A failure or a potential success?
GTRE GTX-35VS Kaveri
The GTRE GTX-35VS Kaveri is an afterburning turbofan engine developed by the Gas
Turbine Research Establishment (GTRE), under the Defense Research and Development
Organization in Bangalore, India. Kaveri was intended to be integrated with the HAL Tejas
Light Combat Aircraft (LCA). However, it failed to satisfy the necessary technical
requirements or keep up with its original timelines and was then scraped from the Tejas
programme in September 2008.
HISTORY
In 1986, DRDO launched a programme to develop an indigenous powerplant for the LCA. It
had already been decided beforehand in the programme to equip the prototype aircraft with the General Electric F404-GE-F2J3 engine, but if this program would have been successful, then the production aircraft would be equipped with this indigenous engine. The lead development responsibility was assigned to the Gas Turbine Research Establishment (GTRE). For the LCA programme, the engine would again take up a turbofan design which it called the GTX-35VS “Kaveri”. Full-scale development of Kaveri was authorized in April 1989 for a period of 93 months and a projected cost of ₹3.82 billion.
DESIGN
The Kaveri engine consists of a low bypass ratio afterburning turbofan engine which features a six-stage core high-pressure compressor with variable inlet guide vanes, a three-stage low-pressure compressor with transonic blading, an annular combustion chamber, and cooled single-stage HP and LP turbines.
The development model is fitted with an advanced convergent-divergent nozzle. The core turbojet engine of the Kaveri is the Kabini. The basic arrangement of the engine is similar to contemporary combat engines like GE F414, Snecma M88, etc. It has a very low bypass ratio (0.16:1).
The engine has been designed for the Indian operating environment, which ranges from hot deserts to high mountain ranges. The GTRE envisions achieving a fan pressure ratio of 4:1 and an overall pressure ratio of 27:1 which will allow the Tejas to cruise supersonically without the use of the afterburner.
PAST DEVELOPMENTS
The original plan was to build 17 prototype test engines. The first engine consisted of only the core module called Kabini. It first ran in March 1995. Test runs of the first complete prototype began in 1996 and all five ground-test examples were in testing by 1998. But progress in the Kaveri development programme was slowed by both political and technical difficulties. The Kaveri engine had a tendency to fail turbine blades, which required procuring blades from SNECMA.
In 2004, Kaveri failed its high-altitude tests in Russia, which ended the last hopes of introducing it with the first Tejas aircrafts. This led the Indian Ministry of Defence to order 40 more IN20 engines in 2005 for the first 20 production aircraft and to appeal for foreign participation in completing the development of the Kaveri engine. In February 2006, the ADA awarded a contract to SNECMA for technological assistance in working out Kaveri’s problems.
In December 2004, the GTRE had spent over ₹13 billion on developing the engine. Furthermore, the Cabinet Committee on Security gave the verdict that the Kaveri would not be installed on the LCA before 2012, and estimated that total development cost for the project would be ₹28.39 billion.
In April 2005, there was good progress on the development of the Kaveri engine. It was planned to integrate a prototype of the Kaveri engine into one of the LCA prototypes in around 2007.
On 5 February 2007, nearly 90 to 93% of the expected performance had been realized and
the government had started to seek partners to move the programme further. Till 11 February 2008, Kaveri had undergone 1,700 hours of tests and had been sent twice to Russia to undergo high-altitude tests. The engine was also being tested to power the next generation of UAVs.
In September 2008, it was announced that the Kaveri would not be ready for LCA Tejas and that another working engine would have to be chosen. Development of the Kaveri by GTRE would continue for future applications. In November 2008 it was announced that the Kaveri engine will be installed on LCA by December 2009 for tests only.
In February 2009, the GTRE had spent ₹20 billion in developing the Kaveri engine since 1989, but it was still overweight and did not have the 93–100 kN of thrust that its customer requires.
On 3 May 2010, of Kaveri had completed about 1880 hours of engine tests on various prototypes. A total of eight engines and four core engines had been manufactured, assembled, and tested. High Altitude testing on the core engine had been completed successfully.
In August 2010, GTRE with the help of the Central Institute of Aviation Motors (CIAM) of Russia was trying to match the objective of fine-tuning of Kaveri engine performance. Until August 2010, altitude testing, simulating the engine performance at different altitudes, and achieving a speed of Mach 1 had been completed successfully. One of Kaveri’s prototypes (K9) had a successful test flight at Gromov Flight Research Institute in Moscow, on 4 November 2010.
In the test, the engine ran right from the take-off to landing, flying over one hour up to an altitude of 6,000 m. The engine helped the IL-76 aircraft test bed to fly at speeds of 0.6 Mach in its maiden flight, according to DRDO. After completing these milestones, the Kaveri engine was considered flight-worthy. The Kaveri engine was tested for the first time on a flying testbed and it was a success.
Till April 2011, the first phase of Kaveri engine FTB trials had been completed successfully and further tests continued from May 2011 onwards. The tests successfully carried out so far were up to 12 km maximum altitude and a maximum forward speed of 0.7 Mach. In its annual report for the year 2010–11, The Comptroller and Auditor General of India noted that ₹18.92 billion had been spent on the development of the engine, with only two out of six milestones prescribed having been met. Among its deficiencies, the engine weight was higher than the design specifications, (1,235 kg against the required 1,100 kg), and there was no progress in developing the compressor, turbine, and engine control systems.
As of 21 December 2011, 9 prototypes of Kaveri engines and 4 prototypes of Kabini (Core) engines had been developed. Further, 2050 hours of test flight of engines had taken place so far. 27 flights for 55 hours had been completed on the IL-76 aircraft testbed as well as 12 km maximum forward altitude and a maximum forward speed of 0.7 Mach had been recorded.
PROBLEMS FACED
The Kaveri program had attracted criticism due to its ambitious objective, prolonged time of development, cost overruns etc. Another major problem was DRDO’s reluctance to admit problems in the engine and its resistance to involve foreign engine manufacturers until the problems became too complicated to handle.
In August 2010, a Ministry of Defense press release reported the following reasons for the
delay:
1.”Ab-initio development of state-of-the-art gas turbine technologies.
2.Technical/technological complexities.
3.Lack of availability of critical equipment & materials and denial of technologies by the
technologically advanced countries.
4.Lack of availability of test facilities in the country necessitating testing abroad.
5.Non-availability of skilled/technically specialized manpower.”
CURRENT STATUS
Kaveri engine project has achieved a high Technology Readiness Level (TRL) in many crucial domains and these results are being used in the various engine development programmes of the country. Further, the engines are being used as test vehicles for testing next-generation technologies. Currently, the LCA Tejas is integrated with an imported engine. However, in the future, it is proposed to develop indigenous engines for powering indigenous aircrafts like LCA variants and AMCA. The technological capabilities gained while building the Kaveri engine project will be utilized. LCA Tejas, Flight Operational Clearance(FOC) configuration requires a higher thrust than the intended engine requirement. Hence the Kaveri in its present form cannot be integrated.
Kaveri engine on display
FUTURE PLANS
The government has planned to declare the project as a ‘national mission and initiate urgent remedial actions. An optimum level of funding for research projects will be provided by the government. Domestic industry and start-ups will be used to provide the necessary support. The army and the air force would be considered stakeholders while designing Military Grade Technologies. Research conducive institutions would be developed by bringing back the overseas Indians, in hopes of stopping brain drain from the country. The success of the Kaveri programme will completely transform the aerospace industry and place India in the front ranks of aeronautical nations. If this opportunity is missed, then we will have to be import-dependent forever in this area.
CONCLUSION
After continuous efforts, India’s jet engine project has made some progress. Kaveri engine is capable of producing 75kN thrust. But the LCA requires 90kN and the AMCA 110kN thrust. A partnership with Rolls-Royce has raised hopes of satisfying these requirements. India is emerging as a global hub for defense aviation. The development of the domestic jet engine is being emphasized here. The initiatives of the central government’s Make in India and Atmanibhar Bharat can have a positive impact here.
SAE-NITK 