Born out of the need to replace what the air force then saw as an aging fleet of aircrafts, the LCA has become one of the costliest defence projects in Indian history. Yet despite the thousands of crores spent on developing the LCA, the dream of a truly indigenous fourth generation multi role fighter remains so near and yet so FAR.
The stumbling block comes in the form of the Kaveri engine that was to power the LCA.  Though the aircraft flew its maiden flight in January 2001, the Kaveri engine never managed to get off the ground. The US made GE F-404 engine took the Kaveri’s role in the LCA and seven years on it remains in place. Developing an engine for the LCA therefore is now top priority for the Gas Turbine Research Establishment (GTRE), the Key DRDO laboratory that is responsible for developing the Kaveri engine.
Development projects around the world usually come with cost overruns and project delays. The Kaveri program however has had more than a fair share of both. Originally projected to cost only three hundred and eighty crore rupees, the total amount spent on the program has thus far exceeded thirteen hundred crore rupees. The Kaveri engine was supposed to power the first batch of initial production LCAs. A series of problems ranging from engines loosing turbine blades to unsatisfactory high altitude performance have kept the kaveri engine far away from the nearest LCA.
The heart of the matter remains that in taking a leap from second to fourth generation technology was never going to be easy and thus these problems were bound to occur.
Clearly India could use some international expertise in this department and the West is only too keen to do so. Originally pitted as a rival to modern low bypass ratio turbofans such as the GE F404, the M88 and the EJ200, it is likely that the kaveri program will need to seek expertise of at least one of these firms if it is to see the light of day. With the West seeking to forge strong long-term alliances with India, getting that desired help is now a whole lot easier.
 While scope of the word ‘develop’ has not been clearly defined by the GTRE it would be fair to assume that the road ahead for the LCA engine would be influenced by the current products on offer by the various aero engine manufacturers.

With the development of the engine costing way beyond in terms of time and money, GTRE and ADA are looking for suitable suitors for Kaveri who will help develop the engine by way of technology transfer. SNECMA of France, which powers the Dassault Rafael seems to be leading the way in this direction. However, despite assistance, the design and development is likely to take a few years as even the best in the field take time to develop, test and evaluate such complicated technologies. With time running out HAL can ill afford to delay the production of the LCA (or produce an inferior specimen), lest this too goes the MBT Arjun way. There is therefore an urgent need to buy a certain number of engines to put the LCA programme on the right track.

The engine fitted currently in the LCA, GE F-404 IN-20 delivers about 82 KiloNewtons(KN) of thrust, which is adequate for take off and cruise but falls short during combat manoeuvres when the aircraft has to engage in a dogfight. The EJ200 and the GE F-414 provide 90-98 KN of thrust, which falls slightly short of the IAF’s wish list.

With the Indian Air Force laying down strict requirements of the engine specifications, ADA is left with few alternatives, as there are only a couple of aircraft engines being produced in this class. These are GE F-414-400 and Eurojet 200, produced by GE of USA and Gmbh comprising of Avio(Italy), ITP(Spain), MTU(Germany) and Rolls-Royce(UK) respectively.

The GE-F414 is a derivative of the highly successful GEF404 that powers the F/A-18 Hornet and is also the platform for the Volvo RM12 engine.  Rated at 98KN with full afterburner the engine is truly a beast. The Engine features a dual channel FADEC for enhanced reliability and durability. The GE F-414 primarily does duty on the F/A-18 E/F Super Hornet and has proved to be a reliable performer. The engine with three fan and seven compressor stages has an overall pressure ratio of thirty is to one. This is about twenty percent higher than that of the EJ200. While a higher-pressure ratio translates into greater efficiency, it also translates into a greater amount of heat stress on the engine. To counter this stress the GE F-414 feature single crystal low-density blisks that are lighter and yet stronger than the conventional blades on disk combination. The engine is also dimensionally identical to the GE F-404, which currently powers the LCA. One serious disadvantage of the F-414 is that it is significantly heavier than the EJ200 and thus has a lower thrust to weight ratio than the EJ 200. 

The Eurojet 200 is a derivative of the Rolls Royce XG-40 technology demonstrator. Designed with the aim of powering the Eurofighter, the engine proved to a major sticking point with the French. The French chose to abandon the Eurofighter project and went on to develop the Dassault Rafale. The EJ200 is a finely tuned orchestra of European technologies with each partner nation playing the right notes at the right time. Given the diverse pool of expertise that went into designing the project it is no surprise that the engine delivers the best of most worlds. The engine features all the latest in aero engine technology such as a Full Authority Digital Engine Control (FADEC) and low-density single crystal blades. Low density single crystal blades are so strong that they have to be grown into shape as they cannot be cut or shaped by any material. The “blisks” a fusion of both blades and disk that are used in constructing the engine give it a high degree of durability. This rugged construction allows the engine to withstand higher pressures and temperatures allowing the engine to work more efficiently. The flipside of using blisks however is that it is not possible change out individual blades. Thus any damage to the blades would call for replacing the entire blisk, which would prove to be a costly affair. The engine also comes equipped with “Active Tip Clearance Control”. Active tip clearance control is a feature that allows the on board computers to regulate to an extent the clearances between the blade tip and the turbine case. Excessive tip clearances reduce the engines efficiency leading to higher fuel consumption and lower power.
With a maximum thrust rating of 90KN with reheat the engine falls short of the IAF’s laid down guidelines by as much as ten percent, which Eurojet experts claim can be enhanced up to 15% as per user’s requirement without changing any component. And there is always more to an engine than mere figures. The EJ200 is noted by aviation experts for the manner in which it delivers power across the entire spectrum. The advanced FADEC software and on board hardware also give individual customers the ability to decide the spread of power delivered by the engine at various setting. This gives the EJ200 exceptional adaptability and makes the engine extremely versatile.

The key factor in choosing an engine will be: which one fits into the LCA with the least re-engineering? Both the engines have different dimensions and the inlet and exhaust ports are located differently. This may necessitate changes in the airframe, which will delay the process further. Apart from the various merits and demerits and technical specifications of the engine, this one factor may turn out to be the most significant one.
An important outcome of the selection of the engine for the LCA would be IAF’s preference for standardization of equipment. Though not an overriding factor, the choice of engine for the LCA Tejas may place a slight bias towards selection of the M-MRCA as well. And that will affect a whole lot of other ancillary suppliers who are developing the radars and armament for the aircraft. Whatever be the outcome, healthy competition bodes well for the Indian Air Force, and the LCA Tejas.

F414
Performance specifications (sea level/standard day)
F414-GE-400
Max. thrust, reheated 22,000 lbf 98 kN
Length 154 in 3,912mm
Air flow rate 170 lbs/s 77.1 kg/s
Maximum diameter 35 in 889mm
Inlet diameter 32 in 810mm
Pressure ratio 30:1 30:1
Thrust-to-weight ratio 9:1 9:1

EJ 200
Thrust (lbf) - 20,000 (13,500 dry) 
Bypass ratio - 0.4 
Pressure ratio - 26
Length (in) - 157 
Diameter (in) - 29 
Basic weight (lb) - 2,180 
Compressor  - 3LP, 5HP  
Turbine - 1HP, 1LP

Interview

“We look at India as a partner country” has been the constant refrain of Team EADS for all the defence projects in which they wish to participate. During their recent visit to India, the Eurojet Turbo Gmbh delegation echoed the same sentiment while briefing a select gathering of representatives of the Indian defence media. In an exclusive talk with ‘South Asia Defence &Strategic Review’, Mr Paul Herrmann, Busines Development Executive and Mr Adrian G Johnson, Sales Director, spoke of various possibilities to help develop the engine for the LCA and also about their state-of-the-art engine which powers the Eurofighter Typhoon.

The conversation covered many aspects of the deal.

On Development of Kaveri.  Development of Kaveri engine by GTRE has been inordinately delayed despite a huge expenditure. Mr Johnson said that development of aircraft engines is a time consuming and tedious process. India’s brave attempt to develop a fourth/fifth generation aircraft engine from scratch would obviously face some snags.
He said that Eurojet would be pleased to help develop the engine, but only if HAL or GTRE asks for the same. At the present moment only SNECMA has been approached for assistance and transfer of technology.
In the meantime Eurojet will be happy to participate in the selection process for a specific number of aircraft engines needed off the shelf for the LCA.
Changes in the Airframe.  Mr Johnson explained that the dimensions of the Eurojet 200 are identical to the existing engine being used by the LCA. Mounting this engine will not require any changes in the existing airframe of the LCA. The same however cannot be said about some other engines, which may necessitate modifications in the airframe, which by itself is a major modification and can significantly derail the project.
Development Potential. One of the interesting aspects of the Eurojet 200 is the inherent design capability to step up performance without tampering with the existing engine. Explaining this Mr Herrmann said that upto 15% improvement in the thrust can be achieved by minor adjustments in the same engine. The user has to specify the purpose for which the increased thrust is needed e.g. during take off, while performing maneuvers or for super cruise. The engine will be adjusted as per the needs of the user. Increased thrust up to 30% can be achieved, but for that we have to replace a few components. Also the user must accept certain reduction in the overall engine life which will be a direct outcome of increased wear and tear.
FADEC. The software that controls the engine is in effect the sophisticated brain behind the raw power. The FADEC in Eurojet provides precise control over the engine’s operation during various manoeuvers to ensure optimal power and fuel efficiency. Another interesting feature explained by Mr Herrmann was the ‘Health Monitoring System’. Wear and tear to various components of the engine is constantly monitored by the software and it can be instantly downloaded on to a hand held computer, which when connected to the mainframe will give precise details of all the engine parts and recommend repair/replacement as and when required.
Modular Design. Eurojet 200 has a modular design which is of great help in repairs and replacement. Mr Herrmann added that the entire engine could be replaced within a remarkably short time of 45 minutes. A demonstration to this effect was made in Singapore during the air show. Traditional engines take as long as a couple of days to replace the entire assembly. This special feature obviously helps in ensuring a high degree of serviceability and operational readiness at all times.
The delegation also spoke of the light weight, high thrust to weight ratio and fuel efficiency provided by the modern Eurojet 200, 5th generation engine.