A few thoughts:
The Flanker as explained already has a fuel capacity well above all other similar fighters and as such a range more than enough. Everything else makes no sens e and brings other issues not worth the mess.
That was true of
Su-27 developed in 1970s as part of a triad of fighters:
- long range interceptor for air defense force - MiG-31
- long range air superiority fighter for air force and air defense force - Su-27
- short range air superiority fighter for air force - MiG-29
All these aircraft had their combat ranges, response times and mission profiles defined based on the requirements of the entire Soviet air defense system.
More importantly that was
43 years ago - before active radar homing, AESA radars, sensor fusion, advancements in compuring, networking etc. Flanker design is as obsolete today as Me-262 would be in the 1980s.
The life of the platform can be extended due to advancements in technology but other limitations apply. That's the reason why PLAAF still orders J-16 which is a F-15E equivalent, and not J-11 which is a F-15C equivalent.
Soviet planners intended for Su-27IB, later developed into Su-34, to replace Su-24. Flankers were never meant to be multirole fighters with performance optimised for low altitude penetration like F-15E. Hi-lo-hi and lo-lo-lo missions are where drop tanks prove invaluable. For long duration CAP aerial refueling is preferable - more fuel, less structural stress. For high intensity air superiority contest in the 1980s you're just as often out of missiles faster than you are out of fuel.
The maximum loadout of a Su-27 was under 2t. And because of that Flanker was designed using a very unique and innovative aerodynamic design which only in retrospect proved to be a dead end. Nobody designs aircraft like that anymore because advances in computation made it possible to optimise traditional and more robust designs. Flanker was the Strv103 of fighter planes.
And then came AMRAAM and everything changed.Interesting that F-15 survived past 2000 mostly due to bomber F-15E rather than fighter F-15C which got mostly replaced by F-16.
In comparison F-15 uses a very similar design to MiG-31. It has high cantilevered wing with twin engines fixed together and all hardpoints under or near the body while the wing is mostly clear. Such design can power through greater drag and can handle asymmetry in mass distribution better than Flankers because the center of mass doesn't change as much. Both F-22 and F-35 follow that design principle. J-20 is also closer to Eagle than Flanker.
China copied Flankers because it needed to build up modern air force
quickly but
for some reason they chose a more traditional design for their next gen, as well as kept building the technically inferior J-10 - likely to develop practical knowledge of other designs, among other reasons. That's because when the Flanker shock happened it
didn't happen because Flankers were pulling Pugachev's cobras against PLAAF in J-7s and J-8s. It was a shock where a 3rd gen light fighter force was confronted with a 4th gen air superiority fighters and was outranged and outgunned. It was a Dreadnought moment rather than "oh shit, his kung fu is better than my kung fu" moment.
Sukhoi got stuck with Flanker design when it was deprived of funding through the 1990s so they oversold it for PAK-FA which is one of the reasons why the delays happened. They needed time for design work that they claimed to have done already.
And this is why Flankers will never get external fuel tanks.
As far as I can tell only the centerline position can work for a drop tank in Flankers and one drop tank doesn't change much in terms of range while it still necessitates a redesign and a rebuild, as well as limits the lift that Flanker's airframe generates between the engines.
There's also the issue of balancing the entire plane, as Flanker is a statically unstable design e.g. "leaning forward" while on the ground.
Adding concentrated 1,5-2t of mass to such plane is not easy. Balancing it symmetrically is even harder.
That's why Russia builds Su-34 in large numbers. Fullbacks were designed for carrying up to three large drop tanks on standard missions while Flankers were designed for zero.
For China it probably won't be necessary because the best solution for improving J-16 would be introducing a loyal wingman drone for carrying munitions and later for serving as frontline aerial refueler. As for J-11 they should be soon relegated to secondary and auxiliary roles. J-11B is soon going to be 20 years old and during the Cold War 20 years was a generational leap.
It's a 40+ year design with 20+ year service history. It's time for retirement and quality time with your grandkids, not for plastic surgery, viagra and a barely legal trophy wife. When you need the latter you know you messed up.
J-11s will have enough "grandkids". Let's let them go in peace.
