New Challenges for Tejas

By Shashank Sinha

07 September 2007

India's protracted Tejas programme may be facing fresh challenges after a recently concluded set of tests. Open media sources have reported critical shortfalls in several performance parameters observed during the week long tests conducted from the naval air station INS Rajali at Arakkonam in Tamil Nadu earlier in august.

The tests comprising a series of 24 test fights were designed to test the aircraft's performance in hot and humid conditions with two airframes (PV-2 and PV-3) participating. The key issue involves Tejas' inadequate performance during take off runs and its inability to achieve the expected maximum speed (being limited to mach 1.05 instead of the expected mach 1.6). Both these issues are presumably related to the inadequate amount of thrust which is available from the commercial General Electric F404-F2/J3 power-plant of the prototype machines.

The limited series production (LSP) airframes now under production at HAL would be integrated with the slightly uprated GE 404 IN20.The IN20 is a FADEC (Full Authority Digital Electronic Control) derivative of the F404-GE-402 Enhanced Performance Engine (EPE) which powers the F/A-18C/D versions of the Hornet. It achieves an increased performance (available thrust) through improved thermodynamic cycle and increased temperature. It would be fitted into the LCA starting from the LSP-2 airframe and is expected to remedy some of the issues observed in Arakkonam. However, F404 series engines as a whole are susceptible to some performance issues in the hot and humid tropical conditions prevalent in the subcontinent and whatever performance benefits the new engines accrue, can only be validated through future tests.

Other factors include some excessive drag and weight issues that were observed. These however, are an intrinsic part of all aircraft development programmes and production versions eventually shed a lot of weight.

Meanwhile, key development programmes remain dogged with continuing hiccups. The Kaveri engine, which was originally planned to power the aircraft, remains stillborn with severe performance shortcomings especially being unable to achieve full afterburner thrust. It is also reported to be about 15 percent overweight. Govt. efforts to find a suitable development partner for the Kaveri also remain in limbo marred by the excruciatingly slow selection process.

Another area of concern has been the development of the MMR (multi mode radar) which is now urgently needed to support the weaponisation process. In what may be a big set back to the Bangalore-based Electronics and Radar Development Establishment (LRDE) developing the MMR, the Govt of India has announced a partnership with Israel's Elta Electronics to develop and integrate a new radar system with the airframe. To expedite the process Elta could develop their existing EL/M-2052 active electronically scanned array (AESA) radar to fill the gap. Israelis quote very advanced capabilities for this multimode radar including a multi-target tracking capability of up to 64 targets, air to ground modes include moving target display and SAR mapping, which IAF is interested in. At an AUW (all up weight) between 130 kg to 180 kg (as per antenna sizes) the EL/M-2052 should be compatible with the Tejas airframe.

The LCA programme is perhaps now entering its most important stage and challenges like these are only to be expected. The focus as of now seems to be getting IOC and inducting the first LSP series into service. IAF seems to be getting serious about inducting the aircraft and a team headed by Air vice Marshal BC Nanjappa has been based with ADA to facilitate the integration process and impending service entry. IAF is also preparing the Sulur AFS to base the first Tejas batches. ACM F H Major recently reaffirmed IAF's commitment to the LCA programme and said that the first LSP aircrafts would be used for training and evaluation process, based on which further orders would be placed.



  1. http://www.ada.gov.in/

  2. http://www.geaviation.com/engines/military/f404/f404-402.html

  3. http://www.misile-iai.com/ELTA.aspx

  4. http://www.flightglobal.com


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