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Bangalore: Sea-level flights of Tejas, the indigenous light combat aircraft (LCA), have thrown up questions relating to its installed thrust. If these are not resolved, it is possible that Indias fourth generation fighter aircraft programme, launched in 1983, could get further delayed.
Prototype vehicles PV2 and PV3 were put through 24 flights over two weeks at INS Rajali at Arakkonam in Tamil Nadu recently. Being at sea level Arakkonam offered a dramatically different environment from that of Bangalore, which is 3,018 feet above sea level. It was in Bangalore that all the LCA flying was until then done. With the longest runway of its kind in India, INS Rajali enabled Tejas to undertake extensive low-level flying, something that is not possible in Bangalore.
The sea-level tests, basically meant to test the reliability of Tejas systems in dense (hot and humid) atmospheric conditions and its low-level flight characteristics, were largely successful. But it also became clear that the performance at sea level did not meet some key points in its flight envelope: notably in terms of maximum speed and take-off. Here the aircraft was not able to meet its targeted maximum speed of Mach 1.05, although it had been touching Mach 1.6 at higher altitudes.
Informed sources attribute this to insufficient installed thrust from the power plant after its integration with the air frame. Engineers working with the programme say modifications including to the aircrafts air intakes will have to be made or a new engine installed. Both solutions will be time-consuming.
Informed sources say a solution would necessarily have to be found since the aircraft is not likely to clear (low-level) final operation clearance (FOC) with the present installed thrust. It is unlikely that the end-user, the Indian Air Force, which in 2006 placed an order for 20 of the aircraft, be happy to induct an under-powered machine.
The LCA now uses the General Electric (GE) designed and manufactured F 404 engine, which generates a static thrust of 80.5 kN (kiloNewton). But installed thrust being dependent on the mating of the engine with the air frame, the amount of air that flows into the engine (air intake), aero dynamism, cowling, wings, and so on, it can be lower than the static thrust. Informed sources say this is what has happened in the case of the Tejas. They say the installed thrust losses are on account of issues with the air intake design and mating of the engine with the airframe.
The LCA programmes limited series production and the 20 aircraft the IAF has ordered will fly with specially modified GE 404 IN20 engines. But informed sources say that though these engines have Full Authority Digital Engine Control, longer life and hot-end components, they may not be able to generate at sea level the needed installed thrust. A new, more powerful engine such as the GE 414 (which powers the F-16 Super Hornet), whose core is the same as the GE 404 but is heavier or a similar engine, may have to be tried.
The genesis of the current issues relating to the engine can be traced to the non-availability of the Kaveri engine that was expected to fly the Tejas, but which is still nowhere in sight. The non-availability of the Kaveri has meant that the Aeronautical Development Agency (ADA), which is designing the LCA, is forced to look elsewhere for an alternative.
The ADA, though, is not too perturbed with the lack of installed thrust at low levels. Says P.S. Subramanyam, its Programme Director (Combat Aircraft): The programme is on the fast track. We are planning to fit drop tanks and mid port bombs very shortly. Missile firing is also being planned. The present engines (F 404) will see me through IOC and FOC.
The LCA, which has so far undertaken 725 flights, is scheduled to get initial operational clearance in late-2010 and FOC in 2011-12.
http://www.hindu.com/2007/08/15/stories/2007081558470100.htm
(sorry double post)
Prototype vehicles PV2 and PV3 were put through 24 flights over two weeks at INS Rajali at Arakkonam in Tamil Nadu recently. Being at sea level Arakkonam offered a dramatically different environment from that of Bangalore, which is 3,018 feet above sea level. It was in Bangalore that all the LCA flying was until then done. With the longest runway of its kind in India, INS Rajali enabled Tejas to undertake extensive low-level flying, something that is not possible in Bangalore.
The sea-level tests, basically meant to test the reliability of Tejas systems in dense (hot and humid) atmospheric conditions and its low-level flight characteristics, were largely successful. But it also became clear that the performance at sea level did not meet some key points in its flight envelope: notably in terms of maximum speed and take-off. Here the aircraft was not able to meet its targeted maximum speed of Mach 1.05, although it had been touching Mach 1.6 at higher altitudes.
Informed sources attribute this to insufficient installed thrust from the power plant after its integration with the air frame. Engineers working with the programme say modifications including to the aircrafts air intakes will have to be made or a new engine installed. Both solutions will be time-consuming.
Informed sources say a solution would necessarily have to be found since the aircraft is not likely to clear (low-level) final operation clearance (FOC) with the present installed thrust. It is unlikely that the end-user, the Indian Air Force, which in 2006 placed an order for 20 of the aircraft, be happy to induct an under-powered machine.
The LCA now uses the General Electric (GE) designed and manufactured F 404 engine, which generates a static thrust of 80.5 kN (kiloNewton). But installed thrust being dependent on the mating of the engine with the air frame, the amount of air that flows into the engine (air intake), aero dynamism, cowling, wings, and so on, it can be lower than the static thrust. Informed sources say this is what has happened in the case of the Tejas. They say the installed thrust losses are on account of issues with the air intake design and mating of the engine with the airframe.
The LCA programmes limited series production and the 20 aircraft the IAF has ordered will fly with specially modified GE 404 IN20 engines. But informed sources say that though these engines have Full Authority Digital Engine Control, longer life and hot-end components, they may not be able to generate at sea level the needed installed thrust. A new, more powerful engine such as the GE 414 (which powers the F-16 Super Hornet), whose core is the same as the GE 404 but is heavier or a similar engine, may have to be tried.
The genesis of the current issues relating to the engine can be traced to the non-availability of the Kaveri engine that was expected to fly the Tejas, but which is still nowhere in sight. The non-availability of the Kaveri has meant that the Aeronautical Development Agency (ADA), which is designing the LCA, is forced to look elsewhere for an alternative.
The ADA, though, is not too perturbed with the lack of installed thrust at low levels. Says P.S. Subramanyam, its Programme Director (Combat Aircraft): The programme is on the fast track. We are planning to fit drop tanks and mid port bombs very shortly. Missile firing is also being planned. The present engines (F 404) will see me through IOC and FOC.
The LCA, which has so far undertaken 725 flights, is scheduled to get initial operational clearance in late-2010 and FOC in 2011-12.
http://www.hindu.com/2007/08/15/stories/2007081558470100.htm
(sorry double post)
