Reduced infrared signature should not be underestimated: the subtleties of the air "hunting" with the radar off

How many legends did not go around with respect to the real effective reflective surface (EOC or EPR) of American Fighter 5 generation F-35A "Lightnung" and F-22A "Raptor"! Thousands and even ten thousandths of a square meter were heard from fans of cars and pro-Western observers; similarly, representatives from Lockheed Martin were heard. Nevertheless, the objective technological reality makes it clear that this coefficient is within 0,2 m2 for Lightning and 0,05-0,07 m2 for Raptor. However, it will be possible to find out only during a real military conflict, when Luneberg lenses will be removed from the machines, turning any “stealth” flying device into a huge radio-contrast target with a radar signature “Eagle” or “Tomkat”.

An equally important indicator of the low visibility of a promising multi-purpose fighter of the 21st century is its small infrared signature, which is extremely important in medium and long range air battles, where enemy fighter pilots turn off their radar and rely solely on external target designation and their own on-board optical-electronic sighting systems, Some kind of “cat-and-mouse game” begins, the winner of which will certainly be the one whose optical-location (infrared) sensors are more sensitive are thermal, and the thermal signature of the airframe is smaller than that of the opponent. In addition, proper piloting of the machine plays a big role in this case, when the pilot relies on his intuition, and as rarely as possible puts the fighter tail parts of his fighter jet warmed up by the turbine gases as rarely as possible, and also uses maximum and afterburner modes of operation engines. The combination of these measures and gives an advantage in such types of air confrontation.

As for the direct thermal signature of the airframe and engine nozzles of modern tactical fighters of the transitional and 5 generations, they are very easy to see thanks to the use of high-resolution infrared cameras, which recently became popular with representatives of the manufacturers of thermal imaging equipment visiting various aerospace salons different parts of the world for the purpose of advertising their products. Thus, infrared images of the American promising F-35B “Lightning II” fighter, taken by FLIR System during its performance at the Farnborough International Air Show this summer, have become very informative. The shooting was carried out with a FLIR Safire 380-HD infrared camera with maximum resolution. What did you manage to observe?

F-35B

In the vertical take-off mode of the F-35B STOVL, in the afterburner mode of operation of the most powerful TRDDF, the F135-PW-600 (19507 kg thrust), the central and tail parts of the airframe had a thermal “luminosity” similar to the nose elements of the fuselage, i.e. no heating occurred. It only says that the manufacturers took good care of reducing the infrared signature of this car, and detecting this fighter into the forward hemisphere at medium thrust modes in 10000-12000 kgf will be real only from minimum distances 25-35 km using such an OLS as Domestic OLS-35 (Su-35С) or OLS-UEM (MiG-35). Domestic fighters, including the entire 4 + generation, on the contrary, have a very high IR "luminosity", since the tail (hottest) part of the nacelle has a more open architecture, and clearly repeats the shape of the engines themselves. The space between the engine nacelle and the outlines of the combustion chamber is not quite enough to install a thick envelope of several layers of heat-absorbing material. In the infrared images obtained by other infrared means, one can see the “luminosity” of our front-line fighter MiG-29, the American Raptor, the European Typhoon and the French Raphal.

The last in this line looks the most serious. Engineers "Dassault" perfectly "covered" engines M88-2 from the leakage of thermal radiation from the surface of the units on the tail of the airframe. The photo shows the "cold" engine nacelles engines, as in the F-35B. At the same time, the Rafale OSF optic-electronic sighting system has a range of detection and tracking of warm-contrast targets in 145 km to the rear hemisphere. At Typhoon, the engine nacelles are already beginning to “warm up”: their contrast with the jet gas stream is not as big as the F-35B or “Rafale”.

"Rafale"

And now the fun part. No matter how paradoxical it may sound, the F-22A F119-PW-100 engines working on afterburner warm up the tail of an unobtrusive fighter strongly enough, the heat radiation can be transferred from the rotary flaps of the nozzles to the fuselage, and during a long flight in a cruiser supersonic "Raptor" will be a “A candle in the night field”, even at the slightest displacement of the angle of flight relative to the enemy.

F-22A "Raptor"

And finally, the most “bright” representatives of the fighter aviation we can consider our MiG-29 and Su-27, which, when infrared, resemble real meteors or fireballs. The afterburner undergoes significant heating and a characteristic glow not only of the rear surfaces of the airframe, but also of the central parts of the fuselage, including the wing attachment areas. Detecting such an object using the same modern infrared system with a distributed DAS aperture (installed on the F-35A) will not be so difficult even from 50-60 km, which gives American and European vehicles advantages in "radar-free" combat.

MiG-29

We can talk about a decent reduction in the infrared visibility of the airframe with respect to the Chinese X-Gen X-generation multipurpose tactical fighter J-5: its propulsion system of two TRDFs WS-20G is “planted” in deep and capacious nacelles, and therefore there is a possibility for numerous experimenting with its intra-fuselage insulation.

As for our cars, there are a lot of technological ways to reduce the infrared airframe on the motor nacelle section, one of which is to install a special multilayer nano screen in the space between the turbofans and internal nacelle surfaces, in which interlayer gaps will be blown with cold air injected from small air intakes, located either at the root of the wing, or on the aerodynamic wing inflows, where there are sufficient internal volumes to scheniya large number of ducts. As is well known, in the first modifications of the MiG-29 (“The 9-12 / 9-13” product) on the upper surfaces of the inrush there were additional upper air inlets for quick take-off from unprepared runways, called upper entrances. The gliders of the MiG-29 and Su-27 family of fighters have enormous potential to upgrade their “thermal” perfection to adequately protect against enemy optical-electronic sighting systems and missiles with infrared homing types AIM-9XXII, IRIS-T or MICA-IR.

Information sources:
http://forum.militaryparitet.com/viewtopic.php?pid=161768#p161768
http://www.airwar.ru/enc/fighter/mig29.html
http://www.airwar.ru/enc/fighter/mig29-13.html
http://www.findpatent.ru/patent/241/2413161.html

Comments

[iouris]

Very relevant article.

[iConst]

Quote: iouris

Very relevant article.

- Yeah, and given that the author didn’t even give a hint about the T-50, but in the light of the above problems, it’s worth looking at our fifth-generation fighter, then you’ll see two almost two-meter cigars.
And if in a lateral projection they are somehow covered by keels and special protrusions, then a little from below or from above appear in all its glory.

Judging from the fact that camouflage is not applied to them, they are warmed up at temperatures that no paint can withstand - it peels off.

Hence the conclusion (according to the topic of the article) - what did our designers lay in the stealth of the T-50? Only not thermal stealth ...

[hirurg]

I do not see such articles for the first time.
I don’t understand one thing ... but what should take off the L / the device must also be invisible? And when landing?
Fast and Furious is not fast and furious! The question is where and when.
Wants to become visible, will become. Well, no, and there is no trial.)))

[disgust]

The latest versions are protected.

[Alexey M]

T-50 is still a prototype. There another dviglo should stand.

[Eduard Egorov]

And in the courtyard of 2019 and everything is closed and the Su 57 is lit up just like the f35, how can we speak of a prototype that only runs the flight program, that our designers did not lay thermal visibility, what do you think Russian designers are worse than you and they don’t see it glowing like Christmas tree, and the new MiGs and Dryers no longer shine as they show here

[11 black]

Quote: iouris

Very relevant article.

All thermal protection, in my humble opinion, is relevant only when the engine torch itself is not visible (that is, when the planes go strictly at each other), although in this case the engine handballs are not visible either.
And if a plane exposes an adversary’s board (an engine’s handball) to an adversary, then it exposes to it both a jet stream and engine nozzles — which we see in the example of the F-22 image — it is not the glider itself that shines, but rather the nozzles and flame. Compare with a regular shot - it is visible that the nozzles and the torch are shining.

Rafal has the same thing - a very long engine torch will shine like a light bulb as soon as an airplane "turns its nose" away from the observer by 30 degrees in any plane.
Here is a great photo - vertical deviation of 0, horizontal degrees of 20 no more - we see the nozzle, and therefore we will see the torch.

The same thing, but the deviation of 30 degrees - the torch and nozzle are visible more clearly.

I’ll venture to suggest that the single-engine F-35 has a longer torch.
PS - the photos of the F-35 and MiG-29 in the article were taken in afterburner mode, so they cannot be taken into account - unless it is concluded that when approaching "head-on" at high speeds, the enemy will sooner notice the friction-heated nose of the car than a torch or a handola ... although it's interesting to look at the MiG in non-afterburner mode, if the tail is also heating up (which I doubt), then the trouble ...

[Rozmyssel]

in these infrared images, the instant has an afterburner, but rafal and f22, in my opinion, aren’t
here is fast and furious f22

here is rafal

[Rus2012]

Quote: Thought

in these infrared shots at the instant really fast and furious

... but how else, why would his nose glow? :)

But the adversaries finally can not fast and the furious ...;))))))))))))))
the author should have been given flight conditions (V, H) when shooting an IR photo, otherwise it turns out we compare a hippo with a turtle ...

In general, our designers have long been engaged in signature visibility in different spectra. And not everything is as simple as the author writes. There are ways and methods to reduce. And most importantly, they are successfully applied ...

[jjj]

If the West thinks like the author of the publication, then this is their problem. But in practice it turns out that every time Russian planes kick their tails to Westerners

[TARSUS]

Where and when they kicked enlighten). Just in a hurry to turn your beckoning little world, it was Western planes in real battles that kicked Russian birds' asses.

[Operator]

TARS from Belarus, which is typical.

[sivuch]

To turn something over to someone, you yourself need to know a little. In this case, the history of local conflicts

[11 black]

Quote: TARS

Where and when they kicked enlighten). Just in a hurry to turn your beckoning little world, it was Western planes in real battles that kicked Russian birds' asses.

I hasten to broaden your horizons - when there are 1 enemy aircraft per 10 your aircraft (Iraq / Yugoslavia), most of your aircraft fleet is MiG-21 with a rare inclusion of MiG-25 and MiG-29, behind which are "Arab chauffeurs" who are on exercises at the airfield the circles are wound - this is not an indicator at all.

[free]

when for example?

[Eduard Egorov]

Vietnam, Korea, this is not enough for you, and not Soviet pilots, Hindus during exercises, Russian pilots away, East German on MiG 29 did all the western ones at the controls.

[Skubudu]

Quote: jjj

If the West thinks like the author of the publication, then this is their problem. But in practice it turns out that every time Russian planes kick their tails to Westerners

This is where Russian planes kicked the tails of the Westerners?
Maybe in Yugoslavia or in Iraq?

[Rus2012]

set a thick gauge of several layers of heat-absorbing material.

... it seems that the author of the article does not fully understand where the temperature of the plane comes from

Here is a picture of the temperature field (temperature increase) of the skin of the aircraft from aerodynamic heating at a speed of 2-3M


Naturally, it will glow like a "Christmas tree in the meadow"

And what about the "heat-absorbing material" - what will happen to it with an allowable 1-hour flight next to the nozzle? You need to put the heat somewhere. It will melt, spread, ... :)))

[Sashka]

Explain to the "couch expert", F-35 is written, it is almost impossible to detect because of the low heating of the case, and the jet stream into all these chambers will not be visible or what ?! Missiles with infrared homing heads cannot fly into the hot stream and jump out there? Even if it detonates at a distance of a couple of meters, the glider will be damaged ?! And if so, then what difference does it make to notice the enemy by the heated metal or jet stream ?!
Enlighten, please.
Good day!

[Rozmyssel]

Quote: Sashka

Explain to the "couch expert", F-35 is written, it is almost impossible to detect because of the low heating of the case, and the jet stream into all these chambers will not be visible or what ?!

during military operations, planes will quietly and stealthily approach closer targets, therefore they will not turn on the afterburner, and the infrared image of f35 was taken during take-off at maximum afterburner, i.e. it is not clear what is being analyzed in this article?
Analysis / comparison of shots should be carried out in real airplane mode in which combat missions are carried out and of course under the same conditions for everyone, and not like in the case of the instant-fast and the furious, f22 and rafal not fast and the furious.

[Vladimirets]

Quote: Thought

during military operations, planes will stealthily and stealthily approach targets

Yeah, using sail and oars, apparently, therefore, they will not give off heat at all.

[Eduard Egorov]

For this, the photo f22 was taken without afterburner, and it can be seen perfectly in the infrared spectrum.

[Iline]

Something somehow about nothing.
I’m not a big specialist in heat engineering, but I’m doing a bit of work at work.
Which specialist will explain: why is the article considered only the thermal contrast of individual parts of the fuselage relative to each other? But the thermal contrast of the aircraft itself relative to the environment is not considered? After all, the higher the plane flies, the more "interesting" this difference will be. Even despite all the thermal insulation, the burnt gases still need to escape somewhere into the atmosphere.
In this case, infrared technology comes into play - the more perfect it is, the greater the detection range of even low-contrast targets. But then the range of air-to-air missiles and their guidance systems are already taking effect.
The development of the 70s heat direction finder "MAK - UT" (standing on the Tu-95MS) allows you to determine the start missiles (not an airplane!) from a distance of 250 km. There, the IR module is cooled with liquid nitrogen to reduce the thermal noise of the matrix itself. The matrix, I must say, for today is very antediluvian. I do not think that today it is impossible to create anything more perfect.

[Engineer]

OLS-35 works not only in infrared mode, if that.

[voyaka uh]

And in what else?
Daytime optical?

[sivuch]

Yes . specifically OLS-35 also in the optical

[Sashka]

Quote: Thought

during military operations, planes will stealthily and stealthily approach targets

Then they will need to fly up on off engines ...
Jet and without afterburner, I think it will be clearly visible. Or I'm wrong?!
Thank you for your reply!

[Rozmyssel]

Quote: Sashka

Jet and without afterburner, I think it will be clearly visible. Or I'm wrong?!

Well, it’s clear that with afterburner the thermal footprint increases many times.

[Bursa]

The future belongs to combat unmanned gliders!

[Operator]

Pictures are absolutely not informative:
- airplanes were shot at various points in time after the engines began to work, for example, F-35 immediately after take-off, the longer the engines work, the more the fuselage warms up;
- Aircraft taken from different angles;
- aircraft shot in different ranges of infrared study, while the F-22 turned out to be the brightest of all.

In general, the French promoted their "Rafale" with imagination

The layout of the nacelles of the 5 generation aircraft provides a ventilated air gap between the fuselage and the engines, which serves as effective thermal insulation. But only from the front of the hemisphere - from the back of the engine nozzle glow like spotlights.
Another thing is that the front parts of an airplane glider when flying at supersonic heat from friction against the air so that they glow at 100-150 km in the infrared range.
Well, the luminosity of afterburning torches of engines generally breaks all records.

[Rus2012]

Quote: Operator

Well, the luminosity of afterburning torches of engines generally breaks all records.

... everything still depends on the degree of bypass and the type of camera - with external mixing or internal ...
And there are a couple of more ways, but they are, as it were, not for public discussion :))))))))))))))))

[Iline]

Quote: Rus2012

... everything still depends on the degree of bypass and the type of camera - with external mixing or internal ...

Has anyone repealed the energy conservation law in the near future? Maybe I missed something, but if the gases of the burned fuel were heated during combustion, how can they be cooled? That's right - in the atmosphere. If this is carried out by the design of the aircraft, then at the moment there are no such heat-absorbing materials to completely fend off this temperature drop over a very short time. And if this is so, then even with all the technical tricks, this problem is solved. Another thing is that you have to stretch yourself a little.

[Rus2012]

Quote: Iline

Maybe I missed something, but if the gases of the burned fuel were heated during combustion, how can they be cooled? That's right - in the atmosphere.

.. makes it easier - by mixing the gases after the turbine with the air of the 2 circuit.
It all depends on the degree of bypass capacity of the engine (the ratio of gas volumes through the turbine to the volume of the 2 circuit), the design of the prechamber and where it mixes - before or after FC.
On T-50, in supersonic mode without afterburner - the temperature at the exit from the nozzle will be the lowest possible ...

[Iline]

On the F-35 is F-135, made on the basis of the F-119 for the F-22. 3-stage low pressure valve with blades made in one piece, 6-speed high pressure valve, combustion chamber borrowed from F-119, temperature in front of the turbine ATTENTION! is 1654 ° C, this is achieved thanks to cooling systems and cobalt alloys, the high-pressure turbine is single-stage, developed on the basis of the F-119, with double cooling, the speed is 15 rpm, the low-pressure turbine is 000-stage, then the afterburner with radar blockers.
Next, we take the principle of the jet engine (this does not depend on the technical implementation of the engine itself) - A thermal jet engine, the working fluid of which is a mixture of air taken from the atmosphere and the products of fuel oxidation with oxygen contained in the air. Due to the oxidation reaction, the working fluid is heated and, expanding, flows out of the engine at high speed, creating reactive thrust.
If this "working fluid" is intensively cooled, then there can be no question of any expansion of it, let alone exit from the engine at a high speed (physics Pupkin, damn it). Those. engine traction performance is lost. The situation can be slightly improved by reducing fuel consumption per unit of thrust. But only in order to slightly reduce the external air intakes for the extraction of additional air for cooling.
Or I'm wrong.

[Rus2012]

Quote: Iline

If this "working fluid" is intensively cooled, then there can be no question of any expansion of it, let alone exit from the engine at a high speed (physics Pupkin, damn it).

... looking how to cool!
If you take away heat, for example, forcing you to WORK on a turbine - then YES, the gas energy decreases (t, V). But, if you lower the temperature by mixing relatively cold air from the 2 circuit (increasing the volumetric flow rate of the working fluid), then NO ...

[Rozmyssel]

Quote: Iline

If this "working fluid" is intensively cooled, then there can be no talk of any expansion of it, and even more of its exit from the engine at high speed.

not to cool intensively, but to cover with heat-insulating screens, like the author says about this, meaning Rafal.

[Rus2012]

Quote: Thought

and cover with insulating screens

... and where does the heat go? ;)

[Rozmyssel]

Quote: Rus2012

Quote: Thought

and cover with insulating screens

... and where does the heat go? ;)

what do you think, but why do the same mi28 or apaches have engine boxes in which the exhaust is cooled by atmospheric air? In helicopters, this problem is solved exactly this way, and in airplanes, of course, not boxes, but simply screens, probably with holes that will cover the engine and shield heat.

[Rus2012]

Quote: Thought

ducts in which the exhaust is cooled by atmospheric air?

... of course everything is great, only at the same time the engine loses efficiency, and the boxes start to "glow" too, well, of course, not up to the exhaust temperature level (up to 700gr), but up to 300g. In addition, the boxes also have mass and dimensions ...
Everywhere there is "+" / "-"

[Rozmyssel]

Quote: Rus2012

everything is of course wonderful, but at the same time the engine loses its efficiency,

if the engine nozzle is completely shielded from free air, then according to the principles of thermodynamics, yes, but take a closer look at the helicopter, does it have fully shielded nozzles? No, in front of the box, cold air enters the nozzles and cools them, a similar option is possible on an airplane, but everything will of course depend on the design, but as for f22, it seems to me there, like jet engines, the nozzle is cooled by force with kerosene through the tubes inside the nozzles. Of course, the screen or box will heat up, but less.
By the way, did you notice the difference between our twigs, dryers and their phantoms and rafals? Our engine nacelles are black from overheating, but they do not, so they really worked more closely on the problem of heat shielding.

[Operator]

Not so - the ducts always remain cold (have an ambient temperature), since heat from the engine is taken away by the pumped air.
The same air at the outlet of the duct mixes with the exhaust of the engine, lowering the temperature of the exhaust gases.
Naturally, the casing and the mixer have additional weight. Additional power for pumping air is not wasted, because the mixer gives a free ejector effect on the suction of air.

[Rus2012]

.

Quote: Operator

... heat from the engine is drawn by the pumped air ...
.... Additional power for pumping air is not wasted, because the mixer gives free ejector effect on air suction.

... uv. colleague, and where you saw the "free ejector effect", for everything someone "pays".
In this case, due to an increase in flight resistance, because the midship is growing, and at the output t is still larger than the surrounding one (approx. 300), but as BE below the capture limit of the infrared seeker ...

[pimen]

Forgive me, it's curious: judging by the figure, the fan will start to slow down as the speed increases - but can't you mechanically "open the throat" in order to bypass the inlet flow directly to the high-pressure compressor?

[Rus2012]

Quote: pimen

to organize the bypass of the input stream directly to the high pressure compressor?

... this is done in a slightly different way - turbo-compressor units have control units in the form of rotary devices of blades of some stages.
There is a bypass, but mainly to eliminate surging.

[pimen]

Is swivel blades really easier? It’s more logical, after all, to bypass, while shading the fan so that it works only like a screen

[Rus2012]

Quote: pimen

Is swivel blades really easier? More logical, after all, bypass

rotary blades are not simpler, but it is also more difficult to coordinate the input parameters with the required ones on the steps in a gas-dynamic manner. And they have a narrow range of agreement on the height and speed of the aircraft.

[Rozmyssel]

Quote: Rus2012

Quote: Operator

Well, the luminosity of afterburning torches of engines generally breaks all records.

... everything still depends on the degree of bypass and the type of camera - with external mixing or internal ...
And there are a couple of more ways, but they are, as it were, not for public discussion :))))))))))))))))

... hit the target from the sun.

[Chukcha]

Some time after take-off, all aircraft will shine with their body infrared radiation. No one has any advantages here. The range is around 4 microns. However, the detection of IR radiation is very difficult, because it depends on the humidity (and in general on the state) of the environment. The higher the humidity, the more the radiation is extinguished. Here is the battle of infrared sensor technology.

[Chukcha]

Yes, I also forgot to mention the law of "detective power D *", which says that the ability to register a receiver decreases nonlinearly with increasing wavelength of infrared radiation.

[mr.redpartizan]

Thermal insulation around the engines will only increase the warm-up time of the airframe, but the heat should still be somehow removed. The only way is to blow air into the engines.

[Pensive]

// In addition, the important role in this case is played by the correct piloting of the machine when the pilot relies on his intuition, and as rarely as possible exposes to the enemy’s view the tail parts of the fuselage of his fighter, the turbines most heated by gases, and also uses the maximum and afterburners as little as possible engine operating modes. //

On modern fighter jets, the computer itself calculates threats of detection and gives advice on tactics. How it is implemented in the F-35 and F-22.

[Rus2012]

Quote: Pensive

he calculates detection threats himself

... the question is from all angles? ;)))
There are things that AI is not able to evaluate, it is determined only at the level of intuition in a stressful situation.
Read - http://www.rusarmy.com/forum/threads/subektivnoe-
vosprijatie-vremeni.4138 /

[Operator]

Rus2012,
I agree about the increase in the midsection and ejection fees.

[Rus2012]

Quote: Operator

I agree about the increase in the midsection and ejection fees.

+ 1!

[DimerVladimer]

Quote: Iline

The development of the 70s "MAK - UT" heat direction finder (installed on the Tu-95MS) makes it possible to determine the launch of a rocket (and not an aircraft!) From a distance of 250 km.

The thermal signature of the Earth-Air rocket - significantly higher, the thermal signature of a conventional fighter - uses highly pulsed solid fuel. The signature of air-to-air medium and long-range missiles is somewhat smaller - it is much easier to detect such a target than a fighter in the infrared range.

In addition, from missiles with infrared seekers there are very effective counter-measures in the form of heat traps, anti-ballistic maneuvers.

[barbiturate]

The author immediately began with a fairy tale about EPR
"Nevertheless, the objective technological reality makes it clear that this coefficient is in the range of 0,2 m2 for Lightning and 0,05-0,07 m2 for Raptor."
Where, what data were used, from what angles is this EPR? What is this "objective technical reality?" Our experts voice other data and they inspire more confidence in me than frank advertising of the manufacturer
And he writes right there
"However, it will be possible to find out only during a real military conflict, when the Luneberg lenses will be removed from the vehicles, turning any stealth aircraft into a huge radio-contrast target with the Igla or Tomketa radar signature."
In general, nothing is known, but I write ...)))

After speaking about the EPR, I personally liked the article, although again, the operating modes of the engines are not clear, the MIG-29 can be removed with full afterburner, and Rafal and F-22 are just at the maximum (i.e. the maximum without afterburner mode) and from another foreshortening. Or F-35, for example, the author writes

"In the vertical takeoff mode of the F-35B STOVL, with the afterburner operation of the most powerful turbojet engine F135-PW-600 (thrust 19507 kgf), the central and tail parts of the airframe had a thermal" luminosity "similar to the nose elements of the fuselage, i.e. no heating It just says that the manufacturers have taken good care of reducing the IR signature of this machine ... "

The author himself writes that the plane takes off, of course it is still cold, and will go on cruising supersonic and immediately become warm) Other ranges and luminosities will go there.