HAL Tejas

In 1969, the Government of India accepted the recommendation by its Aeronautics Committee that Hindustan Aeronautics Limited (HAL) should design and develop a fighter aircraft around a proven engine. Based on a 'Tactical Air Support Aircraft' ASR markedly similar to that for the Marut,[20] HAL completed design studies in 1975, but the project fell through due to inability to procure the selected "proven engine" from a foreign manufacturer and the IAF's requirement for an air superiority fighter with secondary air support and interdiction capability remained unfulfilled.[21]

In 1983, IAF realised the need for an Indian combat aircraft for two primary purposes. The principal and most obvious goal was to replace India's ageing MiG-21 fighters, which had been the mainstay of the IAF since the 1970s. The "Long Term Re-Equipment Plan 1981" noted that the MiG-21s would be approaching the end of their service lives by the mid-1990s, and that by 1995, the IAF would lack 40 percent of the aircraft needed to fill its projected force structure requirements.[22] The LCA programme's other main objective was an across-the-board advancement of India's domestic aerospace industry.[23] The value of the aerospace "self-reliance" initiative was not simply the aircraft's production, but also the building of a local industry capable of creating state-of-the-art products with commercial spin-offs for a global market.[24]

In 1984, the Indian government chose to establish the Aeronautical Development Agency (ADA) to manage the LCA programme. While the Tejas is often described as a product of Hindustan Aeronautics Limited (HAL), responsibility for its development belongs to ADA, a national consortium of over 100 defence laboratories, industrial organisations, and academic institutions with HAL being the principal contractor.[25] The government's "self-reliance" goals for the LCA included the three most sophisticated and challenging systems: the fly-by-wire (FBW) flight control system (FCS), multi-mode pulse-doppler radar, and afterburning turbofan engine.[26]

The IAF's Air Staff Requirements for the LCA were not finalised until October 1985. This delay rendered moot the original schedule which called for first flight in April 1990 and service entry in 1995; however, it also gave the ADA time to better marshal national R&D and industrial resources, recruit personnel, create infrastructure, and to gain a clearer perspective of which advanced technologies could be developed locally and which would need to be imported.[21][27]

Project definition commenced in October 1987 with France's Dassault-Breguet Aviation as consultants. Dassault-Breguet were to assist in the design and systems integration of the aircraft, with 30 top-flight engineers reported to have flown to India to act as technical advisers to IADA, in exchange for $100m / ₹560 crore (equivalent to ₹56 billion or US$790 million in 2019), this phase was completed in September 1988.[27][28]

LCA Tejas Production Partners of HAL

A review committee was formed in May 1989, which reported that infrastructure, facilities and technologies in India had advanced sufficiently in most areas and that the project could be undertaken.[29] A two-stage full-scale engineering development (FSED) process was opted for.[22][29] In 1990, the design was finalised using the "control configured vehicle" concept to define a small tailless delta winged aircraft with relaxed static stability (RSS) for enhanced manoeuvrability.[10][30][29]

Phase 1 commenced in April 1993,[22] and focused on "proof of concept" and comprised the design development and testing (DDT) of two technology demonstrator aircraft which were named as TD-1 and TD-2. This would be followed by the production of two prototype vehicles (PV-1 and PV-2); TD-1 finally flew on 4 January 2001.[29] FSED Programme Phase-I was successfully completed in March 2004 and cost ₹2,188 crore.[22]

The relaxed static stability (RSS) was an ambitious requirement. In 1988, Dassault had offered an analogue flight control system (FCS), but the ADA recognised that digital FCSs would supplant it.[26] First flying in 1974, the General Dynamics F-16 was the first production aircraft designed to be slightly aerodynamically unstable to improve manoeuvrability.[31]

In 1992, the LCA National Control Law (CLAW) team was set up by the National Aeronautics Laboratory (now called National Aerospace Laboratories) to develop India's own state of the art fly-by-wire FCS for the Tejas.[32][33] In 1998, Lockheed Martin's involvement was terminated due to a US embargo in response to India's second nuclear tests in May of that year.[34][35]

Another critical technology is the multi-mode radar (MMR). Initially, the Ericsson/Ferranti PS-05/A I/J-band multi-function radar, also used on Saab's JAS 39 Gripen, was intended to be used.[36] However, after examining other radars in the early 1990s, the Defence Research and Development Organisation (DRDO) became confident that local development was possible. HAL's Hyderabad division and the Electronics and Radar Development Establishment (LRDE) were selected to jointly lead the MMR programme, and work commenced in 1997.[37] The Centre for Airborne Systems (CABS) is responsible for the MMR's test programme. Between 1996 and 1997, CABS converted the surviving HAL/HS-748M Airborne Surveillance Post (ASP) into a testbed for the LCA's avionics and radar.[38]

The NAL's CLAW team completed the integration of the flight control laws with the FCS software performing flawlessly for over 50 hours of pilot testing on TD-1, resulting in the aircraft being cleared for flight in January 2001. The automatic flight control system (AFCS) has been praised by all the LCA test pilots.[39] Phase 2 commenced in November 2001,[22] and consisted of the manufacturing of three more prototype vehicles (PV-3, PV-4 and PV-5), leading to the development of the final version that would join the air force and the navy and 8 Limited Series Production (LSP) aircraft, and the establishment of infrastructure for producing 8 aircraft per year.[29] The phase cost ₹3,301.78 crores, and an additional amount of ₹2,475.78 crores was given for induction into Indian Air Force by obtaining IOC and FOC. The total cost for development of Tejas (including PDP, Phase 1 and Phase 2) was ₹7,965.56 crore as of August 2013.[22]

By mid-2002, the MMR had reportedly suffered major delays and cost escalations. By early 2005, only the air-to-air look-up and look-down modes — two basic modes — were confirmed to have been successfully tested. In May 2006, it was revealed that the performance of several modes being tested "fell short of expectations."[40] As a result, the ADA was reduced to running weaponisation tests with a weapon delivery pod, which is not a primary sensor, leaving critical tests on hold. According to test reports, there was a serious compatibility issue between the radar and the LRDE's advanced signal processor module (SPM). Acquisition of an "off-the-shelf" foreign radar is an interim option being considered.[37][41][42]

Tejas Trainer at 62nd Republic Day of India Parade, New Delhi

Of the five critical technologies the ADA identified at the beginning of the programme as required to design and build a new fighter, two have been successful: the development and manufacture of carbon-fibre composite (CFC) structures and skins, and a modern glass cockpit. ADA has a profitable commercial spin-off in its Autolay integrated automated software for designing 3-D laminated composite elements (which has been licensed to both Airbus and Infosys). However, the development of the other three critical technologies (high performance multimode radar, the propulsion and the flight control system) had lagged behind.[26] By 2008, 70% of the LCA's components were being manufactured in India, the dependence on imported components was stated to be progressively reduced over time. However, problems were encountered with the other three key technology initiatives.[43] For example, the intended engine, the GTRE GTX-35VS Kaveri,[44] had to be replaced with an off-the-shelf foreign engine, the General Electric F404.

Kota Harinarayana was the original Programme Director and Chief Designer for the Tejas Programme.[45][46]

In October 2015, IAF Air Chief Marshal Arup Raha confirmed that the air force plans to order 123 (six squadrons) of Tejas Mark 1, triple the 40 aircraft it had previously committed to buying. Later it was declared that those 83 additional Tejas ordered would be the upgraded Mark 1A version.[18]

On 26 February 2016, Defence Minister Manohar Parrikar said in the Lok Sabha that the Indian Air Force would accept 3–4 Tejas (IOC version) that year and eventually stand up a total of 8 squadrons within 8 years. He also said, "We are also in the process of approving the second line of manufacturing to the HAL so that they can produce 16 aircraft per year."[47]

On 7 November 2016, Parrikar approved procurement of 83 Tejas for the IAF, at a cost of ₹50,025 crore (US$7 billion).[48]

In 2018, IAF formally committed to buying 324 Tejas aircraft of all versions, if HAL and Aeronautical Development Agency (ADA) could deliver an acceptable quality Tejas Mark 2 in time.[15]

By March 2020, the HAL, hoped to expand its production capacity to at least a squadron (16+) of aircraft every year to meet delivery timelines.[49] HAL is setting up a second assembly line in collaboration with private industry to increase the production rate of the LCA from current eight to 16;[50] however the March 2020 deadline has been missed.

On 18 March 2020, the Defence Acquisition Council (DAC) provisionally cleared a procurement deal for 83 Tejas Mk.1A, including 73 single-seat fighters and 10 dual-seat trainers.[51] HAL was to finalise the proposal, for review by the Cabinet Committee on Security (CCS). According to HAL, the first Tejas Mk.1A could fly by 2022 with serial production starting in 2023. The first squadron of Tejas Mk.1A could be delivered by 2025, and delivery of all 83 aircraft could be completed before 2029.[52][53] The Tejas Mk.1A is to support the R-77 and Python-5, along with the Astra Mk.1 missiles. The IAF also requested a strong aircraft maintenance package, and aircraft panel inter-changeability that can be carried out at squadron level, in a minimum amount of time using quick-release fasteners to reduce foreign object damage (FOD). Line-replaceable units (LRU)s are also expected to be pre-positioned.[54]

In 2021, the Cabinet Committee on Security, approved the 2015 agreement to procure 73 LCA Tejas Mk-1A, and an additional 10 LCA Tejas Mk-1 Trainer aircraft, at a cost of ₹45,696 crore (US$6.4 billion), along with ₹1,202 crore (US$170 million) of supporting infrastructure, as part of a ₹48,000 crore (US$6.7 billion) order.[55]

First flight of Tejas LSP-4, 2 June 2010

In March 2005, the IAF placed an order for 20 aircraft, with a similar purchase of another 20 aircraft to follow. All 40 were to be equipped with the F404-GE-IN20 engine.[56][57] In December 2006, a 14-member "LCA Induction Team" was formed at Bangalore to prepare the Tejas and assist with its introduction into service.[58]

On 25 April 2007, the first Limited Series Production (LSP-1) Tejas performed its maiden flight, achieving a speed of Mach 1.1 (1,347.5 km/h; 837.3 mph).[27] The Tejas completed 1,000 test flights and over 530 hours of flight testing by 22 January 2009.[27][59] In 2009, a Tejas achieved a speed of over 1,350 kilometres per hour (840 mph) during sea level flight trials at INS Hansa, Goa.[27][60]

On 16 June 2008 LSP-2 made its first flight[27] followed by the first flight of the trainer variant in November 2009.[61] On 23 April 2010, LSP-3 flew with a hybrid version of the Elta EL/M-2032 multi-mode radar;[27][62] in June 2010, LSP-4 made its maiden flight in an IAF Initial Operating Clearance (IOC) configuration.[27][63] By June 2010, the Tejas had completed the second phase of hot weather trials in an IOC configuration with the weapons system and sensors integrated.[64] Sea trials were also carried out.[65] LSP-5 with IOC standard equipment started flight trials on 19 November 2010.[66]

In December 2009, the government authorized a sum of ₹8,000 crores to begin the production of the fighter for the Indian Air Force and Indian Navy. IAF ordered 20 additional Tejas fighters after the defence acquisition council cleared the plan.[67]

In November 2010, it was reported that the Tejas Mk 1 reportedly fell short of the relaxed Air Staff Requirements stipulated for limited series production (LSP) aircraft. The areas that did not meet requirements were power to weight ratio, sustained turning rate, maximum speeds at low altitudes, AoA range, and weapon delivery profiles; the extent of the deficiencies was classified.[68] On 9 March 2012, LSP-7 took to its maiden flight from HAL airport.[27]

In September 2011, weapons tests, including bombing trials, involving four Tejas aircraft — PV3, and LSP 2, 4 and 5 — began at Pokhran range, followed by missile trials at Goa.[69]

On 27 June 2012, three Tejas (LSP 2, 3 and 5) aircraft completed bombing runs in the desert of Rajasthan, using precision laser-guided 1,000 lb bombs and unguided bombs.[70] The Tejas had completed 1,941 flights by July 2012.[71]

In the later half of 2012, the Tejas was grounded for over three months due to a serious safety issue which arose with the introduction of a new pilots' helmet, which protruded above the ejection seat. There was concern that, during an ejection, the helmet would strike the canopy before the canopy was released. Flight tests resumed in November 2012 after the ejection system had been modified.[72] LSP 8 had a successful maiden test flight on 31 March 2013,[73] and the programme had completed 2,418 test flights by 27 November 2013.[71][74] On 8 November 2014, PV-6 (KH-T2010), a trainer variant, completed its first test flight.[75]

Out of a total of 35 major avionics components and line-replaceable units (LRUs), only three involve foreign systems.[76] These are the multi-function displays (MFDs) by Sextant (France) and Elbit (Israel),[77] the helmet-mounted display and sight (HMDS) cueing system by Elbit,[77] and the laser pod supplied by Rafael (Israel).[78] Production aircraft are expected to have MFDs from Indian suppliers. A few important items of equipment (such as the Martin-Baker ejection seat) have been imported.[76] As a consequence of the embargo imposed on India after its nuclear weapons tests in May 1998, many items originally planned to be imported were instead developed locally; these sanctions contributed to the prolonged delays suffered by the LCA.[76]

Indian test pilots have praised Tejas' high-speed handling and say the Tejas is the IAF's most "pilot friendly" fighter.[79][80] Group Captain Samrath Dhankhar of the Indian Air Force, the commanding officer of its 45 Sqn "Flying Daggers" said about Tejas that it responds to pilot inputs in the entire flight envelope very well, with no need to be at certain speeds to get the maximum out of it.[81]

After the successful completion of laboratory trials, Tejas Mk.1 platform will start flight trials with DRDO developed on-board oxygen generation system (OBOGS) in 2020.[82]

Hot-refueling capability was a requirement for operational clearance of LCA Tejas.

LCA Tejas demonstrating aerial refueling capability to achieve operational clearance.

On 10 January 2011, IOC, allowing IAF pilots to fly the Tejas, was awarded by Defence Minister A K Antony to Chief of Air Staff Air Chief Marshal P V Naik.[83] The IAF raised the first squadron in Bangalore to iron out issues with ADA and HAL, and eventually based these fighters at Sulur Air Force Station, Coimbatore in the southern state of Tamil Nadu. The No. 45 Squadron IAF "Flying Daggers" was the first to get their MiG-21s replaced by Tejas aircraft at the base.[84] Tejas' Final Operational Clearance (FOC) was repeatedly delayed since 2011.[85][86][87]

HAL was instructed by the Indian government to strictly adhere to deadlines to ensure Initial Operational Clearance-II by the end of 2013 and Final Operational Clearance (FOC) by the end of 2014.[88] On 20 December 2013, IOC-II was issued, after which the aircraft was cleared to be flown by regular IAF pilots and begin induction into squadron service. To fulfil the IOC-II standard, the aircraft was certified to carry close to three tons of weapons including laser-guided 500 kg bombs and short-range R-73 missiles,[89][90] reach top speeds of 1,350 km per hour, withstand turns up to 7 g, reach angle of attack of 24 degrees (from 17 degrees initially), and have an operational radius of 400–500 km.[91][92]

To expand the flight envelope to meet service requirements, the programme enlisted assistance from EADS.[93]

These modifications were originally expected to be completed within 15 months of IOC-II, but realistically took far longer.[94][95]

The Final Operational Clearance (FOC) campaign began in December 2013, with three aircraft from Tejas flight-line successfully completing advanced weapon trials. The campaign was held in Jamnagar. New weapons were integrated on the aircraft.[96] As part of the FOC, the aircraft is being readied for all-weather trials in Bangalore and in Gwalior. Tejas had carried out its maiden flight in January 2001, and by December 2013, it had completed 2,587 sorties covering over 1,750 hours.[96] In July 2014, the FOC was pushed back as six or more aircraft were needed for testing and only one had been produced till then.[97] Tejas received IOC-II clearance on 17 January 2015.[98]

In February 2016, LSP-7 test-fired the BVRAAM Derby missile on a BNG (Ballistic Non-Guided) mode in Jamnagar as part of its scheduled weapon trials. These weapon trials are part of the Final Operational Clearance (FOC) mandate. It was the 169th flight of LSP-7 and was piloted by Group Capt Rangachari of the National Flight Test Centre. The aircraft was also scheduled to fire a Close Combat Missile (CCM) Python-5 as part of the FOC trials. The LSP-7 along with LSP-4 were part of Indian flying assets at the Bahrain International Air Show (BIAS-2016).[99]

On 12 May 2017, Tejas successfully demonstrated an Air-to-Air Beyond Visual Range (BVR) missile firing capability by releasing Derby Air-to-Air BVR missile in RADAR guided mode. The missile launch was performed in lock-on after launch mode.[100] The missile destroyed its manoeuvrable aerial target with pinpoint precision at the Interim Test Range, Chandipur in Odisha.[101]

In November 2017, it was reported that the Indian Air Force told the government that the Tejas alone is inadequate for the single-engined fighter program with insufficient flight endurance, smaller payload capacity, increased maintenance hours, etc. compared to larger medium combat aircraft contending in the Indian MRCA competition and may augment them, but cannot be an alternative.[102] HAL's chief rejected the criticisms and called the Tejas a world-class fighter jet that can fill its defined role. He also mentioned that minimum life span of Tejas is 30 years which can be extended.[103] HAL CMD T Suvarna Raju also stated that HAL delivered five Tejas as of 19 November 2017, which have made more than 600 flights.[104]

In February 2018, refuelling of Tejas with the engine running—known as "hot refuelling"—was carried out. Hot refuelling capability is one of the requirements for Tejas Mk 1A and is expected to shorten the turnaround time between sorties.[105]

In September 2018, Tejas successfully completed the trials for mid-air refuelling, which is one of the key items required for the aircraft to obtain FOC.[106] In January 2019, HAL received permission from CEMILAC to start production of FOC standard Tejas, despite the certification not being awarded yet.[107]

On 20 February 2019, during the Aero India 2019 show, Final Operational Clearance (FOC) was formally awarded to the Tejas.[108] After the release of the Drawing Applicability List (DAL) and SOPs by the Centre for Military Airworthiness and Certification (CEMILAC), Tejas SP-21 took 12 months to complete production. The first flight was on 17 March 2020.[109][110] The Tejas FOC variant comes with aerial refuelling probe compatible with both NATO and Russian tankers that will allow flights of over 8 hours, an additional 725 litres (159 imp gal; 192 US gal) centre line drop tank with pressurised refuelling, an improvement over the existing 1,200 litres (260 imp gal; 320 US gal) and 800 litres (180 imp gal; 210 US gal) external fuel tanks that come with the Tejas IOC variants. The FOC variant will also have Derby BVR missile capability and a GSh-23 twin-barrelled gun. Tejas SP-22 will fly by the end of March 2020 and SP-23, SP-24 by end of May 2020. Delivery of the next 15 Tejas FOC aircraft after SP-21 will be completed by financial year 2020–21, due to improvements in manufacturing process and feedback from the Tejas IOC program.[111] The second IAF Tejas squadron No.18 Flying Bullets was formed at Sulur Air Force Station on 27 May 2020 with the first four serial production FOC aircraft.[5][112]

In May 2015, the Mark 1 aircraft was criticised by the Comptroller and Auditor General of India (CAG) for not meeting IAF requirements, such as a lack of a capable tandem-seated trainer aircraft, electronic warfare capabilities, performance shortcomings of radar warning receiver or missile approach warning system, weight and cost increases, limited internal fuel capacity, non-compliance of fuel system protection, inadequate forward-facing pilot protection, and performance shortfalls due to under-powered engine.[113] Most of these issues are to be addressed in the upcoming interim upgrade called Mark 1A and subsequent advanced version called Mark 2 or MWF.

It was reported that IAF agreed to accept 40 aircraft even though the CAG had found serious operational shortfalls, including engine thrust, overweight and pilot protection in front against 7.62 mm rifle calibre rounds. The IAF agreed to accept the initial Tejas aircraft with some deficiencies to keep the programme going.[114] IAF had initially ruled out further acquisition of Tejas Mk 1 until Mk 2 was ready.[115] In 2015, the ADA, DRDO and HAL proposed a more advanced Tejas Mk 1A version; as an improved stop-gap to keep production running as Mark 2 was delayed.[116][117] Following an approval from Defence Acquisition Council for 83 Tejas Mk 1A, HAL invited global bids for AESA radar and ECM pods in December 2016.[118][119] In December 2018, it was reported that HAL had selected Elta's EL/M-2052 AESA radar and EL/L-8222 ECM pod.[120]

Another major improvement in Mark 1A is its higher maintainability,[121] while hot-refuelling and aerial refuelling have both been already demonstrated in prototypes and are to be available features from all FOC standard Tejas.

On 20 December 2017, IAF initiated a tender to buy 83 Mark 1A worth 33,200 crores from HAL.[122] However, with HAL quoting a price of ₹463 crore (US$65 million) per unit, substantially higher than the Mark 1, the Defence Minister Nirmala Sitharaman announced in July 2018 that a committee to look into the cost of the Mark 1A, along with other products manufactured by defence Public Sector Undertakings.[123] On 13 January 2021, political approval, for a ₹48,000 crore (US$6.7 billion) order[55] for 73 Mk1A, and an additional 10 MK1 FOC trainers, was granted. Signing of the contract for the aircraft remains to be done; the first Tejas Mark 1A is expected to be delivered 36 months after signing the contract.[124]

The Aircraft Research and Design Centre (ARDC) of Hindustan Aeronautics Limited (HAL) had completed the structural design for Tejas Mark 1A which is now awaiting clearance from Centre for Military Airworthiness and Certification (CEMILAC), Directorate General of Aeronautical Quality Assurance (DGAQA) and Aircraft and Systems Testing Establishment (ASTE) while system design works are in progress which will be completed by February 2021. A total of 200 flight trials will be conducted with upgraded systems on two limited series production (LSP) aircraft, while final configuration for Tejas Mark 1A will be ready for production by 2022–23. The major improvements on Tejas Mark 1A are in operational roles and increasing the combat ability by addition of active electronically scanned array (AESA) radar, unified electronic warfare suite (UEWS), self protection jammer (SPJ), Astra Mark 1, ASRAAM, digital 2D and 3D moving maps with perspective view for pilot, integration of GNSS augmentation like GAGAN and additional GLONASS, NAVIC satellite navigation systems. To increase turn around time and ease of long term maintainability, new set of cables will be incorporated in Tejas Mark 1A to add space inside aircraft while a technique called panel-in-panel will increase visibility of components and reduce daily inspection time.[6]

To meet air staff qualitative requirements (ASQR) of the Indian Air Force (IAF), ADA had to make substantial changes to the basic Mark1 and Mark 1A air-frame to improve payload and performance in the more advanced upgrade called Tejas Mark 2. Initially they had planned to simply elongate the Mark 1 with a 0.5 m fuselage plug to hold more fuel, while fitting a more powerful General Electric F414-GE-INS6 engine with 64–98 kN of thrust.[125][126]

To be renamed eventually,[127] the Mark 2, which is now classified as a medium-weight fighter, is also to feature an indigenous integrated life support system-onboard oxygen generation system (ILSS-OBOGS) weighing 14.5 kg which uses pressure swing adsorption technique and a built-in integrated electro-optic electronic warfare suite among other improvements to avionics.[128][129] The oxygen generation system is developed by Defence Bioengineering and Electromedical Laboratory (DEBEL).[130] It will have an infra-red search and track (IRST) system and a missile approach warning system (MAWS).[131] An increase in payload capacity to 6,500 kg (14,300 lb), and an increase in number of weapons stations from 7 to 11, will allow the MWF to carry more weapons. Defence Institute of Advanced Technology (DIAT) is developing aircraft health and usage monitoring system (HUMS) to integrate various sensors onboard Tejas Mark 2.[132]

It was reported in March 2020 that HAL planned to set up logistic facilities in Indonesia, Malaysia, Sri Lanka and Vietnam as part of potentially exporting the Tejas.[133]

First ski-jump take-off by Naval Tejas NP-1 from Shore Based Test Facility, INS Hansa on 20 December 2014.

In December 2009, the government sanctioned ₹8,000 crore (US$1.1 billion) to begin production of the fighter for the Indian Air Force and Indian Navy.[67] The Indian Navy has a requirement for 50 Tejas aircraft and the first prototype, NP-1 was rolled out in July 2010.[134] The Naval LCA made its first flight, almost two years after being rolled out, on 27 April 2012.[135] In December 2012, the Indian Navy expressed interest in procuring 8 Tejas aircraft,[136] which did not materialise.

In December 2014, the LCA Navy successfully conducted ski-jump trials at SBTF, INS Hansa. The navy variant has a special flight control law mode. It controls a hands-free take-off, which reduces the pilot workload, as the ramp launches the aircraft on an upward flight path.[137][138]

In December 2016, the Indian Navy (IN) announced that the naval variant of the fighter is overweight, and they will look for other alternatives.[139][140] The Indian Navy eventually issued an RFI for 57 naval multirole fighters.[141] However, despite rejecting the Tejas initially for being overweight, the Navy restarted testing with the NP-2 (Naval Prototype 2) in August 2018; the naval variant of the Tejas conducted its first "taxi-in" engagement on a naval platform in Goa to prove its hook-arrester system. The Indian Defence Minister, Nirmala Sitharaman's backing of the Tejas programme allowed the restarting of tests and gave its naval variant a fresh lease on life.[142][143] The first mid-air refueling of the Naval Tejas took place in September 2018.[49]

A two-seater naval variant of Tejas successfully completed its first arrested landing on 13 September 2019 at the Shore Based Test Facility (SBTF) in Goa. Once the aircraft completes several successful trials on the SBTF, it would demonstrate a landing on the aircraft carrier INS Vikramaditya.[144] On 11 January 2020, the Naval LCA Tejas successfully carried out its first arrested landing on the aircraft-carrier INS Vikramaditya.[145][146] On 12 January 2020, the Tejas performed its first ski-jump assisted take-off from the aircraft-carrier.[147]

The experience gained in operating the Naval Prototype will help in proving input to the development of Twin Engine Deck Based Fighter (TEDBF) aircraft.[148] The HAL TEDBF will be powered by two General Electric F414 and will carry higher and heavier payloads and range. Labelled as the Omni-Role Combat Aircraft it is to sport two engines, elongated fuselage and an expanded wing-span, Diverterless supersonic inlets, Conformal Fuel Tanks etc.[149]

• ₹11,096 crore (US$1.6 billion) (up to March 2020)[150]
• ₹1,202 crore (US$170 million) additional design and development (Jan 2021)[55][151]

• ₹162 crore (equivalent to ₹208 crore or US$29 million in 2019) for IOC Mk. 1 (2014)[152]
• ₹299.45 crore (equivalent to ₹541 crore or US$76 million in 2019) for FOC Mk. 1 (2010)[153]
• ₹309 crore (US$43 million) for Mk. 1A (2021)[154][155][156]

The Tejas is a single-engine multirole fighter which features a tailless, compound delta wing and is designed with "relaxed static stability" for enhanced manoeuvrability. Originally intended to serve as an air superiority aircraft with a secondary ground-attack role, its flexibility permits a variety of guided air-to-surface and anti-shipping weapons to be integrated for multirole and multimission capabilities.[157] The tailless, compound-delta planform is designed to be small and lightweight.[158] This platform also minimises the control surfaces needed (no tail-planes or fore-planes, just a single vertical tail-fin), permits carriage of a wider range of external stores, and confers better close-combat, high-speed, and high-alpha performance characteristics than comparable cruciform-wing designs. Extensive wind tunnel testing on scale models and complex computational fluid dynamics analyses have optimised the aerodynamic configuration for minimum supersonic drag, a low wing-loading, and high rates of roll and pitch.[157]

HAL Tejas airshow demo

The maximum payload capability of Tejas is 5,300 kg (11,684 lb).[159] All weapons are carried on one or more of seven hardpoints with total capacity of greater than 5,000 kg: three stations under each wing and one on the under-fuselage centreline. An eighth offset station beneath the port-side intake trunk can carry a variety of pods like FLIR, IRST, laser rangefinder/designator, as can the centre line under-fuselage station and inboard pairs of wing stations.[34][160] Auxiliary fuel tanks of 725, 800 and 1,200 litres can be carried under the fuselage to extend range. An aerial refuelling probe on the starboard side of the forward fuselage can further extend range and endurance.[161] RAFAEL's Derby fire-and-forget missile will serve as the Tejas' initial medium range air-air armament.[78] The Brahmos NG supersonic cruise missile is being developed for the Tejas.[162]

Stealth features have been designed into Tejas.[163] Being small provides an inherent degree of visual stealth, the airframe's high usage of composites (which do not reflect radar waves), a Y-duct inlet which shields the engine compressor face from probing radar waves, and the application of radar-absorbent material (RAM) coatings are intended to minimise its susceptibility to detection and tracking.[164]

Tejas uses Martin-Baker 16LG zero-zero ejection seat.[165] DRDO integrated an indigenous CSS, or canopy severance system, in the Tejas which allows the pilot to eject safely.[166]

Tejas is constructed of aluminium-lithium alloys, carbon-fibre composites, and titanium alloys.[167] Composite materials make up 45% of the airframe by weight and 95% by surface area. Upper and lower wing skins are manufactured from a single piece of carbon-fibre reinforced polymer. Wing spars and ribs are also made out of carbon composites.[168] The percentage of carbon composites in the airframe by weight rose from 30% in the technology demonstrators to 42% in the prototype vehicles. The construction of elevons, tailfin, rudder, air brakes and landing gear doors use co-cured and co-bonded manufacturing techniques. The radome is made out of Kevlar, while the fin tip is made out of glass-fibre reinforced plastic.[165] Composite materials are used to make an aircraft lighter compared to an all-metal design, and the LCA's percentage employment of carbon-fibre composites is one of the highest among contemporary aircraft of its class.[169] Apart from making the plane much lighter, there are also fewer joints or rivets, which increases the aircraft's reliability and lowers its susceptibility to structural fatigue cracks.[170] The wing and fin of the compound-delta aircraft are of carbon-fibre-reinforced polymer, and were designed to provide a minimum weight structure and to serve as integral fuel tanks.[171][172] The tailfin is a monolithic honeycomb structure piece, reducing the manufacturing cost by 80% compared to the "subtractive" or "deductive" method, involving the carving out of a block of titanium alloy by a computerized numerically controlled machine. No other manufacturer is known to have made fins out of a single piece.[173]

Underside of HAL Tejas

In 2001 it was envisaged that the naval variant would have nose droop to provide improved view for carrier landings, and wing leading–edge vortex controllers (LEVCON) to increase lift during approach.[21] The LEVCONs are control surfaces that extend from the wing-root leading edge and thus afford better low-speed handling for the LCA, which would otherwise be compromised by the increased drag that results from its delta-wing design. The LEVCONs should also increase controllability at high angles of attack (AoA).[174] The naval Tejas also has a strengthened spine, a longer and stronger undercarriage, and powered nose wheel steering for deck manoeuvrability.[78][175] The Tejas trainer variant will have "aerodynamic commonality" with the two-seat naval aircraft design.[176]

The Tejas has a night vision goggles (NVG)-compatible "glass cockpit", domestically-developed head-up display (HUD) by Central Scientific Instruments Organization (CSIO), three 5 in x 5 in multi-function displays, two Smart Standby Display Units (SSDU), and a "get-you-home" panel with fail-operational/fail-safe air data computer (ADC) manufactured by Bharat Electronics Limited (BEL) that uses computational intelligence based autoland system to provide the pilot with essential flight information in case of an emergency and is connected with IAF ground station network to take over emergency controls of the unstable aircraft. The displays provide information on key flight systems and controls on a need-to-know basis, along with basic flight and tactical data. The pilot interacts with onboard systems through a multi-functional keyboard and several selection panels. The CSIO-developed HUD, Elbit-furnished DASH helmet-mounted display and sight (HMDS) with night-vision goggles compatible glass cockpit,[77] and hands-on-throttle-and-stick (HOTAS) controls reduce pilot workload and increase situation awareness by allowing access to navigation and weapon-aiming information with minimal need to spend time "head down" in the cockpit.[164]

The first 20 production Tejas Mk 1 are equipped with a hybrid version of the EL/M-2032 radar. It features look-up/look-down/shoot-down modes, low/medium/high pulse repetition frequencies (PRF), platform motion compensation, doppler beam-sharpening, moving target indication(MTI), Doppler filtering, constant false alarm rate (CFAR) detection, range-Doppler ambiguity resolution, scan conversion, and online diagnostics to identify faulty processor modules.[164] The Tejas Mk 1A will be equipped with an improved version of the EL/M-2052 AESA radar being developed jointly by Elta and HAL.[177]

The electronic warfare suite is designed to enhance combat survivability during deep penetration. The EW suite is developed by the Defence Avionics Research Establishment (DARE) with support from the Defence Electronics Research Laboratory (DLRL). This EW suite, known as Mayavi, includes a radar warning receiver (RWR), Missile Approach Warning (MAW) and a Laser warning receiver (LWR) system, Infrared & Ultraviolet Missile warning sensors, self-protection jammer, chaff, jaff and flares dispenser, an electronic countermeasures (ECM) suite and a towed radar decoy (TRD). In the interim, the Indian Ministry of Defence has revealed that an unspecified number of EW suites had been purchased from Israel's Elisra for the LCA prototypes.[178][179][180]

Tejas is also to be equippable with an infra-red search and track (IRST) sensor, which can detect and track thermal energy emissions, VHF to UHF radio communication with in-built counter-countermeasure system that supports air-to-air and air-to-ground mode connected via secure datalink network.[181] This system shall be pod-based, additional sensor pods are to include drop tanks for ferry flight/extended range/loitering time, FLIR targeting pod, ECM pods, Flares/Infrared decoys dispenser pod and chaff pod, EO/IR sensor pod, LITENING targeting pods, forward looking infrared (FLIR) sensor, and a laser designator/laser rangefinder, which can be used in various capacities, including reconnaissance, training, or attack. The identification friend or foe (IFF) system is developed by Centre for Airborne Systems (CABS).[34][160] Tejas comes with flight utility system and management system (USMS) to monitor various parameters from sensors like ADA developed hybrid environmental monitoring and control system (EMCS), engine and electrical/electronics monitoring system (EEMS), digital fuel monitoring system (DFMS), digital hydraulics and brake management system (DHMS), MIL-STD-1760C stores management system and aircraft weapon management system (AWMS). Tejas uses various form of onboard navigation instruments like tactical air navigation (TACAN) system, terrain referenced navigation system (TERPROM), VHF omnidirectional range–instrument landing system (VOR–ILS), DARE developed enhanced ground proximity warning system (EGPWS) and ring laser gyroscope based inertial navigation system integrated with satellite guidance from Research Centre Imarat (RCI).[182]

Tejas conducting an inverted pass

Since the Tejas is a relaxed static stability design, it is equipped with Aeronautical Development Establishment (ADE) developed full authority quadruplex fly-by-wire digital automatic flight control system (DAFCS) with fail-operational/fail-safe safety feature for automatic manoeuvre limiting and to ease pilot handling. The Tejas flight control system is operated with dual redundant modular MIL-STD-1553B standard databus and open architecture Digital Flight Control Computer (DFCC) developed by Defence Avionics Research Establishment (DARE). The mission computer uses a 32-bit processor based on Power ISA developed by Solid State Physics Laboratory (SSPL).[183] The Tejas aerodynamic configuration is based on a pure delta-wing layout with shoulder-mounted wings. Its advanced flight control surfaces actuators are all hydraulically actuated with dual redundant hydraulic system powered by quad redundant electrical power supply. The wing's outer leading edge incorporates three-section slats, while the inboard sections have additional slats to generate vortex lift over the inner wing and high-energy air-flow along the tail fin to enhance high-AoA stability and prevent departure from controlled flight. The wing trailing edge is occupied by two-segment elevons to provide pitch and roll control. The only empennage-mounted control surfaces are the single-piece rudder and two airbrakes located in the upper rear part of the fuselage, one each on either side of the fin.[184]

General Electric F404 engine during ground testing

Early on, it was decided to equip prototype aircraft with the General Electric F404-GE-F2J3 afterburning turbofan engine while a program to develop a domestic powerplant led by the Gas Turbine Research Establishment (GTRE) was launched.[185] In 1998, after Indian nuclear tests, US sanctions blocked sales of the F404, leading to a greater emphasis on the domestic Kaveri. In 2004, General Electric was awarded a US$105 million contract for 17 uprated F404-GE-IN20 engines to power the eight pre-production LSP aircraft and two naval prototypes;[186] deliveries began in 2006.[187] In 2007, a follow-on order for 24 F404-IN20 engines to power the first operational Tejas squadron was issued.[186]

Cost overruns and delays were encountered in the Kaveri's development.[188] In mid-2004, the Kaveri failed high-altitude tests in Russia, ruling out it powering the first production Tejas aircraft.[187][N 2] In February 2006, the ADA awarded a contract to French engine company Snecma for technical assistance on the Kaveri.[189] Using Snecma's new core, an uprated derivative of the Dassault Rafale's M88-2 engine, providing 83–85 kilonewtons (kN) of maximum thrust was being considered by DRDO. The IAF objected that since Snecma already developed the core of the engine, the DRDO will not be participating in any joint development but merely providing Snecma with an 'Indian-made' stamp.[190] In November 2014, the DRDO was submitting documents to cancel development of Kaveri.[78]

In 2008, it was announced that an in-production powerplant would have to be selected; this was required to be in the 95 to 100 kilonewton (kN) (21,000–23,000 lbf) range to execute combat manoeuvres with optimal weapons load.[191][192] After evaluation and acceptance of technical offers for both the Eurojet EJ200 and the General Electric F414, the commercial quotes were compared in detail and GE's F414 was declared as the lowest bidder. The deal covered the purchase of 99 GE F414 engines, an initial batch will be supplied directly by GE and the remainder to be manufactured in India under a technology transfer arrangement.[193][194] According to the IAF, adopting the new powerplant required a three-to-four years of redesign work.[195]

The Tejas made its international debut on 21 January 2016, when two aircraft flew in the Bahrain International Air Show.[204] On 21 November 2016, the Indian Ministry of Defence proposed exporting the Tejas, with preliminary talks taking place with several friendly countries.[205]

The jet has solicited interest with United Arab Emirates (UAE) with some discussions made during a visit by UAE Minister of State and Defence Mohammed Ahmed Al Bowardi Al Falacy during a state visit in October 2018 as part of growing defence relations between India and UAE.[206] In January 2019, the Royal Malaysian Air Force issued a request for information to HAL regarding the Tejas for their light combat aircraft requirement.[207] In November 2019, Malaysia announced its interest to purchase the Tejas despite differences with India over Kashmir.[208] In December 2020, HAL proposed the Tejas-LIFT as a contender for the US Navy's RFI for a new naval trainer.[209]

Aircraft already built and projected models to be built. Model designations, tail numbers and dates of first flight are shown.

Technology Demonstrators (TD)

• TD-1 (KH2001) – 4 January 2001.[210]
• TD-2 (KH2002) – 6 June 2002.[210]

Prototype Vehicles (PV)

• PV-1 (KH2003) – 25 November 2003.[210]
• PV-2 (KH2004) – 1 December 2005.[210]
• PV-3 (KH2005) – 1 December 2006.[210]
• PV-5 (KH-T2009) – 26 November 2009 – Fighter/Trainer variant.[210]
• PV-6 (KH-T2010) – 8 November 2014 – Fighter/Trainer variant.[75]

Naval Prototypes (NP)

• NP-1 (KH-T3001) – Two-seat Naval variant for carrier operations. Rolled out in July 2010.[211] NP-1 made its first flight on 27 April 2012.[135]
• NP-2 (KH3002) – First flight on 7 February 2015 with ski-jump take-off and arrested landing required in STOBAR carrier.[212]

Limited Series Production (LSP) aircraft

• LSP-1 (KH2011) – 25 April 2007. This LCA is powered by F404-F2J3 Engine.[213]
• LSP-2 (KH2012) – 16 June 2008. This is the first LCA fitted with F404-IN20 engine.[213]
• LSP-3 (KH2013) – 23 April 2010. The first aircraft to have the Hybrid MMR radar[62] and will be close to the IOC standard.
• LSP-4 (KH2014) – 2 June 2010. The first aircraft that was flown in the configuration that will be delivered to the Indian Air Force.[63] In addition to the Hybrid MMR, the aircraft flew with a Countermeasure Dispensing System and an identify friend or foe electronic system.[214]
• LSP-5 (KH2015) – 19 November 2010. IOC standard, with all sensors including night lighting in the cockpit, and an auto-pilot.[215]
• LSP-6 – Not built.[216]
• LSP-7 (KH2017) – 9 March 2012.[217] APU intake has been aerodynamically reshaped.
• LSP-8 (KH2018) – First flight trial completed in March 2013. LSP 8 is the final version upon which production is based.[73]

• Tejas Mark 1 (IOC standard) − Single-seat variant for Indian Air Force with Initial Operational Clearance. The 45 Squadron (Flying Daggers) operates 16 jets of this variant. All 16 IOC fighters will later be upgraded to FOC standard.[218][219]

LCA Tejas FOC

• Tejas Mark 1 (FOC standard) − Single-seat operational variant for Indian Air Force with Final Operational Clearance. All 16 jets to be inducted would be BVRAAM capable, with general flight envelope expansion, increased angle of attack, higher g-limit of +8 g, as well as hot and Aerial refueling.[220] Supply of Tejas Mk 1 (FOC standard) has begun and 18 Squadron (Flying Bullets) has been raised with the first aircraft in May 2020.[5] Delivery of balance 15 aircraft to No. 18 Squadron is expected to be completed by September 2021.[221]

HAL Tejas Mk2

• Tejas Mark 1A - Tejas Mark 1A is to enhance manoeuvrability, aerodynamics, radar signature, maintainability, and pilot survivability; and adding an EL/M-2052 AESA fire control radar, self-protection jammer, radar warning receiver, as well as being able to mount an external ECM pod[222][223][117] In January 2021, the Cabinet Committee on Security, approved the procurement of 73 LCA Tejas Mk-1A, as part of a ₹48,000 crore (US$6.7 billion) order for 83 Tejas.[55][224]
• Tejas Trainer − Two-seat operational conversion trainer for the Indian Air Force. Initially 8 Mk1 trainers were to be delivered to the IAF, as part of the order of 40 Tejas Mk1 aircraft. The IAF put in an additional caveat—that all Mk1 trainer aircraft are to be of FOC Mk1 configuration, a move that HAL stated would affect the delivery.[225] As part of the January 2021 order of 83 aircraft, the IAF has asked for an additional 10 Mk1 trainer aircraft, be added to the back order.[55] A separate production line is being established by HAL for constructing the 18 trainer aircraft on order.[221]
• SPORT [LCA LiFT] - Supersonic Omni-Role Trainer aircraft is a two-seater Lead-in Fighter Training [LiFT] aircraft being developed from LCA Trainer Mark 1 for export purposes as light fighter.[226]
• Medium Weight Fighter - or "Tejas Mark 2", is to feature the more powerful General Electric F414-GE-INS6 engine with 98 kN of thrust.[125][227][108] In November 2009, Ministry of Defence sanctioned ₹2,431.55 crore (equivalent to ₹49 billion or US$690 million in 2019) for development of Tejas Mk 2, which was expected to be completed by 2018. However, a delay in procurement of engines pushed back the initiation of development till 2013. As of 2018, the project is expected to be completed by 2022. Mk 2 will feature an AESA radar, an on-board oxygen generation system, and a built-in electronic warfare suite among other improvements to avionics.[128] In January 2019, Air Chief Marshal Birender Singh Dhanoa said that the IAF has committed to procure twelve squadrons of Tejas Mk 2 aircraft.[228] In Aero India 2019, a model of Tejas Mk 2 with close-coupled canards was displayed. Mk 2 will be slightly larger with a length of 14.6 m (48 ft) and a wingspan of 8.5 m (28 ft). An increase in payload capacity to 6,500 kg (14,300 lb) will allow it to carry more weapons. It will include an infra-red search and track system and a missile approach warning system.[229]
• Twin-engine deck based fighter (TEDBF)- A new twin-engine carrier–based fighter variant, to be developed from Naval Tejas Mark 2 or independently. Chances are it will be totally different program based on Tejas Mk2 MWF and AMCA asper interest of Indian Navy. Planned for operation from INS Vikrant and INS Vishal and can replace current MiG-29K used in INS Vikramaditya and planned for use in INS Vikrant also. First 3 prototypes will be ready by 2028.[149]

Omni Role Combat Aircraft

• Omni Role Combat Aircraft (ORCA) - It is twin engine variant of MWF will be developed for Indian Air Force and Airforce variant of TEDBF. Which is currently in design stage and waiting for approval from Government of India and Indian Air Force.

• Tejas Mark 1 Navy - Single seat prototypes (NP1 & NP2) powered by F404 engines are used for the initial testing. The Naval variant of Tejas successfully completed testing in Goa during which the short take off (200 meter) from Shore Based Test Facility were carried out along with hot refueling. In December 2016, the navy stated that the aircraft is overweight for carrier operations.[230]
• Tejas Mark 2 Navy - Twin and single-seat variants with strengthened airframe and telescopic landing gear for Indian Navy equipped for carrier operation including ski-jump take-off and arrested landing.[231] Declared as cancelled in favour of new twin-engine naval fighter.[232]
• Tejas Trainer IN - Two-seat operational conversion trainer for the Indian Navy. Cancelled in favour of new twin-engine naval fighter.[233]