Finally, a deadline for the Tejas Light Combat Aircraft's new engine

(Part 1 of a two-part series on the Tejas LCA's engine)

by Ajai Shukla
Business Standard, 16th July 08

For years, the Indian Air Force (IAF) has argued bitterly with the Aeronautical Development Agency (ADA) --- which is developing India’s Tejas Light Combat Aircraft (LCA) --- over who is to blame for the LCA’s low engine power. The IAF accuses the ADA of failing to develop a suitable engine; the ADA retorts that the IAF’s demands for extra combat punch added two tons to the LCA’s original weight of 8 tons. The naval version of the LCA, with its strengthened undercarriage, will be even heavier.

And with the promised Kaveri engine nowhere in sight, the LCA makes do with the underpowered General Electric F-404 engine. An upgraded version, the IN-20, which will power the first two squadrons of the LCA, provides only marginally more thrust.

But now there’s a happy ending in sight. Business Standard has learned that the ADA has a deadline of October 2008 to choose between two foreign engines for powering the LCA. The final choice of engine, which will power several hundred Tejas fighters over the next three decades, is between Eurojet’s EJ200; and the General Electric F-414.

The current GE F-404 IN-20 engine delivers about 82-85 KiloNewtons of thrust, which is adequate for take off and even climbing rapidly, but falls short during combat manoeuvres when the fighter has to turn sharply to fire missiles at enemy aircraft. The EJ200 and the GE F-414 provide 90-95 KiloNewtons of thrust, which the IAF considers adequate.

Both engine manufacturers are lobbying intensively. Which engine is chosen could reverberate beyond the LCA, affecting the selection of the Medium Multi-Role Combat Aircraft (MMRCA), an $11 billion purchase for which bids have already been submitted. The Anglo-European Eurofighter, a leading contender, is powered by two EJ200 engines. A single GE F-414 engine powers the Swedish Grippen fighter. Both vendors believe that if their engine were selected for the LCA, that could open the door to the MMRCA contract.

The key factor in choosing an engine will be: which one fits into the LCA with the least re-engineering? Each engine has different dimensions and the inlet and exhaust ports are located differently; this means that the LCA airframe will need changes to accommodate the new engine. Hindustan Aeronautics Limited (HAL) Chairman, Ashok Baweja, explains that, “Any change in the basic structure of the aircraft will mean going through the test and evaluation process all over again. This is a time-consuming business.”

Selecting the engine will involve difficult choices. IAF sources say the EJ200 will demand less re-engineering; but the GE F-414 will give up to 5 KiloNewtons more of thrust.

Re-engineering the LCA to fit in the engine, and obtaining fresh operational clearances, could take up to three years. Meanwhile HAL will manufacture the first Tejas squadron of 20 fighters with the old GE F-404 IN-20 engine. Top MoD sources confirm to Business Standard that the IAF will shortly order a second squadron of Tejas, also with the GE F-404 IN-20. LCA number 41 onwards will be fitted with the new engine.

Comparison of EJ200 and GE F-414 engines:

                                   EJ 200                     GE F-414-400
Power on reheat        90-92 kNewtons             96-98 kNewtons
Inlet diameter            740 mm                          777.24 mm
Cross section              430.1 cm.sq                    474.4 cm.sq
Mass flow (Kg/sec)      74                                     78
Weight                       1040 kilos                       1110 kilos
Centre of gravity         Smaller shift                   Large shift
Design vintage             Late 1990s                      Late 1970s
Growth potential         Up to 30%                       Far less

(Tomorrow: Powering up the first 40 LCAs, with the IN-20 engine... HAL's plan)