With the Indian Air Force’s (IAF’s) MMRCA program getting serially delayed and recast more than once, there was a feeling in various quarters that the Tejas Mk2 design should perhaps evolve further than what was initially envisaged to provide an indigenous option for the IAF’s requirements. Thus, the IAF and the Aeronautical Development Agency (ADA) sat down to redefine the Tejas Mk2 with more elaborate modifications such that it could function as a medium weight fighter for ground attack roles while continuing to be nimble in the air to air (A2A) role. In fact, the version of the Tejas Mk2 currently envisaged has been rebadged as the Medium Weight Fighter or (MWF) and is being designed as a replacement for the Mirage 2000 with a view to surpassing its capabilities in almost every respect
Tejas Mk2 also known as Medium Weight Fighter (MWF) looks very much similar to Tejas Mk1. However the main differences are prolonged fuselage. The overall length of Tejas Mk2 is 14.7 meter from increased from 13.2 meter in Tejas Mk1. While studying the aerodynamics and its constrains in Tejas Mk1, it was observed that it was unable to comply to Area ruling because of short length. So it was decided to take care of this concern of Tejas Mk1 by increasing the length. Other aerodynamic issues such as elevating canopy, redesigning pylon, putting short range missile on wing tip etc is freezed in Mk2 design. All this will reduce aerodynamic drag and will improve transonic acceleration by a very good margin.
Mark-2 MWF will continue to have the legacy LCA-Tejas Mk1 and Mk1A design elements which will be powered by single F414-GE-INS6 engine supplied by General Electric which has already started to arrive in India from 2017 on wards. MWF will exceed the performance of Upgraded Mirage-2000 when Inducted into air force but actually will replace Mig-29 first. MWF will also be replacing Jaguar fighter-Bomber which are due to be retired from service from 2034 on wards
Development of MWF was convinced only in 2014-15 period and the whole platform was redesigned and the previous Mk-2 design concept which was just Mk1 air frame with 0.5m fuselage plug has been discarded to allow the platform to be classified as a Medium class aircraft. Since the 5th generation AMCA program was unofficially commissioned way before MWF was conceived, designers were able to feature in a lot of Radar cross-section (RCS) reduction measures in the air frame design to reduce electromagnetic and infrared signatures of the aircraft with use of carbon composite and thermoplastic composites at the frontal section of the aircraft to achieve better RCS reduction.
Another big issue which is addressed is increasing fuel capacity from 2.5 tons to 3.3 ton which will give it a big boost in ferry range and combat radios. Supersonic fuel tanks are also developed. It offers a big fuel capacity with minimum addition of drag. This will further add to range and mission capability to carry out operation in large geographical area.
It is not only a betterment but was necessary. In fact, ADA had considered canard in LCA Tejas as one the short-selected design concepts in the 1980s. Later the idea was dropped because that was the first time India was developing a Flight Control System (FCS)- that too for a highly unstable aircraft like Tejas; so adding canard i.e. an extra control surface would have increased the complexities and risk with no significant aerodynamic advantage relative to the complexity. Now that a robust FCS has been developed, adding canard is an incremental development challenge that ADA can handle.
The canard is ‘close-coupled’ (meaning it is located just above and forward of the wing)
A close-coupled has many positive aerodynamic effects like:
i) It increases wing lift. For Delta wing design aircraft (like Tejas), close-coupled canard benefits even more- increases lift both in low speed flight and high (transonic) speed flight.
ii) It creates better aerodynamic stability of wing vortices
iii) It reduces wing-loading
iv) It gives an extra control surfaces for pitch and roll control, and on the ground, as air-brakes.
v) It reduces take-off distance.
vi) A good area ruling that includes the canard helps to reduce various aerodynamic drag (wave drag, trim drag etc.) hence enhancing its performance.
vii) Compensation for shift of CG with respect to CL (as said in 1st point)
At least Four RCS reduction measures will be incorporated in the air frame design so that ” Semi Stealth ” can be achieved with help from the use of fully internal electronic warfare system to defuse radar frequency (RF) and infrared (IR) threats while on the mission.
MWF will also get a stealth coating paint which has been developed specifically for the AMCA program but only at certain sections to manage absorption of all radar frequencies. Critical RCS reduction measures in the air frame will be
1) Wing and Canard edge alignment to reduce drag and also reduce friction heat and improve RF deflection,
2) Air intakes ducts will have twisted design so that engine blades can be carefully hidden inside the intake duct.
3) Radar-absorbent materials on the critical sections of the fuselage will be used 4) Sharp edges at front fuselage will also help reduce radar cross-section.
MWF fighter jet program will be replacing entire Mirage 2000, MiG-29 and Jaguar fighter fleet from Indian air force inventory of nearly 200 jets and since it will need to be operated in contested environments where stealth features will come in handy to improve the survivability of the platform and the pilot. MWF cannot be classified as a stealth aircraft but measures to reduce its RCS will ensure its survivability.
MWF will be getting new AESA Radar, on-board oxygen-generating system, Internal advanced electronic warfare (EW) suite, larger Multi-functional displays, the upgraded digital flight control computer (DFCC), Infra-Red Search and Track (IRST). Missile Approach warning system (MAWS) and Higher thrust engines which makes it distinctively class apart from the baseline LCA-Tejas fighter jets.
After building huge inventory of heavy category fighter like SU 30 MKI and developing light weight Tejas MK1, Entire focus of India is now centered on acquiring medium weight fighter like Rafale or other MMRCA. Tejas Mk2 is a surprising sweet option which has emerged for Indian air force.
Radar, Infrared track and search system and electronic warfare: