The GTRE GTX-35VS Kaveri is an afterburning turbofan being developed by the Gas Turbine Research Establishment (GTRE), a lab under the DRDO in Bangalore, India. An indigenous Indian design, the Kaveri was intended to power production models of the HAL Tejas fighter, originally called the "Light Combat Aircraft" (LCA), but it was officially de-linked from HAL Tejas program in September, 2008. Now GTRE is running two separate program for engine, the two different platforms are K9+ Program and the K 10 Program.
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 afterburning 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 authorised in April 1989 in what was then expected to be a 93-month programme projected to cost 382 crore (US$72.6 million). A new engine typically costs up to $2 billion to develop, according to engine industry executives.
The original plans called for 17 prototype test engines to be built. The first test engine consisted of only the core module (named "Kabini"), while the third engine was the first example fitted with variable inlet guide vanes (IGV) 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.
In 2002, little information had been publicly released concerning the nature of the Kaveri's technical challenges, but it was known that the Kaveri had a tendency to "throw" turbine blades, which required securing blades from SNECMA (as well as digital engine control systems).
Continuing development snags 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 US$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. 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.
In Dec. 2004, it was revealed that the GTRE had spent over 1,300 crore (US$247 million) 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 2,839 crore (US$539.4 million).
In Feb. 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 and Whitney, told PTI. But DRDO secretary Natrajan told PTI that "But Kaveri is and would remain an Indian project."
On February 5, 2007, Scientific Advisor to Defence Minister M Natarajan said nearly 90 to 93 per cent of the expected performance had been realised and the government had recently floated an expression of interest to seek partners to move the programme further. Till February 11, 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 K 10 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 K 10 Program is a Joint Venture (JV) partnership with a foreign engine manufacturer. K 10 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 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 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 20 billion (US$380 million) in developing the Kaveri engine since 1989, but the powerplant is still overweight and does not have the 21,000-22,500 lb of thrust (93-100 kN) 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 Dec 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 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.
On May 3, 2010, about 1880 hrs 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 83-85 Kilonewtons (KN) of maximum thrust is being considered an option by DRDO.
In July 2010, according to Vinayak shetty, Tejas aircraft will be Integrated with Kaveri engine and will be flying on board a Tejas Air frame by early 2011 or some time later in the year.
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. Till 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 at the Flying Test Bed 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 6,000 metres. 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).
"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 12 km maximum altitude and a maximum forward speed of 0.7 Mach No.
In its annual report for 2010-11, The Comptroller and Auditor General of India noted that 1,892 crore (US$359.5 million) had been spent on development, with only two out of the six milestones prescribed having being met. Among its deficiencies, CAG says the engine weight was higher than the design specifications (1235 kg against 1100 kg) and there was no progress on developing the compressor, turbine and engine control systems.
On Dec 21 2011, "9 prototypes of Kaveri engines and 4 prototypes of Kabini (Core) engines have been developed" told Defence Minister Shri AK Antony in Rajya Sabha. Further on, 2050 hours of test flight of engines has been taken place so far. 27 flights for 55 hours duration have been completed on testbed IL-76 aircraft as well as 12 km maximum forward altitude and a maximum forward speed of 0.7 Mach No had been recorded.
The Kaveri program has attracted much criticism due to its ambitious objective, protracted development time, cost overruns, and the DRDO's lack of clarity and openness in admitting problems. Much of the criticism of the LCA program has been aimed at the Kaveri and Multi-Mode Radar programs. There has been much criticism of the degree of realism in the DRDO's planning schedules for various elements of the LCA programme, most particularly for the Kaveri development effort. France's SNECMA, with over half a century of successful jet engine development experience, took nearly 13 years to bring the Rafale fighter's M88 engine to low-volume production after bench testing had begun; a similar timespan for the less-experienced GTRE would see Kaveri production beginning no earlier than 2009. Another criticism has been DRDO's reluctance to admit problems in the engine and its resistance to involve foreign engine manufacturers until the problems became too large to handle.
In August 2010, regarding the reasons for delay, a Ministry of Defence press release reported:
- "Ab-initio development of state-of-the-art gas turbine technologies.
- Technical/technological complexities.
- Lack of availability of critical equipment & materials and denial of technologies by the technologically advanced countries.
- Lack of availability of test facilities in the country necessitating testing abroad.
- Non availability of skilled/technically specialized manpower."
The Kaveri is a low-bypass-ratio (BPR) afterburning turbofan engine featuring a six-stage core high-pressure (HP) compressor with variable inlet guide vanes (IGVs), a three-stage low-pressure (LP) 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 ("con-di") variable nozzle, but the GTRE hopes to fit production Tejas aircraft with an axisymmetric, multi-axis thrust-vectoring nozzleto further enhance the LCA's agility. The core Turbojet engine of the Kaveri is the Kabini.
The general arrangement of the Kaveri is very similar to other contemporary combat engines, such as the Eurojet EJ200, General Electric F414, and Snecma M88. At present, the peak turbine inlet temperature is designed to be a little lower than its peers, but this is to enable the engine to be flat-rated to very high ambient temperatures. Consequently, the bypass ratio that can be supported, even with a modest fan pressure ratio, is only about 0.16:1, which means the engine is a "'leaky' turbojet" like the F404.
The Kaveri engine has been specifically designed for the demanding Indian operating environment, which ranges from hot desert to the highest mountain range in the world. The GTRE's design envisions achieving a fan pressure ratio of 4:1 and an overall pressure ratio of 27:1, which it believes will permit the Tejas to "supercruise" (cruise supersonically without the use of the afterburner). The Kaveri is a variable-cycle, flat-rated engine and has 13% higher thrust than the General Electric F404-GE-F2J3 engines equipping the LCA prototypes.
Plans also already exist for derivatives of the Kaveri, including a non-afterburning version for an advanced jet trainer, and a high-bypass-ratio turbofan based on the Kabinicore. Another concept being considered is an enlarged version of the Tejas with two engines fitted with fully vectoring nozzles, which might make the vertical tail redundant (the Tejas has no horizontal tail).
An indigenous Full-Authority Digital Engine Control (FADEC) unit, called Kaveri Digital Engine Control Unit (KADECU) has been developed by the Defence Avionics Research Establishment (DARE), Bangalore. The Combat Vehicles Research and Development Establishment (CVRDE) of Avadi was responsible for the design and development of the Tejas aircraft-mounted accessory gear box (AMAGB) and the power take-off (PTO) shaft.
The DRDO currently hopes to have the Kaveri engine ready for use on the Tejas in the latter half of the 2010s decade and according to latest news still research on it is going on and date to complete its research has been extended to 2011-2012.
“In recent times, the engine has been able to produce thrust of 82 Kilo Newton but what the IAF and other stake-holders desire is power between 90—95 KN" , senior officials told The Hindu. "On using the Kaveri for the LCA, they said the engine would be fitted on the first 40 LCAs to be supplied to the IAF when they come for upgrades to the DRDO in the latter half of the decade." Article further adds that in 2011,50-60 test flights will be carried out to mature the engine in terms of reliability, safety and airworthiness.
Plans are also already under way for derivatives of the Kaveri, including a non-afterburning version for an advanced jet trainer and a high-bypass-ratio turbofan based on theKaveri core, named as Kabini.
- GTX-35VS Kaveri:
- HAL Tejas (planned for production models)
- Kaveri Engine for LCA
- Name of the Project / Programme -- Kaveri Engine for LCA
- Date of Sanction—30 Mar 1989
- Original Probable Date of Completion (PDC) -- 31 Dec 1996
- Revised PDC—31 Dec 2010
- Technologies / Products developed and status of Projects / Programmes on 3 May 2010—About 1880 hrs on engine test has 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.
- HAL Medium Combat Aircraft (conceptual)
- Unmanned Aerial Vehicles
- The Indian government plans to adapt and further develop the Kaveri engine design and technology to create a gas-turbine powerplant for armoured fighting vehiclessuch as the Arjun tank.
- Kaveri Marine Gas Turbine (KMGT), a recently developed derivative of the GTX-35VS Kaveri engine for ships.
- Indian Railways has expressed interest in utilizing Kaveri to power locomotives
Specification (GTX-35VS Kaveri)
- Type: Afterburning turbofan
- Length: 137.4 in (3490 mm)
- Diameter: 35.8 in (910 mm)
- Dry weight: 2,427 lb (1,100 kg) [Production model goal: 2,100 lb (950 kg)]
- Compressors: two-spool, with low-pressure (LP) and high-pressure (HP) axial compressors:
- LP compressor with 3 fan stages and transonic blading
- HP compressor with 6 stages, including variable inlet guide vanes and first two stators
- Combustors: annular, with dump diffuser and air-blast fuel atomisers
- Turbines: 1 LP stage and 1 HP stage
- Maximum thrust:
- Military thrust (throttled):11,687 lbf (52.0 kN)
- Full afterburner:18,210 lbf (81.0 kN)
- Specific fuel consumption:
- Military thrust: 0.78 lb/(lbf•h) (79.52 kg/(kN·h))
- Full afterburner: 2.03 lb/(lbf•h) (207.00 kg/(kN·h))
- Thrust-to-weight ratio: 7.8:1 (76.0 N/kg)
- Airflow: 172 lb/s (78.0 kg/s)
- Bypass ratio: 0.16:1
- Overall pressure ratio: 21.5:1 [Goal: 27:1]
- LP compressor pressure ratio: 3.4:1 [Goal: 4:1]
- HP compressor pressure ratio: 6.4:1
- Turbine entry temperature: 2,218-2,601 °F (1,214-1,427 °C; 1,487-1,700 K) [Goal: 3,357 °F (1,847 °C; 2,120 K)]