posted on Feb, 14 2005 @ 10:28 PM
some details of the airplane :
LCA is the world's smallest, light weight, multi-role supersonic combat aircraft. It has been designed to meet the requirements of Indian Air Force
as its frontline multi-mission single-seat tactical aircraft.
It is India's second indeginous fighter, the first one being the 1960's HF-24(Hindustan Fighter) 'Marut'. 129 Marut fighters were manufactured.
Marut had limited supersonic capability (It could go supersonic in dives). The LCA will be the first supersonic combat aircraft to be built and flown
in India itself. Interestingly, the requirements of both LCA and HF-24 and very similar. India had previously attempted to build a supersonic fighter
: the HF-73, a development of the Marut. HF-73 was to use engines with more power. The project was cancelled after a crash
LCA has a double delta wing configuration with no tailplanes or foreplanes and features a single vertical fin. The LCA is constructed of
aluminium-lithium alloys, carbon-fibre composites, and titanium. It's design has been configured to match the demands of modern combat scenario such
as speed, acceleration, maneuverability and agility. Other features of the design include Short takeoff and landing, excellent flight performance,
safety, damage-tolerant design, reliability and maintainability.
According to current estimates, the LCA will cost about $17million and efforts are being made to bring down the cost to $15 million.
It integrates modern design concepts and the state-of-art technologies such as relaxed static stability, flyby-wire Flight Control System, Advanced
Digital Cockpit, Multi-Mode Radar, Integrated Digital Avionics System and a Flat Rated Engine.
Around 70% of the jet is to be made in India itself. The rest will have to be imported for sometime. No mistake must be made with regards to LCA's
modernity and design. It is truly advanced and has all the necessary equipment and more.
A naval carrier based version of LCA is also being developed. This version will feature a strengthened undercarriage and sturucture, additional
leading edge control surfaces (in the area where the wing joins the fuselage) and lowered nose for better visibility. News reports suggest that US
help has been sought for the LCA Navy. The 8th and 9th LCA prototypes built will be Naval version.
Among the most significant breakthrough is the use of advance carbon composites for more than 40% of the LCA air frame, including wings, fin and
fuselage. Apart from making it much lighter, there are less joints or rivets making the aeroplane more reliable. Fatigue strength studies on computer
models optimise performance. National Aerospace Laboratory (NAL) has played a lead role. Materials include Aluminium - Lithium alloys , Titanium alloy
and Carbon compositites. Composities for wing (skin , spars and ribs ) fuselage (doors and skins), elevons, fin, rudder, airbrakes and landing gear
The skin of the LCA measures 3 mm at its thickest with the average thickness varying between 2.4 to 2.7 mm. 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 reduces by 80 per cent from Rs 2.5
million in 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.
A striking feature of the LCA is its small size. It is much smaller than even the JAS-39, which a ~1m longer. An effort was made to reduce the number
of individual composite parts to the minimum and hence keep the plane light.
The use of composites results in a 40 per cent 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 per cent, 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.
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 Electr-Magnetic Interference. Aluminum foils cover bolt heads while the fuel
tank is taken care of with isolation and grounding.
LCA is expected to be highly maneuverable by virtue of its double delta wing and relaxed static unstability of its Fly-By-Wire system.
Flight Control and Software and Other Avionics
The LCA uses advanced digital fly-by-wire technology which essentially employs computers to optimise the aircraft's performance. Foreign companies
were consulted. Infact, LCA avionics were first flight tested on a US F-16XL.
Witout the automatic flight control, the LCA will not be flyable, due to the Delta wing's inherent instability. As more and more flights are
conducted, the software is updated to allow the aircraft to do more complex maneuvours.
To combat the threat of obsolescence in the LCA Programme, a concerted effort has been made to introduce an Open-architecture Avionics system which
permits hardware scalability and upgradability to state-of-the-art technology levels with reusability of the software.
LCA Avionics architecture is configured around a three bus system (MIL-STD-1553B) in a distributed environment. The heart of the system is a 32-bit
Mission Computer (MC) which performs mission oriented computations, flight management, reconfiguration / redundancy management and in-flight system
self-tests. In compliance with MIL-STD-1521 and 2167A standards, Ada language has been adopted for mission computer software.Accurate navigation and
guidance is realised through RLG based Inertial Navigation System (INS) with provision for INS / Global Positioning System (GPS) integration. Jam
resistant radio commumication system with advanced Electronic Warfare (EW) environment. In the EW suite, Electromagnetic and Electroptic receivers and
jammers provide the necessary "soft-kill" capability.
The digital FBW system of the LCA 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 1x10-7 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
multifunction displays through MIL-STD-1553B avionics bus and RS 422 serial link.
For maintenance the aircraft has more than five hundred Line Replaceable Units (LRUs), each tested for performance and capability to meet the severe
operational conditions to be encountered.
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.
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)
Digital Hydraulics and Brake Management System Electronics Unit (DH-EU)
V/UHF Equipment: V/UHF equipment is a secure jam resisant airborne radio communication set which provides simplex two way voice and data communication
in the VHF and UHF frequency bands. This unit is developed by HAL, Hyderabad.
Multi Function Keyboard (MFK): MFK is an interfce for pilot dialogue concerning certain selected equipment of Avionics system. It comprises LCD panel,
alphanumeric keys, push buttions for power ON / OFF and LEDs indicating power ON / OFF status of certain Avionics equipment. This unit is developed by
Head Up Display (HUD): HUD is of conventional type with a Total Field of View (TFOV) of 24 degrees circular. A Change Coupled Device (CCD) based
camera is mounted on the HUD for recording purposes. HUD dsplays various navigation and weapon related data. This unit is developed by CSIO,
Colour Multi Function Displays (MFDs): LCD based colour MFDs hava a useful screen area of 125 mm x 125 mm. They have soft keys around their periphery
for interaction with the systems. This display provides various aircraft system pages and navigation pages in addition to RADAR & FLIR display.
Digital fly-by-wire Flight Control System is another advanced feature of LCA. The unstable configuration of LCA demands a highly efficient Integrated
Flight Control System (IFCS) to fly the aircraft. Control law resident in the flight control computer synthesises inputs from pilot's stick and
rudder pedals with flight parameters from inertial and airdata measurements to generate commands to the actuators that move various control surfaces.
The design of the control law is evaluated susing real-time flight simulator for acceptable flight handling qualities. The IFCS ensures stability,
agility, manoeuvrability and carefree handling over the entire operating envelope of LCA. The Digital Flight Control Computer (DFCC) is the heart of
IFCS, and uses a quadruplex redundant system to achieve high reliability and safety.
Independent Verification and Validation (IV&V) activity is an integral part of the Software development process. From requirement specification to
final testing, IV&V ensures correctness, consistency, completeness and adherence to MIL standards of the software.
The flight control system along with all the associated software is tested and validated at the iron-bird rig.
Its new-generation glass cockpit has the latest avionics systems for pilot comfort and efficiency. No tangle of dials and switches. Multi-function
digital displays provide information of all vital parameters with the click of a button. Critical information is flashed on the head-up display.
Aeronautical Development Establishment (ADE) and NAL were major partner in these developments.
Two Multi Function Displays present required information to the pilot. Critical information required in close combat situations is flashed onto the
Head Up Display. Hands on Throttle and Stick (HOTAS) concept ensures availability of every control needed during a critical combat situation, right
under the fingers of the pilot. The Environmental Control System (ECS) is designed to give a high degree of comfort to the pilot and to provide
adequate cooling to all onboard electronic systems. The compressed air for pressurisation of cockpit, radar and fuel tank is also supplied by ECS.
ADA has also tied up with India's National Institute of Design (NID), Ahemdabad to bring in the elements of ergonomics and modular design. The aim is
to help build the aircraft in such a manner that it has more standardised units or dimensions allowing increased flexibility.
The LCA has a choice of seven pylons three under each wing and one under its fuselage to carry a wide range of armoury. It is designed to be a
precision launch platform with air-to-air missiles and air-to-ground weapons, including laser guided bombs. A total of 4000 kg can be carried. Plenty
of work to be done. It is expected that the R-73 (AA-12 Archer) will be integrated into the PV-1.
LCA will be armed with a Gasha Gsh-23mm gun. The R-73 will be directed by a Helmet Mounted Sight (HMS) ensuring quick action. It is not clear what
medium range AAMs it will carry - the IAF currently operates the Matra Super 530D, R-27RE1 and RVV-AE(R-77) BVR missiles. The choice depends a lot on
the radar, unlike dogfight missiles which are usually heat seeking. For example, IAF has integrated both Magic-2 and R-60MK with the MiG-21. A range
of weapons, from Russia, West or India will be made available.
A total of 7 hardpoints will be available: 3 on each wing plus one under the fuselage.
As the name itself suggests, LCA's delivery capacity will not be high compared to say the Su-30, but it can carry as much as the MiG-2ML, which the
IAF's primary Close Air Support (CAS) fighter
The multi-mode radar is to take care of detection, tracking, terrain mapping and delivery of guided weapons. The track-while-scan feature keeps track
of multiple targets (maximum 10) and also allows simultaneous multiple target engagement. Pulse-Doppler gives the look-down shoot-down capability.
Ground mapping feature, frequency agility and other ECCM techniques make the radar truly state-of-the-art.
The antenna is a light weight (less than 5 kg), low profile slotted waveguide array with a multilayer feed network for broad band 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.
Stealth is an important feature of the LCA. Although it does not have any stealth charactristics like in F-117 or F-22, but considering its small
size, simple delta wing config, a GE-404 engine(atleast for now) - which is also used in the F-117 - it should be stealthier that atleast a MiG-21 or
MiG-23/27. It will get DRDO developed Radar-absorbent paint. Composites are inherently stealthier than metal.
The RCS of the tejas will be 1/3rd that of the mirage 2000, according to a DRDO press release.