HAL Tejas

The HAL Tejas is an Indian, single engine, delta wing, light multirole fighter designed by the Aeronautical Development Agency (ADA) in collaboration with Aircraft Research and Design Centre (ARDC) of Hindustan Aeronautics Limited (HAL) for the Indian Air Force and Indian Navy. It came from the Light Combat Aircraft (LCA) programme, which began in the 1980s to replace India's ageing MiG-21 fighters but later became part of a general fleet modernisation programme. In 2003, the LCA was officially named "Tejas". It is the smallest and lightest in its class of contemporary supersonic combat aircraft.

The Tejas is the second supersonic fighter developed by HAL after the HAL HF-24 Marut. The Tejas achieved initial operational clearance in 2011 and final operational clearance in 2019. The first Tejas squadron became operational in 2016, as No. 45 Squadron IAF ''Flying Daggers'' was the first to have their MiG-21s replaced with the Tejas.

The Tejas currently has three production models – Tejas Mark 1, Mark 1A and trainer variant. The IAF currently placed an order for 40 Tejas Mark 1 and 73 Tejas Mark 1A and 10 trainer aircraft. The IAF plans to procure 324 aircraft in all variants, including the Tejas Mark 2 currently being developed by the HAL. The Tejas Mark 2 is expected to be ready for series production by 2026.

indigenous content in the Tejas Mark 1 is 59.7% by value and 75.5% by number of line replaceable units. As the defense minister announced, the indigenous content of the Tejas Mk 1A is expected to be 50% and rise to 60% by the end of the programme.

Development

LCA programme

The origin of LCA programme can be traced back to the early 1980s. In 1983, the Government of India established the LCA project with the initial goal to develop a new light combat aircraft to replace the ageing IAF fighters, especially the MiG-21 variants, which had been the mainstay of the IAF since 1963. At one point the IAF had operated as many as 874 MiG-21s. The "Long Term Re-Equipment Plan 1981" noted that most of these IAF fighters were approaching the end of their service lives by the early-1990s, and that by 1995, the IAF would be 40 percent short of the aircraft needed to fill its projected force structure requirements.

In 1984, the Government of India established Aeronautical Development Agency (ADA) under the aegis of Defence Research and Development Organisation (DRDO) to manage the LCA programme. The ADA was entrusted with the design and development of LCA while HAL was chosen as the principal contractor. 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, multi-mode pulse-doppler radar, and afterburning turbofan engine.

The project definition phase was commenced in October 1986 with France's Dassault-Breguet Aviation as consultant. Dassault-Breguet's expertise was mainly utilised in the design and system integration of the Tejas. In 1988, Dassault had offered a hybrid fly by wire flight control system for the LCA. It consists of three digital channels and one analogue channel, the French idea was to have a fourth analogue channel as a back up in case the digital channels fails. But the ADA was in favour of having a quadruplex digital FBW flight control system on LCA.

The design of the Tejas was finalised in 1990 – a small tailless compound delta wing design with inherent relaxed static stability which necessitates the need for digital FBW flight control system ( ''control configured vehicle'' concept) for enhanced manoeuvrability. Kota Harinarayana was the Programme Director and Chief Designer of Tejas. In 1992, a dedicated ''National Control Law (CLAW)'' team was set up by the National Aerospace Laboratories to develop India's own state of the art FBW flight control system for the Tejas. Earlier Lockheed Martin's consultancy was utilized for the development of fly by wire flight control system. However Lockheed Martin withdrew its assistance In 1998, owing to the US embargo in response to India's second nuclear tests in that year, which delayed the programme.

The NAL's CLAW team completed the design and integration of the flight control laws with the flight control system software, and put to test at the ''Iron-Bird'' test rig. The quadruplex digital fly-by-wire flight control system, performing flawlessly for over 50 hours of pilot testing on Technology Demonstrator TD-1 cleared for flight test by early 2001. On 4 January 2001, on its maiden flight, the TD-1 successfully flew with an indigenous quadruplex digital FBW flight control system.

Another critical technology needed for LCA was 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. However, DRDO decided to develop an indigenous multi-mode radar for the Tejas. HAL's Hyderabad division and the DRDO's Electronics and Radar Development Establishment (LRDE) laboratory were selected to jointly lead the MMR programme, and work commenced in 1997. The Centre for Airborne Systems (CABS) was responsible for the MMR's test programme. An HAL-748 airborne surveillance aircraft was converted for this purpose. The development of multi-mode was not smooth, as it suffered some setbacks. By 2005, only two radar modes – the air-to-air look-up and look-down were confirmed to have been successfully tested. The performance of several other modes that had been tested were suboptimal. The problem with the radar was mainly attributed to the lack of compatibility between the LRDE/HAL multi mode radar and the LRDE's advanced signal processor module. Using an "off-the-shelf" foreign radar as an interim option was considered.

ADA met with success in the development of three of the five key technologies identified at the beginning of the LCA programme. The successful endeavours were mastery in the FBW flight control system, the development and manufacturing of carbon-fibre composite structures and skins, and a modern glass cockpit. The ''Autolay'' computer-aided design software developed as part of the LCA programme has been licensed to Airbus for its A380 wide-body aircraft project. The development of a multi-mode pulse-doppler radar, once delayed was completed as the Active electronically scanned array (AESA) radar and is currently undergoing flight trials. India's self-reliance goal oriented development for the LCA programme has considerably increased the indigenous components in Tejas and contributed to an aviation industry expansion in the country.

On 20 December 2021, Ministry of Defence (MoD) in a written reply during winter session of Rajya Sabha clarified that the HAL Tejas is no longer considered as a replacement for the Mikoyan-Gurevich MiG-21, instead it is now part of a general IAF fleet modernisation programme.

Prototypes and testing

Prototype testing began in 2003, a year after the first flight of the second Technology Demonstrator (TD-2). The first prototype aircraft, PV-1, made its maiden flight in 2003. The first trainer prototype PV-5 was rolled out in 2009 and made its first flight on 26 November 2009. A total of two trainer prototypes were built and designated PV-5 and PV-06. The first naval prototype, designated NP-1, made its first flight on 27 April 2012. It was a twin-seater aircraft, while the second naval prototype, designated as NP-2, was a single seater. Both naval prototypes were used extensively for various aircraft carrier-related trials at the Shore Based Test Facility in Goa. NP-2 was used in the actual carrier trials, where it made an arrested recovery and ski-jump assisted take-off from the aircraft-carrier INS Vikramaditya in January 2020.

The first Limited Series Production aircraft (LSP-1) performed its maiden flight on 25 April 2007. A total of seven limited series production (LSP) aircraft were built. The LSPs were extensively used for developmental trials such as weapon testing – involving test firing of the R-73 and Python-5 close combat missiles, the I-Derby ER beyond visual range air-to-air missile and guided–unguided munition releases. The LSPs were also used for sensor trials involving integration and testing of the Israeli Elta EL/M-2032 multi-mode radar, Indian Uttam AESA Radar and Rafael Litening targeting pod. The Uttam radar was integrated on the Tejas LSP-2 and LSP-3, and logged about 30 hours of flight testing on the Tejas alone. The high altitude trials and hot weather trials were carried out with the LSPs and the PV-3 prototype, in IOC and FOC configurations. These trials were mainly focused on assessing the performance of the various sensors and avionics on board, at temperatures ranging from below -10 degree Celsius to more than +45 degrees Celsius.

Sea trials to assess the radar performance in air-to-air and air-to-sea modes, at various altitudes were carried out in 2010. Flutter vibration tests were also carried out in different configurations at high angles of attack (AoA) to assess the structural integrity across the flight envelope. LSP-4 completed the successful trial of BDL developed Counter Measure Dispensing System (CMDS) with R-73 missile on 2 December 2010. It worked well Open Architecture Mission Computer and Digital Stores Management System.

In the second half of 2012, the Tejas fleet was grounded for over three months and the ejection system had to be modified to resume flight tests by the end of 2012. In 2013, Tejas (LSP-7) conducted an inflight engine relight test at high altitude to assess the engine response on flameout, a critical parameter for operational clearance. The inflight engine relight test is crucial for single engine combat aircraft.

Operational clearance

In December 2006, the IAF announced that it would form an "LCA Induction Team" to manage the aircraft's service introduction. The Tejas was awarded initial operational clearance-I (IOC-I) in January 2011.Prasad, K. V
"Tejas gets Initial Operational Clearance."
''The Hindu'', (Chennai, India), 10 January 2011. Retrieved 30 May 2012. To ease up the process of FOC, an interim IOC-II was issued to Tejas in December 2013. The IOC-II expanded the g-limit, angle of attack and allowed the aircraft to carry precision guided munitions and close combat missiles. The IOC-II Tejas have an operational radius of 400–500 km. The first squadron, consisting of Tejas in IOC-II configuration, became operational in 2016. The No. 45 Squadron IAF based at Sulur Air Force Station, Coimbatore was the first to have their MiG-21s replaced by Tejas aircraft at the base.

The FOC campaign began in December 2014. Two critical parameters set by IAF for FOC clearance was expansion of angle of attack from 24 degree in IOC-II to 28 degree in FOC and inflight refueling capability. In February 2018, as part of the FOC campaign, the Tejas carried out a "hot refuelling" - refuelling with engine running, which shortens the turnaround time by 30% and doubles the sortie rate. In September 2018, the Tejas successfully completed its mid-air refuelling trials required for the aircraft to obtain its FOC. In January 2019, HAL received permission from CEMILAC to start production of the FOC standard Tejas.

On 20 February 2019, during the Aero India 2019 show, FOC was formally awarded to the Tejas. The second 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.

A full mission simulator (FMS) phase-1 was commissioned at Sulur Air Force Station on 23 October 2021. The Phase 1 of the FMS features training in aircraft handling and full envelope flying. Phase 2 will further augment the training with focus on weapons system and advance sensors onboard Tejas.

Upgrades and further development

In May 2015, the Comptroller and Auditor General of India (CAG) noted some shortcomings in the then-delivered Tejas Mark 1 IOC standard aircraft, which according to the CAG would limit the survivability and operational deployability of the aircraft in actual combat. A few of these shortcomings, including lack of combat endurance, were addressed in the Tejas Mark 1 FOC configuration aircraft. Tejas Mark 1 FOC resolved the issue of onboard fuel monitoring with an integrated Environmental Control and Fuel Management (ECFM) system. It can now perform aerial refueling from Ilyushin Il-78 and buddy refueling with Sukhoi Su-30MKI. Tejas is also undergoing butt firing trials and air-to-air firing at HAL, Nashik facility with Gryazev-Shipunov GSh-23.

The shortcomings, such as the increased weight and reduced speed would be addressed in the upcoming Tejas Mark 1A aircraft by increasing the use of composites in manufacturing and reducing the supersonic drag by using more aerodynamic pylons. The MK1A will also have AESA radar, a self-protection jammer, updated avionics and electronic warfare capabilities, among other improvements. The shortcomings identified by CAG that require redesign and structural modification such as increasing internal fuel capacity, are planned to be rectified in the Tejas Mark 2.

Tejas Mark 1A

The Tejas Mark 1A, which has more than 40 improvements over the Mark 1 variant, is expected to begin production in 2023–24. Upgraded Mark 1A aircraft will retain basic Mark 1 airframe while featuring a new avionic suite centered on EL/M-2052 AESA Radar and Uttam AESA Radar, DARE Unified Electronic Warfare Suite (UEWS), an externally mounted self protection jammer (SPJ) for enhanced survivability, instrument flight rules (IFR) capability, Onboard Oxygen Generation System (OBOGS) developed by Defence Bioengineering and Electromedical Laboratory (DEBEL) for endurance and an expanded weapon suite consisting of Astra BVRAAM and ASRAAM. HAL will install in-house developed Combined Interrogator and Transponder (CIT) with digital map generator by Mission and Combat Systems R&D Centre which helps transfer the required mission map on pilot display, an upgraded IFF+ from older identification friend or foe system. To better accommodate the pilots, cockpit floor is also reshaped. The upgraded Tejas Mark 1A will have a reduced turnaround time.

According to HAL Chairman and Director R Madhavan, the design activity of Tejas Mark 1A is moving ahead and the testing of subsystems will be completed by 2021. The taxi trials will commence in the first half of 2022 and the first flight of Mark 1A prototype will happen in second half of 2022. Delivery of the aircraft for the IAF will begin from March 2024. BEL will supply 20 types of locally developed critical avionics and upgrades such as Digital Flight Control Computers from ADA, Air Data Computer from DRDO, Weapon Computers from ADE, Radar Warning Receiver from Combat Aircraft Systems Development and Integration Centre (CASDIC) and Head-up display from Central Scientific Instruments Organisation (CSIO) from 2023 to 2028 for ₹2,400 crore.

On 20 June 2022, the Tejas Mark 1A prototype completed its first flight. HAL intends to obtain a certificate from Centre for Military Airworthiness and Certification (CEMILAC) within 30 months before this version enters mass production. Two ASRAAMs are intended for use on Tejas Mark 1A. The production variant will come equipped with dual-rack pylons with weapon systems integration. HAL is on track to deliver first Tejas Mark 1A by February 2024.The order of 83 aircraft for IAF will be completed by 2029 at the rate of 16 units per year.

Tejas Mark 2

The HAL Tejas design has been further developed into the Tejas Mark 2, incorporating a more powerful General Electric F414 INS6 engine, canards and other design changes. The Tejas Mark 2, which is expected to be rolled out in 2022, will have an increased payload carrying capacity and internal fuel capacity, more external hardpoints, improved combat range, a completely redesigned cockpit, and an integrated infrared search and track (IRST) system, in addition to the AESA radar. The Defence Institute of Advanced Technology (DIAT) is developing aircraft health and usage monitoring systems (HUMS) to integrate the various sensors on board the Tejas Mark 2. The first flight of Tejas Mark 2 is expected to be in 2023.

Naval variant

The ''Naval LCA programme'' was commenced in 2003. According to ADA, the ''Naval LCA (N-LCA) Programme'' was envisaged to be completed in two phases, under Phase-1 two naval prototypes were developed - the two-seat ''NP-1'' and the single-seat ''NP-2'', based on the Tejas Mark 1 design, to carryout carrier suitability certification and weapons integration. Under Phase 2, two single-seat prototypes were planned to be built, based on the Tejas Mark 2 design, with further design optimisation and integration of the General Electric F414 INS6 engine. The first naval prototype NP-1 was rolled out in July 2010, and made its first flight on 27 April 2012.Kumar, Chethan
"LCA naval variant's first flight on Friday."
''Deccan Herald'', 25 April 2012. Retrieved 30 May 2012. The naval LCA has stronger landing gear to absorb the forces generated during carrier take off and arrested recovery.

In December 2014, the LCA Navy successfully made its first ski-jump assisted take off from a SBTF at INS Hansa. The navy variant has a distinctive flight control law mode which allows hands-free take-off.

In December 2016, the Indian Navy (IN) opted out of the programme, owing to the long delay and technical reasons – such as inadequate thrust to weight ratio of N-LCA for carrier based combat operations, and issued a fresh RFI for the procurement of 57 multi-role carrier borne fighters.

Because the technologies developed for the Tejas programme will be carried over to other platforms currently being developed by the ADA, test flying was continued.

In 2019, an LCA navy prototype successfully carried out the first arrested landing at the SBTF in Goa in day time and night time. As of December 2019, the Naval LCA programme completed 209 test flights, of these 50 were ski jump take-offs.

In January 2020, the naval prototype NP-2 successfully carried out its first arrested landing and ski-jump assisted take-off from the aircraft-carrier INS ''Vikramaditya''.

In July 2020, the DRDO announced that the plan to develop an LCA Mark 2 Navy had been dropped and they were working on a new carrier-borne fighter according to the Indian Navy's ''multi-role carrier borne fighter requirement'' floated in 2016 to replace the current fleet of MIG-29K/KUB carrier-based fighters. In Aero India 2021 a new twin engine naval fighter was unveiled, the '' Twin Engine Deck Based Fighter'' (TEDBF). The experience gained in the N-LCA programme will help in the development of TEDBF.

Program costs

Development costs

* LCA Programme - (up to March 2020)
* Kaveri engine programme -
* additional design and development (Jan 2021)

Flyaway costs

* for IOC Mark 1 (2014)
* for FOC Mark 1 (2010)
* for Mark 1A and for export variant (2021)

Design

Overview

The Tejas is a single-engine multirole combat aircraft which has a tailless, compound delta wing design with "relaxed static stability" for enhanced manoeuvrability and agility. The Tejas is a multi-role combat aircraft and its flexibility permits it to carry out Interception, air-to-surface and anti-shipping roles in a single mission. The wind tunnel testing and computational fluid dynamics analysis have optimised the design of Tejas for minimum transonic and supersonic wave drag, as well low wing-loading.

Tejas has eight hardpoints – one beneath the port-side air-intake, one under the fuselage (centreline station) and three hardpoints under each wing, of these, three are wet hardpoints which can carry drop tanks. The hardpoint beneath the port side air-intake is dedicated to carrying sensor pods such as FLIR, IRST or laser rangefinder/designator. These can also be carried on the centreline pylon and inboard pairs of wing stations. The Mark 1A has an aerial refuelling probe on the starboard side of the forward fuselage. The Tejas weapon suite consists of I-Derby ER and Astra beyond visual range air-to-air missiles and R-73, Python-5 and ASRAAM close combat missiles. The Tejas has an internal 23 mm Gryazev-Shipunov GSh-23 twin-barreled autocannon under the starboard side air-intake. The BrahMos-NG

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