By Girish Linganna

On January 4, 2001, Wing Commander Rajiv Kothiyal successfully flew the first flight of the Technology Demonstrator TD-1. Indian Prime Minister Atal Bihari Vajpayee subsequently named the aircraft the Light Combat Aircraft (LCA) “Tejas,” which means “Radiance” in the ancient Indian language of Sanskrit.

The Light Combat Aircraft (LCA) programme has made substantial progress in recent months, with the Mk1 model receiving official Final Operational Clearance (FOC) on February 20, 2019, and Hindustan Aeronautics Limited (HAL) ramping up manufacturing.

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The Tejas Mk1 is already a fixture at IAF air exercises, accumulating high-range scores and gaining the trust of its operators. As a result, the attention has switched to developing and manufacturing the Tejas Mk1A variant, as the Indian Air Force (IAF) has been granted authorisation to acquire 83 aircraft of this kind.

Composite Power: LCA Tejas Mk1 Makes a Big Impact


Tejas Mk1 is a lightweight, single-engine, multi-role, tactical fighter aircraft of the fourth generation. It utilises an unstable tailless delta-wing layout primarily intended for mobility and agility.

Composite structures comprise over 90 per cent of its surface area and 45 per cent of its airframe by weight. This is one of the greatest composite utilisation rates for any aircraft worldwide. This substantial use of composites has decreased the aircraft’s weight by 21% and its component count by 40% compared to what would have been the case if it had been made entirely of metal.

The Indian aircraft industry was facing challenges due to the non-availability of composites, essential materials used in aircraft construction. The high demand for composites in the aerospace industry worldwide, combined with the impact of COVID-19 on global supply chains, had led to a shortage of supply, causing delays in production and hindering the growth of the Indian aircraft industry. Efforts were being made to increase domestic production of composites, but it would take time for these measures to impact the material’s availability significantly. In the meantime, the industry was working to find alternative solutions to mitigate the effects of the composite shortage.

The aeroplane has been built purposefully longitudinally unstable to improve its manoeuvrability. In reality, its static margin, a measure of its instability (and, consequently, its mobility), is among the highest of any current fighter aircraft. It is fitted with a completely redundant quadruple digital fly-by-wire flight control system to recover stability and provide good handling qualities (FCS). This FCS is one of the LCA program’s most outstanding achievements.

Its robustness has ensured that over 4,300 test flights have occurred without incident. The aircraft has also been outfitted with advanced autopilot features like auto-level (in case of pilot disorientation), safe altitude recovery (which automatically pulls the plane back up if it gets too low), and auto navigation modes.

Aircraft that are now in use have been certified to fly at G-forces ranging from -3.5 to +8.0, at an altitude that can reach up to 50,000 feet, at a speed that can reach up to Mach 1.6, and at an angle of attack (AoA) that can reach up to 24 degrees. The prototypes have been pushed to their limits by the test pilots, who have achieved 8.5 Gs and 26 degrees angle of attack.

The Mk1 demonstrated a low-speed pass of 110 knots at the Bahrain Air Show in 2016. The FCS has been upgraded to reduce the minimum speed at which automatic recovery is initiated to 100 knots. The 2016 demonstration in Bahrain also highlighted another significant aspect: After the previously reported low-speed pass, the aircraft immediately commenced a vertical rise. Only fighters with a thrust-to-weight ratio (TWR) greater than 1.0 have the potential to accelerate while climbing. The Mk1 displayed an instantaneous turn rate (ITR) of approximately 30 degrees per second and a sustained turn rate (STR) between 15 and 16 degrees per second in Bahrain. In addition, a minimum radius turn of 350 metres (m) was demonstrated. These figures are imposing for air-to-air (A2A) combat situations.

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The Mk1 features an effective MultiMode Radar (MMR) with A2A, air-to-sea, and air-to-ground (A2G) target detection modes. When operating in A2A mode, the Tejas Mk1 can launch R-73 close combat missiles (CCMs) and Derby beyond visual range A2A missiles (BVRAAMs). The Mk1 is planned to be integrated with India’s Astra BVRAAM. With state-of-the-art helmet-mounted display and sight (HMDS) and hands-on throttle-and-stick (HOTAS) controls, as well as navigation aids such as Very High Frequency (VHF), Instrument Landing System (ILS), Omnidirectional Range (VOR), and tactical air navigation system (TACAN), Tejas Mk1 permits the pilot to focus on mission-critical requirements rather than basic flying.

A2G weapon delivery accuracy is one of Tejas’s main assets. The Mk1 has consistently achieved some of the highest range scores of all IAF aircraft in all flying tests and air exercises. In addition to carrying 250 kg and 450 kg dumb bombs, it can also transport laser-guided bombs (LGBs) guided to their targets by a Litening laser designation pod (LDP). It is possible to carry a single LGB on either the centre fuselage, the wing inboard, or the mid-board armament station of the aircraft. Two dumb bombs can be carried in tandem on the wing-inboard pylons, whereas only one can be carried on the fuselage centre and wing-mid-board pylons.

From Jaisalmer to Leh, the Mk1’s all-weather and day/night performance has been demonstrated in numerous extreme heat and cold weather trials. In Leh, for instance, the aircraft was successfully started after a 42-hour cold soak in temperatures of -20°C. The efforts to start the aeroplane with a partially depleted battery were successful. Several Multi-Medium Role Combat Aircraft (MMRCA) competitors failed this test during trials for this contract. Similarly, during hot and high trials, the aircraft took off with 1.9 tonnes (50 per cent of its maximum payload), which is a remarkable feat considering its massively swept delta wings.

The Tejas Mk1 features five ‘wet’ points: one under the fuselage and two under each wing. The hardpoint beneath the fuselage can hold either a 725-litre (L) subsonic or a 710-litre (L) supersonic drop tank (still under development). The wing inboard pylon can carry a 1200 L subsonic drop tank, whereas the mid-board pylon can carry an 800 L drop tank. Although the developer of the MK-1, the Aeronautical Development Agency (ADA), reports a cautious ferry range of 1,750 kilometres, flights of approximately 2,100 kilometres have been accomplished in the past. Additionally, the FOC version of the Tejas MK-1 has been equipped with a fixed refuelling probe that can be deployed to replace all of its internal and external fuel tanks, effectively increasing its range and endurance.

Some important points in indigenisation include four leading edge actuators, gyro referencing unit GRU and more than 100 LRUs under progress.

LCA Tejas Mk1A Impresses International Interest: Malaysia, Argentina, Philippines, and Egypt Show Support


While ADA worked on the Tejas Mk2 for the IAF, HAL recommended a more straightforward interim upgrade. Thus, the Tejas Mk1A, outfitted with an ELTA EL/M-2052 active electronically scanned array (AESA) radar and a suitable electronic warfare suite, including a self-protection jammer (SPJ) pod, carried on the outboard wing pylon. On the outboard pylon, there would be a dual-rack pylon that would carry both of the CCMs.

HAL would also upgrade several line replacement units (LRUs) to accommodate obsolescence control, weight reduction, ease of manufacture, and maintenance. Additionally, the aircraft would be equipped with an Onboard Oxygen Generation System (OBOGS) that would enable pilots to conduct long-duration flights. SAAB wanted to highlight the hot refuelling feature on its Gripen fighter aircraft during the MMRCA competition to minimise its turnaround time. The IAF declined the request because it lacked a standard operating procedure (SOP) for the activity. This capability has now been demonstrated by a Tejas test aircraft.

The LCA Tejas Mk1A is the variant of the aircraft that is available for export, and several countries have expressed interest in purchasing it. Malaysia, Argentina, the Philippines, and Egypt are among the countries that have shown interest in acquiring the Tejas Mk1A. The deal with Malaysia was on hold due to elections, and the new government will likely bring the sale to fruition. Meanwhile, Argentina will soon be in India for another round of testing with its pilots. Both the Philippines and Egypt have been provided with an anticipatory budget for the export.

ADA’s Tejas Mk2: The Next Step in the Evolution of the Light Combat Aircraft


To meet the IAF’s strict air staff qualitative requirements (ASQR) for the LCA project, ADA recognised that significant alterations to the original Mk1/Mk1A airframe were necessary, and this is where the Tejas Mk2 development programme got its start. The IAF desired a fighter with faster transonic acceleration and a (sustained turn rate (STR) approximately 18 degrees per second higher. At Aero India 2017, ADA presented scale models that hoped to expand the Mk1 fuselage by 0.5 metres and install a more powerful F414 engine with a maximum rated thrust of 98kN. The plug had to be put just behind the canopy where the area curve had the greatest discontinuity. In addition to the plug, ADA examined a bulged canopy to enhance area ruling further. The total result was a 6 per cent reduction in supersonic drag, which led to a 20 per cent increase in transonic acceleration and a 2 per cent increase in maximum speed. The fuselage plug and spine bulge would give additional room for internal fuel and LRUs.

Even with a minor increase in weight, it was expected that the Tejas Mk2 would have much less transonic and supersonic drag. A higher-power engine would significantly enhance this variant’s transonic and supersonic performance. The higher thrust engine also provided a higher TWR, which, when combined with the superior L/D, meant the fighter would have an exceptional rate of turn and an excellent rate of ascent. The fuselage plug allowed for increased internal fuel capacity and an internal SPJ. This would result in increased endurance and range. ADA proposed modifications that could have been planned, constructed, flight-tested, and certified relatively quickly.

In response to the IAF’s expanding needs, ADA is developing a far more capable and larger Mk2 design, nicknamed the Medium Weight Fighter (MWF).

LCA Tejas Project: A 22-Year Legacy of Innovation


Other key variants of the LCA project have been developed, such as the LCA Navy and the LCA Lead-in Fighter Trainer (LIFT), and a multitude of technologies have been taken from the LCA project for use in other aircraft projects as well. The LCA Tejas project has been active for more than 22 years and is thriving. There are approximately forty LCA Tejas fighters now in service with the air force, and additional orders demonstrate this.

According to a report in Vayu Aerospace MBDA General Delegate India, Boris Solomiac, has confirmed that the Tejas Mk1A fleet will be equipped with the advanced short-range air-to-air missile (ASRAAM) developed by MBDA. It is also possible that other Indian platforms will receive this weapon in the future. The integration of ASRAAM on the LCA-Tejas fleet is a significant improvement to the jet’s combat capabilities, as both ASRAAM and Python-5 are considered the best short-range air-to-air missiles in the world. MBDA has agreed with Bharat Dynamics Ltd to conduct the final assembly, integration, and testing of ASRAAM missiles in India for the Indian Air Force. The existing block 4 ASRAAM offers a unique combination of lethality, agility, and range and is currently used on the Jaguar Deep-Strike aircraft fleet. It is still being determined if MBDA will provide the block 6 ASRAAM, which features new and updated subsystems such as a high-density seeker and a built-in cryogenic cooling system. The first flying test bed of the Tejas Mk1A is expected to make its maiden flight in June, followed by another test bed in the following year. HAL will begin deliveries of the first batch of Tejas Mk1A in 2024, with production scheduled to end by 2028. After this, the current production line will be used to manufacture the Tejas MkII and LCA-LIFT. The Advanced Medium Combat Aircraft (AMCA) program will receive a new production line in the Tamil Nadu Defense Corridor.

The LCA Tejas Mk1 has proven to be a reliable and agile aircraft, with over 4,300 test flights completed without incident. Its composite construction has made it lightweight and efficient, and its advanced technology has allowed it to perform at high speeds and G-forces. The aircraft has also demonstrated its capabilities in air-to-air and air-to-ground combat with various weapons and advanced radar and navigation systems. The success of the LCA Tejas Mk1 has led to the development of the Tejas Mk1A, which is available for export to several countries, and the Tejas Mk2, which is being designed to meet the evolving needs of the Indian Air Force. The LCA Tejas project has been active for over 22 years and continues to make significant contributions to the aerospace industry.

Author is Defence and Aerospace Analyst.

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