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Russian and Indian Versions of 5th Generation Airplane to Have Substantial Differences
The fifth generation fighters intended for Russia and India's air forces that are being jointly developed will have substantial differences. Whereas the Russian air force plans to bring a single-seat variant of the fighter into the inventory, India's air force intends to obtain a twin-seat airplane. This is determined by the doctrine that has been adopted which envisions the solution as an airplane with a wide spectrum of combat missions, "India Today" reports.
As the head of HAL ((in Latin letters)), Ashok Baweja, has announced, the Indian fifth generation FGFA (Fifth Generation Fighter Aircraft) ((in English)) fighter will differ significantly from the Russian variant, since the availability of a second pilot requires increasing ((the size of)) the fuselage, wing and rudder surfaces.
Analyzing the results of the India-Russian intergovernmental commission on military and technical cooperation, A. Baweja reported that the parties made advances in the question of agreeing to the areas of participation in the creation of the new fighters, an agreement on joint development of which was signed in 2007.l As is expected, India will concentrate on the production of light, high-strength composites for construction of the airplanes, the use of which should reduce the fighter's weight significantly.
As Unified Airplane Building Company president Aleksey Fedorov has declared, at the present time the company is determining which part of the work on the creation of the airplane will be transferred to India manufacturers. It is planned to adopt a decision on this question not later than the end of this year.
According to A. Baweja, the new airplane will be created using low-observable technologies, equipped with engines which allow flying at supersonic speeds without using the afterburner, fitted with weapons systems mounted internally that are capable of attacking several targets on the ground, sea and in the air simultaneously and with the newest communications systems.
The first prototype of the FGFA will be equipped with AL-31FP engines. However, according to the wishes of the Indian side, the series-built fighter is supposed to receive a power plant that is 15 - 20 percent more powerful that the existing one. It is planned that the FGFA, which is supposed to reach the Indian air force inventory by 2015, will replace three types of combat airplanes presently in service.
Source: 02.10.08, ARMS-TASS
Dopuna: 26 Okt 2008 11:58
Razlog zašto če Rusi imati obične izduvnike a ne onakve kakve ima F-22
http://vayu-sena.tripod.com/interview-chepkin1.html
The AL-31FP boasts an axial exit nozzle. That is to say the nozzle is circular. It is known that your overseas counterparts used to try to solve the thrust vector control problem via the use of a flat nozzle that should be easier to swivel. What do you think of that?
In the late 1980s, we were engaged in the development of the flat nozzle too and conducted a thorough research. The Ufa-based Motor Scientific Production Enterprise under the guidance of Chief Designer Alexei A. Ryzhov manufactured an experimental flat nozzle that underwent a series of tests. The conclusions were as follows. Presently, the flat nozzle has two inherent snags which, in principle, have not been dealt with yet. Firstly, the turbine is round but the nozzle is flat with a distance between them being small. The distance cannot be increased because this would lead to an increase in the overall length of the aircraft, a loss of thrust, etc. While transforming the circular gas stream into the flat one, the nozzle, developed by Mr. Ryzhov, was losing 14-17% of thrust. Unfor-tunately, the gas stream cannot be "bent" as we would like it to. It has its own laws too. So far, no one has managed to transform the circular gas stream into the flat one without losing thrust. The very same snag was hit by the Americans in developing their F-117 featuring a non-afterburning engine. Such engines lose approximately 15% of thrust too. However, the F-117 is a specialised Stealth aircraft with the main requirement of ensuring "invisibility". It does not need a real good thrust/weight ratio. That is why the Americans put up deliberately with an unavoidable loss of thrust but benefited from reduced signatures.
Secondly, the other primary problem is weight. The circular TVC nozzle produces only tensile stress while the flat one exerts bending stress as well. Those stresses require special measures to be taken to ensure the nozzle strength in order to avoid deformation of the nozzle. Those measures mean additional weight. The flat nozzle made of metal is heavier than the circular one by approximately half a tonne. Mind you, the whole AL-31FP fitted with its circular swivel nozzle weighs a little bit more than 1500 kg only. So, the use of a flat nozzle implies an extra tonne at the rear of a plane (two-engine are meant here, which make up the most of modern fighters). The problem can be circumvented through the use of the "carbon-carbon" materials which have low specific weight and can stand high temperature. But they burn in the end anyway, since they are based on the very same coal. Nobody has solved the problem of preventing carbon-carbon units from burning during their operation as part of an aircraft engine. Currently, such materials covered by a thick layer of fire-resistant ceramics are used only in manufacturing the control surfaces of rocket engines. The latter are actually disposable since their operation never exceeds 40-50 seconds while an aircraft engine service life amounts to 1,000 hours or more.
So, the problem of ensuring an effective long-term protection of the non-metal nozzle is still to be solved. Thus, development of the flat nozzle encounters two problems - the loss of thrust (and it is not resolved even in theory) and the extra weight. With those two problems in mind, we stick to the circular nozzle.
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