Every country has different priorities.
And you are right 5th gen jets can't be smaller and in lightweight category.
But a single engine jet with high cost-efficiency like jf17 is the need of Pakistan and will be fulfilled through pfx program.
But it will take time as we replace our jf17s with pfx beyond 2035-2040 era or even after some years beyond as India will still lack in next gen tech
They are now trying to go for their AMCA instead of buying F35 or su57.
AMCA will be Tejas 2.0 and my provide Pakistan air superiority over India in foreseeable future/
Well, it does seem that you're not clear on the issues here.
Modern turbofan engines, in addition to propelling the entire airplane, convert some of that propulsion into electricity to power the avionics on the airplane.
In the early days, the avionics consumed very little electricity, so the engine converted very little of it. However, modern advanced fighters consume a lot of electricity, so more engine thrust is needed to be converted into electricity.
The conversion of turbofan engine thrust into electricity is dynamic.
For example, when the airborne radar is running at full power, the power consumption is at its maximum. At this time, if the total power output capacity of the turbofan engine reaches the upper limit, the thrust given to the fighter by the turbofan engine shrinks accordingly. That is to say, at this time, the fighter can not do high maneuvering and other large energy consumption action. On the contrary, when the fighter jet does high maneuver, the radar can not run at full power.
If the fighter can still achieve full power operation of the radar during high maneuvers, we call it a perfect match. However, the length of time the radar can operate at full power is still limited.
The RD-93 engine can only support the JF-17B1/B2 at maximum, and the JF-17B3 needs to do power distribution to operate normally. The JF-17B3 requires power distribution to operate properly, i.e., multiple avionics cannot be operated at the same time or, alternatively, some of the equipment needs to be operated at reduced power. This is the core reason why the JF-17B3 does not come with IRST.
WS-19/WS-21 can support JF-17B3.
However, if the JF-17 is upgraded to the avionics level of the 5th-Gen fighters, then, so far, no medium thrust engine can support it.
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The F135 engine in the F-35 is actually an act of technical compromise, not an act of innovation.
The F135 engine is based on the F119 and increases engine thrust by increasing the culvert ratio. It is actually a balanced value between a military turbofan engine (small culvert ratio) and a civilian turbofan engine (large culvert ratio).
It gives a huge boost to the F-35. However, it has side effects that cause a lot of problems with the F-35.
For example:
The F-35 is very fat.
The F-35 has very poor high altitude performance and is slow. Maximum speed is only Mach 1.6 and it cannot cruise supersonically.