There are so many legends about the real effective reflective surface (EOC or EPR) of the 5th generation American fighters F-35A "Lightnung" and F-22A "Raptor"! From fans of cars and pro-Western-minded observers heard thousandths and even ten-thousandths of a square meter, from representatives of "Lockheed Martin" - similar indicators. 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 only be possible to find out 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 Tomcat radar signature.
An equally important indicator of the stealthiness of a promising multipurpose fighter of the XXI century is its small infrared signature, which is extremely important in medium and long-range air battles, where enemy fighter pilots turn off their onboard radars and rely solely on external target designation and their own onboard optical-electronic sighting systems. a kind of "cat-and-mouse game" begins, the winner of which will certainly be the one whose optical-location (infrared) sensors are more sensitive, and the glider's thermal signature is lower than that of the opponent. In addition, correct piloting of the machine plays an important role in this case, when the pilot relies on his intuition, and as rarely as possible exposes the tail parts of the fuselage of his fighter, the most heated turbine gases, to the enemy's view, and also uses maximum and afterburner operating modes as rarely as possible. engines. The combination of these measures gives an advantage in such types of air confrontation.
As for the direct thermal signature of the airframe and engine nozzles of modern transitional and 5th generation tactical fighters, they are very easy to see thanks to the use of high-resolution infrared cameras, which have recently become fashionable for representatives of thermal imaging equipment companies visiting various aerospace shows in different parts of the world to advertise their products. So, the infrared images of the American promising fighter F-35B "Lightning II", obtained by the "FLIR System" company during its performance at the International Airshow in Farnborough this summer, became a very informative work. Filming was carried out with a FLIR Safire 380-HD infrared camera with maximum resolution. What did you manage to observe?
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 occurred. This only suggests that the manufacturers took good care of reducing the IR signature of this aircraft, and it will be possible to detect this fighter in the front hemisphere at medium thrust modes of 10,000-12,000 kgf only from a minimum distance of 25-35 km using such an OLS such as domestic OLS-35 (Su-35S) 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 engine nacelles has a more open architecture, and clearly repeats the shape of the engines themselves. The space between the engine nacelle and the contours of the combustion chamber is not quite enough to establish a thick envelope of several layers of heat-absorbing material. Infrared images obtained by other infrared means show the "luminosity" of our front-line fighter MiG-29, the American Raptor, the European Typhoon, and the French Raphael.
The last one in this line looks the most serious. Engineers "Dassault" perfectly "covered" the M88-2 engines from the leakage of thermal radiation from the surface of the units to the tail of the airframe. The photo shows "cold" engine nacelles, like the F-35B. At the same time, the Rafale OSF optoelectronic sighting system has a detection and tracking range of heat-contrast targets of 145 km to the rear hemisphere. The Typhoon's nacelles are already beginning to "warm up": their contrast with the jet gas jet is no longer as great as that of the F-35B or Rafale.
Now comes the fun part. As paradoxical as it may sound, the F-22A F119-PW-100 engines running on afterburner warm up the tail of an inconspicuous fighter quite strongly; "A candle in the night field", even with the slightest displacement of the flight angle relative to the enemy.
And, finally, our MiG-29 and Su-27 can be considered the most "striking" representatives of fighter aircraft, which resemble real meteors or fireballs in infrared photography. The afterburner causes 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. It will not be so difficult to detect such an object using the same modern infrared system with a distributed aperture DAS (installed on the F-35A), even from 50-60 km, which gives American and European vehicles advantages in "radarless" combat.
A worthy decrease in the infrared visibility of the airframe can be said about the Chinese 5th generation multipurpose tactical fighter J-20: its power plant of two WS-10G turbofan engines is "planted" in deep and capacious engine nacelles, which makes it possible to carry out numerous experiments with its internal fuselage insulation.
As for our machines, there are a lot of technological ways to reduce the infrared signature of the airframe in the nacelle area, one of which is to install a special multi-layer nano-screen in the space between the turbojet engine and the inner surfaces of the nacelle, in the interlayer gaps of which cold air will be blown in from small air intakes. located either at the root of the wing, or on the aerodynamic influx of the wing, where there is sufficient internal volume to accommodate a large number of air ducts. As you know, in the first modifications of the MiG-29 ("Product 9-12 / 9-13") on the upper surfaces of the sag there were additional upper air intakes for the possibility of quick take-off from unprepared runways, called upper entrances. The gliders of the MiG-29 and Su-27 family fighters have great potential for modernizing their "thermal" perfection for proper protection against optical-electronic targeting systems of the enemy and missiles with infrared homing heads such as AIM-9X Block II, "IRIS-T" or " MICA-IR ".
