why not to post a vid (it's at the site of imagining gear manufacturer
):
what a burner:
Confirmed he have a big IR signarure, very good for RCS ( less than exceptionnal F-22 ) remains EM emited with sensors the more big with radar more difficult to known.
The much-touted ‘stealth’ features of the Lockheed Martin F-35 making it nearly invisible to radar, could be negated by a pronounced ability to be detected by infra red devices.
The heat signature released by the aircraft engines and other power consumption devices such as the radar could negate gains main by its stealthy characteristics aimed at remaining invisible to radar.
Fighter aircraft add-on devices such as the infra-red scan and track (IRST) sensor which several European and Russian aircraft are equipped with for certain missions, can easily detect the F-35 in beyond-visual range engagements, a
said.
A video released by FLIR Systems which specializes in the manufacture of infra-red sensors shows the heat signature of the plane in clear detail. The sensor used is theFLIR Star SAFIRE 380-HDc and tracking the heat signature has been done from a rather close range.
Nevertheless, it could be a potential chink in the armor for the US Air Force and other countries which have put billions of dollars in buying the F-35 whose main USP is its stealth capability.
Considering it for begin we look for IR signature/heat after we see about RCS, EM a little, visual also but very small in general 3/5 km max for get an idea about detection/engagment range with weapons ofc for know if vs her main rivals he can get the first shot which is the more important in a combat, and for all types.
I precise we have accurate range for weapons but impossible get it for sensors, RCS ofc.
So F-35 IR signature détails and how evaluate a IR signature according several good ( i hope

) sites/blogs i have see :
In terms of IR signature, primary factors are size, speed and engine emissions
1/ engine emissions are less significant if divided in two engines, leading to increased cooling due to greater ratio of plume surface area to crosssection
2/ While normally this advantage would be negated by aerodynamic superiority of single-engined aircraft, not the F-35.
3/ F-35s unaerodynamic fuselage means that it requires full dry thrust to achieve fast speeds
Despite that F-35 get a advantage in stealth mode get weapons inside with an inferior drag than no stealth fighters with externals weapons but even it normaly F-35 remains inferior for this matter.
If F-35 is medium for some characterictis it is coz build for 3 services with different employments and desired cheaper for US but also export and that's why he get only one engine.
Considering these points from long time we know F-35 get an enough big IR signature the video is not a surprise.
IR signature evaluation about for give an idea
1/ rear signature is 50% superior to frontal
2/ with afterburner for supersonic speed 50% Superior
So for both + 100 %
But despite IR signature can be enough significative she is clealy inferior to RCS and much more as EM.
The best IRST F-35, Typhoon, Rafale sure presumably last Sukhoi especialy Su-35 get a max identification range of 50+ km and detection depnds IR signature... up to 145 km for pratice reasons normaly only possible to fired in the identification range otherwise can be a friend...
Then we will see a comparison btw IR range, EM a little and mainly radar range with RCS ofc for know if IR system can to be a problem for stealth fighter especialy F-35.
I precise S-300 especialy the last and S-400 get IRST.