets of interest around the aircraft at a 360-degree bubble.

Advanced avionics and glass cockpit, and improved secure, jamming-resistant data-links are other features. Avionics suites rely on extensive use of very high-speed integrated circuit (VHSIC) technology and high-speed data buses. Fifth-generation fighters target “first-look, first-shot, first-kill capability”. In addition to high resistance to ECM, they can function as a ‘mini-AWACS’. Integrated electronic warfare systems, integrated communications, navigation, and identification (CNI), centralised “vehicle health monitoring”, fibre-optic data transmission, and stealth are important features. Manoeuvring performance is enhanced by thrust-vectoring, which also helps reduce take-off and landing distances.

Super-cruise is inbuilt. To maintain low radar cross signature (RSC), the primary weapons are carried in internal weapon bays. The current fifth-generation fighter projects include Lockheed Martin F-35 Lightning II, Russia‘s Sukhoi PAK FA (SU-57), China’s Chengdu J-20 and Shenyang J-31, and India’s AMCA. Japan is also exploring the technical feasibility to produce fifth-generation fighters.


IAF has committed to inducting 200 Tejas Mark-2 aircraft, taking the total requirement of Tejas to over 300 over the next 15 years. Tejas Mark-2 was originally planned to retain basic aircraft shape and incorporate the larger and more powerful 98 Kilonewton thrust GE F-414 engine, which was more likely to meet the originally agreed specifications of Tejas.

This would have meant a significant change to the air inlets and also the aircraft dimensions and weight would have to increase. At Aero India-2019, ADA unveiled a new model of the Tejas Mark-2, and called it a Medium Weight Fighter (MWF). This aircraft was expected to fit into IAF’s requirement for the Medium Multi-Role Combat Aircraft (MMRCA). This enhanced version of Tejas, the Tejas Mark-2 MWF would be 14.6-metre-long with a wingspan of 8.5 metres (compared with 13 metres and 8.2 metres for the Tejas and 14.36 metres and 9.13 metres for Mirage 2000 respe

The aircraft will have a compound delta-wing with close-coupled canards. This would reduce drag in all angles of attack it was announced. The longer fuselage will allow for more fuel behind the cockpit. The Tejas Mark-2 would carry much more internal and external fuel. The maximum weight of the plane would be around 17.5 tonnes (compared to Mark-1’s 13.5 tonnes). Its external stores carrying capacity will also increase from 5.3 to 6.5 tonnes. It will be equipped with a higher thrust General Electric GE-F414-INS6 turbofan engine that features a Full Authority Digital Electronics Control (FADEC) system.

The Tejas Mark-2 will also feature an indigenous integrated life support system-onboard oxygen generation system (ILSS-OBOGS) weighing 14.5 kg, a built-in integrated Electro-optic electronic-warfare suite among other improvements to avionics. It will have an infrared search and track (IRST) system and a missile approach warning system (MAWS) and a modern AESA radar.

An increase in payload capacity to 6.5 tonnes and an increased number of weapons stations from seven to 11, will allow the MWF to carry more weapons. It is said to be designed for a swing role, with BVR and close-combat capability, and precision strike.

Beyond the Tejas programme, the AMCA- India’s fifth-generation fighter, can only move forward once the Tejas Mark-2 design is frozen. The realistic first-flight timeline would be around 2028. The aircraft may be inducted into the IAF around 2034-35. In any case, HAL will require at least 7-8 years to deliver the 123 Mark-1 and Mark-1A jets.


The Indian Navy has issued a Request for Information (RFI) with reference to the possible acquisition of 57 naval multirole fighter jets. However, despite rejecting the Tejas initially for being overweight, the Navy restarted testing with the NP-2 (Naval Prototype-2) in August 2018, with the first mid-air refuelling being held in September 2018.

The experience gained in operating the naval prototype will help in proving input to the development of a twin-engine deck-based fighter (TEDBF) aircraft. The TEDBF will be powered by two General Electric F-414 turbofans and will carry heavier payloads with greater range.


As per reliable sources, India’s future twin-engine Medium Class Omni-Role Combat Aircraft (ORCA) fighter is also in the works. Some of the planned features for this platform are the canards, diverterless supersonic inlet, conformal wing root tanks/containers, a larger number of hard points, and an option for folding wingtips.

It will weigh around 23 tonnes. An ambitious timeline of maiden flight in 2026 and production start in 2030 are being spoken of.


The AMCA is a fifth-generation fighter aircraft being designed by ADA and will be manufactured by HAL. It will be a twin-engine, all-weather multirole fighter. It will combine super-cruise, stealth, advanced AESA radar, super manoeuvrability and advanced avionics. The jet is meant to replace the Jaguar and Mirage 2000 aircraft and complement the Sukhoi-30 MKI, Dassault Rafale and LCA Tejas in the IAF and MiG 29K in the Indian Navy.

On April 4, 2018, the then Defence Minister Nirmala Sitharaman told parliament that the feasibility study of the programme had already been completed and the programme has already been given the nod by the IAF to initiate the AMCA technology demonstration phase before launching the full-scale engineering development phase.

Earlier, in October 2008, IAF had asked the ADA to prepare a detailed project report for a next-generation medium combat aircraft. In April 2010, IAF issued the ASQR for the AMCA, which placed the aircraft in the 25-tonne class. The first flight test of the prototype aircraft was originally scheduled to take place in 2017.

DRDO proposed to power the aircraft with two GTX Kaveri engines. In October 2010, the government released Rs 100 crore to prepare feasibility studies. Meanwhile, in November 2010, ADA sought Rs 9,000 crore to fund the development which would include two technology demonstrators and seven prototypes. ADA unveiled a 1:8 scale model at Aero India-2013. The AMCA design will have shoulder-mounted diamond-shaped trapezoidal wings and an all-moving canard-vertical V-tail with a large fuselage-mounted tail-wing. It will be equipped with a quadruple digital fly-by-optics control system using fibre optic cables.

The reduced radar cross-section (RCS) would be through the airframe and engine inlet shaping and the use of radar-absorbent materials (RAM). AMCA will have an internal weapons bay, but a non-stealthy version with external pylons is also planned.

Low-speed and supersonic wind tunnel testing and Radar Cross Section (RCS) testing were reportedly completed by 2014, and the project definition phase by February 2014. The Engineering Technology & Manufacturing Development (ETMD) phase was started in January 2014 after HAL Tejas attained IOC, and it was announced that the AMCA will have its first flight by 2018.

At Aero India-2015, ADA confirmed that work on major technological issues, thrust vectoring, super-cruising engine, AESA radar and stealth technology was going on at full swing. Russia was to support for the development of Three-Dimensional Thrust Vectoring (TDTVC), AESA Radar and stealth technology. Saab, Boeing and Lockheed Martin also offered to help with key technologies.

AMCA will initially fly with two GE-414 engines. Eventually, it is planned to be powered by two GTRE, 90-kilonewton thrust, K-9 or K-10 engines which are successors to the troubled Kaveri engine. France has offered full access to the Snecma M-88 engine and other key technologies, and the United States offered full collaboration in the engine development with access to the GE F-414 and F-135.


Two technology demonstrators and four prototypes were scheduled to go under various types of testing, and analysis in 2019. The ground reality is that they are far from it. As of 2022, the defence ministry was seeking approval from Cabinet Committee on Security (CCS) to go ahead with the prototype development phase. AMCA is intended to be a test case for fundamental Indian research in the unfamiliar field of cutting-edge aviation. DRDO’s Aeronautical Development Agency (ADA), had earlier announced the targeted first flight of AMCA by 2020, and production by 2025, but has now revised the maiden flight to 2026.


The Indian Navy first got ‘involved’ in the AMCA project in March 2013 when it formally asked the DRDO/ADA if they were planning a naval version of the proposed jet. They were looking at it in relation to the upcoming indigenous aircraft carrier- IAC-2. The navy has already sought 57 aircraft of MMRCA-2.0 class. Naval AMCA (NAMCA) timeshares will match IAC-2 they feel. The Navy’s requirements were sent to DRDO on September 7, 2015. They have suggested a separate team for NAMCA development.


Unsure of indigenous capability, India has informed the foreign vendors of the MMRCA-2.0 programme that the nation’s quest for fighters would need commitments towards the AMCA. In anticipation, most vendors have set up joint ventures with Indian defence majors and set up research and manufacturing facilities. IAF is fully supporting the project but hopes that the timelines stated are realistic because otherwise it upsets its procurement cycles.

In any case, IAF’s 114 Make-in-India fighters will partly act as a cushion for delays. Meanwhile, DRDO has been discussing with Indian defence companies including Tata, Mahindra Defence, Larsen & Toubro and many smaller specialised firms for workshare for AMCA. Part of the private Indian industry is already doing major fabrication work for defence majors like Lockheed Martin, Boeing, Airbus, BAE Systems and others.

Technologically, the AMCA is a project that runs concurrent to India’s Ghatak stealth unmanned combat aircraft. Many laboratories are researching common technologies for both platforms, including shape, stealth, network-centricity, sensors and materials.


The turbofan engine is considered the most vital component of a jet aircraft without which it simply can’t take to the skies. A turbofan-based powerplant provides the requisite thrust to aerial combat vehicles for atmospheric glide and supermanoeuvrability. DRDO’s GTRE (Gas Turbine Research Establishment) started the project to develop an indigenous turbofan engine christened ‘Kaveri’ in 1986.

As a part of the Light Combat Aircraft (LCA)- ‘Tejas’ project, the turbofan engine was to be developed from scratch. Full-scale development of the powerplant was authorised in April 1989 as a 93-month programme with a budget of $55.3 million. The original plan called for 17 prototype test engines to be built. The first test engine consisted of only the core module christened ‘Kabini, while the third prototype was the first one to be fitted with variable inlet guide vanes (IGV) on the first three compressor stages.

The Kabini core engine first ran in March 1995. Test runs of the first complete prototype of Kaveri began in 1996 and all five ground-test prototypes were in testing by 1998, while the initial flight tests were planned for the end of 1999 with its maiden flight test onboard a LCA prototype to follow the next year.

However, progress in the Kaveri development programme was slowed by both political and technical difficulties. The United States imposed economic and technological sanctions on India following the Pokhran-2 series of nuclear weapon test explosions in 1998, thus hampering the transfer of critical aero-engine technologies and components from the US to India.

The Indian scientific establishment had to develop everything through in-house research in the following years and the first prototypes were found to be throwing up blades during ground testing. In mid-2004 the engine failed its high-altitude tests in Russia ending the hopes for its introduction with the first production batch of Tejas fighter jets. As the dillydallying continued through the first half of the 2000s decade, the engine had undergone 1700 hours of tests and had been sent twice for high altitude tests to Russia by February 2008.

In July 2007, GTRE divided the Kaveri programme into two separate programmes- the K9+ programme and the K-10 programme. K9+ is to prove the concept of complete design and gain hands-on experience in aircraft engine integration and flight trials to cover a defined truncated flight envelope prior to the launch of the production version of the K-10 standard engine.
The K-10 programme is a joint venture (JV) partnership with a foreign engine manufacturer. K-10 is supposed to be the final production standard Kaveri engine and shall have less weight and more reheat thrust along with certain other changes to meet the original design intent. By May 3, 2010, about 1880 hours of engine tests had been completed on various prototypes.

A total of eight Kaveri engines and four core engines had been manufactured, assembled and tested. High-altitude testing on the core engine had also been completed successfully. One of the Kaveri prototypes (K-9) was successfully flight tested at Gromov Flight Research Institute in Moscow, on November 4, 2010. The test was conducted at the Flying Test Bed at Gromov, with the engine running right from take-off to landing, flying for a period of over one hour up to an altitude of 6 km.

The engine helped the IL-76 testbed aircraft fly at speeds of around Mach 0.6 in its maiden flight. The engine control, performance and health during the flight were found to be excellent. With this test, Kaveri had completed a major milestone in the development programme. But the CAG report released in 2011 came as a shock for many as it highlighted the cost overruns of the programme with only two out of the six milestones having been met. CAG stated that the engine was overweight and there was no significant progress towards developing the compressors, turbines and engine-control systems.

The Kaveri project was finally on the verge of closure as DRDO planned to abandon the programme in 2014 due to prolonged delay. But an offer by France’s Safran Aircraft Engines (previously known as Snecma) suddenly spurred hopes in all stakeholders. France offered to spend 1 billion Euros as a part of Dassault Rafale’s offsets deal and proposed a joint-venture plan with DRDO to quickly revive the Kaveri engine programme and make the first upgraded powerplants airworthy.

The good news finally came on November 20, 2016, when CP Ramanarayanan, Director General for Aeronautics Cluster of DRDO confirmed that the collaborative deal with the French company- Safran Aircraft Engines, had been sealed for the upgradation of Kaveri and making it airworthy for testing by 2018.

As of 2022, the plan is to upgrade the first batch of prototypes with significant transfers of M-88 engine technology from France to India so that Kaveri is made airworthy and integrated onboard Tejas PV-1 (Prototype Vehicle-1) aircraft by in the ongoing decade.

French experts who have assessed the engine, have stated that 25-30 per cent more work is needed to make the engine flightworthy. It is understood that there are many arms import lobbies in the government which don’t want the indigenous turbofan engine programme to materialise as it will hamper the import of F-404 and F-414 engines from the United States.
These arms import czars are so powerful that they can make the people believe that night is day and vice versa. Critical technical know-how like the ‘single crystal blade’ technology for manufacturing of aero-engines was never given to India. DRDO had to develop almost everything from scratch. The onus now lies upon the NDA-3 government to operationalise Kaveri at the earliest with immediate execution of the maiden historic flight onboard LCA-Tejas aircraft, possibly during the next edition of the Defence Expo in 2024.


Tejas and AMCA are flagship programmes of the Indian defence manufacturing sector. Aviation technologies are much more complex and expensive than building warships and battle tanks. The fact that India struggled a lot to get FOC aircraft production for the base Tejas model indicates that there is a need for foreign help. The variables and anxieties will continue to hit the AMCA. Joint ventures or technology transfers are essential for the engine, AESA and EW systems.

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Moreover, external help will also be required in handling complex aerodynamic configurations and stealth of the AMCA. Considering the slow progress in the Tejas project, it is going to be an uphill task. The indigenous fifth-generation fighter programme would require more concerted energies and professional administrative attention.

During technological holdups, there is a need to accept the harsh reality and raise the hands rather than carrying on ‘hit and trial’. Foreign collaboration for the development of cutting-edge technologies and platforms will prevent unprecedented delays and cost overruns. The time to act is now, without any further delay.
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It’s a matter of time before India is able to master the crystal blade technology to make its own engines.

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