Monday, 1 July 2013

HAL LIGHT COMBAT AIRCRAFT (LCA) TEJAS



The HAL LCA TEJAS is lightweight multirole aircraft designed and developed by Hindustan Aeronautical limited. LCA was officially named “ Tejas ", meaning "Radiance" by then Prime Minister Atal Bihari Vajpayee.
Tejas is a single engined, light weight, highly agile, multi-role supersonic fighter. It has quadruplex digital fly-by-wire Flight Control System (FCS) with associated advanced flight control laws. The aircraft with delta wing is designed for ‘air combat’ and ‘offensive air support’ with ‘reconnaissance’ and ‘anti-ship’ as its secondary roles.

DESIGN
The Tejas is single-engined multirole fighter and is designed with "relaxed static stability" for enhanced manoeuvrability. 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.
The Tejas is  a tailless, compound delta planform. This planform is designed to keep the Tejas small and lightweight. 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 conventional 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

AIRFRAME
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.
The Tejas employs CFC* materials for up to 45% of its airframe, including in the fuselage (doors and skins), wings (skin, spars and ribs), elevons, tailfin, rudder, air brakes and landing gear doors.
*  CFC=CARBON-FIBRE COMPOSITES
USE OF COMPOSITES IN TEJS
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.
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.

AVIONICS
Tejas incorporates a highly reliable quadruplex digital fly-by-wire Flight Control System. The new generation glass cockpit comprises Multi Function Displays (MFD), Head Up Display (HUD) and Stand by Instrumentation System driven by Open Architecture Mission and Display Computer. This provides effective
TEJAS' GLASS COCKPIT
Human Machine Interface (HMI).The advanced utility and health management system provides system health and warnings to the pilot through a Open Architecture Computer (OAC).

·         The Tejas has a night vision goggles (NVG)-compatible "glass cockpit".
·         IT HAS 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.
·          The aircraft also features a ground proximity warning system based on the Terrain Referenced Navigation (TRN) system.
·         Threat detection methods include a Radar Warning Receiver (RWR) and a Laser Warning Receiver (LWR)
·         Protection is provided by Chaff, Jaff and Flares, Electronic Counter Measures (ECM) and a Towed Radar Decoy (TRD).
RADAR
The coherent pulse-Doppler Multi Mode Radar is designed to operate equally effectively in the Air to Air and Air to Surface domains. Jointly developed as an Indian – Israeli venture, it features multi-target Air to Air Track, Hi Resolution Synthetic Aperture Mapping and specialized Air to Sea modes. The radar
TEJAS' MULTIMODE RADAR
facilitates all weather employment of a variety of Air to Air and Air to Surface Weaponry, and is the primary targeting sensor on the Tejas.


ARMAMENTS
The Tejas is designed to carry air to air, air to surface, precision guided and standoff weaponry. In the air to air arena, the Tejas carries long range beyond visual range weapons, with highly agile high off-boresight missiles to tackle any close combat threat. A wide variety of air to ground munitions and an extremely accurate navigation and attack system allow it to prosecute surface targets over land or at sea with unparalleled accuracy, giving the Tejas true multi/swing role capability
HARDPOINTS :
·         1  beneath the port-side intake trunk
·         6  under-wing
·         1  under-fuselage with a capacity of 4000 kg external fuel and ordnance

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.