The fan establishes a minimum section but that alone is not the main problem. It removes the prime location for the weapons bays, centered and before the engine, so they need to be taken to the sides of the main engine, massively increasing the cross sectional area, in turn demanding a bigger engine in turn increasing weight etc. Then payload requirements were increased. Additional requirements about max size for the lifts of carriers and the fact that the fan needs to compensate for the power of the engine forced to the engine forward, further making a fuselage which is short and thick.
The problem is the requirement for vertical takeoff and landing and of course hovering.
Even someone who doesn't know anything about aircraft will know that to hover you need to balance lift along the length of the aircraft and its width... the main wing generates the lift that holds the aircraft in the air in normal flight but in hover it means nothing... but it is where wing mounted ordinance is stored... the main jet engine nozzle is at the rear of the aircraft well behind the wing so the balancing lifting fan needs to be in front and the internal weapon bay needs to be between those two as well. The fan and jet nozzle need to balance the weight of the aircraft from take off with full fuel and weapons right through to full weapons and tiny fuel load or no weapons and almost no fuel... it is a variety of fuel and payload states where it needs to be able to balance... bloody nightmare with a subsonic plane that can have a huge high lift wing that gives positive lift on rolling takeoffs to allow higher weights in fuel and weapons, but super high lift wing is hard to combine with thin profile supersonic wing.
The biggest problem with the Yak-38 was its tiny wing because they wanted it to fly as fast as possible. The wing on the Harrier was vastly better and made it a much better plane... but still not better than something like an F-16 or MiG-29.
Smaller and lighter and cheaper and with better aero than F-35, no doubt. That is why I made my layout exercise and I stand by what I got. The main lesson is to keep cross sectional area down, bays in front of the engine and to satisfy the unquestionable weight/volume increase demands of the 5G (weapons bays & range) by extending the middle section of the fuselage. Maybe my model is too ambitious in terms of payload but I think it is a workable approach while F-35 is a fighter just in the name.
My position is that you focus too much on cross section area like the US focussed too much on stealth and nothing else and ended up with a dog.
5th gen fighters need internal volume for fuel and weapons so they are never going to be the sleek super low drag cheap and simple fighters you want them to be. That ship has sailed... the closest anyone got was probably the F-5 in the west or the MiG-21 in the east.
If you want a good 5th gen fighter make two big planes... make one with all the expensive high tech super components that will give it an edge in combat and fill the other with proven trusted good but not great equipment and stuff that will get the job done and be affordable.
Or they should have waited for the unmanned version where cockpit can be substituted by the fan with great advantages of all orders. Bays return to its right position, lifting force is taken forward as much as possible, allowing the main engine in turn to move rearwards too. That solves most of the problems with the STOVL layout or at least reduces its downsides to the unavoidable volume and weight needed for the lifting devices without further compromising other aspects of the plane.
The VSTOL model is such a niche aircraft it was a terrible waste that compromised the design of all the different types... if you are making them unmanned then launch them vertically like a rocket and recover them in a net and make them more conventional without lifting fan crap... just a tail mounted thrust vectoring engine... should be enough to get them airborne from a short takeoff run...
Modern jet will detect the launch of the missile directly in dogfight situation and release automatically flares.
Lock on after launch increase the probability that the missile locks onto flares. The pilot can't know what the missiles is locking onto. The locking will happen with the flares around.
Locking before launch means you are sure to lock on the real target and it's easier to keep the track.
The claims for teh X model Sidewinder suggested the IIR seeker allows the operator to lock on to a specific part of the aircraft and that flares and jammers will be ineffective... yet an Su-22 evaded it in Syria with some Flares which should not have been effective.
Previous generation missiles use much more basic IR sensors that see hotspots and patterns but not shapes or images, so if you saw what it locked on to you could not identify it as an aircraft, which is why modern procedure is to release large numbers of flares to generate patterns of hotspots to fool the missiles seeker.
With IIR that should not be possible because no pattern of hot dots is going to look like the thermal heat map image of an aircraft.
Something is not quite right here...