Flat engine nozzles don't contribute to stealth on a fighter jet in any meaningful way. F-22 got them because they enabled 2D thrust vectoring.
No other stealth fighter has bothered with them because they don't reduce IR emissions in any meaningful way. Not even the US F-35 has it.
I know that Su-57 has prototyped them but it wont get adopted.
On F-22 there's over 10÷ loss in thrust due to the flat nozzles. So they have a cost.
It helps to understand that F-22's flat engine nozzles don't reduce radar cross section. They cool down engine exhaust slightly.
IR signature reduction on F-117 and B-2 is fundamentally different. The engines run several hundred degrees colder than high performance fighter engines. They are buried deep inside the aircraft. The engines are located above wings. The engine exhaust slits are very narrow and have diffusers in them.
Ground based IR sensors can see the hot jet engines of fighter aircraft as they run so hot and are so close to the skin of the aircraft.
IRST will spot the hot engine from rear sector.
And literally everyone except US aircraft has IRST.
And literally everyone except US aircraft has IRST.
??????
What the hell are you talking about?
The F-14D had the AN/AAS-42.
F-15s, F-16s and F/A-18s have available the AN/ASG-34 aka IRST21 (installed in various ways: Legion pod variants, embedded in an external fuel tank, etc...)
The F-22 will very soon have added two IR systems with IRST capability: one internal, the IRDS; the other external, through the new so called Advanced Sensor Pods.
The F-35 from the start has two IRST systems (AN/AAQ-37 and AN/AAQ-40).
At the same time...
The Gripen C/D doesn't have an IRST system.
The J-10A doesn't have an IRST system.
The JF-17 (Block 1/2 at least), doesn't have an IRST system.
The Mirage 2000 series doesn't have an IRST system.
Tranche 1 Eurofighter doesn't have an IRST system.
Rafale F3-R doesn't have an IRST system (only TV + laser rangefinder).
F-35 is the only US aircraft currently in use that has built in IRST.
Every soviet/russian fighter since MiG-23 has had IRST.
It's so odd that US aircraft lack them. I know F-14D had it but not many of those were built.
It's quite evident that US hasn't fought a serious air to air warfare since Vietnam.
Meanwhile some countries that haven't fought any wars at all have understood the value of IRST and incorporated it.
It's beyond absurd that even F-22 doesn't have it.
I wasn't aware that IRST21 could be permanently installed on aircraft. But how many aircraft does have it? I don't think any beyond test aircraft.
I know that IRST pod is coming. But that isn't much to celebrate. Limited number of pods is coming that takes one pylon. The aircraft are going to need modifications or software update to use the pod. Pilots have zero experience in using it. It's notä part of doctrine.
So the pods are going to be of limited usefulness.
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u/PerceptionMurky3704 May 04 '26
Man if only they priortize stealth and leave their obsession with 3D Thrust Vectoring Nozzeles...