I have always been amused by the design philosophy of creating an unstable ac and than adding more and more contol surfaces to just to make it fly. Addition of these control surfaces add weight and consequently results in degradation of performance besides making the ac heavier. All you aerodynamics experts must remember the qudraple rule for designing an ac and need to know few basic facts about aerodynamics.
The vetted area of an ac and its wings matters the most for high speed ac as skin friction drag increases with increase in size and speed.
The design of airfoil (wing Planform) has direct bearing on the overall weight of the ac as the weight of the undercart increases and can be anywhere from 2.5% of MTOW to 4.5% of MTOW of the ac. This is what made LCA go beyond the design OEW. Infact the weight of undercart for a carrier based ac is 25% higher than a shore based ac. The CLmax of an airfoil is directly proportional to its sweep angle.
Now, we started LCA project with an aim to have a small light fighter. We used F-16XL as a baseline. The net result is that we have an ac which flies better than M2K but has control surfaces much bigger than that of M2k resulting in overall degradation of load carrying ability and also problems with C of P control. The control deflection for a tail less RSS delta has these problems.
Using movable LEVCONS in LCA will only add to these problems. My best suggestion is to make LCA positively stable design with maneuover margins kept between 5% to 1% like F-16 blk-52. AND ADD CRUCIFORM TAIL TO IT AS IT ALREADY HAS A FLAT RUDDER.
What made the LCA go beyond the targeted empty weight is not the large wing, but the later insistence from IAF for the deployment of higher launch stress inducing, higher weight longer range BVR missiles on all the pylons, which led to the strengthening of the wing and the consequent weight increase and the sudden increase in cross section from x=5000 mm to x=6000 mm along the fuselage axis.
Even with this weight increase and some drag issues related to the sudden fuselage cross section increase needed to strengthen the section there to attach the higher weight wing, (due to the revised IAF BVR missile needs) the LCA mk-1 still managed to clear many of the targets set for it.MK-2 will be in the grippen NG class.
Since the design phase of LCA all the fighters be it RAFALE, TYPYHOON, F-22, J-20, J-31,FGFA(T-50) all followed the Relaxed static stability Fly by wire based, low wing loading massive wing area delta type design of Tejas, thereby vindicating the wing design.
The benefit of lower wing loading obviously offsets the higher drag of higher wetted area resulting in superior lift to drag performance in all flight envelopes is the reason for this continued adherence to the low wing loading theory.
Any positive static stability fighter will have it's center of gravity ahead of the center of lift in subsonic and trans sonic flight regime , where maneuvering at corner speeds and all other close combat maneuvers will be performed.
The CoG positioned in front of the CoP will act against the center of the lift by nose down momentum thereby delaying the fighter from attain higher bank angles quickly and reach higher Gs quickly.
Even Mirage-2000 has it's wings positioned far below the CG, meaning it's thrust line is well below the CG, But still it is supposed to be RSS fighter. If this lower thrust line alone makes the fighter nimble, then why Dassault went in for Analogue FBW based RSS aerodynamic layout for this fighter?
Having the thrust line right below the Cg will remedy this problem to some extent, But will it completely solve it? Only detailed wind tunnel modelling will clarify these things.
In the same way bigger control surfaces only increase the maneuverability, not decrease it. Now with the advent of 60 G plus BVR and WVR missiles the emphasis is on agile maneuvers to avoid these mssiles as much as possible, opposed to the low drag, positive static stability,highter STR fighters of the previous era.
That is the reason for RSS fighters with larger and more in number control surfaces to attain this goal. Rather than having smaller control surfaces and the low drag configuration,