HAL Tejas

The HAL Tejas (Sanskrit: "Radiance") is a lightweight, supersonic multirole fighter aircraft being developed by India. It is a tailless, compound delta wing design powered by a single engine. Until the aircraft was formally christened Tejas (pronounced “thay' jus”) on 4 May 2003, the project was known as the Light Combat Aircraft (LCA), which continues in popular usage.

The LCA programme was launched in 1983 for two primary purposes. The principal and most obvious goal is the development of a replacement aircraft for India’s ageing Mikoyan-Gurevich MiG-21 (NATO reporting name 'Fishbed') fighters. The MiG-21 has been the mainstay of the Indian Air Force (IAF) since the 1970’s, but the initial examples were nearly 20 years old by 1983. The “Long Term Re-Equipment Plan 1981” noted that the MiG-21’s would be approaching the end of their service lives by the mid-1990’s, and that by 1995 the IAF would lack 40% of the aircraft needed to fill its projected force structure requirements.

The LCA programme’s other main objective is to serve as the vehicle for an across-the-board advancement of India’s domestic aerospace industry. Although the Tejas is most often described as a product of Hindustan Aeronautics Limited (HAL), responsibility for the development of the Tejas actually belongs to a national consortium known as the Aeronautical Development Agency (ADA). The ADA formally falls under the auspices of the Indian Defence Ministry’s Defence Research and Development Organisation (DRDO). HAL, a key member of the ADA, serves as the prime contractor for the LCA and is responsible for its integration, flight testing and production.

Production of the Tejas is scheduled to start in 2007; it is currently projected to enter limited initial operational clearance with the IAF in 2008, followed by full operational clearance by the end of 2010. A naval variant capable of operating from the Indian Navy’s aircraft carriers is in development. The IAF is reported to have a requirement for 200 single-seat and 20 two-seat conversion trainers, while the Indian Navy may order up to 40 single-seaters to replace its Sea Harrier FRS.51 and Harrier T.60.

National Development

Soon after gaining independence in 1947, Indian leaders established an ambitious national objective of attaining self-reliance in aviation and other strategic industries. The value of the “self-reliance” initiative is not simply the production of an aircraft, but also the building of a local industry capable of creating state-of-art products with commercial spin-offs for a global market. When the DRDO received authorisation in 1983 to initiate a new Light Combat Aircraft (LCA) programme, it was intended in part to further expand and advance India’s indigenous aerospace capabilities across the broadest range of modern aviation technologies. To better accomplish this goal, the government chose to take a different management approach, and in 1984 established the Aeronautical Development Agency to manage the LCA programme. The ADA is effectively a “national consortium” with more than 100 Indian research and development (R&D) establishments, major industrial organisations, and academic institutions as participating partners. HAL is the principal partner in the LCA programme and serves as the prime contractor.

The Indian government’s “self-reliance” goals for the LCA include indigenous development of the three most sophisticated — and hence most challenging — systems on fourth-generation fighter aircraft: the fly-by-wire (FBW) flight control system (FCS), multi-mode pulse-Doppler radar, and afterburning turbofan engine. Although India has had a policy of strictly limiting foreign participation in the LCA programme, these are the only major LCA systems on which the ADA has had to invite significant foreign technological assistance and consultancy. Moreover, the engine and radar are also the only major systems for which the ADA has seriously considered substituting foreign equipment, albeit as an interim measure on the initial LCA aircraft where needed to allow more time for the full development of the indigenous versions — as has been the case with the LCA’s Kaveri powerplant.

The ambitiousness of the LCA programme in terms of pursuing national self-reliance in a broad range of aviation technologies is illustrated by the fact that of a total of 35 major avionics components and line-replaceable units (LRUs), only three involve foreign systems. These are the multi-function displays (MFDs) by Sextant (France) and Elbit (Israel), the helmet-mounted display and sight (HMDS) cueing system by Elbit, and the laser pod supplied by Rafael (Israel). However, even among these three, when LCA reaches the production stage, the MFDs are expected to be supplied by Indian companies. A few other important items of equipment (such as the Martin-Baker ejection seat) have been imported, but in some cases, items originally planned to be imported — like the landing gear — were instead developed indigenously as a consequence of the embargo imposed on India after its nuclear weapons tests in May 1998.

It is little appreciated, though, that of the five critical technologies the ADA identified at the beginning of the LCA programme that would need to mastered for India to be able to claim to design and build a completely indigenous fighter, two have been completely successful: the development and manufacture of advanced carbon fibre composite (CFC) structures and skins (especially on the order of the size of a wing) and a modern “glass cockpit.” In fact, the ADA has had a profitable commercial spin-off in its ‘Autolay’ integrated automated software system for the design and development of 3-D laminated composite elements (which has been licenced by both Airbus and Infosys). Unfortunately, these successes have gone mostly unnoticed in the shadow of the problems encountered by the other three aforementioned initiatives. As a result of the accomplishments of India’s domestic industries, it is anticipated that, overall, about 70% of the LCA is to be manufactured in India itself.

History

Programme Origins

In October 1948, HAL was authorised to start development of an indigenously designed basic trainer, the HT-2, which first flew 5 August 1951. Based on the experience gained from the HT-2 programme and the manufacturing capabilities gained from licenced production of the de Havilland Vampire FB.52 and T.55, HAL took up the challenge of a 1955 Air Staff Requirement (ASR) that called for a multirole fighter aircraft suitable for both high-altitude interception and low-level ground attack. The ASR also required that the basic design be suitable for adaptation as an advanced trainer and for shipboard operation, options which would be later dropped. The result would be India’s first domestically developed jet fighter, the subsonic HF-24 Marut, which first flew in June 1961. (The ASR originally specified a Mach 2.0 fighter, but this proved unachievable at the time.) Although first flight occurred after less than five years of design and development, the Marut did not enter service with the IAF until 1967 due to problems obtaining or developing a suitable turbojet engine — a problem the Tejas programme has also encountered. In the meantime, HAL gained additional experience completing the development and testing of the Folland Gnat F.1, which it produced under licence from 1962-74, and from which it later developed a much-modified variant, the Gnat Mk.II Ajeet.

Parallel to the Gnat program, HAL designed and developed the HJT-16 Kiran turbojet trainer, which first flew in September 1964 and entered service in 1968. In 1969, the Indian government accepted the recommendation by its Aeronautics Committee that HAL should design and develop an advanced technology fighter aircraft around a proven engine. Based on a Tactical Air Support Aircraft ASR remarkably similar to that for the Marut, HAL completed design studies in 1975, but the project fell through due to inability to procure the selected “proven engine” from a foreign manufacturer.

With production of the Ajeet attack aircraft underway, this left little design work for HAL’s engineers, while the IAF's requirement for an air superiority fighter with secondary air support/interdiction capability remained. In 1983, the DRDO obtained permission to initiate a programme to design and develop a Light Combat Aircraft (LCA), only this time a different management approach would be taken.

In 1984, the Aeronautical Development Agency was established to manage the LCA programme. The ADA is effectively a “national consortium” for which HAL is the principal partner; it serves as the prime contractor and has leading responsibility for LCA design, systems integration, airframe manufacturing, aircraft final assembly, flight testing, and service support. The ADA itself for has primary responsibility for the design and development of the LCA’s avionics suite and its integration with the flight controls, environmental controls, aircraft utilities systems management, stores management system (SMS), etc.

Of particular importance are the initiatives to develop an indigenous flight control system, radar, and engine for the LCA. The National Aeronautics Laboratory (NAL) was selected to lead the development of the flight control laws, supported by the Aeronautical Development Establishment (ADE), which is responsible for developing the integrated FCS itself. HAL and the Electronics and Radar Development Establishment (LRDE) are jointly developing the Tejas’ Multi-Mode Radar (MMR). The Gas Turbine Research Establishment (GTRE), which is responsible for the design and parallel development of the GTX-35VS Kaveri afterburning turbofan engine for the Tejas — which will be using the General Electric F404 turbofan as an interim powerplant until the Kaveri becomes available. (The challenges encountered in these three areas will be addressed in more detail in the Development History section below.)

The IAF’s Air Staff Requirement for the LCA would not be finalised until October 1985. This delay would render moot the original schedule which called for first flight in April 1990 and service entry in 1995; however, it would also prove a boon in that it gave 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 indigenously and which would need to be imported.

Project definition (PD) commenced in October 1987 and was completed in September 1988. Dassault Aviation of France was hired as a consultant to review the PD and provide advice based on its extensive aviation expertise. Engineers, connected with design and development of aircraft know how vital it is to getting the 'definition' correct is vital because from this flow key elements of the detailed design, manufacturing approach, maintenance requirements, and — most importantly — overall programme costs. Subsequent changes can cost dramatically more to incorporate, and the further down the path of development they are introduced, the more disproportionately those costs increase.

Development History

The LCA design was finalised in 1990 as a small, delta-winged machine with relaxed static stability (RSS) to enhance maneuverability performance. The sophisticated avionics and advanced composite structure specified caused some concern almost immediately, and the IAF expressed doubt that India possessed sufficient technological infrastructure to support such an ambitious project. A review committee was formed in May 1989 which reported out a general view that Indian infrastructure, facilities and technology had advanced sufficiently in most areas to undertake the project. As a measure of prudence, though, it was decided that the full-scale engineering development (FSED) stage of the programme would proceed in two stages.

Phase 1 would focus on "proof of concept" and would comprise the design, development and testing (DDT) of two technology demonstrator aircraft (TD-1 and TD-2) and construction of a structural test specimen (STS) airframe; only after successful testing of the TD aircraft would the Indian government give its full support to the LCA design. This would be followed by the construction of two prototype vehicles (PV-1 and PV-2), and creation of the necessary basic infrastructure and test facilities for the aircraft would begin. Phase 2 would consist of the construction of three more prototype vehicles (PV-3 as the production variant, PV-4 as the naval variant, and PV-5 as the trainer variant), construction of a fatigue test specimen, and the creation of further development and test facilities at various work centres.

Phase 1 commenced in 1990 and HAL started work on the technology demonstrators in mid-1991, however, a financial crunch resulted in full-scale funding not being authorised until April 1993, with work on FSED Phase 1 commencing in June. The first technology demonstrator, TD-1, was rolled out on 17 November 1995 and was followed by TD-2 in 1998, but they were kept grounded for several years due to structural concerns and trouble with the development of the flight control system.

Fly-by-Wire Control Laws

One of the most ambitious requirements for the LCA was the specification that it would have "relaxed static stability." Although Dassault had offered an analogue FCS system in 1988, but the ADA recognised that digital flight control technology would soon supplant it. RSS technology was introduced in 1974 on the General Dynamics (now Lockheed Martin) YF-16, which was the world's first aircraft to be slightly aerodynamically unstable by design. Most aircraft are designed with “positive” static stability, which means they have a natural tendency to return to level and controlled flight in the absence of control inputs; however, this quality tends to oppose the pilot's efforts to maneuver. An aircraft with “negative” static stability (i.e., RSS), on the other hand, will quickly depart from level and controlled flight unless the pilot constantly works to keep it in trim; while this enhances maneuverability, it’s very wearing on a pilot relying on a mechanical flight control system. What made RSS practical on the YF-16 was a new technology — the “fly-by-wire” (FBW) flight control system — which employs flight computers to electronically keep the aircraft’s instability in check whenever it is not desired.

Development of a FBW flight control system requires extensive knowledge of flight control laws and the expensive writing of a considerable amount of software code for the flight control computers, as well as its integration with the avionics and other electronic systems. When the LCA programme was launched, FBW was a state-of-the-art technology and such a sensitive one that India could find no nation willing to export it. Therefore, in 1992 the LCA National Control Law (CLAW) team was set up by the National Aeronautics Laboratory to develop India’s own version. The CLAW team’s scientists and mathematicians were successful in developing their control laws, but could not test them since India did not possess advanced real-time ground simulators at that time. Accordingly, British Aerospace (BAe) and Lockheed Martin were brought in to help in 1993, but the effort required for the Aeronautical Development Establishment ADE to code the control laws into the FCS software proved a much larger job than originally anticipated.

Specific control law problems were tested on BAe’s simulators (and on HAL’s, once theirs became available). As it was being developed, progressive elements of the coding were checked out on the ‘Minibird’ and ‘Ironbird’ test rigs at the ADE and HAL, respectively. A second series of inflight simulation tests of the integrated flight control software were conducted on the F-16 VISTA (Variable In-flight Stability Test Aircraft) simulator in the U.S. in July 1996, with 33 test flights being carried out. However, Lockheed Martin’s involvement was terminated in 1998 as part of an embargo enacted by the U.S. in response to India's second nuclear tests in May 1998.

NAL’s CLAW team eventually managed to successfully complete integration of the flight control laws indigenously, 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 early 2001. The LCA’s maiden flight was made by TD-1 from Yelahanka AFS, near Bangalore, on 4 January 2001, and its first successful supersonic flight followed on 1 August 2003. TD-2 was scheduled to make its first flight in September 2001, but this was not achieved until 6 June 2002. The Tejas’ automatic flight control system (AFCS) has been highly praised by all of its test pilots, one of whom said that he found it easier to take off with the LCA than in a Mirage [2000].

Prototypes

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The PV-series prototype air vehicles were meant to evolve progressively toward the actual production Tejas aircraft. The first prototype, PV-1, saw the initial attempt at achieving major weight reduction — achieving a cut of 350 kg (770 lb) — and was intended to be representative of the production-standard airframe. Carbon fibre composites are employed extensively in the fuselage, and PV-1’s overall composite content was increased over that of the technology demonstrators to 45% by weight and 95% by surface area. The remaining structural material consists (by weight) of 43% aluminium alloys, 5% titanium alloys, 4.5% steels, and 2.5% other materials. The part count was reduced to 7,000 from TD-1’s 10,000. The PV-1 first flew on 25 November 2003.

The second prototype, PV-2, was a significant step forward in the evolution to the production Tejas, especially in the fit of its Integrated Digital Avionics Suite (IDAS). This suite, developed by HAL, integrates the cockpit through an open architecture with the flight controls, environmental controls, aircraft utilities systems management, ADA-developed stores management system, etc. The production-standard cockpit has no standby electromechanical instruments; instead, it features three 5”x 5” multi-function active-matrix liquid crystal displays (AMLCD), two Smart Standby Display Units (SSDU), and the indigenous head-up display (HUD) developed by the Central Scientific Instruments Organisation (CSIO). An integral part of the cockpit avionics suite is the DASH helmet-mounted display and sight supplied by Elbit of Israel. PV-2 initially flew 1 December 2005, and is scheduled to be the first Tejas aircraft to be fitted with the indigenous Multi-Mode Radar, following completion of the radar’s flight tests on a HAL HS 748 “Avro” testbed.

The technology demonstration phase was formally completed on 31 March 2004, but FSED Phase 2 was authorised in November 2001, shortly after international sanctions were lifted on 22 September 2001. Phase 2 also included a plan to order several “Limited Series Production” (LSP). ADA and HAL signed a memorandum of understanding (MoU) in 2001 for 8 LSP aircraft to be delivered by the end of 2006; the order was placed in June 2002, and production go-ahead was given in March 2003. The three Phase 2 PV-series prototypes are very similar to PV-2 and all are claimed to be full production-standard aircraft, but PV-3 is said to be the actual baseline production model. PV-3 made its first flight in February 2006. PV-4 was originally planned to be a naval variant, but will actually be very similar to PV-3. PV-4 is anticipated to be the final baseline model for production aircraft, whereas PV-3 has effectively become the baseline for the pre-production LSP batch aircraft. Delivery of the PV-5, the two-seat operational trainer variant, and induction into service of the first LSP aircraft are also anticipated in 2006.

PV-4 has been replaced as the naval prototype by two prototypes designated NP-1 and NP-2; confusingly, these are respectively the two-seat and single-seat variants. A design permitting operation from a carrier deck with a 14º ski-jump was approved in early 1999, and development go-ahead was granted in mid-2002, although major funding was not released until early 2003. The naval prototypes have strengthened landing gear and other necessary modifications for service on an aircraft carrier. NP-1 is planned to achieve first flight in 2007, followed by NP-2 the next year.

Multi-Mode Radar

Another critical technology area tackled by the ADA team for indigenous development is the Tejas’ Multi-Mode Radar (MMR). It was initially planned for the LCA to use the Ericsson Microwave Systems PS-05/A I/J-band multi-function radar, which was developed by Ericsson and Ferranti Defence Systems Integration for the Saab JAS-39 Gripen; however, after examining other radars in the early 1990s, the DRDO became confident that Indian industry was up to the challenge. HAL’s Hyderabad division and the LRDE were selected to jointly lead the MMR program; it is unclear exactly when the design work was initiated, but the radar development effort began in 1997.

The DRDO’s Centre for Airborne Studies (CABS) is responsible for running the test programme for the MMR. Between 1996 and 1997, CABS converted the surviving HAL/HS-748M Airborne Surveillance Post (ASP) testbed into a testbed for the avionics and radar of the LCA. Known as the 'Hack', the only major structural modification besides the removal of the rotodome assembly was the addition of the LCA's nose cone in order to accommodate the MMR.

By mid-2002, development of the MMR was reported to be experiencing major delays and cost escalations. By early 2005 only the air-to-air look-up and look-down modes — two very basic modes — were confirmed to have been successfully tested. In May 2006 it was revealed that the performance of several modes being tested still “fell short of expectations.” 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, the crux of the problem is a serious compatibility issue between the radar and the advanced signal processor module (SPM) built by the LRDE. Acquisition of an “off-the-shelf” foreign radar like Elta’s EL/M-2032 or Lockheed Martin’s AN/APG-67 is an interim option being seriously considered. However, others are suggesting that the MMR programme be dropped altogether in favor of an advanced electronically scanned phased-array (AESA) radar such as the solid-state L-band Irbis (“Snow Leopard”) AESA radar which the LRDE is co-developing with Tikhomirov NIIP of Russia.

Kaveri Engine

Although it had been decided early in the LCA programme to equip the prototype aircraft with the General Electric F404-GE-F2J3 afterburning turbofan engine, a parallel programme was also launched in 1986 to develop an indigenous powerplant. Being led by the Gas Turbine Research Establishment, the GTRE GTX-35VS, christened Kaveri, was expected to replace the F404 on all production aircraft. The GTRE’s design envisions achieving a fan pressure ratio of 4:1 and an overall pressure ratio of 27:1, which it believes will permit the Tejas to “supercruise” (cruise supersonically without the use of the afterburner). A digital engine control system is also under development, as well as an axisymmetric thrust-vectoring nozzle to further enhance the LCA’s agility. Plans are also already under way for derivatives of the Kaveri, including a non-afterburning version for an advanced jet trainer and a high bypass-ratio turbofan based on the Kaveri core.

The original plans called for 17 prototype test engines to be built. The first test engine consisted of only the core module (named “Kabini”), while the third engine was the first example fitted with variable inlet guide vanes (IGV) on the first three compressor stages. Test runs of the first complete prototype Kaveri began in 1996 and all five ground-test examples were in test by 1998; the initial flight tests were planned for the end of 1999, with its first test flight in an LCA prototype to follow the next year. However, progress in the Kaveri development programme was slowed by technical difficulties.

The 1998 sanctions forced General Electric to suspend delivery of the F404 engines that were to power the prototypes after only 11 F404’s had been supplied. Alternative engines was considered — including the Rafale’s SNECMA M88, the Eurofighter's Eurojet EJ200, and the MiG-29’s Klimov RD-33 — but no decision had been made by the time sanctions were lifted in September 2001. In February 2002, the U.S. government agreed to supply an additional 40 F2J3 engines to permit flight testing of several previously engineless LCA prototypes to begin.

Continued development snags with the Kaveri resulted in the 2003 decision to procure the uprated F404-GE-IN20 engine for the 8 pre-production LSP aircraft and two naval prototypes. The ADA awarded General Electric a $105 million contract in February 2004 for development engineering and production of 17 F404-GE-IN20 engines, delivery of which is to begin in 2006. In mid-2004, the Kaveri failed its high-altitude tests in Russia, ending the last hopes of introducing it with the first production Tejas aircraft. This unfortunate development led the Indian Ministry of Defence (MoD) to order 40 more IN20 engines in 2005 for the first 20 production aircraft and to openly appeal for international participation in completing development of the Kaveri. In February 2006, the ADA awarded a contract to the French aircraft engine company SNECMA for technical assistance in working out the Kaveri’s problems. The DRDO currently hopes to have the Kaveri engine ready for use on the Tejas by 2009-10.

Development Costs

The LCA was originally expected to fly in 1993, and in May 1989 the program was projected by the Review Committee to cost Rs. 5,600 crores (56 billion rupees or about US $1.2 billion at the time). FSED Phases 1 and 2 were projected to cost, respectively, Rs. 2,188 crores ($467 million) and Rs. 2,340 crores ($499 million). According to the 1999 Comptroller and Auditor General (CAG) report, the first phase of the project had by the end of 1998 consumed Rs. 2,500 crores, and by the end of 2000, the total Phase 1 cost had risen to about Rs. 3,000 crores. The delays have also led to further indirect costs. For instance, the unavailability of the Tejas compelled the air force to upgrade its MiG-21bis aircraft at a cost of Rs. 2,135 crores.

When FSED Phase 2 was launched in November 2001, it was authorised under a budget of Rs. 3,302 crores (about $704 million). The overall programme financing at that time included not only the manufacture of two technology demonstrator aircraft, but also five prototypes (PV-1 to PV-5) and eight limited series production (LSP) planes. In July 2001 it was reported that beyond the FSED, HAL would require a further Rs. 400-600 crores to set up facilities for the manufacture of 12 to 14 LCAs a year.

In the first quarter of 2003, the Indian Government approved the equivalent of $210 million (nearly Rs. 1,000 crores) for a programme to develop a carrier-capable variant of the LCA for the Indian Navy. The cost covers development and testing of two prototypes, the two-seat NP-1 and single-seat NP-2. NP-1 is expected to achieve clearance for carrier operation in 2007 (followed a year later by NP-2), with service entry no later than 2010.

In July 2006, the Times of India revealed that the overall cost of the LCA project could well eventually reach Rs 10,000 crores (about $2.26 billion). By that date, the government had authorised Rs 5,489.78 crores (over $1.24 billion) for the total program, through the production of the eight LSP pre-production aircraft (but excluding costs for the separate Kaveri program).

Development of the Kaveri engine was projected in 1989 to cost Rs. 382.81 crores (nearly $82 million). In Dec. 2004, it was revealed that the GTRE had spent over Rs. 1,300 crores (around $295 million) on developing the Kaveri. Furthermore, the Cabinet Committee on Security judged that the Kaveri would not be installed on the LCA before 2012, and revised its estimate for the projected total development cost to Rs. 2,839 crores (more than $640 million). The DRDO, however, currently hopes to have the Kaveri engine ready for use on the Tejas by 2009-10.

Status

As of 17 July 2006, the LCA has completed 548 test flights in all. On 13 May 2006 the PV-2 went supersonic for the first time and on 14 May 2006 it did so again, but this time in a weaponised state (i.e., carrying a load of weapons such as missiles and an internal gun).

In a May 2006 interview, HAL chairman Ashok Baweja said that the fifth prototype vehicle, trainer prototype, and the first of the eight LSP aircraft will be delivered before the end of 2006. These aircraft will help accelerate the initial operational clearance for the LCA. The first limited-series-production LCA is expected to be inducted into the IAF by the end of 2006, with the LCA’s System Design & Development (SDD) phase finally being completed in 2010.

Senior HAL officials have said since March 2005 that an Rs. 2,000 crores (over $450 million) order will be placed for 20 Tejas aircraft in 2006 (a unit cost of $22.6 million each), with an similar purchase of another 20 aircraft to follow. All 40 will be equipped with the F404-GE-IN20 engine. The MoD expects the Tejas to achieve initial operational capability (IOC) in mid-2008 with delivery of half a squadron, followed by clearance for full operational capability (FOC) by the end of 2010; independent analysts and officials in the IAF expect that deliveries of operational Tejas fighters are more likely to begin in 2010, with combat service entry around 2012.

Unit Costs

At the end of 2001, Dr. Kota Harinarayana, director of the ADA and of the LCA programme, stated that the unit cost for the LCA — based on an expected total order of 220 Tejas for the IAF — will be between $17 million and $20 million, and claimed that once production ramped up, this could drop to $15 million each. However, as far back as December 1996, A. P. J. Abdul Kalam, the Scientific Adviser to the Prime Minister, had said that the cost would be around $21 million, and by 2001 others were indicating that the LCA would cost $24 million (in excess of Rs. 100 crores per aircraft). Considering cost escalations, aviation experts feel that when the aircraft comes out it could cost upwards of $35 million apiece.

Since March 2005, senior HAL officials have been saying that an Rs. 2,000 crores (over $450 million) order will be placed for 20 Tejas aircraft in 2006 (costing $22.6 million each), with an similar purchase of another 20 aircraft to follow. At a price tag of around Rs. 100-110 crores, the Tejas will be much cheaper than other contemporary fighters in the world. By comparison, the Times of India quoted the price tags for the Swedish JAS-39 Gripen and French Rafale as Rs. 150 crores ($34 million) and Rs. 270 crores ($61 million), respectively, while pricing the new American F-22 Raptor stealth fighter at Rs. 480 crores ($108 million).

Design Features

Airframe

Basics: The LCA is the smallest and lightest 4th generation combat jet in the world. Confusion may arise with respect to the South Korean T-50, but it must be remembered that T-50 is primarily a hybrid trainer, that can assume fighter roles when necessary. The T-50 has a higher height and longer wingspan than the LCA, while its length is shorter by 22 cms. Thus, overall the LCA is the smallest combat jet in the world.

It is much smaller than even the JAS-39, which is ~1 m longer. An effort was made to reduce the number of individual composite parts to the minimum and hence keep the plane light.

Detailed description: The LCA is a tail-less compound delta planform with relaxed static stability. Extensive wind tunnel testing on scale models and complex computational fluid dynamic analyses have optimised the aerodynamic configuration of LCA, giving it minimum supersonic drag, low wing loading and high rates of roll & pitch.

The tail-less compound delta planform helps in keeping LCA small and light. It also means fewer control surfaces, wider choice of external stores and better close combat, high-speed and high-alpha characteristics.

The LCA has 45% composite frame, which make it light and strong at the same time as compared to other all-metal aircraft. The configuration is a delta wing, with no tailplanes or foreplanes, and a single vertical fin. The LCA is constructed of aluminium-lithium alloys, carbon-fibre composites, and titanium. The design incorporates "control-configured vehicle" concepts to enhance manoeuvrability, and quadruplex fly-by-wire controls.

Among the most significant breakthrough is the use of advance carbon composites for up to 45% of the LCA air frame, including wings, materials fin and fuselage. This percentage of composites is one of the highest as compared to other contemporary aircraft of its class. Apart from making it much lighter, there are fewer joints or rivets making the aeroplane more reliable. Fatigue strength LCA studies on computer models optimise performance. National Aerospace Laboratory (NAL) has played a lead role. Materials include Aluminium-Lithium alloys, Titanium alloy and Carbon composites. Composites for wing (skin, spars and ribs), fuselage (doors and skins), elevons, fin, rudder, airbrakes and landing gear doors.

The skin of the LCA measures 3 mm at its thickest with the average thickness varying between 2.4 to 2.7 mm. BAe was consulted in its design. The fin for the LCA is a monolithic honeycomb piece. No other manufacturer is known to have made fins out of a single piece. The cost of manufacture is reduced by 80% from Rs 2.5 million by this process. This is contrary to a subtractive or deductive method normally adopted in advanced countries, when the shaft is carved out of a block of titanium alloy by a computerized numerically controlled machine. A 'nose' for the rudder is added by 'squeeze' riveting.

The use of composites results in a 40% reduction in the total number of parts (if the LCA were built using a metallic frame): for instance, 3,000 parts in a metallic design would come down to 1,800 parts in a composite design. The number of fasteners has been reduced to half in the composite structure from 10,000 in the metallic frame. The composite design helped to avoid about 2,000 holes being drilled into the airframe. Though the weight comes down by 21%, the most interesting prediction is the time it will take to assemble the LCA -- the airframe that takes 11 months to build can be done in seven months using composites.

Flight Envelope:

• AoA : 35 deg.
• Roll-rate : 290-300 deg/sec
• Sustained load G-limit : 9/-3.5g
• Short take-off and landing capabilities.

According to defence analyst B. Harry, the Naval LCA shall feature with LEVCONs or (Leading Edge Vortex Controllers). This shall require development of new control laws for it. These LEVCONs shall be control surfaces that extend from wing-root leading edge and thus afford better low-speed handling of the LCA which otherwise is slightly hampered due to increased drag that results from its delta-wing design. It shall also increase controllability at high AoA. At high speeds though, the delta-winged design offers better manoueverability than conventional winged-designs.

According to him, such a feature (as in the Naval LCA), has not been implemented on any other combat aircraft.

Stealth: It is expected that being the smallest combat jet, and coupled with a highly composite airframe (that do not reflect radar waves) and RAM (Radar Absorbent Material) coating, the LCA shall exhibit a very low RCS to radar detections from airborne enemy aircraft and AWACs. The Y-duct intake shields the engine compressor from radar waves.

LCA is expected to be highly maneuverable by virtue of its double delta wing and relaxed static unstability of its Fly-By-Wire system. Provisions for the growth of hardware and software in the avionics and flight control system, available in Tejas, ensure to maintain its effectiveness and advantages as a frontline fighter throughout its service life. For maintenance, the aircraft has more than five hundred Line Replaceable Units (LRSs), each tested for performance and capability to meet the severe operational conditions to be encountered.

Lightning tests: When lightning strikes the LCA, four metal longerons stretching from end to end, afford protection. In addition, all the panels are provided with copper mesh. One out of five is 'bonding' bolt with gaskets to handle Electromagnetic interference. Aluminum foils cover bolt heads while the fuel tank is taken care of with isolation and grounding.

Air intakes: The wing shielded side mounted bifurcated Y-duct air intake with optimised diverter configuration ensures buzz-free air supply to the engine, at acceptable distortion levels.

Weapon stations: Seven weapon stations provided on Tejas offer flexibility in the choice of weapons Tejas can carry in various mission roles. Provision of drop tanks and inflight refueling probe ensure extended range and flight endurance of demanding missions.

Cockpit: The LCA has a glass cockpit with two Multi Function Displays, Head-Up Display, Multi Function Keyboard and Get-You-Home Panel.

Avionics

The avionics system enhances the role of Light Combat Aircraft as an effective weapons platform. The glass cockpit and hands on throttle and stick (HOTAS) controls reduce pilot workload. Accurate navigation and weapon aiming information on the head up display helps the pilot achieve his mission effectively. The multi-function displays provide information on engine, hydraulics, electrical, flight control and environmental control system on a need-to-know basis along with basic flight and tactical information. Dual redundant display processors (DP) generate computer-generated imagery on these displays. The pilot interacts with the complex avionics systems through a simple multifunction keyboard, and function and sensor selection panels.

A state-of-the-art multi-mode radar (MMR), laser designator pod (LDP), forward looking infra-red (FLIR) and other opto-electronic sensors provide accurate target information to enhance kill probabilities. A ring laser gyro (RLG)-based inertial navigation system (INS), provides accurate navigation guidance to the pilot. An advanced electronic warfare (EW) suite enhances the aircraft survivability during deep penetration and combat. Secure and jam-resistant communication systems, such as IFF, VHF/UHF and air-to-air/air-to-ground data link are provided as a part of the avionics suite. All these systems are integrated on three 1553B buses by a centralised 32-bit mission computer (MC) with high throughput which performs weapon computations and flight management, and reconfiguration/redundancy management. Reversionary mission functions are provided by a control and coding unit (CCU).

Most of these subsystems have been developed indigenously.

The digital FBW system of the Tejas is built around a quadruplex redundant architecture to give it a fail op-fail op-fail safe capability. It employs a powerful digital flight control computer (DFCC) comprising four computing channels, each powered by an independent power supply and all housed in a single line replaceable unit (LRU). The system is designed to meet a probability of loss of control of better than 1×10^-7 per flight hour. The DFCC channels are built around 32-bit microprocessors and use a safe subset of Ada language for the implementation of software. The DFCC receives signals from quad rate, acceleration sensors, pilot control stick, rudder pedal, triplex air data system, dual air flow angle sensors, etc. The DFCC channels excite and control the elevon, rudder and leading edge slat hydraulic actuators. The computer interfaces with pilot display elements like multi-function displays through MIL-STD-1553B avionics bus and RS 422 serial link.

Multi-mode radar (MMR), the primary mission sensor of the Tejas in its air defence role, will be a key determinant of the operational effectiveness of the fighter. This is an X-band, pulse Doppler radar with air-to-air, air-to-ground and air-to-sea modes. Its track-while-scan capability caters to radar functions under multiple target environment. The antenna is a light weight (<5 kg), low profile slotted waveguide array with a multilayer feed network for broadband operation. The salient technical features are: two plane monopulse signals, low side lobe levels and integrated IFF, and GUARD and BITE channels. The heart of MMR is the signal processor, which is built around VLSI-ASICs and i960 processors to meet the functional needs of MMR in different modes of its operation. Its role is to process the radar receiver output, detect and locate targets, create ground map, and provide contour map when selected. Post-detection processor resolves range and Doppler ambiguities and forms plots for subsequent data processor. The special feature of signal processor is its real-time configurability to adapt to requirements depending on selected mode of operation.

Following are the important avionics components:

Mission Computer (MC): MC performs the central processing functions apart from performing as Bus Controller and is the central core of the Avionics system. The hardware architecture is based on a dual 80386 based computer with dual port RAM for interprocessor communication. There are three dual redundant communication channels meeting with MIL-STD-1553B data bus specifications. The hardware unit development was done by ASIEO, Bangalore and software design & development by ADA.

HUD: The Head-up-Display of the LCA is a unit developed by the state-owned CSIO, Chandigarh. The HUD is claimed to be superior to similar systems in the international market. According to Mr. CV M L Narasimham, head of CSIO's Applied Optics division, compared to Israel's HUD, the CSIO equipment is noiseless, silent, and offers a better field of view. It is compact, reliable, non-reflective and designed for high-performance aircraft. It was first put on the PV-2 version of the LCA.

Control & Coding Unit (CCU): In the normal mode, CCU provides real time I/O access which are essentially pilot's controls and power on controls for certain equipment. In the reversionary mode, when MC fails, CCU performs the central processing functions of MC. The CCU also generates voice warning signals. The main processor is Intel 80386 microprocessor. The hardware is developed by RCI, Hyderabad and software by ADA.

Display Processors (DP): DP is one of the mission critical software intensive LRUs of LCA. The DP drives two types of display surfaces viz. a monochrome Head Up display (HUD) and two colour multifunction displays (MFDs). The equipment is based on four Intel 80960 microprocessors. There are two DPs provided (one normal and one backup) in LCA. These units are developed by ADE, Bangalore.

Mission Preparation & Data Retrieval Unit (MPRU): MPRU is a data entry and retrieval unit of LCA Avionics architecture. The unit performs mission preparation and data retrieval functions. In the preparation mode, it transfers mission data prepared on Data Preparation Cartridge (DPC) with the help of ground compliment, to various Avionics equipment. In the second function, the MPRU receives data from various equipment during the Operational Flight Program (OFP) and stores data on Resident Cartridge Card (RCC). This unit is developed by LRDE, Bangalore.

USMS Electronic Units: The following processor based digital Electronics Units (EU) are used for control and monitoring, data logging for fault diagnosis and maintenance: Environment Control System Controller (ECSC), Engine and Electrical Monitoring System Electronics Unit (EEMS-EU), Digital Fuel Monitoring System Electronics Unit (DFM-EU) and Digital Hydraulics and Brake Management System Electronics Unit (DH-EU)

Changes in PV-2: The production standard cockpit has no electro mechanical standby instruments. The cockpit is dominated by three 5”x 5” AMLCD MFD’s, two Smart Standby Display Units (SSDU) and the indigenous HUD. The HUD has an Up Front Control Panel (UFCP) which is a significant man machine interface (MMI) enhancement which allows the pilot to program, initialize the avionics and enter mission and system critical data through an interactive soft touch keyboard. Although the FOV of this HUD is slightly less than that of contemporary units on other aircraft of this generation it is not considered significant because the ELBIT, Israel furnished DASH helmet mounted display and sight (HMDS) will form an integral part of the avionics suite.

The four utilities system monitoring LRUs have been reduced to two dual redundant units. These units perform the control, monitoring, data logging for fault diagnosis and maintenance functions.

A HAL Korwa developed Flight data recorder will be fitted after the initial flights.

The PV2 is a much lighter aircraft and possesses advanced software technology, unlike the Test Demonstrator I, II and PV1. There is an advancement in the build standard of PV2, which is a software intensive fourth generation combat aircraft built to production standard. Besides having a high percentage of composite materials in its airframe structure, it incorporates a state-of-the-art, integrated, modular avionics system with open architecture concepts to facilitate easy hardware and software upgrades and re-usability.

MMR: The Multi Mode Radar (MMR) jointly developed by LRDE and HAL Hyderabad will be fitted in the nose after redistributing the FTI carried in the first three aircraft. The MMR features LPRF, MPRF and HPRF modes, platform motion compensation, MTI and Doppler filtering, CFAR detection, range-Doppler ambiguity resolution, scan conversion, display of target and ground map data on MFDs and on line diagnostics to identify faulty processor modules.

The aircraft has the ADA developed Stores Management System (SMS) which will provide fully integrated control of weapon systems, external stores and fuel tanks. The SMS is based on a 32 bit, single chip micro controller with dual redundant architecture. Its main components include the single Stores Interface Box (SIB) and multiple pylon interface boxes (PIB) for each hard point.

EW suite: A state of the art EW suite will be integrated and tested later in the program. Primary responsibility for development of the EW suite is that of the Defence Avionics Research Establishment (DARE), Bangalore.

Miscellaneous

Ejection Seat: Pune-based premier Armament Research and Development Establishment has developed an innovative high-tech line-charged Canopy Severance System for the Light Combat Aircraft, for safe ejection of the pilot.

Since testing laboratories and facilities are not present in India, the certification was done by Martin Baker AIC Co London. After nearly 40 test trials, Martin Baker,--the certifying authority-- has certified commercial production of the canopy severance system.

Dr. Sudharshan Kumar Salwan, director of ARDE, said in an interview to rediff.com, "While in the conventional system, the entire canopy flies off and can result in an injury to the pilot, in the newly indigenously developed system, only a certain portion of the canopy which is line-charged, gets severed. This absolutely minimises injury to the pilot."

He stressed in the same interview, that no aircraft in the world had this kind of live system which could be operated from outside the aircraft, especially when the pilot was unconscious due to some injuries or in the event of crash-landing.

Software: The ADA developed a software called 'Autolay' as part of the LCA project. Autolay is used in the design of integrated virtual manufacturing capability for laminated composite components. It is due to it that the LCA uses 45% composites in its airframe.

Autolay enables parallel processing of composite design activities viz.., details design studies, laminate engineering and generation of design and manufacturing drawings, thus providing concurrrent engineering benefits in a project environment. The resulting data is accessible for tool design, lay-up process (both manual and automatic), and generation of substructure drawings,without any loss of geometric information and thereby help in striving towards the concept for paperless design office. Development of Autolay is the result of more than 300 man-years effort over the last 13 years.

Airbus Industries purchased Autolay for their 600-seater A380 project from ADA for $3.2 milion in 2001.

Titanium tubes : Nuclear Fuel Complex (NFC) has developed titanium half alloy tubes, critical components in the LCA. It is a key component for the LCA, as the tubes were used for hydraulic power transmission.

Versions

Prototypes

• TD-1 (Technology Demonstrator-1)
• TD-2 (Technology Demonstrator-2)
• PV-1 (Prototype Vehicle-1)
• PV-2 (Prototype Vehicle-2)
• PV-3 (Prototype Vehicle-3) – This will be the production variant.
• PV-4 (Prototype Vehicle-4) – Originally a Naval variant for carrier operations, but now a second production variant.
• PV-5 (Prototype Vehicle-5) – Two-seat Trainer variant aircraft.
• NP-1 (Naval Prototype-1) – Two-seat Naval variant for carrier operations.
• NP-2 (Naval Prototype-2) – Single-seat Naval variant for carrier operations.

Planned Production Variants

• Tejas – Single-seat fighter for the Indian Air Force.
• Tejas Trainer – Two-seat operational conversion trainer for the Indian Air Force.
• Tejas Naval – Two- and one-seat carrier-capable variants for the Indian Navy.

Operators

The Tejas is currently still in development, although 8 pre-production aircraft are on order, with deliveries scheduled to begin in late 2006. Officially, IOC is currently anticipated for mid-2008, with FOC following in 2010.

• India – The Indian Air Force (Bharatiya Vayu Sena) may acquire up to 220 aircraft; the Indian Navy may also acquire 40 carrier-capable variants.

Specifications (HAL Tejas)

General characteristics

• Crew: One

Performance

• Thrust/weight: 1.07

Armament

• Single internally mounted 23 mm twin-barrel GSh-23 cannon with 220 rounds of ammunition.
• Eight external stations: three hardpoints under each wing, one fuselage centreline hardpoint, and one station beneath the port-side intake trunk for a pod (FLIR, IRST, laser designator, or reconnaissance).
• Air-to-air missiles include Astra BVRAAM, Vympel R-77 (NATO reporting name: AA-12 Adder), and Vympel R-73 (NATO reporting name: AA-11 Archer).
• Air-to-surface munitions include anti-ship missiles, laser-guided bombs, unguided bombs, cluster bomb dispensers, rocket launchers.

Other equipment

• Drop tanks
• Electronic warfare (EW) pods
• Recce pods
• Targeting pods

External links

News:

• http://www.hindustantimes.com/news/181_1617494,00020016.htm
• http://frontierindia.com/content/view/19/33/
• http://www.rediff.com/news/1998/sep/24pune.htm
• http://www.rediff.com/news/2000/jul/19lca.htm
• http://www.ada.gov.in/others/MoreCurrentNews/morecurrentnews.html
• http://www.newindpress.com/Newsitems.asp?ID=IE120060514131438&Title=Bangalore&Topic=0
• http://www.hindu.com/2006/06/09/stories/2006060903561400.htm
• No Takeoff in sight

Technical:

• Development of Flight Control Laws of the LCA:
  http://www.nal.res.in/pages/ipjun01.htm
• An approach to high AoA testing of the LCA:
  http://www.csirwebistad.org/aesi/pdf/ftgseminar05/presentations/2005/HIGH_AOA_TEJAS.pdf
• Radiance of Tejas

http://rapidshare.de/files/9986319/tejas.pdf.html

General:

• LCA and Economics, by Sunil Sainis and George Joseph (External reference)
• LCA Photo Gallery compiled by Bharat-Rakshak.com
• The Light Combat Aircraft Story, by Air Marshal MSD Wollen (Retd)
• http://aerospaceweb.org/aircraft/fighter/lca/
• http://www.fighter-planes.com/info/lca.htm
• http://www.geocities.com/spacetransport/aircraft-lca.html

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