Can the F-35 match the PAK-FA

[hornetfinn]

The UV sensors should also be able to pick up afterburner activities within range, but that's mostly academic. It might be desirable to pick up an attacker on AB to gain a better BVR shot position, but the front aspect approach points that AB in the most challenging direction for the detector. If the Russians seriously wanted to track aircraft in those arcs occupied by the UV arrays (if they were serious about spherical SA), they'd have gone IR.

I doubt UV sensors can detect jet engine exhaust at meaningful ranges even if it was on full AB. Rocket engines have much higher exhaust temperatures than jet engines even on AB and even then the amount of UV radiation is rather small (especially compared to IR). The amount of UV radiation from jet engine on full AB would be dozens or hundreds of times smaller than most rocket engines and thus detection range would be very low.

Anyway, I agree that UV arrays give very little in spherical SA due to being only usable for missile launch and boost detection/tracking at shorter ranges. They are of little if any use for anything else. I think Russians had to use UV arrays as they have not enough technology to produce useful IR systems. IR arrays would need modern staring arrays with a lot of computing power and complex software to attain low false alarm rate and high reliability in detecting missiles. They require even more computing power and more complex software and very powerful databuses to be used for other tasks like DAS is used. I think Russian companies can not produce small and powerful enough systems (both detectors and computing systems) and decided that having UV arrays was better than nothing. When it comes to spherical SA, F-22 has very large advantages and F-35 is on a league of its own.

I'm not sure what you are getting at with your post.
The Russians have sinse the early SU days fielded IRIST for their Mig-29 and a bit later for Su-27S.
So they should have cracked any code of developing IR systems years ago..
The same goes for IR seekers in missiles.
And its clearly a fact that the T-50 Himalaya defence suite will corporate both IR and UV in this package.
But not only these two, but all the other sensors/radar as well.

There are many kinds of IRST systems. Earlier western ones and current Russian IRST systems are non-imaging types like used in many older IR missiles. Basically the seeker in those systems will only detect IR energy (or heat) and can only tell if there is some hot/warm object somewhere. It will not be able to tell what the object is or how large it is or how close it is or what the speed or heading is. This makes them totally unsuitable for detecting missile launches. Or actually they can detect the heat generated from the launch, but there is no way to tell whether the detected heat is a missile launch, a fighter aircraft, flares or a forest fire somewhere. These sensors use MWIR or LWIR band and max out when temperature gets to several hundred degrees Celsius and temperatures of 600 degrees Celsius look exactly like 6 000 degrees C. So they can not tell difference between the heat emitted by jet engine, regular fire or rocket engine. Another problem for scanning IRST system is that it's far too slowly scanning (several seconds each scan usually) to detect a missile launch reliably. IR MAWS all are either staring systems (like DAS) or very quickly scanning (several scans a second, like PIMAWS). IMO, it's very unlikely that fighter pilot using non-imaging IRST would recognize missile launch reliably even if the sensor was directly looking at it.

All UV systems are similar in that they can not tell where the UV radiation comes from or how large the object is or anything like that. Then why are UV systems used? Because very few things will be able to generate UV radiation in the wavelengths those UV sensors are sensitive (part of UV-C spectrum). Sun is an extremely powerful UV radiator, but all UV-C radiation is absorbed by the atmosphere well before it reaches the earth or even close to it. Pretty much all the UV-C radiation is totally gone before 40 km altitude.

Here is a picture about UV radiation and ozone concentration:


So there is almost zero chance that something radiating UV-C is going to be something else than missile rocket burning. That's why UV sensors have been used. It's very reliable and simple technology and requires relatively little computing power to be effective.

Then why use IR sensors in new missile warning systems, especially in fighter aircraft? It's because UV systems have several drawbacks and restrictions:

1. They are short ranged systems in all conditions. At best they can detect missile launch at several kilometers away (maybe up to 10 km) , but rarely much further than that because UV radiation is quickly absorbed by atmospheric ozone and oxygen.

2. UV systems work best at lower level where ozone concentration is usually quite low. At medium to high altitudes the ozone concentration is usually several times higher and thus effective range of the systems is much lower than at low altitudes. We are talking about only a few kilometers here at best and hundreds of meters at worst.

3. They can only detect the UV radiation from rocket plumes and pretty much nothing else. This means the missile launch has to happen at relatively close ranges.

4. UV sensors can be countered using better propellants in missiles which burn more cleanly and produce less particles to act as UV radiators. Refer to pdf I linked later for information about how rocket fuel can affect UV sensor detection range. For example a rocket engine with HTPB-AP-Al (aluminized) can be detected about over 10 times longer range than HTPB-AP. Incidentally modern missiles do not use aluminum as it would produce dense smoke which would be seen both visually and by UV sensors (because the hot smoke particles would be responsible for almost all of the UV radiation).

If you wish to learn more about UV and IR based MLD/MAWS systems, please read these:

Missile plume detection using UV sensors:
http://publications.tno.nl/publication/34607514/4ThnOV/neele-2003-electro.pdf
and
http://dspace.dsto.defence.gov.au/dspace/bitstream/1947/4256/1/DSTO-TR-0002%20PR.pdf

Imaging IR systems are something totally different. They create images from IR radiation that are very similar to regular photographs. This means each detector cell measures the temperature of very small part of the field of view of the sensor. These temperature differences are then converted to visual images. Imaging systems can measure very fine temperature differences and are much more sensitive than non-imaging ones. Problem is that they are much more complex and expensive systems requiring a lot of computing power to go along.

When these sensors are used for missile warning systems, they also have the problem of maxing out in temperature. The difference from older IRST systems is that by creating images, they use complex image processing and image recognition to filter out targets and track them. Missiles (or aircraft) are detected and classified by how objects move in sequential images and from their heat signature when close enough to get several pixels from the system. For example ballistic missiles move totally differently to surface to air missile or air to air missiles.

Imaging IR sensors have far longer range compared to UV sensors when used for missile launch detection and approach warning. We are talking about at least an order of magnitude longer range. They can detect and track both missile launch and missile in flight without burning rocket (although at much shorter range). They can also detect and track all kinds of systems besides missiles and can track far higher number of targets.

So all of this tells us:

1. Russians do not have suitable imaging IR sensors and/or processing systems available

2. F-35 (and F-22 and Dassault Rafale) has far superior performance in missile warning system

3. F-35 has far superior IRST systems with far larger coverage, very high resolution and range.

4. Missile warning system for PAK FA is mostly to protect it from MANPAD missiles taking off and landing as it's supposed to operate at high altitudes where UV systems are next to useless due to high ozone concentration. The placement of the sensors seem to confirm this as they are directed to sectors most likely attacked by such missiles. It would have very little chance of detecting fighter aircraft firing an AAM towards it.

[XanderCrews]

The F35 will not operate in A10 altitudes. It's too vulnerable to small arms.

Just as a quick aside, what are "A10 altitudes" and how is it "too vulnerable"

??

[borg]

A nice long post there Hornetfinn.
You will have to forgive me if i don't chop it up with quotes.

So i reply in short.
You accedently forgot to mention ANY shortcomings and limitations on a IR focal staring array on the F-35.
What about its POV. How can it detect anything above its nose and its upper hemisphere. There is a huge blind spot.
I hope you are not gonna say it could fly upside down..
This F-35 vs Pak-Fa, so its also about system and platform.
The Pak-Fa will clearly operate in high altidude on a A2A mission.
So the multi billion $ IR system on F-35 clearly has several limitations.
And its range is also in question.

cantaz posted earlier on the different atmospheric conditions which severly hamper any usage of IR-focal array from a 10000ft + altitude.
Imo, the higher the F-35 fly, the harder and more difficult it will be to perform any A2G mission due to atmospheric cloud interference.

So i'm also interesting in hearing what are A10 altidude and how "too valnerable"?
The F-35 cant choose to only do mission on optimal atmospheric conditions..

[cantaz]

You accedently forgot to mention ANY shortcomings and limitations on a IR focal staring array on the F-35.
What about its POV. How can it detect anything above its nose and its upper hemisphere. There is a huge blind spot.
I hope you are not gonna say it could fly upside down..

Based on your question, I don't think you know where all the staring arrays are located on the F-35.

http://i.imgur.com/6oNqcW5.jpg

This F-35 vs Pak-Fa, so its also about system and platform.
The Pak-Fa will clearly operate in high altidude on a A2A mission.
So the multi billion $ IR system on F-35 clearly has several limitations.
And its range is also in question.

The fact that IR has limitations in certain conditions is not at all equal to the fact that UV is straight up blind in many more conditions.

[SpudmanWP]

You accedently forgot to mention ANY shortcomings and limitations on a IR focal staring array on the F-35.
What about its POV. How can it detect anything above its nose and its upper hemisphere. There is a huge blind spot.

The F-35 has TWO IR systems, EOTS and EADAS.

EOTS is the combination of a traditional IRST and a FLIR/designation pod. It is mounted under the nose and can see to the front at +15 degree and -115 (IIRC). It is a long-range sensor that can ID fighters out to well beyond 75km.

EODAS is composed of 6 staring IR focal arrays that are spaced around the airframe and covers the F-35 in a complete 360 sphere of detection. It's primary duty is to track items that are identified by other systems and to act as a MLD/MAWS. It's likely limited to a tradition WVR rangeband for typical airborne targets and longer for MLD targets.

[castlebravo]

EOTS can ID fighters out to well beyond 75km.

That is impressive! Can you give me a source for that?

[SpudmanWP]

This is what the older Sniper pod can see at 36nm (66km). Take into account that the lettering is blurry (meaning that the original image is sharper than this video screen grab) and that EOTS is newer, 75km is easy.

[sprstdlyscottsmn]

I have the MGM grand picture somewhere... Taken by EOTS from 50nm as I understand it. If it can see a window, it can definitely ID a fighter.

[hornetfinn]

cantaz posted earlier on the different atmospheric conditions which severly hamper any usage of IR-focal array from a 10000ft + altitude.
Imo, the higher the F-35 fly, the harder and more difficult it will be to perform any A2G mission due to atmospheric cloud interference.

So i'm also interesting in hearing what are A10 altidude and how "too valnerable"?
The F-35 cant choose to only do mission on optimal atmospheric conditions..

There is no atmospheric conditions which would hamper IR focal plane arrays more than any other form of IR system. Actually IR FPAs have much higher sensitivity than for example non-imaging systems like used in Russian systems and have thus much better performance especially in poor conditions. Modern imaging IR focal plane arrays systems can see much better through clouds, haze and rain than can be done using optical systems and also UV systems.

See for example these:




Yes, when there is enough clouds, haze or smoke, then any IR system will be useless. That's why there is advanced radar in F-35 with very good air-to-ground capabilities to be used in those situations.

[mrbsct]

I never said the A10 was vulnerable to small arms fire. I said the F35 was. So it can't fly super low since it has a higher stall speed and flying too fast will cause an over-shoot, plus its skin is much lighter making it less durable than the A10 to small arms fire.

I don't see how this IRST thing is going to play a significant advantage. Not only is the F35's IRST better, the T50's IRST is said according to Bill Sweetman to be based off the OLS-35 which has an effective range of only 50 km, and only with low azimuth. Its laser range-finder is only 20 km range. The F35 has IR stealth, the T50 does not. The T50 if flying at higher altitude is more prone to getting tracked by IRST due to IR signatures being higher when the altitude increases.

Either way the F35 can see the T50 with its radar first, flank the IRST azimuth, and shoot without the T50 even knowing.

[sergei]

I never said the A10 was vulnerable to small arms fire. I said the F35 was. So it can't fly super low since it has a higher stall speed and flying too fast will cause an over-shoot, plus its skin is much lighter making it less durable than the A10 to small arms fire.

I don't see how this IRST thing is going to play a significant advantage. Not only is the F35's IRST better, the T50's IRST is said according to Bill Sweetman to be based off the OLS-35 which has an effective range of only 50 km, and only with low azimuth. Its laser range-finder is only 20 km range. The F35 has IR stealth, the T50 does not. The T50 if flying at higher altitude is more prone to getting tracked by IRST due to IR signatures being higher when the altitude increases.

Either way the F35 can see the T50 with its radar first, flank the IRST azimuth, and shoot without the T50 even knowing.

OLS-35 Detection range non afterburner aerial target (Front/Rear HemiSphere) 50/90 km.
What is " IR stealth" on F-35?

[mrbsct]

OLS-35 is effective at 50km at a frontal cruising target.

Infared stealth as in topcoat and loan nozzle.

[sergei]

OLS-35 is effective at 50km at a frontal cruising target.

Infared stealth as in topcoat and loan nozzle.

I doubt that the " loan nozzle" effect it will be very significant.
F-35 Engine exhaust is seen further when T-50 exhaust.

[sferrin]

F-35 Engine exhaust is seen further when T-50 exhaust.

Justify that comment.

[XanderCrews]

I never said the A10 was vulnerable to small arms fire. I said the F35 was. So it can't fly super low since it has a higher stall speed and flying too fast will cause an over-shoot, plus its skin is much lighter making it less durable than the A10 to small arms fire.

A-10s fly at thousands of feet now, they haven't done the low level thing in decades save for strafing or some special circumstances. Thats why they have things like targeting pods. And A-10stry to avoid flying at Stall speeds--- especially at low level for obvious reasons.

and the F-35 is no more vulnerable to small arms than any of the aircraft its replacing. and the USMC is going to use it for CAS

OLS-35 is effective at 50km at a frontal cruising target.

Infared stealth as in topcoat and loan nozzle.

I doubt that the " loan nozzle" effect it will be very significant.
F-35 Engine exhaust is seen further when T-50 exhaust.

You do realize you can't visually measure temperature?

Low observability, is not just for Radar, but also for Electronic Emissions, and Infra Red. There seems to be this stereotype that IR masking hasn't been thought about on the F-35, And that is dead wrong. In the mean time, the T-50 has two engines, and they are older Flanker engines. Russia has yet to develop anything like the F119/F135, so Its a safe bet the T-50 IR Signature is higher, and this is before we get into the exposed metal panels on the T-50...

I know every fanboi is praying that some little IRST ball is going to detect a F135 (amazingly from head on) but its not going to happen, espeically when the F-35 is detecting the I'm-down-to-my-IRST-in-a-world-of-radar-airplane first which is the whole purpose of all the work that went into the F-35s LO.