Detecting Stealth Aircraft in Infrared

[Martian2]

Conventional wisdom says that a stealth aircraft cannot be detected with infrared until WVR (ie. within visual range). The reason is due to geometry. The engine nozzles are in the back of the aircraft. As the F-22 is flying towards you, the aircraft itself is blocking the infrared signature.

Perpendicular patrol path

The obvious solution is to obtain a good look at the stealth aircraft engine exhaust. Thus, you need a stealth drone with EODAS to fly perpendicular to the expected flight path of incoming stealth aircraft. After a stealth aircraft passes the drone patrol line, the hot engines and exhaust should be clearly visible in infrared.

EODAS inhibits use of supercruise

Also, the stealth drone will inhibit the use of supercruise. The use of supercruise will light up the drone's infrared detectors like a Christmas tree.

By assigning a squadron of stealth fighters to the stealth drone, the defender can capitalize on the infrared detection of a stealth aircraft. In actual practice, there should be multiple groups of stealth drones and accompanying protective stealth fighters.

Infrared overhead perspective

In theory, a high-flying stealth drone (with infrared detectors) at 85,000 feet using an overhead perspective should be effective as well. There should be an F-22 or B-2 sized moving-infrared signature that does not comport with the infrared signature of the East China Sea waters.

Thousand of buoys with infrared detectors looking up

A third option is to deploy thousands of buoys with infrared detectors in the East China Sea. The sky is a uniform temperature. A jet exhaust passing overhead should register as a temperature anomaly. Of course, infrared detectors can also be placed on fishing boats, commercial ships, and military ships. On land, thousands of infrared detectors looking up can be deployed as well.

The objective is to look for the weak point of a stealth aircraft and devise a strategy to capitalize on it. By combining my suggestions on detecting a stealth aircraft in X-band/S-band and infrared, the incoming stealth aircraft will have a fight on their hands long before they reach their intended target.

Passive infrared detection is superior to active X-band/S-band overhead look-down search

Obviously, infrared detection is superior to X-band/S-band detection. Infrared is passive. X-band/S-band from an overhead high-flying drone is active. If you haven't read it, here's the link to my overhead X-band/S-band search for a stealth aircraft: Detecting Stealth Aircraft with X-band or S-band radar

Passive infrared will also pick up stealth cruise missiles

Thousands of passive infrared detectors on buoys have multiple uses. Not only are they useful at detecting stealth aircraft, the buoys can also detect stealth and regular cruise missiles. The buoy lines are an early-warning alert system.

In conclusion, my opinion is that stealth technology is being eroded when the other side has a comprehensive understanding of the strengths and weaknesses of stealth. By exploiting the weaknesses of stealth, a stealth aircraft becomes highly vulnerable.

 

[Donatello]

IR is simple, a fast moving body through a fluid (like air in this case) will put with the heat due to aerodynamic drag. That would be most evident at the leading edges, like the radar nose cone, slats, wind tips etc. A good IR sensor can pick that up and differentiate from the surrounding temperature. When flying at altitude of 40,000ft, the air is cold, so the greater the difference in the ambient temperature and the heat due to friction, the greater the quality of image you can obtain. Easy in principle, but difficult due to other factors, like Range and targeting, and weather permitting. Haze, Cloud, Rain etc will definitely smudge your image up. But that might be your only chance at detecting a true stealth aircraft, which wouldn't show up on a normal PD/AESA radar unless it is like right in front of your face. I was always curious about IR detection or LIDAR in place of RADAR for stealth detection. Any useful discussion and literature is welcome.

@sandy_3126 @Oscar

@SvenSvensonov
Any input on the IR detection of flying objects?

 

[gubbi]

you need a stealth drone with EODAS to fly perpendicular to the expected flight path of incoming stealth aircraft.

Defeats the whole purpose of 'stealth', doesnt it?

 

[SvenSvensonov]

IR is simple, a fast moving body through a fluid (like air in this case) will put with the heat due to aerodynamic drag. That would be most evident at the leading edges, like the radar nose cone, slats, wind tips etc. A good IR sensor can pick that up and differentiate from the surrounding temperature. When flying at altitude of 40,000ft, the air is cold, so the greater the difference in the ambient temperature and the heat due to friction, the greater the quality of image you can obtain. Easy in principle, but difficult due to other factors, like Range and targeting, and weather permitting. Haze, Cloud, Rain etc will definitely smudge your image up. But that might be your only chance at detecting a true stealth aircraft, which wouldn't show up on a normal PD/AESA radar unless it is like right in front of your face. I was always curious about IR detection or LIDAR in place of RADAR for stealth detection. Any useful discussion and literature is welcome.

@sandy_3126 @Oscar

@SvenSvensonov
Any input on the IR detection of flying objects?

It's an underutilized option, but an effective one. The rise of IR sensors is part of the reason the USAF is looking less towards stealth with its 6th gen program and more towards ECM and ECCM systems. Any fast moving body moving through a medium will generate a noticeable IR signature... the main issue facing a detection system is how significant that signature actually is.

CNO: Next-Generation Navy Fighter Might Not Need Stealth | Defense Tech

For long ranges, forget it, as you rightfully stated there are variables that will mess with an IR picture, radar will remain the sensor of choice, but when in tight, IR is the best method of detecting and attacking an enemy aircraft - hence why short range missiles are IR guided and not guided by radar.

Detecting electromagnetic signatures would work much the same as IR. Over long distances its effectiveness is dissipated by clutter and other signals, but up close it can be used to detect and vector munitions towards an enemy system.

What matters more than the amount of thermal energy (not to be confused with heat) generated by a system is if it can be discerned against the background. For land systems, operating on cold soil or a warm desert, an idle engine will produce a noticeable IR signature (and a noticeable EM signature). For an aircraft operating at altitude, even if the air around the plane is freezing, the amount of thermal energy in the background picture will still make for a confusing image.

The OP is interesting and has some novel proposals such as floating a bunch of IR buoys, good luck with that, but I disagree with a lot of the other stated items.

Remember, even if you detect a stealth aircraft, do your sensors and seekers have enough fidelity to accurately attack that aircraft? Does it matter if you can't detect the system if you can vector munitions to it? No at all.

I was always curious about IR detection or LIDAR in place of RADAR for stealth detection. Any useful discussion and literature is welcome.

http://www.researchinventy.com/papers/v3i12/D0312015019.pdf - hope this helps (it's about stealth/counter-stealth and does discuss Lidar)!

Defeats the whole purpose of 'stealth', doesnt it?

Yeah, and anyone suggesting this should be checked into a mental hospital. No military planner will fly their systems in predictable patterns or paths anymore. The US learned that the hard way when one of its F-117s was downed in Yugoslavia doing the exact same thing. The Yugoslavs learned the path the US aircraft took, the same one they always did, they set up a defense system and shot down the F-117. DON"T FLY PREDICTABLE PATHS!!!

As the F-22 is flying towards you, the aircraft itself is blocking the infrared signature.

The biggest emitter is suppressed, not blocked - leakage from the engine still heats the skin of the aircraft, but there is more than one emitter on the aircraft. Its wings generate friction, its surface heats up due to friction, engine heat and sunlight, the engines produce the largest and most noticeable signature... not the only one.

All stealth aircraft can be detected. The reason for creating stealth to begin with is to surprise your enemy, launch an attack, and supercruise to escape.

How do you sneak up on someone who can see you from over one-hundred miles away?

The U.S. Navy's Secret Counter-Stealth Weapon Could Be Hiding in Plain Sight - USNI News

Hard to hide from the very system that illuminates you. Small stealth aircraft can't support low-frequency protection, hence why they are optimized for high frequencies such as X, Ka, Ku and C. Modern ULF sensors will light up stealth aircraft from hundreds of miles, and the APY-9 has enough fidelity to vector missiles onto a stealth aircraft, something ULF radars have had a problem with historically.

The APY-9 radar has been suspected of being capable of detecting fighter-sized stealth aircraft, which are typically optimized against high frequencies like Ka, Ku, X, C, and parts of the S-bands. Small aircraft lack the size or weight allowances for all-spectrum low-observable features, leaving a vulnerability to detection by the UHF-band APY-9 radar, potentially detecting fifth-generation fighters like the Russian Sukhoi PAK FA and the Chinese Chengdu J-20 and Shenyang J-31. Historically, UHF radars had resolution and detection issues that made them ineffective for accurate targeting and fire control; Northrop Grumman and Lockheed claim that the APY-9 has solved these shortcomings in the APY-9 using advanced electronic scanning and high digital computing power via space/time adaptive processing. According to the Navy's NIFC-CA concept, the E-2D could guide fleet weapons, such as AIM-120 AMRAAM and SM-6 missiles, onto targets beyond a launch platform's detection range or capabilities.

Lockheed Martin AN/APY-9 - Scramble

E-2C/D Hawkeye Early Warning Aircraft - Airforce Technology

The E-2D and APY-9 have proven the fidelity of American anti-stealth radars and their ability to track and vector missile using their own sensors. This practice is known as Cooperative Engagement Capability:

Cooperative Engagement Capability - Wikipedia, the free encyclopedia

Run, but we wont let you hide. The days of stealth are coming to an end. The US recognizes this. Do you?

@Oscar @gambit - anything to add?

 

[Martian2]

Detecting hot engine plume temperature

As you can see in the citation below, the hot engine plume ranges from a temperature of 1,000 degrees Fahrenheit near the engine nozzle to a temperature of 100 degrees Fahrenheit at 100 feet away from the aircraft. This large moving heat source should be easily detectable with today's sensitive IR sensors. The hot plume cone is continuous and is "carried" by the aircraft.
----------
http://www.0x4d.net/files/AF1/R11 Segment 11.pdf (page 51)

 

[Hamartia Antidote]

Next up...drones flying around with 3 mile wires behind them with intermittent hotspots to confuse sensors.

 

[Indos]

Interesting, beside that Russia said that its new PESA is also developed to detect Stealth (into some extent)

Irbis-E development started in 2004 and the first radar prototype entered flight tests on board an Su-30M2 aircraft acting as a test bed in early 2007. The resulting radar system provides air-to-air, air-to-sea and air-to-ground (ground mapping, Doppler beam sharpening and Synthetic Aperture Radar modes) modes with improved performance in intense clutter (radar)environments compared to its predecessor, the Bars system. In addition, Irbis has been designed to detect low and super-low observable/stealth airborne threats.

@Horus @gambit @madokafc

 

[Norwegian]

Even aliens could not make their flying saucers stealth. You are kidding right?

 

[xunzi]

All stealth aircraft can be detected. The reason for creating stealth to begin with is to surprise your enemy, launch an attack, and supercruise to escape. Now if F-35 can't supercruise, then it is really junk.