HAL Tejas

Tejas
Role	Multirole light fighter
National origin	India
Manufacturer	Hindustan Aeronautics Limited (HAL)
Design group	Aeronautical Development Agency
First flight	4 January 2001
Introduction	17 January 2015[1]
Status	In service[2]
Primary user	Indian Air Force
Produced	2001–present
Number built	21 (including prototypes as of July 2017)[3]
Program cost	₹7,399.69 crore (US$1 billion) (LCA total in 2015)[4]
Unit cost	₹160 crore (US$25 million) for Mark I[5][6] ₹602.71 crore (US$94 million) for Mark IA[7]

The HAL Tejas is an Indian single-seat, single-jet engine, multirole light fighter designed by the Aeronautical Development Agency (ADA) and Hindustan Aeronautics Limited (HAL) for the Indian Air Force and Navy. The aircraft has a tail-less compound delta-wing configuration, which provides for high maneuverability.^[8] It came from the Light Combat Aircraft (LCA) programme, which began in the 1980s to replace India's ageing MiG-21 fighters. LCA was officially named "Tejas" in 2003, meaning "Radiant" in Sanskrit by the then Prime Minister Atal Bihari Vajpayee.^[9]

Tejas has a pure double delta wing configuration (wing root leading edge sweep 50°, outer wing leading edge sweep 62.5° and trailing edge forward sweep 4°), with no tailplanes or canard, and a single dorsal fin. It integrates technologies such as relaxed static stability, fly-by-wire flight control system, multi-mode radar, integrated digital avionics system, composite material structures, and a flat rated engine. It is the smallest and lightest in its class of contemporary supersonic combat aircraft.^[10][11]

The Tejas is the second supersonic fighter developed by Hindustan Aeronautics Limited (HAL) after the HAL HF-24 Marut. As of 2016 the Tejas MK1 was in production for the Indian Air Force (IAF) and the naval version was undergoing flight tests for Indian Navy (IN). The projected requirement for IAF is 200 single-seat fighters and 20 twin-seat trainers, while the IN expects to operate 40 single-seat fighters. The first Tejas IAF unit, No. 45 Squadron IAF Flying Daggers was formed on 1 July 2016 with two aircraft. Initially being stationed at Bangalore, the first squadron will be placed at its home base at Sulur, Tamil Nadu.^[12]

Development

Origins

In 1969, the Indian government 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,^[13] 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.^[14]

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% of the aircraft needed to fill its projected force structure requirements.^[15] The LCA programme's other main objective was an across-the-board advancement of India's domestic aerospace industry.^[16] The value of the aerospace "self-reliance" initiative is 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.^[17]

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.^[18] The government's "self-reliance" goals for the LCA include 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.^[19]

The IAF's Air Staff Requirement 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.^[14][20] Out of a total of 35 major avionics components and line-replaceable units (LRUs), only three involve foreign systems.^[21] These are the multi-function displays (MFDs) by Sextant (France) and Elbit (Israel),^[22] the helmet-mounted display and sight (HMDS) cueing system by Elbit,^[22] and the laser pod supplied by Rafael (Israel).^[23] 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.^[21] 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.^[21]

LCA programme

In 1990, the design was finalised as a small tailless delta winged machine with relaxed static stability (RSS) and control-configuration for enhanced manoeuvrability.^[10][24][25] 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.^[25] In October 1987, project definition commenced with France's Dassault Aviation in a reviewing/advisory role; this phase, costing ₹560 crore (equivalent to ₹49 billion or US$770 million in 2016), was completed in September 1988.^[15][20] A two-stage full-scale engineering development (FSED) process was opted for.^[15][25]

Phase 1 commenced in April 1993,^[15] 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.^[25] FSED Programme Phase-I was successfully completed in March 2004 and cost ₹2,188 crore.^[15]

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.^[19] First flying in 1974, the General Dynamics F-16 was the first production aircraft designed to be slightly aerodynamically unstable to improve manoeuvrability.^[26] Many aircraft have positive static stability to induce them to return to a straight, level flight attitude when the controls are released, maneuverability is reduced as the inherent stability has to be overcome. Aircraft with negative stability are designed to deviate from controlled flight and thus be more manoeuvrable.^[27][28]

In 1992, the LCA National Control Law (CLAW) team was set up by the National Aeronautics Laboratory to develop India's own state of the art fly-by-wire FCS for the Tejas.^[29][30] 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.^[31][32]

Another critical technology is the Multi-Mode Radar (MMR). The Ericsson/Ferranti PS-05/A I/J-band multi-function radar was initially intended to be used,^[33] as used on Saab's JAS 39 Gripen. However, after examining other radars in the early 1990s,^[34]</ref> the Defence Research and Development Organisation (DRDO) became confident that local development was possible. HAL's Hyderabad division and the LRDE were selected to jointly lead the MMR programme, and work commenced in 1997.^[35] The DRDO's Centre for Airborne System (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.^[36]

The NAL's CLAW team completed integration of the flight control laws by themselves, 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 test pilots, one of whom remarked that he found the LCA easier to take off in than in a Mirage 2000.^[37]

Phase 2 commenced in November 2001,^[15] and consisted of the manufacturing of three more prototype vehicles (PV-3, PV-4 and PV-5), leading to the development of the final variant that would join the air force and the navy and 8 Limited Series Production (LSP) aircraft, and establishment of infrastructure for producing 8 aircraft per year.^[25] The phase cost ₹3,301.78 crore, and an additional amount of ₹2,475.78 crore 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.^[15]

By mid-2002, the MMR had reported 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."^[38] 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.^[35][39][40]

Of the five critical technologies the ADA identified at the programme's onset as required to design and build a new fighter, two have been entirely 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).^[19] 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. Successes have often been overshadowed by problems encountered with the other three key technology initiatives however.^[41]

Kota Harinarayana was the original Programme Director and Chief Designer for the Tejas Programme.^[42][43]

Prototypes and testing

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.^[44][45] In December 2006, a 14-member "LCA Induction Team" was formed at Bangalore to prepare the Tejas for service and assist with its induction into service.^[46]

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).^[20] The Tejas completed 1,000 test flights and over 530 hours of flight testing by 22 January 2009.^[20][47] 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.^[20][48]

On 16 June 2008, LSP-2 made its first flight.^[20] In November 2009, the trainer variant prototype took to the skies.^[49] On 23 April 2010, LSP-3 flew with a hybrid version of the Elta EL/M-2032 multi-mode radar;^[20][50] in June 2010, LSP-4 took its first flight in an IAF Initial Operating Clearance (IOC) configuration.^[20][51] By June 2010, the Tejas had completed the second phase of hot weather trials in an IOC configuration with the weapon system and sensors integrated.^[52] Sea trials were also being carried out.^[53] On 19 November 2010, LSP-5 with IOC standard equipment took to skies.^[54]

In December 2009, the government sanctioned ₹8,000 crore to begin production of the fighter for the Indian Air Force and Indian Navy. The Indian Navy has a requirement for 50 Tejas aircraft and the first prototype, NP-1 was rolled out in July 2010.^[55] IAF ordered 20 additional Tejas fighters after the defence acquisition council cleared the plan.^[56] In December 2014 the LCA Navy successfully conducted ski-jump trials at SBTF Goa. The navy variant has a special flight control law mode which allows hands-free take-off relieving the pilot workload, as the aircraft leaps from the ramp and automatically puts the aircraft in an ascending trajectory.^[57][58]

In November 2010, it was reported that the Tejas Mk1 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.^[59]

On 9 March 2012, LSP-7 took to its maiden flight from HAL airport.^[20] The Naval LCA made its first flight, almost two years after being rolled out, on 27 April 2012.^[60]

In September 2011, weapon tests, including bombing runs, begun at Pokhran range, to be followed by missile tests at Goa.^[61] On 27 June 2012, three Tejas (LSP 2, 3 and 5) aircraft completed precision bombing runs in the desert of Rajasthan, having deployed laser-guided 1,000 lb bombs and unguided bombs.^[62] The Tejas had completed 1,941 flights by July 2012.^[63]

In the later half of 2012, the Tejas was grounded for over three months due to a serious safety issue with the pilot's helmets, which extended above the ejection seats, potentially prevented smooth ejection by striking the canopy before the latter was blown off. Flight tests resumed in November 2012 after the ejection systems were modified in response.^[64] LSP 8 had a successful maiden test flight on 31 March 2013,^[65] and the programme had completed 2,418 test flights by 27 November 2013.^[63][66] On 31 March 2013, LSP-8 took to its maiden flight from HAL airport.^[20] On 8 November 2014, PV-6(KH-T2010), a trainer variant, completed its first test flight.^[67]

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. The IAF plans to raise the first squadron in Bangalore to iron out issues with ADA and HAL, and eventually base these fighters at Sulur Air Force Station, Coimbatore in the southern state of Tamil Nadu.^[45][68] In October 2011, Tejas' Final Operational Clearance (FOC) was reportedly delayed from December 2012 until mid-2013 or later.^[69][70] In mid-2012, some sources claimed that the aircraft would not reach FOC and become fully combat capable until 2015.^[71] This was later pushed to June 2017.^[72]

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.^[73] On 20 December 2013, the IOC-II was issued, after which the aircraft was cleared to be flown by regular IAF pilots and begin induction into squadron service. The first squadron of 18 to 20 Tejas will be based at Sulur Air Force Station, Coimbatore in the state of Tamil Nadu,^[74] and it will work to achieve FOC by December 2014.^[75] To fulfill the IOC-II standard, the aircraft was certified to carry close to three tons of weapons which include laser-guided 500 kg bombs and short-range R-73 missiles,^[76][77] 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.^[78][79]

To obtain FOC, the fighter will have to be certified for six more criteria. Integration of Derby and Python BVR missiles weighing 150 kg, with a range of 70 km, as well as a Gryazev-Shipunov GSh-23 gun will be undertaken. An air-to-air refuelling probe supplied by Cobham will be added. The angle of attack will be increased from 24 to 28 degrees,^[78] the braking system will be enhanced, and the existing nose cone radome made of composites will be replaced by a quartz model in a bid to increase the current radar range of 45–50 km to more than 80 km. These modifications are expected to be completed within 15 months of IOC-II.^[75][80] In order to expand the flight envelope to meet service requirements, the programme enlisted assistance from EADS.^[81]

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.^[82] As part of the FOC, the aircraft is being readied for all-weather trials in Bangalore and in Gwalior. Tejas took its maiden flight in January 2001, and by December 2013, it had completed 2,587 sorties covering over 1,750 hours.^[82] In July 2014, the FOC was pushed back as six or more aircraft were needed for testing and only one had been produced then.^[83] Tejas received IOC-II clearance on 17 January 2015 and the FOC was expected by year's end for induction in the Indian Air Force,^[84] but has been further pushed down to end of 2016.^[85]

In May 2015, the Mark I aircraft was criticized by the Comptroller and Auditor General of India (CAG) for not meeting IAF requirements, such as a lack of a two-seat trainer, electronic warfare capabilities, the Radar Warning Receiver/Counter Measure Dispensing System, weight increases, reduced internal fuel capacity, non-compliance of fuel system protection, forward-facing pilot protection, and reduced speed. Most of these issues are expected to be rectified in the future Mark II version.^[86]

In October 2015, IAF Air Chief Marshal Arup Raha confirmed that the air force had ordered 120 (six squadrons) of Tejas Mark 1A, triple the 40 aircraft it had previously committed to buying. NDTV reported that IAF agreed to accept 40 aircraft even though the CAG had found serious operational shortfalls, including engine thrust, weight and pilot protection in front against 7.62 mm rifle calibre ammunition. The IAF agreed to accept the flawed Tejas to keep the programme alive; the DRDO and HAL promised an improved Tejas Mark 1A version; changes to the ballast and landing gear will reduce its weight by 1,000 kg and the delivery will begin by 2016.^[87][88] Tejas Mark 1A shall also have electronic warfare equipment, better air to air capability, aerial refueling and improved ease of maintenance.^[89]

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 National Flight Test Centre. The aircraft is also scheduled to fire a Close Combat Missile (CCM) Python-5 missile as part of the FOC trails. The LSP-7 along with LSP-4 were part of Indian flying assets at the just-concluded Bahrain International Air Show (BIAS-2016).^[90]

On 26 February 2016, Defence Minister Manohar Parrikar said in the Lok Sabha that the Indian Air Force will accept three to four Tejas this year and stand up a total of eight squadrons in eight 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."^[91] On 7 November 2016, Parrikar approved procurement of 83 Tejas for the IAF, at a cost of ₹50,025 crore (US$8 billion).^[7]

In December 2016, the Indian Navy announced that the fighter is overweight, and they will look for other alternatives.^[92][93] The Indian Navy eventually issued an RFI for 57 naval multirole fighters.^[94]

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^[95].The missile destroyed its manoeuvrable aerial target with pinpoint precision at the Interim Test Range, Chandipur in Odisha.^[96]

As of 13 July 2017, the Tejas fleet has flown 3,478 test sorties and 4,200 hours without any accidents.^[97]

Design

Overview

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.^[98] The tailless, compound-delta planform is designed to be small and lightweight.^[99] This platform also minimises the control surfaces needed (no tailplanes or foreplanes, just a single vertical tailfin), 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.^[98]

The maximum payload capability of Tejas is 4,000 kg (8,818 lb).^[100] All weapons are carried on one or more of seven hardpoints with total capacity of greater than 4,000 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 centreline under-fuselage station and inboard pairs of wing stations.^{[31][101][102]} Auxiliary fuel tanks of 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.^[103] RAFAEL's Derby fire-and-forget missile will serve as the Tejas' initial medium range air-air armament.^[23] The Brahmos NG supersonic cruise missile is being developed for the Tejas.^[104] The long range Nirbhay cruise missile is being considered for use on the Tejas, but will require extensive modifications, including being shortened by 25%, to fit the aircraft.^[105]

Stealth features have been designed into Tejas.^[106] 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.^[107]

Although two-seat variants are planned, the examples built to date are crewed by a single pilot on a Martin-Baker zero-zero ejection seat; a locally developed ejection seat is planned for future installation.^[108] Tejas requires a very short runway and "rockets off the runway and into the air in a mere 500 metres".^[109]

Airframe

The LCA is constructed of aluminium-lithium alloys, carbon-fibre composites (C-FC), and titanium alloy steels. The Tejas employs C-FC materials for up to 45% of its airframe by weight, including in the fuselage (doors and skins), wings (skin, spars and ribs), elevons, tailfin, rudder, air brakes and landing gear doors.^[109] Composite materials are used to make an aircraft both lighter and stronger at the same time compared to an all-metal design, and the LCA's percentage employment of C-FCs is one of the highest among contemporary aircraft of its class.^[110] 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.^[111] 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.^[112][113] 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 computerised numerically controlled machine. No other manufacturer is known to have made fins out of a single piece.^[114]

The use of composites resulted in a 40% reduction in the total number of parts, including half the number of fasteners required, compared to a metallic frame design. The composite design also helped to avoid about 2,000 holes being drilled into the airframe. Overall, the aircraft's weight is lowered by 21%. While each of these factors can reduce production costs, an additional benefit — and significant cost savings — is realised in the shorter time required to assemble the aircraft — seven months for the LCA as opposed to 11 months using an all-metal airframe.^[115] The wing-shielded, side-mounted bifurcated, fixed-geometry Y-duct air intakes with splitter plates,^[101] can ensure buzz-free air supply into the engine compressor for thrust generation.^[116]

The airframe of the naval variant will be modified with a nose droop to provide improved view during landing approach, and wing leading edge vortex controllers (LEVCON) to increase lift during approach.^[14] 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 slightly hampered due to the increased drag that results from its delta-wing design. As an added benefit, the LEVCONs will also increase controllability at high angles of attack (AoA).^[117] The naval Tejas will also have a strengthened spine, a longer and stronger undercarriage, and powered nose wheel steering for deck manoeuvrability.^[23][118] The Tejas trainer variant will have "aerodynamic commonality" with the two-seat naval aircraft design.^[119]

Avionics

The Tejas has a night vision goggles (NVG)-compatible "glass cockpit", dominated by an CSIR-CSIO domestically-developed head-up display (HUD), three 5 in x 5 in multi-function displays, two Smart Standby Display Units (SSDU), and a "get-you-home" panel providing the pilot with essential flight information in case of an emergency. 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 multifunctional keyboard and several selection panels.^[109] The CSIO-developed HUD, Elbit-furnished DASH helmet-mounted display and sight (HMDS),^[22] 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.^[101][107]

The first 20 production Tejas Mk1 equipped with 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.^[107] The Tejas Mark IA will be equipped with an improved version of the EL/M-2052 AESA radar being developed jointly by Elta and HAL.^[120] The Mark 2 will feature an indigenously-developed AESA fire control radar named Uttam.

The Tejas is equipped with both GPS and a ring laser gyroscope based inertial navigation system; for flying in poor conditions, a Very-High Frequency Omni Range/Instrument Landing System (ILS), TACAN for bearing and distance to ground indication and a ground proximity warning system based on the Terrain Referenced Navigation (TRN) system is also employed.^{[102][121][122][123]} The LCA also has secure and jam-resistant communication systems such as the IFF transponder/interrogator, VHF/UHF radios, and air-to-air/air-to-ground datalinks. The ADA Systems Directorate's Integrated Digital Avionics Suite (IDAS) integrates the flight controls, environmental controls, aircraft utilities systems management, stores management system (SMS), etc. on three 1553B buses by a centralised 32-bit, high-throughput mission computer.^[101]

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.^{[121][122][124]}

Tejas is also to be equippable with an Infra-red search and track (IRST) sensor, which can detect and track thermal energy emissions.^[109][125] This system shall be pod-based, additional sensor pods are to include a 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.^{[31][101][102]}

Flight controls

Since the Tejas is a relaxed static stability design, it is equipped with a quadruplex digital fly-by-wire flight control system to ease pilot handling.^[126] The Tejas aerodynamic configuration is based on a pure delta-wing layout with shoulder-mounted wings. Its control surfaces are all hydraulically actuated. 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.^[127]

The digital FBW system of the Tejas employs a powerful digital flight control computer (DFCC) made by Aeronautical Development Establishment (ADE) comprising four computing channels, each with its own independent power supply and all housed in a single LRU. The DFCC receives signals from a variety of sensors and pilot control stick inputs, and processes these through the appropriate channels to excite and control the elevons, rudder and leading edge slat hydraulic actuators. The DFCC channels are built around 32-bit microprocessors and use a subset of the Ada programming language for software implementation. The computer interfaces with pilot display elements like the MFDs through MIL-STD-1553B multiplex avionics data buses and RS-422 serial links.^{[109][128][129]} The aircraft features in-flight refuelling capability via retractable probes on the aircraft's starboard side, and an on-board oxygen-generating system for longer missions.

Propulsion

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 was launched.^[130] 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;^[131] deliveries began in 2006.^[132] In 2007, a follow-on order for 24 F404-IN20 engines to power the first operational Tejas squadron was issued.^[131]

Cost overruns and delays were encountered in the Kaveri's development.^[133] In mid-2004, the Kaveri failed high-altitude tests in Russia, ruling out it powering the first production Tejas aircraft.^{[132][N 1]} In February 2006, the ADA awarded a contract to French engine company Snecma for technical assistance on the Kaveri.^[134] 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.^[135] In November 2014, the DRDO was submitting documents to cancel development of Kaveri.^[23]

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.^[136][137] 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.^[138][139] According to the IAF, adopting the new powerplant required a three-to-four years of redesign work.^[140]

Operational history

The formation of the first Tejas-equipped squadron started in July 2011. The Tejas entered service with No. 45 Squadron IAF (Flying Daggers) based at the Yelahanka Air Base at Bangalore on 1 July 2016 before being moved to Sulur Air Force Station in Coimbatore.^[141] The squadron will initially have four aircraft. The IAF's Aircraft & Systems Testing Establishment will receive four aircraft already built including two development aircraft.^[142]

The Tejas made its international debut on 21 January 2016, when two aircraft flew in the Bahrain International Air Show.^[143]

In June 2017, Hindustan Aeronautics stated that it expects to have delivered 123 Tejas aircraft to the Indian Air Force by 2024-25. HAL outlined a three–pronged approach to accelerate aircraft production. It will build an additional assembly line, reuse the Hawk assembly line, and outsource major components to the private sector.^[144]

Variants

Prototypes

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 Jan 2001
• TD-2 (KH2002) – 6 June 2002

Prototype Vehicles (PV)

• PV-1 (KH2003) – 25 November 2003
• PV-2 (KH2004) – 1 December 2005
• PV-3 (KH2005) – 1 December 2006. This is the production variant.
• PV-4
• PV-5 (KH-T2009) – 26 November 2009 – Fighter/Trainer Variant
• PV-6 (KH-T2010) - 8 November 2014 - Fighter/Trainer Variant.^[67]

Naval Prototypes (NP)

• NP-1 (KH-T3001) – Two-seat Naval variant for carrier operations. Rolled out in July 2010.^[145] NP-1 made its first flight on 27 April 2012.^[60]
• NP-2 (KH3002) – First flight on 7 February 2015 with sky-jump take-off and arrested landing required in STOBAR carrier.^[146]
• NP-3 & NP-4 – Single-seat LCA MK 2 Naval variant for carrier operations to be powered by the GE-414 engines. The design work on the two aircraft is nearly complete.^[60]
• NP-5 – Another Single-seat LCA MK 1 Naval variant is planned so as to enhance the pace of certification process for Naval LCA.^[60]

Limited Series Production (LSP) aircraft

Currently, 8 LSP series aircraft plus 40 aircraft are on order.

• LSP-1 (KH2011) – 25 April 2007. This LCA is powered by F404-F2J3 Engine.^[147]
• LSP-2 (KH2012) – 16 June 2008. This is the first LCA fitted with F404-IN20 engine.^[147]
• LSP-3 (KH2013) – 23 April 2010. The first aircraft to have the Hybrid MMR radar^[50] 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.^[51] In addition to the Hybrid MMR, the aircraft flew with a Countermeasure Dispensing System and an identify friend or foe electronic system.^[148]
• LSP-5 (KH2015) – 19 November 2010. IOC standard, with all sensors including night lighting in the cockpit, and an auto-pilot.^[149]
• LSP-6 – Not built.^[150]
• LSP-7 (KH2017) – 9 March 2012. APU intake has been aerodynamically reshaped.
• LSP-8 – First flight trial completed in March 2013. LSP 8 is the version that will go for production.^[65]
• SP-1 to SP-20 – First production batch, the first aircraft had its first flight on 30 September 2014. On 17 January 2015 SP-1 was handed over to Indian Air Force by Defence Minister Sh. Manohar Parrikar.^[151]

Planned production variants

• Tejas Trainer - Two-seat operational conversion trainer for the Indian Air Force.
• Tejas Mark 1A HAL is now working on developing a new variant named Tejas Mark IA^[152] which will be equipped with an advanced AESA Radar and an electro-optic Electronic Warfare (EW) sensor suite. It will also incorporate weight reduction along with easier service maintainability which will thus reduce downtime of each aircraft. It will also have a mid-air refuelling probe to enhance its endurance and operational range. The timeline for this variant has been set at 2017.^[153][154] On 25 October 2015, it was reported that 100 Tejas aircraft will be equipped with an improved version of the EL/M-2052 AESA radar being developed jointly by Elta and HAL.^[120]
• Tejas Trainer IN - Two-seat operational conversion trainer for the Indian Navy.
• Tejas Mk1 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. The flight test from aircraft carrier is scheduled for 2017.^[155] In December 2016, the navy stated that the aircraft is overweight for carrier operations.^[156]
• Tejas Mk2 Navy -Twin- and single-seat carrier-capable variants for the Indian Navy. It will be equipped for carrier operation with ski-jump take-off and arrested landing. It will include strengthened airframe and landing gear and drooped nose for better cockpit vision.^[157] The Tejas Mk 2 Navy will have a length of 14.2 metres (1 metre more than that of the Tejas Mk 1, for incorporating a stretched nose section and a modified fuselage section aft of the cockpit for housing an expanded complement of mission avionics LRUs), height of 4.6 metres (as opposed to 4.4 metres of the Tejas Mk 1, to accommodate an enlarged vertical tail-section) and a wingspan of 8.2 metre, same as that of the Tejas Mk 1, however with an increased wing area. External stores capacity will be boosted to 5,000 kg (as opposed to 4,000 kg for the Tejas Mk 1), while the twin internal air-intake ducts will be minimally enlarged to cater to the increased airflow requirements of the 98 kN thrust F414-GE-INS6. The Ministry of Defence had sanctioned US$542.44 million (Rs 2,431.55-crore) for ADA to develop the Indian Navy's LCA Mk 2 (Navy) variant. The IAF is committed to procuring an initial 83 Tejas Mk 2s and the Indian Navy has expressed a firm requirement for 46 LCA Mk2 (Navy).^{[44][158][159]} The Mark 2 may feature an indigenously developed active electronically scanned array (AESA) fire control radar named Uttam.^[160] The Mk2 will also see the incorporation of a new electronic warfare suite which is being jointly developed with Israel. This is to have a new glass cockpit with larger 8 x 12 inch displays. The Mk2 will have some 25-30 percent commonality in parts with the Mk1 and these parts are already in production.^[161] The Mark 2 is scheduled for flight testing by 2018, but this may be delayed by two or three more years to allow time to engineer the installation of the GE 414 engine.^[162] In August 2015, the Indian defence minister stated the first flight is likely to be 2019 with an entry into service in 2022.^[163]
• Tejas Mark 2 - The Tejas Mark 2 is to feature the more powerful General Electric F414-GE-INS6 engine with 98 kN of thrust and refined aerodynamics. The Mark 2 is being developed to meet the latest IAF requirements and will incorporate fifth-generation jet fighter elements which are intended to make way into the FGFA and AMCA. The Tejas Mk 2 will have a length of 14.2 metre (1 metre more than that of the Tejas Mk 1, for incorporating a stretched nose section and a modified fuselage section aft of the cockpit for housing an expanded complement of mission avionics LRUs), height of 4.6 metre (as opposed to 4.4 metres of the Tejas Mk 1, to accommodate an enlarged vertical tail-section) and a wingspan of 8.2 metres, same as that of the Tejas Mk 1, however with an increased wing area. External stores capacity will be boosted to 5,000 kg (as opposed to 4,000 kg for the Tejas Mk 1), while the twin internal air-intake ducts will be minimally enlarged to cater to the increased airflow requirements of the 98 kN thrust F414-GE-INS6. The Ministry of Defence had sanctioned US$542.44 million (Rs 2,431.55-crore) for ADA to develop the IAF's Tejas Mk 2 variant. The IAF is committed to procuring an initial 105 Tejas Mk 2s.^{[44][158][159]} The Mark 2 may feature an indigenous developed active electronically scanned array (AESA) fire control radar named Uttam.^[160] The Mk2 will also see the incorporation of a new electronic warfare suite which is being jointly developed with Israel. This is to have a new glass cockpit with larger 8 x 12 inch displays. The Mk2 will have some 25-30 percent commonality in parts with the Mk1 and these parts are already in production.^[161] The Mark 2 is scheduled for flight testing by 2018, but this may be delayed by two or three more years to allow time to engineer the installation of the GE 414 engine.^[162]In August 2015, the Indian defense minister stated the first flight is likely to be 2019 with an entry into service in 2022.^[163] In October 2015, media reports suggested the government has decided to order the modified Tejas Mk 1A instead of the Tejas Mk 2.^[164]

Operators

 India

• Indian Air Force – 123 LCA aircraft [40 x Mk 1 + 83 x Mk 1A]^[165] aircraft planned to be acquired. Four squadrons of LCA Mk 2 aircraft planned to be acquired after completing production of LCA Mk 1.^[166][167] The IAF was considering at least 14 Tejas squadrons with 294 aircraft in February 2014, with each squadron to have 21 aircraft.^[168][169]
  • No. 45 Squadron IAF (Flying Daggers) - Bangalore, Karnataka^[170]
• Indian Navy – Signed an order for six Naval LCAs at an approximate cost of US$31.09 million per aircraft.^[171] The Indian Navy has a requirement for 40 Tejas aircraft.^[55] In December 2016, the Indian Navy announced that Tejas is overweight for carrier operations and rejected it.^[92]

Specifications (HAL Tejas Mk.1)

Data from tejas.gov.in,^[172] DRDO Techfocus,^[173] Aero India 2011^[174]

General characteristics

• Crew: 1
• Length: 13.20 m (43 ft 4 in)
• Wingspan: 8.20 m (26 ft 11 in)
• Height: 4.40 m (14 ft 9 in)
• Wing area: 38.4 m² (413 ft²)
• Empty weight: 6,560 kg (14,300 lb)
• Loaded weight: 9,500 kg^[172] (20,944 lb)
• Max. takeoff weight: 13,500 kg^[172][175] (29,100 lb)
• Internal fuel capacity: 2,458 kg
• External fuel capacity: 2 x 1,200-litre drop tank inboard, 1 x 800-litre drop tank under fuselage
• Powerplant: 1 × General Electric F404-GE-IN20 turbofan
  • Dry thrust: 53.9 kN^[103] (12,100 lbf)
  • Thrust with afterburner: 89.8 kN (20,200 lbf^[176])

Performance

• Maximum speed: Mach 1.8 (2,205 km/h) for FOC version;^[101] Mach 1.6 (2,000 km/h) for IOC version;^[177][178]
• Combat radius: 500 km^[179] (270 nmi, 311 mi)
• Ferry range: 1,700 km^[180] (1,056 mi)
• Service ceiling: 16,000 m^[175] (52,500 ft)
• Wing loading: 247 kg/m² (50.7 lb/ft²)
• Thrust/weight: 1.07^[172]
  
• g-limits: +8/−3.5 g^[181]

Armament

• Guns: 1× mounted 23 mm twin-barrel GSh-23 cannon with 220 rounds of ammunition
• Hardpoints: 8 (1× beneath the port-side intake trunk for targeting pods, 6× wing, and 1× fuselage) with a capacity of 3,500 kg external fuel and ordnance^[182] and provisions to carry combinations of:
  • Rockets: S-8 rocket pods, Bofors 135 mm rocket
  • Missiles:
    
    • Air-to-air missiles:
      • Astra
      • Derby^[183]
      • Python-5
      • R-77
      • R-73
    • Air-to-surface missiles:
      • DRDO Anti-Radiation Missile^[184]
      • Kh-59ME (TV-guided standoff missile)
      • Kh-59MK (Laser-guided standoff missile)
    • Anti-ship missiles
      • Kh-35
      • Kh-31
  • Bombs: ^[185]
    • KAB-1500L laser-guided bombs
    • GBU-16 Paveway II
    • FAB-250
    • ODAB-500PM fuel-air explosives
    • ZAB-250/350 incendiary bombs
    • BetAB-500Shp powered concrete-piercing bombs
    • FAB-500T gravity bombs
    • OFAB-250-270 gravity bombs
    • OFAB-100-120 gravity bombs
    • RBK-500 cluster bomb stake
  • Other: ^[185]
    • Drop tanks for ferry flight/extended range/loitering time
    • LITENING targeting pod^[186][187]

Avionics

• Hybrid version of Israel's Elta EL/M-2032 multi-mode fire control radar^[188]

See also

• HAL Tejas timeline

Related lists

• List of fighter aircraft
• List of active Indian military aircraft

References

Notes

Citations

Bibliography

External links

Wikimedia Commons has media related to HAL Tejas.

• Official Government of India Tejas site

Features and analysis:

• "Flying into the unknown" — A feature by The Hindu on the Tejas test pilots.
• "LCA and Economics" by Sunil Sainis and George Joseph
• "The Light Combat Aircraft Story", by Air Marshal MSD Wollen (Retd).
• The case to support the indigenous LCA programme, by Ashok Parthasarathi and Raman Puri.

Technical:

• An Approach to High AoA Testing of the LCA
• Development Flight Testing of the Tejas Light Combat Aircraft
• LCA Avionics And Weapon System Mission Computer Software Development: A Case Study

General:

• "Tejas / Light Combat Aircraft (LCA)", Fighter-planes.com
• "Dawn of Tejas" Aero India special report from flightglobal.com