The GTRE GTX-35VS Kaveri is an afterburning turbofan project under development by the Gas Turbine Research Establishment (GTRE), a lab under the Defence Research and Development Organisation (DRDO) in Bengaluru, India. An Indian design, the Kaveri was originally intended to power production models of the HAL Tejas developed by Hindustan Aeronautics Limited. However, the Kaveri programme failed to satisfy the necessary technical requirements on time and was officially delinked from the Tejas programme in September 2008. As of 2025, a dry variant of the Kaveri engine is now being developed to power the DRDO Ghatak.
History
Programme In 1986, the Indian Defence Ministry's Defence Research and Development Organisation (DRDO) was authorized to launch a programme to develop an indigenous powerplant for the Light Combat Aircraft. It had already been decided early in the LCA programme to equip the prototype aircraft with the General Electric F404-GE-F2J3 afterburning turbofan engine, but if this parallel program was successful, it was intended to equip the production aircraft with this indigenous engine.
The DRDO assigned the lead development responsibility to its Gas Turbine Research Establishment (GTRE), which had some experience in developing jet engines. It had developed the GTX37-14U after-burning turbojet, which first ran in 1977, and was the first jet engine to be designed entirely in India. A turbofan derivative, the GTX37-14UB, followed. The GTRE returned to turbojet technology with the greatly redesigned, but unsatisfactory, GTX-35.
For the LCA programme, the GTRE would again take up a turbofan design which it designated the GTX-35VS "Kaveri" (named after the Kaveri River). Full-scale development was authorized in April 1989 in what was then expected to be a 93-month programme projected to cost . The project was expected to be completed by December 1996. A new engine typically costs up to $2 billion to develop, according to engine industry executives.
Development timeline
1990s The original plans called for 17 prototype test engines to be built. The first test engine consisted of only the core module (named "Kabini", a major tributary and often cited starting point of the Kaveri river), while the third engine was the first example fitted with variable stator vanes on the first three compressor stages. The Kabini core engine first ran in March 1995. Test runs of the first complete prototype Kaveri began in 1996 and all five ground-test examples were in testing by 1998; the initial flight tests were planned for the end of 1999, with its first test flight in an LCA prototype to follow the next year. However, progress in the Kaveri development programme was slowed by both political and technical difficulties. There had been some difficulties in the development due to the sanctions imposed on India after 1998 Pokhran tests.Mama, Hormuz (November 1998). LCA Update . Flight International via Bharat-Rakshak.com.
2000s In 2002, little information had been publicly released concerning the nature of the Kaveri technical challenges, but it was known that the Kaveri had a tendency to fail turbine blades, which required procuring blades from Snecma (as well as digital engine control systems).Anon. (30 May 2002). Snecma Aerospace India: a new stage in cross-border collaboration . SAFRAN Group website Le Webmag. Retrieved from "Military Aviation and Defense" section 14 September 2006.
Continuing development problems with the Kaveri resulted in the 2003 decision to procure the uprated F404-GE-IN20 engine for the eight pre-production Limited Series Production (LSP) aircraft and two naval prototypes. The ADA awarded General Electric a 105 million contract in February 2004 for development engineering and production of 17 F404-IN20 engines, delivery of which is to begin in 2006.
In mid-2004, the Kaveri failed its high-altitude tests in Russia, ending the last hopes of introducing it with the first production Tejas aircraft.Since India does not possess suitable aircraft, the high-altitude testing of the Kaveri is contracted to Russia, which uses a Tu-16 bomber for the purpose. Another Kaveri engine was delivered to Russia for further flight testing from June to September 2006, but on an Il-76 testbed instead of a Tu-16. This unfortunate development led the Indian Ministry of Defence (MoD) to order 40 more IN20 engines in 2005 for the first 20 production aircraft, and to openly appeal for international participation in completing development of the Kaveri. In February 2006, the ADA awarded a contract to Snecma for technical assistance in working out the Kaveri's problems.Jackson, Paul; Munson, Kenneth; & Peacock, Lindsay (Eds.) (2005). "ADA Tejas" in Jane's All The World's Aircraft 2005-06. Coulsdon, Surrey, UK: Jane's Information Group Limited. p. 195. .
In December 2004, it was revealed that the GTRE had spent over on developing the Kaveri. Furthermore, the Cabinet Committee on Security judged that the Kaveri would not be installed on the LCA before 2012, and revised its estimate for the projected total development cost to .Pandit, Rajat (16 July 2006). IAF may not get to fly LCA before 2010 . The Times of India.
In April 2005, M. Natarajan, Scientific Adviser to the Defence Minister told The Hindu that "there is good progress" on the development of the Kaveri engine. "We are planning to integrate a prototype Kaveri engine into one of the LCA prototypes sometime in 2007 to understand the nuances of such a complex power-pack," he further told The Hindu.
In February 2006, the US experts told PTI that "Kaveri is truly a world-class engine." "We are ready to join in partnership with the Defence Research and Development Organisation to make Kaveri work," General William J Begert of Pratt & Whitney, told PTI. But DRDO Secretary Natrajan told PTI that "But Kaveri is and would remain an Indian project."
On 5 February 2007, Scientific Adviser to Defense Minister M Natarajan said nearly 90 to 93 per cent of the expected performance had been realized and the government had recently floated an expression of interest to seek partners to move the programme further.Anon. (5 February 2007). Rediff.com , Rediff news website. Retrieved from "Rediff.com" on 15 May 2007. Till 11 February 2008, Kaveri had undergone 1,700 hours of tests and has been sent twice to Russia to undergo high-altitude tests for which India has no facility. The engine is also being tested to power the next generation of Unmanned Aerial Vehicles.
In July 2007, GTRE divided Kaveri program into two separate programs. They are K9+ Program and K10 Program. K9+ Program is a program to prove concept of complete design and gain hand-on experience of aircraft engine integration and flight trials to cover a defined truncated flight envelope prior to the launch of production version of K10 Standard engine. While K10 Program is a joint venture (JV) partnership with a foreign engine manufacturer. K10 program engine will be final production standard Kaveri engine and shall have less weight and more reheat thrust along with certain other changes to meet the original design intent.
In July 2008, a press release announced a development of modified Kaveri Marine Gas Turbine (KMGT) to propel Indian Navy warships. It was already demonstrated to the then Prime Minister Dr Manmohan Singh. The turbine was tested for a power rating of 12 MW at ISA SL 35 °C condition. The testing took place in Indian Navy's Naval Dock Yard, Visakapatnam's Marine Gas Turbine test bed facility which is capable of testing the Gas Turbines up to 25 MW of shaft power.
In September 2008, it was announced that the Kaveri would not be ready in time for the Tejas, and that an in-production powerplant would have to be selected. Development of the Kaveri by the GTRE would continue for other future applications. It was announced in November 2008 that the Kaveri engine will be installed on LCA by December 2009, apparently for tests only.
In February 2009, it was published in FlightGlobal that the GTRE had spent in developing the Kaveri engine since 1989, but the power-plant is still overweight and does not have the of thrust that its customer requires. Natarajan told FlightGlobal that the programme will not be scrapped. "A team of air force engineers is working with GTRE and ADA in addressing the issues. As an ongoing project, the air force will be involved at the point of integrating the upgraded version of the engine with the aircraft," he told Flightglobal. "Discussions with Snecma have been going on for two years," he further adds. "Development and flight-testing of the new engine will take at least five to six years."
In December 2009, Kaveri-Snecma JV was trying Back-door Entry in LCA. The People's Post reported that GTRE has agreed to de-link Kaveri from LCA, but has put in a proposal that when the first 40 GE F-404 engines in the initial two squadrons of the LCA for the IAF, get phased out should be replaced by the Kaveri-Snecma engine, in future.
2010s As of 3 May 2010, about 1,880 hours of engine test had been completed on various prototypes of Kaveri Engine. A total of eight Kaveri Engines and four core engines have been manufactured, assembled and tested. High Altitude testing on core engine has been completed successfully.
In June 2010, the Kaveri engine based on Snecma's new core, an uprated derivative of the M88-2 engine that powers the French Rafale fighter, providing of maximum thrust is being considered an option by DRDO.
A press release in August 2010, stated that GTRE with the help of Central Institute of Aviation Motors (CIAM) of Russia is trying to match objective of fine tuning of Kaveri engine performance. Until August 2010, one major milestone which is altitude testing, simulating Kaveri engine performance at different altitude and achieving speed of Mach 1 had been completed successfully. One of Kaveri prototype (K9) was successfully flight tested at Gromov Flight Research Institute in Moscow, on 4 November 2010. The test was conducted with the testbed aircraft at Gromov, with the engine running right from the take-off to landing, flying for a period of over one hour up to an altitude of . The engine helped the Il-76 aircraft test bed fly at speeds of 0.6 Mach in its maiden flight, according to the Defence Research and Development Organisation (DRDO). It was revealed that in the next few months 50-60 test flights would be carried out. During that timeframe, 27 flights encompassing 57 hours of duration was completed.
"The engine control, performance and health during the flight were found to be excellent. With this test, Kaveri engine has completed a major milestone of development programme," it added. After completing these milestone Kaveri engine is flight-worthy. The Kaveri engine was tested for the first time on a flying testbed and the trials were a success.
Till April 2011, the first phase of Kaveri engine FTB trials have been completed successfully and further tests will continue from May 2011 onwards. The flight tests successfully carried out so far are up to maximum altitude and a maximum forward speed of 0.7 Mach.
In its annual report for 2010–11, The Comptroller and Auditor General (CAG) noted that had been spent on development, with only two out of the six milestones prescribed having been met as of July 2009. Among its deficiencies, CAG says the engine weight was higher than the design specifications, being against , though the weight of first prototype, K1 was at initially. There was no progress on developing the compressor, turbine and engine control systems. The developmental deadline was progressively delayed from 1996 to 2000 to 2004 and finally 2009. After missing the 2009 deadline, GTRE initiated a process of foreign collaboration. Only 2 engines had been upgraded to K9+ standard.
In August 2010, regarding the reasons for delay, a Ministry of Defence press release reported: