By Hormuz Mama
Flight International, November 1998
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With the first flight of its Light Combat Aircraft (LCA) now put back to mid-1999, nearly four years after its roll-out, the program appears to be plagued with difficulties and delays and the target date of 2003 for first deliveries to the Indian Air Force looks increasingly over-optimistic. Not so, according to the Aeronautical Development Agency (ADA), which is responsible for the program. For the ADA, India's project to develop the LCA is frequently underestimated, highlighting that the aircraft is the first 4th-generation multi-role fighter to be developed from the ground up in Asia. Japan's Mitsubishi F-2 is a substantial upgrade of the US Lockheed Martin F-16, and China's new Chengdu F-10, based on technology from Israel's cancelled Lavi fighter, India's Ministry of Defence's agency points out.
ADA emphasizes that the LCA is the first Asian-designed fighter to have an ingeniously developed engine, unlike the F-2 (powered by a General Electric F110-GE-129 turbofan) and the F-10 (which uses a Russian engine - the Saturn Lyulka AL-31F). Combining a new airframe and engine puts development of the LCA in the same class as the Dassault Rafale and Eurofighter Typhoon, according to the agency. Add to that the requirement to develop a naval variant, and the scale of India's undertaking becomes more evident. The task is complicated by the country's lack of recent experience with combat aircraft development. India's last indigenously designed fighter, the HAL HF-24, first flew in 1967. India blames this lack of experience on the fact that the first LCA technology demonstrator, aircraft TD-1, has not flown since its roll-out in Nov. '95.
Reports that the delays have been caused by systems integration problems are off the mark, says Dr. Kota Harinarayana, LCA program director at ADA. In an exclusive interview with Flight International, he explains that the entire development test infrastructure has had to be built up from scratch. Standalone test rigs have been developed for over 500 line replaceable units (LRUs) in the LCA's avionics and systems, he says. All the test rigs were developed in-house, which took time. "We have developed numerous rigs; a dynamic avionics integration rig, iron bird for testing flight controls, environmental control system rig, fuel control system rig, and the like," he explains. Certification of each rig was a major project in itself, he says, but it will minimize the testing which has to be done on the actual aircraft. Another time-consuming step has been the independent verification and validation of all on-board software. India has worked to ensure that documentation is up to the U.S. Mil. Std. 21 67A level, and that the software design and coding meets all requirements, says Dr. Harinarayana.
Lockheed Martin was selected in 1993 to help ADA design & develop the quadruplex-redundant flight control system for the LCA, but following a US embargo, India was forced to complete the software independently (Flight International, 1-7 July). Aircraft TD-1 is now ready, awaiting completion of tests on the quadruplex, digital, fly-by-wire flight control system. The demonstrator's G.E. F404-F2J3 engine has been integrated with the controls and, in early April, test pilot Wg. Cdr. (retd.) Rakesh Sharma began ground test runs. Several systems parameters have been studied and these tests will soon be followed by ground taxi trials and will be among the last steps before the first flight of TD-1.
Aircraft TD-2, also powered by an G.E. F404-F2J3, was rolled out on 14 August. Phase 1 development involves these first two aircraft and is intended to prove only the core technologies. Also, the aircraft will not be fitted with all the defence equipment. Phase One is still on budget and will cost Rs.21.88 billion ($515 million). Work is under way on two prototypes, PV-1 & PV-2. Five prototypes, including a two-seat trainer, are to be produced under Phase 2 of the development program. PV-1 will be the first aircraft to have the radar and the electronic warfare suite. Dr. Harinarayana emphasizes that equipment installation in PV-1 will be based on a virtual prototype, and that no physical mock-ups will be built. While a mock-up was required for TD-1, the electronic mock-up will help eliminate assembly problems in advance. Phase 2 should cost another Rs.30 billion and will cover the rest of the flight test program, bringing the total cost of the LCA development, up to the start of low-rate initial production, to only about Rs.55 billion, says Dr. Harinarayana.
Entry into service is still scheduled for 2003, and unit flyaway cost still stands at $21 million for a production run of 220 aircraft. Ultimately, the price will depend on the cost of imported components, the use of which is being minimized. Dr. Harinarayana says that a brass-board model of the indigenously designed radar is already complete, and development is on schedule. Flight testing of the multimode radar, being developed by Electronics Research & Development Establishment and HAL, will be performed initially in a HAL Hs.748. The radar is optimized for the air superiority role. It's functions include: air-to-air; search (range while search & velocity search), and tracking (track while scan, priority target track and continuous tracking); air-to ground/sea; search, tracking, and mapping (including air-to-ground ranging and contour mapping). The coherent, pulse-Doppler, radar has low, medium and high pulse-repetition frequency modes. Capabilities include Doppler beam- sharpened ground mapping and air-to-surface moving target indication.
Ambitious Plans
Changes are being made to the basic LCA design, Dr. Harinarayana says. The original mission computer is to be replaced with an advanced version, with a more powerful 32-bit processor. ADA has teamed up with Silicon Graphics to set up a Virtual Reality Centre at ADA's Bangalore facilities. While carbon-fiber composites make up 30% of the weight of TD-1, from PV-1 onwards the proportion will be increased to 45%. Use of aluminum alloy will be reduced from 57% to 43%, again by weight. Despite the delays, India has ambitious plans for the LCA, with more far-reaching changes planned in the longer term. The system is designed so that improvements, such as additional LRUs or modifications to existing software or hardware, can easily be undertaken.
Dr. Harinarayana says that among the planned new subsystems is a missile approach warning system, infrared search & track sensor, high-definition television camera, and programmable radar warning receiver. A laser rangefinder and designator will also be added. A secure data-link is to be added from the third prototype, PV-3, onwards. To improve the pilot/vehicle interface, new equipment such as a helmet-mounted display/sight is being developed. In the longer term, the radar may be replaced by an active phased-array unit. Work is already under way on the necessary transmit/receive modules, Dr. Harinarayana says. The advanced, electronically scanned radar would have such features as multiple beams, increased beam agility and better electronic counter-counter measures capability. The aircraft's all-composite wing will be ultimately be of co-cured, co-bonded design and the LCA's 1200 litre (31.5 US gallon) under fuselage external fuel tank will be replaced by a low-drag conformal unit.
Development of the LCA's Kaveri turbofan engine is progressing well at Gas Turbine Research Establishment (GTRE). Five engines are being ground tested; while the first test engine, the Kabini, consisted of only the core module, test runs of the first complete prototype Kaveri began in 1996. The third engine was the first with variable inlet guide- vanes on the first three compressor stages. The fifth unit is already close to the production engine weight, Dr. Harinarayana says. About 17 test engines are to be built, and initial flight tests of the Kaveri are planned for the end of 1999. The first flight in an LCA may follow a year later.
For initial flight tests, Dr. Harinarayana says, an agreement has been signed with Russia for loan of a Tu-16 twinjet, on which the test Kaveri will be mounted in a ventral pod. Engine tests are also planned at a high-altitude test facility, as an important feature of the Kaveri for operation in hot-and-high conditions is flat rating of the engine to maintain thrust to higher temperatures and altitudes. The production Kaveri, with a reheat thrust of 20,200 lbs. (80kN), will be more powerful than the 17,000 lbs. Snecma M88-2 now powering the twin-engined Rafale. It matches the output of the uprated M88-3. GTRE says a growth version of the Kaveri will have a turbine entry temperature of 1 ,8500 C and single-crystal turbine blades being developed by GTRE with the Defence Metallurgical Research Laboratory. Directionally solidified blades are now used.
The new variant, which India says will be at the technology level of the M88, will have a fan pressure ratio of 4:1 and an overall pressure ratio of 27:1. A new combustor will be shorter and lighter than the present unit. The increased, unspecified, dry thrust should allow the aircraft to super cruise (cruise supersonically without the use of reheat). Also under development is a thrust-vectoring nozzle, to enhance its agility, as well as a digital engine control system. The axisymmetric TV nozzle is planned to be flight tested on a later prototype. The nozzle could possibly permit the elimination of the vertical stabiliser and decrease the radar cross section. Plans are already under way for derivatives of the Kaveri; a non-afterburning version for an advanced jet trainer, a high bypass-ratio turbo fan based on the Kaveri core, as well as variants for other applications.
Two-Seat Trainer
The two-seat trainer version of the LCA, of which there will be one prototype, is almost identical to the fighter. Space for the second seat will be made by eliminating the 410 L forward fuselage fuel tank and some of that fuel may be relocated in the fuselage. The trainer will be fully combat capable and could be used in that role, should the Indian Air Force wish. Project definition on the naval LCA is complete, Dr. Harinarayana says, and pre-project work such as design of naval flight control laws, long-stroke undercarriage and the ski-jump launch await government go-ahead. A virtual prototype is to be created before the first metal is cut. Two flying prototypes are planned to be produced for tests off an aircraft carrier.
Airframe and undercarriage strengthening, to withstand the rigors of carrier landing, will make the Naval LCA about 500 kg (1000 lbs.) heavier than the air force version. The nose will be slightly drooped for better visibility at high angles of attack. About 99% of the avionics will be common to both types. Among other changes will be a system for jettisoning fuel in case of an unplanned landing soon after take-off. Aircraft take-off will be via a ski-jump deck, without a catapult. Landing will be conventional, using an arrester hook. In view of the LCA's small size, the wing and nose will not need to fold to fit the carrier's elevator.
An important departure from the standard LCA wing will be the addition of movable vortex control devices at the wing leading-edge roots. These act as canards and increase lift during landing. They will be deflected up during landing to increase drag as well as pitching moment and, when deflected down, they enhance manoeuvrability. India's Cochin Shipyard awaits the go-ahead to begin work on a new 20,000 ton class carrier, on which the LCA would be based. Concept studies on the twin-engined Medium Combat Aircraft (MCA) have been under way for some time. It is a stealth aircraft optimised for the ground attack role. About the only components common with the LCA will be part of the wing, the Kaveri engine, and some systems and subsystems.
"The LCA wing gives good performance, we understand its aerodynamics well, and would like to retain it for the MCA," says Dr. Harinarayana. It will operate at a much higher wing loading than that of the LCA. The MCA will be in the 12 ton clean weight class, with a maximum take-off weight of about 18 ton. With the emphasis on stealth, the MCA will have two small, outward-canted fins. For stealth reasons, the Kaveri engines will be without afterburners. They will have a slightly higher dry thrust than the LCA engine. These engines will also have thrust-vectoring nozzles for manoeuvring. A super cruise capability is not being sought for the MCA. The MCA will use the radar-absorbent material to reduce RCS.
A speculative drawing of the Medium Combat Aircraft
[Image Courtesy: Hindustan Aeronautics Limited]
Also for stealth reasons, external fuel tanks will be mounted above the wings, as is being considered for the LCA. Stores will be carried externally, however, possibly conformally under the wing & fuselage, and will therefore increase radar cross section until released. If all goes well, the LCA and the MCA, along with the indigenously developed Advanced Light Helicopter (ALH), which is approaching certification, will put India on the map as a major aerospace manufacturing country.
LCA Specifications
Type: All weather air-superiority fighter and light close support aircraft.
Variants: Single-seat multi-role fighter.
.............Single-seat multi-role naval fighter.
.............Dual-seat combat-capable trainer.
Design Features: The airframe is based on an oval-section fuselage with a shoulder-set double delta wing. It has a compound sweep on its leading edges, which exhibit considerable twist between their inboard & outboard ends. The moving surfaces comprise three-segment flaps on the leading edge and two-section trailing-edge elevons (or elevators). All control surfaces are operated via a full quadruplex digital FBW control system, designed jointly by Lockheed Martin Electronics and ADE. Composite materials, which amounts for over 30% of the weight, and aluminum-lithium alloys have been used to keep the weight down. A special type of material - CFRP (Carbon Fibre Reinforced Plastics) - is used in the wings, control surfaces and vertical tail. Titanium alloy is used near 'hot spots' such as the engine. A brake parachute improves landing field performance.
Avionics: The LCA will have a multi-mode pulse-Doppler radar and FLIR (Forward-Looking Infra-Red). The cockpit is equipped with HOTAS, HUD and two color multi-function CRTs compatible with the use of NVGs. They are integrated with other elements of the electronic suite such as the INS via a central computer and three MIL-1553B data-buses. The LCA has a Utility Systems Management System to monitor the health of each of its systems and optimize their performance. For maintenance the LCA has 500+ Line Replaceable Units (LRUs), each tested for performance and capability to meet the severe operational conditions to be encountered.
Engine: LCA prototypes will feature a G.E. F404-F2J3 turbofan rated at 18,097 lbs. of thrust with afterburning. Production aircraft will have a Kaveri GTX-35VS turbofan rated at 20,200 lbs. of thrust with afterburning. The engine is operated by a Dowty/Smiths FADEC (Full Authority Digital Engine Control System).
Fuel Capacity: Internal fuel capacity - 3000 litres. The centreline and the two-inner hard points under each wing, can carry five 800 litres fuel tanks. The aircraft also has an in-flight refueling probe fitted on the starboard side of the forward fuselage to increase range.
Maximum Range: ?
Maximum Speed: Mach 1.7
Service Ceiling: 50,000 feet.
G Limits: +9/-3.5
Armament: The LCA is fitted with an internally mounted GSh-23mm twin barrel gun with 220 rounds of ammunition. Seven external hard points, can carry air-to-air missiles, air-to-surface missiles, anti-ship missiles, rocket launchers and ECM pods. The aircraft is designed to use armament from Western, Russian and Indian sources.
Maximum External Stores Load: 4000kg (8818 lbs.)
Self Defence: A RWR system, jammer and chaff & flare dispensers.
Important Milestones: TD1 Prototype 1 unveiled - 17 November 1995
..............................TD2 Prototype 2 unveiled - 14 August 1998
