The Tejas single-seat, single-engine, lightweight, high-agility supersonic fighter aircraft has been undergoing flight trials in preparation for operational clearance, and by mid 2005 had flown over 400 flights up to speeds of Mach 1.4. The Tejas light combat aircraft design and development programme is being led by the Aeronautical Development Agency (ADA) of the Indian Department of Defence with Hindustan Aeronautics Limited (HAL) as the prime industrial contractor.
Tejas, the smallest lightweight, multirole, single-engined tactical fighter aircraft in the world, is being developed as a single seat fighter aircraft for the Indian Air Force and also as a two-seat training aircraft. In November 2008, the Indian Air Force confirmed a requirement for 140 Tejas aircraft to equip seven squadrons.
The design of a carrier-borne Tejas in single-seat and two-seat versions with a modified nose, strengthened landing gear and an arrestor hook was granted approval in 1999. The carrier variant has retractable canards and adjustable vortex control.
The development programme for the carrier-borne versions was agreed by the Indian government in 2002 and the first flights of two prototype aircraft are scheduled for late 2009. The carrier variant may replace the fleet of Sea Harriers.
The Indian Aeronautical Development Agency (ADA) is carrying out a conceptual design study of the ADA medium combat aircraft, which will be an advanced, stealthy version of the Tejas, to replace the Indian Air Force Jaguar and Mirage 2000 fleet. The medium combat aircraft has two engines with fully vectoring nozzles and no vertical or horizontal tail.
Delta planform design
The aircraft is of delta planform design with shoulder-mounted delta wings. The aircraft has a fin but no horizontal tail. Lightweight materials including aluminium and lithium alloys, titanium alloys and carbon composites have been used in the construction. The wing structure includes composite spares and ribs with a carbon fibre-reinforced plastic skin.
The National Aerospace Laboratories (NAL), based in Bangalore, has designed and is responsible for the manufacture of the fin and the rudder and the construction of the aircraft fuselage.
Tejas cockpit
The aircraft is fitted with a night vision compatible glass cockpit with Martin Baker (UK) zero-zero ejection seats.
The cockpit has two 76mm×76mm colour liquid crystal multi-function displays developed by Bharat Electronics, a head up display developed by the Indian government-owned Central Scientific Instruments Organisation (CSIO) in Chandigarh, a liquid crystal return-to-home-base panel and keyboard. The pilot also has a helmet-mounted display.
The aircraft has a quadruplex fly-by-wire digital automatic flight control. The navigation suite includes Sagem SIGMA 95N ring laser gyroscope inertial navigation system with an integrated global positioning system.
The communications suite includes VHF to UHF radio communications with built-in counter-countermeasures, air-to-air and air-to-ground data links and a HAL information friend-or-foe interrogator. The cockpit is fitted with an environmental control system developed by Spectrum Infotech of Bangalore. The avionics suite has an integrated utility health-monitoring system.
Fighter weapons
The aircraft has eight external hardpoints to carry stores, with three under each wing, one on the centre fuselage and one installed under the air intake on the port side. A 23mm twin barrelled GSh-23 gun with a burst firing rate of 50 rounds a second and muzzle velocity of 715m a second is installed in a blister fairing under the starboard air intake.
The aircraft can be armed with air-to-air, air-to-ground and anti-ship missiles, precision-guided munitions, rockets and bombs. Electronic warfare, targeting, surveillance, reconnaissance or training pods can be carried on the hardpoints. Drop tanks can also be carried.
In October 2007, the Tejas successfully test-fired the R-73 air-to-air missile. The Vympel R-73 (Nato codename AA-11 Archer ) missile is an all-aspect short-range missile with cooled infrared homing. The missile can intercept targets at altitudes between 0.02km and 20km, g-load to 12g, and with target speeds of up to 2,500km/h.
Countermeasures
The aircraft's electronic warfare suite, developed by the Advanced Systems Integration and Evaluation Organisation (ASIEO) of Bangalore, includes a radar warning receiver and jammer, laser warner, missile approach warner, and chaff and flare dispenser.
Sensors
The Electronics Research and Development Establishment and HAL have jointly developed the aircraft's multi-mode radar. The radar has multiple target search and track-while-scan and ground-mapping modes of operation. The radar incorporates pulse Doppler radar with Doppler beam shaping, moving target indication and look-up / look-down capability. The radar is mounted in a Kevlar radome.
Turbofan engines
The prototype development aircraft are fitted with General Electric F404-GE-F2J3 turbofan engines with afterburn. Production aircraft will be fitted with one General Electric 85kN F404-GE-IN20 turbofan engine with full authority digital engine control. HAL placed an order for 24 F404-GE-IN20 engines in February 2007.
LSP-2 (limited series production 2) will be the first aircraft to be fitted with the engine. Flight trials with the production engine began in June 2008.
It was planned that a new turbofan engine, the GTX-35VS Kaveri, under development by Gas Turbine Research Establishment (GTRE), would be fitted to the production aircraft, but delays in development led to the purchase of the General Electric engines. Snecma-Larzac has been chosen as the industrial partner in the engine development.
The Kaveri engine develops 52kN dry power and 80.5kN with afterburn. The aircraft will use multi-axis thrust vectoring nozzles. The engine has Y-duct air intakes.
The aircraft has wing and fuselage tanks and an in-flight refuelling probe on the front starboard side. Drop tanks with a capacity up to 4,000l, can be carried on the inner and mid-board wing and fuselage centreline hardpoints.
The aircraft is fitted with a HAL gas turbine starter unit model GTSU-110.
