Jump to content

HAL Tejas

From Wikipedia, the free encyclopedia

This is an old revision of this page, as edited by 96.52.193.72 (talk) at 16:08, 23 January 2009. The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.

HAL Tejas
File:DRDO-Tejas-.JPG
LCA Tejas LSP-01
Role Multirole fighter
National origin  India
Manufacturer Hindustan Aeronautics Limited
Designer Aeronautical Development Agency
First flight 4 January 2001
Status Flight testing
Primary users Indian Air Force
Indian Navy
Number built 9

The HAL Tejas (Sanskrit: तेजस्ⓘ: "Radiance") is a lightweight multirole fighter aircraft developed by India. It is a tailless,[1] compound delta wing design powered by a single engine. Originally known as the Light Combat Aircraft (LCA) – a designation which continues in popular usage – the aircraft was officially named "Tejas".[2] by then Prime Minister Atal Bihari Vajpayee on 4 May 2003.[3]

Limited series production of the Tejas commenced in 2007; it is currently projected to achieve limited initial operational clearance (IOC) with the Indian Air Force (IAF) by 2008, followed by full operational clearance (FOC) by the end of 2010.[4] A two-seat trainer variant is also in development (exited the production line as of November 2008), as is a naval variant capable of operating from the Indian Navy's aircraft carriers. 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.[5]The LCA naval variant is expected to take to the skies by 2009.[6]

Through the use of modern design techniques, lightweight materials and composites, it is expected to become the lightest modern jet fighter in production.

Development

LCA programme

The HAL Tejas conducting an inverted fly pass in the new colour scheme.

The LCA programme was launched in 1983 for two primary purposes. The principal and most obvious goal was 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 since the 1970s, 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-1990s, and that by 1995 the IAF would lack 40% of the aircraft needed to fill its projected force structure requirements.[7]

The LCA programme's other main objective was to serve as the vehicle for an across-the-board advancement of India's domestic aerospace industry.[8] 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 aerospace "self-reliance" initiative is not simply the production of an aircraft, but also the building of a local industry capable of creating state-of-the-art products with commercial spin-offs for a global market. The LCA program was intended in part to further expand and advance India's indigenous aerospace capabilities across the broadest range of modern aviation technologies.[9]

To better accomplish these goals, the government chose to take a different management approach, and in 1984 established the Aeronautical Development Agency (ADA) to manage the LCA programme. 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 ADA, a national consortium of over 100 defence laboratories, industrial organisations, and academic institutions with HAL being the principal contractor.[10] The ADA formally falls under the auspices of the Indian Defence Ministry's Defence Research and Development Organisation (DRDO).

The Indian government's "self-reliance" goals for the LCA include indigenous development of the three most sophisticated — and hence most challenging — systems: the fly-by-wire (FBW) flight control system (FCS), multi-mode pulse-doppler radar, and afterburning turbofan engine.[11] 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 self-reliance in aviation technologies is illustrated by the fact that out 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 the 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. As a consequence of the embargo imposed on India after its nuclear weapons tests in May 1998, many items originally planned to be imported — like the landing gear — were instead developed indigenously .

Of the five critical technologies the ADA identified at the beginning of the LCA programme as needing to be mastered for India to be able to design and build a "completely indigenous" fighter, two have been entirely 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, 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 licensed to both Airbus and Infosys).[11] These successes have gone mostly unnoticed in the shadow of the problems encountered with the other three key technology initiatives. Nonetheless, 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.[12]

Programme origins

In 1955, based on experience gained from the HT-2 programme[13] and the manufacturing capabilities gained from licenced production of the de Havilland Vampire FB.52 and T.55, HAL took up the challenge of an 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 Marut did not enter service with the IAF until 1967 due to problems obtaining or developing a suitable turbojet engine. In the meantime, HAL gained additional experience completing the development and testing of the Folland Gnat F.1, which it produced under licence from 1962-1974, and from which it later developed a much-modified variant, the Gnat Mk.II Ajeet, as well as the HJT-16 Kiran turbojet trainer, which 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 markedly similar to that for the Marut,[14] 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 and interdiction capability remained unfulfilled.

In 1983, the DRDO obtained permission to initiate a programme to design and develop a Light Combat Aircraft, 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. HAL serves as the prime contractor and has leading responsibility for LCA design, systems integration, airframe manufacturing, aircraft final assembly, flight testing, and service support.[10] The ADA itself 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, 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) — now called the National Aerospace Laboratories — 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 fly-by-wire FCS itself. HAL and the Electronics and Radar Development Establishment (LRDE)[15] are jointly developing the Tejas' Multi-Mode Radar (MMR). The Gas Turbine Research Establishment (GTRE) 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 IAF's Air Staff Requirement for the LCA would not be 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 would also prove a boon in that it 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 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. The PD phase is a critical early element in the aircraft design and development process because from this flow key elements of the detailed design, manufacturing approach, and maintenance requirements. Moreover, this is the point at which overall programme costs are most effectively controlled. The costs to implement subsequent changes to design requirements, capabilities and features become increasingly expensive the further down the path of development they are introduced, and the more likely the program is to suffer schedule and cost overruns.

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 governmental 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 fabrication 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 production 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 manufacturing of three more prototype vehicles (PV-3 as the production variant, PV-4 as the naval variant, and PV-5 as the trainer variant) and a fatigue test specimen, and the construction 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 authorized until April 1993, with significant 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" (RSS). Although Dassault had offered an analogue FCS system in 1988, the ADA recognised that digital flight control technology would soon supplant it.[11] 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 is 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" 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 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 of that year.

The 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 National Flight Test Centre (NFTC), 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].[16]

Multi-Mode Radar (MMR)

File:TEJAS MMR.jpg
The Multi-Mode Radar shown here is to be used from LSP-3 onwards

Another critical technology area tackled for indigenous development by the ADA team 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,[17] which was developed by Ericsson and Ferranti Defence Systems Integration for the Saab JAS-39 Gripen.[18] However, after examining other radars in the early 1990s,[19] the DRDO became confident that indigenous development was possible. 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.[20]

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."[21] 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-2052 is an interim option being seriously considered.[20]

Engine and Propulsion

Main article: GTRE GTX-35VS Kaveri
GTRE GTX-35VS Engine on the Testbed
Picture of the GTRE GTX-35VS Engine on display at AERO INDIA 2007.

Kaveri Engine and Delays

Initially, it had been decided to equip the prototype aircraft with the General Electric F404-GE-F2J3 afterburning turbofan engine. Simulataneously, in 1986, a parallel programme to develop an indigenous powerplant was also launched. Led by the Gas Turbine Research Establishment, the GTRE GTX-35VS, named "Kaveri", was expected to replace the F404 on all production aircraft. However, progress in the Kaveri development programme was slowed by technical difficulties. 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.[22]

RFP inviting companies for further development of Kaveri was issued. 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.[5] At that time, the DRDO had hoped to have the Kaveri engine ready for use on the Tejas by 2009-10.

GE F404

Continued development snags with the Kaveri resulted in the 2003 decision to procure the uprated General Electric F404, F404-GE-IN20 engine for the eight pre-production LSP aircraft and two naval prototypes. The ADA awarded General Electric a US$105 million contract in February 2004 for development engineering and production of 17 -IN20 engines, delivery of which began in 2006.

In Feb 2007, HAL ordered an additional 24 F404-GE-IN20 afterburning engines to power the first operational squadron of Tejas fighter aircraft for the Indian Air Force.[23] Before the subsequent order, F404-GE-IN20 was trial-installed in Light Combat Aircraft (LCA) as part of final evaluations toward flight-testing, scheduled for mid-2007. The F404-GE-IN20 engine generated more than 19,000 pounds (85 kN) uninstalled thrust and completed 330 hours of Accelerated Mission testing, equivalent of 1,000 hours of flight operation. The -IN20 succeeds -F2J3 development engines used for nearly 600 flights, cumulatively covering eight engines.

New Engine Evaluations

In September 2008, it was announced that the Kaveri would not be ready in time for the Tejas, and that an in-production powerplant would have to selected.[24] The ADA plans to issue a request for proposal (RFP) for a more powerful engine in the 95-100 kilo Newtons (kN) range. The contenders are likely to be the Eurojet EJ200 and the General Electric F414.

Prototypes

File:LCA form1.jpg
LCA TD-1, TD-2 and PV-1 in echelon formation

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 — resulting in 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 in x 5 in 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) aircraft. The 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 maiden flight on 1 December 2006, reaching an altitude of 2.5 km and a top speed of Mach 0.8.[25] 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.[26]

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.

Design

PV-3 in Indian Air Force grey camouflage pattern.

The Tejas is single-engined multirole fighter which features a tailless, compound delta-wing planform and is designed with "relaxed static stability" for enhanced maneuverability. Originally intended to serve as an air superiority aircraft with a secondary "dumb bomb" ground-attack role, the flexibility of this design approach has permitted a variety of guided air-to-surface and anti-shipping weapons to be integrated for more well-rounded multirole and multimission capabilities. (It should also be noted that all equipments and technologies mentioned in this section were indigenously developed, unless noted otherwise.)

The tailless, compound-delta planform helps keep the Tejas small and lightweight — in fact, it is reputed to be the smallest and lightest supersonic combat jet in the world.[27] The use of this planform 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 of the LCA, giving it minimum supersonic drag, a low wing-loading, and high rates of roll and pitch.

All weapons are carried on one or more of seven hardpoints with total capacity of > 4,000 kg: three stations under each wing and one on the under-fuselage centreline. There is also an eighth, offset station beneath the port-side intake trunk which can carry a variety of pods (FLIR, IRST, laser rangefinder/designator, or reconnaissance), as can the centreline under-fuselage station and inboard pairs of wing stations.

The Tejas has integral internal fuel tanks to carry 3,000 kg of fuel in the fuselage and wing, and a fixed inflight refuelling probe on the starboard side of the forward fuselage. Externally, there are "wet" hardpoint provisions for up to three 1,200- or five 800-litre (317- or 211-US gallon; 264- or 176-Imp gallon) fuel tanks on the inboard and mid-board wing stations and the centreline fuselage station.

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. Composites 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.[28] 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.

The tailfin for the LCA is a monolithic honeycomb piece, an approach which reduced its manufacturing cost by 80% compared to the customary "subtractive" or "deductive" method, whereby the shaft is carved out of a block of titanium alloy by a computerized numerically controlled machine. No other manufacturer is known to have made fins out of a single piece.[29] A 'nose' for the rudder is added by 'squeeze' riveting.

The use of composites in the LCA resulted in a 40% reduction in the total number of parts compared to using a metallic frame. Furthermore, the number of fasteners has been reduced by half in the composite structure from the 10,000 that would have been required in 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.[12]

The airframe of the naval variant of the Tejas 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. 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).

The naval Tejas will also have a strengthened spine, a longer and stronger undercarriage, and powered nose wheel steering for deck manoeuvrability.[26][30] The Tejas trainer variant will have "aerodynamic commonality" with the two-seat naval aircraft design.[31]

Landing gear

The Tejas has a hydraulically retractable tricycle-type landing gear with a pair of single inward-retracting mainwheels and a steerable, twin-wheel forward-retracting nose gear. The landing gear was originally to have been imported, but following the imposition of trade sanctions, HAL developed the entire system independently.

India's Nuclear Fuel Complex (NFC) led the team that developed the titanium half-alloy tubes that are used for hydraulic power transmission and they are critical components in the LCA. India is one of only six nations which have developed this technology, which also has space applications.[32]

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 handling by the pilot.[33] 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 yaw 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.

The digital FBW system of the Tejas employs a powerful digital flight control computer (DFCC) 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 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.

Propulsion

The wing-shielded, side-mounted bifurcated, fixed-geometry Y-duct air intakes have an optimised diverter configuration to ensure buzz-free air supply to the engine at acceptable distortion levels, even at high AoA.

The original plan was for the LCA prototype aircraft to be equipped with the General Electric F404-GE-F2J3 afterburning turbofan engine, while the production aircraft would be fitted with the indigenous GTRE GTX-35VS Kaveri turbofan being developed in a parallel effort by the Gas Turbine Research Establishment. Continued development snags with the Kaveri resulted in a 2003 decision to procure the uprated F404-GE-IN20 engine for the eight pre-production LSP aircraft and two naval prototypes. After accelerated trials of -IN20 engine an order was placed for 24 more IN20 engines for installation on the first 20 production aircraft.

The Kaveri is a low-bypass-ratio (BPR) afterburning turbofan engine featuring a six-stage core high-pressure (HP) compressor with variable inlet guide vanes (IGVs), a three-stage low-pressure (LP) compressor with transonic blading, an annular combustion chamber, and cooled single-stage HP and LP turbines. The development model is fitted with an advanced convergent-divergent ("con-di") variable nozzle, but the GTRE hopes to fit production Tejas aircraft with a multi-axis thrust-vectoring version. The Defence Avionics Research Establishment (DARE) developed an indigenous Full-Authority Digital Engine Control (FADEC) unit for the Kaveri (KADECU). The DRDO's Central Vehicle Research and Development Establishment (CVRDE) was responsible for the design and development of the Tejas' aircraft-mounted accessory gear box (AMAGB) and the power take-off (PTO) shaft.

Avionics

The Tejas has a night vision goggles (NVG)-compatible "glass cockpit" that is dominated by an indigenous 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[34]). The CSIO-developed HUD, Elbit-furnished DASH helmet-mounted display and sight (HMDS), and hands-on-throttle-and-stick (HOTAS) controls reduce pilot workload and increase situation awareness by allowing the pilot to access navigation and weapon-aiming information with minimal need to spend time "head down" in the cockpit.

The MFDs provide information on the engine, hydraulics, electrical, flight control, and environmental control systems on a need-to-know basis, along with basic flight and tactical information. Dual redundant display processors produce 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.

Target acquisition is accomplished through a state-of-the-art radar — potentially supplemented by a laser designator pod, forward-looking infra-red (FLIR) or other opto-electronic sensors — to 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. The LCA also has secure and jam-resistant communication systems such as the "identify friend or foe" (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.

Radar

The LCA's coherent pulse-Doppler Multi-Mode Radar is designed to keep track of a maximum of 10 targets and allows simultaneous multiple-target engagement. Jointly developed by the LRDE and HAL Hyderabad, the MMR will be fitted in production Tejas aircraft, supplanting the flight test instrumentation carried in the prototype aircraft. The MMR performs multi-target search, track-while-scan (TWS), and ground-mapping functions. It features look-up/look-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. Developmental delays, however, have resulted in consideration being given to procuring foreign "off-the-shelf" radars for early production examples of the Tejas.

Due to delay in development of MMR, government have come out with the collaboration with IAI for development of Radar the sensor for the new radar is supposed to be EL/M-2052 AESA from Elta and the remaining item and software will be combination of MMR and IAI developed products. Varadarajan, (Director - LRDE) has said that LRDE has initiated development of active electronically scanning array radar[35] for airborne applications. And that these radars will be integrated with Tejas light combat aircraft-Mach II by 2012-13.

Self-protection

An advanced electronic warfare suite enhances the Tejas' survivability during deep penetration and combat. The LCA's EW suite is being developed by the Defence Avionics Research Establishment (DARE) — which was known as the Advanced Systems Integration and Evaluation Organisation (ASIEO) until June 2001 — with support from the Defence Electronics Research Laboratory (DLRL).[15] This EW suite, known as "Mayavi" (Sanskrit: Illusionist), includes a radar warning receiver (RWR), self-protection jammer, laser warning system, missile approach warning system, and chaff/flare dispenser. In the interim, the Indian Defence Ministry has revealed that an unspecified number of EW suites have been purchased from Israel's Elisra for the LCA prototypes.[36]

The ADA claims that a degree of "stealth" has been designed into the Tejas. Being very small, there is an inherent degree of "visual stealth", but the airframe's use of a high degree of composites (which do not themselves 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 by the radars of enemy fighters, airborne early warning and control (AEW&C) aircraft, active-radar air-to-air missiles (AAM), and surface-to-air missile (SAM) defence systems.

Escape systems

Although two-seat variants of the LCA are planned, the examples built to date are crewed by a single pilot on a Martin-Baker zero-zero ejection seat. The ejection seat is slated to be replaced with an indigenous ejection seat[37] To improve pilot safety during ejection, the Armament Research and Development Establishment (ARDE), Pune, India created a new line-charged canopy severance system, which has been certified by Martin-Baker. This system, which is the first of its kind, can be operated from outside the aircraft, an important consideration when the pilot is trapped or unconscious.

Flight Simulator

To support the aircraft a dome-based Mission Simulator has been developed by the Aeronautical Development Establishment (ADE), Bangalore. It was inaugurated by deputy chief of air staff of Indian Air Force. It has been used to provide design support during the initial phase of LCA development in particular handling quality evaluation and planning and practicing mission profiles.

Costs

Unit costs

In December 1996, A. P. J. Abdul Kalam, the then Scientific Adviser, calculated unit costs of US$21 million.

At the end of 2001, Dr. Kota Harinarayana, director of the ADA and of the LCA programme, estimated the unit cost for the LCA (for an expected order of 220 aircraft) to be between US$17-20 million, and once production ramped up, that could drop to US$15 million.

However, by 2001 others were indicating that the LCA would cost US$24 million (in excess of Rs. 100 crores per aircraft). Considering cost escalations, some aviation experts feel that when the aircraft comes out, it could cost upwards of US$35 million apiece.[38]

A Rs. 2,000 crores (over US$450 million) order for 20 Tejas aircraft would represent a unit procurement cost of US$22.6 million for each, which would be consistent with Abdul Kalam's estimates. At a price tag of around Rs. 100-110 crores, the Tejas will be much cheaper than other contemporary fighters.

By comparison, the Times of India quoted the costs for the Swedish JAS-39 Gripen and French Rafale as Rs. 150 crores (US$34 million) and Rs. 270 crores (US$61 million)

Program Milestones

  • 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 weapons such as missiles and an internal gun).
  • On 1 December 2006, the PV-3 flew for the first time for 27 minutes at an altitude of 2.5 km and at a speed of Mach 0.8. According to LCA Programme Director P.S. Subramanyam, this flight-test was meant for "product enhancement" and clearing the Indian Air Force's Initial Operational Clearance envelope. He said that the PV-3 is equipped with a more advanced pilot interface, refined avionics and higher control law capabilities compared with the previous versions.[39] LCA has flown at speeds of Mach 1.4.
  • On 25 April 2007, the first Limited Series Production LCA (LSP-1) made its first flight and it reached a speed of Mach 1.1.
File:Tejas R-73.jpg
Tejas PV-1 firing an R-73 missile during weapons trials in Goa
  • PV-2 and PV-3 underwent sea-level trails at INS Rajali Naval Air Station, Arakkonam to study the effects of flying at sea-level, as all earlier trials have been conducted at Bangalore which is 3,000 feet above sea-level.[40][41] The reliability of the LCA systems under the hot and humid conditions, as well as low level flight characteristics was tested.[42] It is due to this intense flight testing schedule that the LCA was not able to fly at the Paris air show-2007, as was originally planned.[43]
  • On 7 September 2007, Tejas Prototype Vehicle (PV-1) made a successful maiden flight with two 800 litre drop tanks.[44][45]
  • On 7 February 2008, Tejas Prototype Vehicle (PV-1) made a successful flight powered by fuel from two 800 litre drop tanks. It made a one hour and 24 minute long sortie. On internal fuel LCA can perform a 40-minute sortie. [48]
  • LCA Tejas prototypes PV-2 & PV-3 underwent hot weather flight trials at Air Force Station, Nagpur from 28 May 2008 to 04 June 2008. The trials were declared successful.
  • On 16 June 2008, Tejas second Limited Series Production LCA (LSP-2) made its first flight and it reached a speed of Mach 1.1.
  • On 13 December, 2008 PV-3 and LSP-2 completed the high altitude at the Leh air base.[50]
  • On January, 2009 Tejas completed 1000 flights. [51]

Status

Tejas trainer under construction.
File:Tejas LeH.JPG
Flight-testing of Tejas at LeH

The Tejas is presently undergoing flight testing. It will be inducted into the IAF in limited numbers once Initial Operating Clearance (IOC) is achieved. Full scale induction will commence once Final Operating Clearance (FOC) is achieved. IOC testing is expected to be completed by 2009, and FOC by 2010. Independent analysts and officials in the IAF expect that deliveries of operational Tejas fighters are likely to begin in 2010, with combat service entry around 2012.[52][53]

The IAF has created a 14 member "LCA Induction Team", composed of IAF pilots and officers and headed by Air Vice Marshal BC Nanjappa. This team's objectives are to oversee the induction of the LCA, help to solve any challenges that may arise, help the developers customize the Tejas for operational use, as well as help create doctrine, training programs, maintenance programs and help prepare the IAF to speedily ready the Tejas for operational service. This reveals the IAF's desire to be more involved in the LCA development as well as its urgency to induct new aircraft. The team is stationed in Bangalore.[54][55]

Senior HAL officials had said in March 2005 that the IAF would place a Rs. 2,000 crores (over US$450 million) order for 20 Tejas aircraft, with a similar purchase of another 20 aircraft to follow. All 40 will be equipped with the F404-GE-IN20 engine.[26] So far, Rs. 4806.312 cr have been spent on development of various versions of Light Combat Aircraft.[56]

The first squadron of the indigenously developed Light Combat Aircraft (LCA) named Tejas will be deployed down south in Tamil Nadu, when the first batch of the 20 fighter aircrafts are expected to be inducted by the Indian Air Force (IAF) in 2009-2010.

Light combat aircraft hot weather trial was successful conducted on 30 May 2008. Production version of LCA 'Tejas' took to skies on 16 June 2008.As of december 2008,HAL Tejas high-altitude trials at Leh were successful.[57]

Delay

The delay in development of the LCA was attributed mainly to India's lack of experience in designing sophisticated fighter aircraft. India had only previously manufactured a second generation fighter (HF-24 Marut). Taking a leap from 2nd Generation to 4.5 Generation did prove to be an obstacle. US sanctions over India's controversial nuclear tests along with the IAF's ever-changing requirements did not help the LCA project. In a May 2006 interview, HAL chairman Ashok Baweja had said that the fifth prototype vehicle (PV-5), the trainer prototype, and the first of the eight LSP aircraft would be delivered before the end of 2006. These aircraft will help accelerate the initial operational clearance for the LCA.

It was 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.[58] A trainer version is under development and the design of the Naval version is complete, and are expected to fly in 2008. However LSP-1 made its first flight only in April 2007, while the Trainer prototype is yet to be delivered.

The twenty aircraft order by the Indian Air Force (16 single-seat and four two-seat trainers) are not now expected to gain operational clearance until after 2012.[59]

Mark 2 Version

Due to the inability of the Tejas to meet the Indian Air Staff requirements the India Air Force will not order any more Mark 1 aircraft other than the original twenty aircraft it had ordered in 2005. It is still considering an order of up to 125 aircraft when a re-designed Mark 2 is developed.[59]The Mark 2 will have a more powerful engine, refined aerodynamics and replacing other parts to reduce obsolescence according to an IAF spokesman.[59]

Variants

File:LCATrainerModel.jpg
Model of Tejas Naval version

Prototypes

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

Technology Demonstrators (TD)
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 - Originally planned to be a Naval variant for carrier operations, but now a second production variant.
  • PV-5 - Fighter/Trainer Variant
Naval Prototypes (NP)
  • NP-1 - Two-seat Naval variant for carrier operations.
  • NP-2 - Single-seat Naval variant for carrier operations.
Limited Series Production (LSP) aircraft

Currently, 8 LSP series aircraft are on order.

  • LSP-1 (KH2011) - 25 April 2007
  • LSP-2 (KH2012) - 16 June 2008 This is the first LCA fitted with GE-404 IN20 engine.
  • LSP-3 - Will be the first aircraft to have the MMR and will be close to the IOC standard.
  • LSP-4 to LSP-8 - Planned to fly by late 2009.

Planned production variants

  • Tejas Trainer – Two-seat operational conversion trainer for the Indian Air Force.
  • Tejas Navy – Twin- and single-seat carrier-capable variants for the Indian Navy.

Operators

 India

Specifications (HAL Tejas)

Three view of the Tejas
Three view of the Tejas

Data from Aviationfans.com[61][62]

General characteristics

  • Crew: 1Internal fuel capacity: 3000 liters
  • External fuel capacity: 5×800 liter tanks or 3×1,200 liter tanks, totaling 4,000/3,600 liters

Performance

Armament

Avionics
EL/M-2052 AESA radar (In future models, 2012 onwards.)

See also

References

  1. ^ Note: The term "tailless" here means that the aircraft lacks horizontal tailplanes, there is still, in this instance, a single vertical tailfin.
  2. ^ Anon. (27 April 2003). PM to select Sanskrit name for LCA on May 4Indiainfo.com. According to then Scientific Advisor to Defence Minister Dr. Vasudev K. Aatre, "Tejas" was selected from a list of 20 names considered for the LCA; the other alternate name would have been "Sarang".
  3. ^ Anon. (21 August 2003). LCA first prototype vehicle to fly next month. Indiainfo.com.
  4. ^ Pandit, Rajat (16 July 2006). IAF may not get to fly LCA before 2010. The Times of India.
  5. ^ a b Jackson, Paul; Munson, Kenneth; & Peacock, Lindsay (Eds.) (2005). “ADA Tejas” in Jane’s All The World’s Aircraft 2005-06’’. Coulsdon, Surrey, UK: Jane's Information Group Limited. p. 195. ISBN 0710626843.
  6. ^ http://www.hindu.com/2008/11/26/stories/2008112651981400.htm
  7. ^ Anon. (15 August 2006). Tejas Light Combat Aircraft (LCA). Global Security. Retrieved 25 August 2006.
  8. ^ Iyer, Sukumar R. (March-April 2001). LCA: Impact on Indian Defense. Bharat Rakshak Monitor.
  9. ^ Anon. (2004). Remembrance of Aeronautical Matters Past. Vayu Aerospace & Defence Review. Retrieved 31 March 2007.
  10. ^ a b Anon. (January 2001). Light Combat Aircraft (LCA) Test-Flown Successfully. DRDO website. Retrieved 31 March 2007.
  11. ^ a b c Reddy, C. Manmohan (16 September 2002). LCA economics The Hindu.
  12. ^ a b Anon. (19 August 2002). Aircraft: LCA. Space Transport.
  13. ^ In October 1948, HAL was authorised to start development of an indigenously designed basic trainer, the HT-2, which first flew 5 August 1951.
  14. ^ Chatterjee, K. (n.d.). Hindustan Fighter HF-24 Marut; Part I: Building India's Jet Fighter. Retrieved 23 August 2006.
  15. ^ a b Note: The LRDE is sometimes mis-abbreviated as "ERDE". To distinguish between "Electrical" and "Electronic", the latter is abbreviated with the first letter of its Latin root (lektra). The same approach is used with for the DLRL.
  16. ^ Interview with Mr. Shyam Shetty, head of the National Control Law team. "NAL and LCA-1: Flight Control Laws". National Aerospace Laboratories (NAL) Information Pasteboard (25 June – 1 July 2001).
  17. ^ Taylor, John W. R.; Munson, Kenneth; & Taylor, Michael J. H. (Eds.) (2005). "HAL Light Combat Aircraft" in Jane's All The World's Aircraft 1989-1990. Coulsdon, Surrey, UK: Jane's Information Group Limited. p. 104. ISBN 0-7106-0896-9.
  18. ^ Note: Ericsson Microwave Systems was bought by Saab in June 2006; Ferranti Defence Systems Integration was acquired by GEC-Marconi in 1990, which in turn merged with British Aerospace (BAe) to form BAE Systems in November 1999.
  19. ^ Note: The Westinghouse — now Northrop Grumman — AN/APG-66, which is carried on the F-16, was among the radars evaluated by the ADA in 1992. (See Sharma, Ravi (16-29 July 2005). LCA puzzle. Frontline.)
  20. ^ a b Aroor, Shiv (8 April 2006). 'Indigenous' aircraft needs foreign lift, for its radar. The Sunday Express.
  21. ^ Mudur, Nirad (1 May 2006). Glitches in LCA radar. Vijay Times.
  22. ^ Since India does not possess suitable aircraft, the high-altitude testing of the Kaveri is contracted to Russia, which uses a Tu-16 bomber for the purpose. Another Kaveri engine was delivered to Russia for further flight testing from June to September 2006, but on an Il-76 testbed instead of a Tu-16.
  23. ^ According to a GE press release
  24. ^ Sharma, Ravi (2008-09-27). "Kaveri engine programme delinked from the Tejas". The Hindu. Retrieved 2008-09-28.
  25. ^ LCA: third prototype makes maiden flight The Hindu
  26. ^ a b c Anon. (17 February 2006). India: LCA Tejas by 2010 - But Foreign Help Sought With Engine. Defense Industry Daily.
  27. ^ Aeronautical Development Agency (n.d.). LCA and its Features. Retrieved 24 September 2006.
  28. ^ Harry, B. (Vol. I, February 2005; Vol. II, April 2005). Radiance of the Tejas (2 Parts). Vayu Aerospace & Defence Review.
  29. ^ Prakash, Sqn. Ldr. B.G. (16 February 2001). Dreams lighten in LCA. Strategic Affairs - Technology (page 3).
  30. ^ Wollen, M. S. D., Air Marshal (Retd.) (March-April 2001). The Light Combat Aircraft Story. Bharat Rakshak Monitor.
  31. ^ Aeronautical Development Agency (n.d.). LCA Trainer. Retrieved 24 September 2006.
  32. ^ Anon. (9 June 2006). NFC develops titanium product for LCA, GSLV. Business Line.
  33. ^ rediff.com Special: The saga of India's Light Combat Aircraft
  34. ^ http://frontierindia.net/light-combat-aircraft-tejas-testing - Retrieved July 5, 2008
  35. ^ http://www.bharat-rakshak.com/NEWS/newsrf.php?newsid=10439
  36. ^ Raghuvanshi, Vivek (24 July 2006). India, Israel Propose Joint Electronic Warfare Venture. Rantburg.
  37. ^ B. Harry of ACIG.org 's report from DEFEXPO-2004
  38. ^ Sharma, Ravi (20 January – 2 February 2001). Airborne, at last. Frontline.
  39. ^ Anon. (2 December 2006)[1] LCA: third prototype makes maiden flight. The Hindu.
  40. ^ zeenews.com
  41. ^ newkerala.com news homepage
  42. ^ India-Defence report about the INS Rajali Sea Trails of the Tejas
  43. ^ David Donald, India’s Tejas missed the show because of tests, Aviation International News, Paris Air Show, June 2007.
  44. ^ Tejas prototype makes successful flight with drop tanks
  45. ^ Tejas Makes Successful First Flight With Stores
  46. ^ Tejas fires R-73 missile
  47. ^ Litening pod tests on LCA Tejas
  48. ^ The Hindu : National : Tejas flight, with drop tanks, successful
  49. ^ http://www.hinduonnet.com/thehindu/holnus/001200811081550.htm India's Tejas LCA makes maiden flight by night
  50. ^ "LCA high-altitude trials at Leh successful: DRDO". Retrieved 2008-12-14.
  51. ^ LCA Tejas crosses 1000 sorties landmark [2]
  52. ^ Anon. (22 August 2006). HAL's LCA likely to have Lockheed participation. WebIndia123.com.
  53. ^ Anon. (16 May 2006). HAL to pursue LCA-Tejas vigorously to meet 2008 deadline. One India.
  54. ^ IAF team to oversee LCA induction and operation, The Hindu, December 12 2006 report.
  55. ^ Fighter project on fast track mode – newindpress.com report. Retrieved: 6 April 2008
  56. ^ "Flight Testing of LCA" (Press release). Ministry of Defence (India), Press Information Bureau, GoI. 3 March 2008. Retrieved 2008-04-06. {{cite press release}}: Check date values in: |date= (help)
  57. ^ http://timesofindia.indiatimes.com/LCA_high-altitude_trials_at_Leh_successful_DRDO_/articleshow/3847266.cms?TOI_latestnews
  58. ^ Anon. (15 May 2006). HAL to go into supersonic mode. Indian Express (via ICAST archives).
  59. ^ a b c The Hindu 5 December 2008
  60. ^ http://economictimes.indiatimes.com/rssarticleshow/msid-3135119,prtpage-1.cms
  61. ^ http://www.aviationfans.com/node/17
  62. ^ http://www.ada.gov.in/Activities/lca/lca.html

News reports:

Features and analysis:

Technical:

General:

Photo links:

Video links:

Retrieved from "https://en.wikipedia.org/w/index.php?title=HAL_Tejas&oldid=265931422"