F-35 air-to-air - Pro and Con

[exosphere]

Firstly why disrail this thread with a post not related to topic?

Sorry -- I thought this would be related to the thread since it's about the ability of the F-35 to hide from IRST sensors (I.e. the OLS) and thus be able to effectively conduct engagements without being detected. Anyways, that was what I was thinking as well -- the camera was at close range and was focused in on the F-22. I just didn't know the exact range, and I'm not sure how well optical detection scales with distance (I.e. how does a F-22's IR detectability at one or two kilometers scale to its detectability at BVR ranges), so I was wondering if anyone else had any answers.

If the post was really off-topic, feel free to have it removed/moved -- I just thought it related to the F-35s air to air capabilities. I didn't know I was derailing the thread.

[Lieven]

Firstly why disrail this thread with a post not related to topic?

Now now, don't be to harsh on a newbie poster. I'm sure there was no bad intent. Also, thanks for pointing out that other thread and answering his question.

[sprstdlyscottsmn]

Firstly why disrail this thread with a post not related to topic?

Sorry -- I thought this would be related to the thread since it's about the ability of the F-35 to hide from IRST sensors (I.e. the OLS) and thus be able to effectively conduct engagements without being detected. Anyways, that was what I was thinking as well -- the camera was at close range and was focused in on the F-22. I just didn't know the exact range, and I'm not sure how well optical detection scales with distance (I.e. how does a F-22's IR detectability at one or two kilometers scale to its detectability at BVR ranges), so I was wondering if anyone else had any answers.

If the post was really off-topic, feel free to have it removed/moved -- I just thought it related to the F-35s air to air capabilities. I didn't know I was derailing the thread.

Some one correct me if I am wrong, but thermal energy is a fourth order reduction with respect to distance. Thus doubling the range results in 1/16th the thermal energy making it to the sensor.

[count_to_10]

Some one correct me if I am wrong, but thermal energy is a fourth order reduction with respect to distance. Thus doubling the range results in 1/16th the thermal energy making it to the sensor.

Radiated power goes as temperature to the fourth power. In vacuum, the power per unit area at a detector will go down as distance squared, but in atmosphere there will also be an exponential absorption/reflection fall off (the rate of which depends heavily on frequency, air composition, and air density).
So, halving the temperature results in 1/16th of the total power being radiated (and potentially much less than that at a given frequency), but doubling the range reduces the power received by the detector by at least three quarters, possibly more if the wavelength you are looking at is strongly absorbed by air.

[newmanfrigan]

Also, you're relying on your amazing IRST system, getting ready to destroy the evil West with your coalition of like-minded partners, Russia, Serbia, Venezuela, Belarus, Iran and Syria. Everything's going great and stealth is a gimmick (and there are no gays in Russia).

...then it rains and IRST is on the blink. Gays are at the gates of Moscow.

Evil triumphs!

Your move...


On a less serious note: IR sig. reduction was part of the F-22, B-2, F-35 requirements. Figures are classified as far as I know.

[smsgtmac]

Okay, disclaimer first: I know this is from Keypubs, and I know that makes it of dubious reliability, but I saw something interesting while I was perusing the forums (it's great entertainment value!). I saw a thread where they were claiming that IR stealth is "impossible", and that the F-35 and F-22 can thus be detected by IR systems. One of them posted a link to this video of the F-22 at the Farnborough air show and used it as evidence that IR stealth doesn't work, that the F-22 is virtually as visible as other non-VLO aircraft, and that the F-22's RAM coating actually makes it MORE visible to IR, because it is rough and thus causes more friction heating.
...
This was followed by much congratulating by the other Keypublicans about the wit and intelligence of the poster for bringing up such hard evidence.

Personally, I can think of a few things wrong with this "analysis", but I was wondering if I could get any feedback from the people on this forum, as I'm not an expert on aircraft design or air warfare, and I know there are at least a few people that post regularly here that are.

Ah yes. I remember the thread Spaz linked to. Can't remember if I chimed in at the time, but most of all that big beautiful plume in the video disappears over a relatively short distance in free air. The natural constituents of the atmosphere absorb almost all of the IR emitted at just about the center frequency band of the exhaust plume. Conversely, the IR band (mid-high) from skin friction heating is where you find most IRST systems "looking". But unless your going supersonic low, you're probably not putting off much heat to detect.

[exosphere]

Ah yes. I remember the thread Spaz linked to. Can't remember if I chimed in at the time, but most of all that big beautiful plume in the video disappears over a relatively short distance in free air. The natural constituents of the atmosphere absorb almost all of the IR emitted at just about the center frequency band of the exhaust plume. Conversely, the IR band (mid-high) from skin friction heating is where you find most IRST systems "looking". But unless your going supersonic low, you're probably not putting off much heat to detect.

So, from what you guys are saying, it seems to me that the F-22 was in afterburner and going supersonic when the video was taken. Is that correct? I couldn't really tell...

[zero-one]

So, from what you guys are saying, it seems to me that the F-22 was in afterburner and going supersonic when the video was taken. Is that correct? I couldn't really tell...

Not really, No aircraft is allowed to go supersonic at dispalys because the sonicboom may result in some broken windows and eardrums.

Fastest Ive seen was a Hornet calling out his speed up until he went to .98 Mach, then he immidietly pulled up to stop accelerating,

The commentator jokingly said "you don't want to break any windows don't ya?"
Pilot said "no sir that'd be a bad idea"

Anyway point is, at that distance, flying a display, accelrating here and there using AB all the time, its prety easy for an IRST to pick you up,

go out a mile or two away (still considered a phone booth fight) then it won't be so easy.

Even for the state of the art Aim-9X test seen here.
[YouTube]http://www.youtube.com/watch?v=6YMSfg26YSQ[/YouTube]


at about a kilometer or two away the F-4 looks like a big white blob, its not until you get really really close that its starts to look like a plane.

The F-22 and F-35 will be much harder to detect

[zero-one]

The advancement of technology has changed the game and its important to be ahead of the game dictating the terms. In terms of building a fighter for BVR or WVR, you would elect for BVR. If I flip the scenario and said Russia had dominant BVR aircraft and the US had dominant WVR aircraft you would feel extremely exposed.

Well actually the idea is to be domminant in all forms of combat.

No one wants to design a fighter that would compromise WVR in order to emphasize BVR or vise-versa,

Even the Russians dont want this, they are doing everything they can to make their fighters as effective in BVR as possible, investing in Ram-jet powered weapons, AESA radars for fighter and missiles.

The requirement for the F-22 was to be uncompromising in its close combat WVR capability even though most people believed it would never need this.

Plus when it comes to WVR, the US still has many advantages, one of which is training, American pilots spend around 300 hours a year in training while Russians only spend 100-150 hours.

So in combat, the US will not fight BVR while the Russians fight WVR, its going to be a mixed fight, both sides fighting long and close range. and today fighters are being designed to fight both types of fights as effectively as possible

[hornetfinn]

IR stealth is definitely not impossible and I'm sure most modern 4+ generation fighter aircraft do have some IR reduction measures. F-35 and F-22 seems to have more extensive measures to reduce the IR signature. Of course totally hiding IR signature is impossible but there are many ways to reduce the signature. Just like radar stealth, the aim is to reduce detection and tracking range and increase the effectiveness of countermeasures (like flares, DIRCM systems). A close range high end thermal camera will see stealth aircraft just as well as non-stealth ones as there is more than enough radiated energy available to it.

Basically IR stealth can be achieved by reducing the amount of radiated infrared energy through masking and cooling. F-35 engine is well buried inside the aircraft and nozzle seems to have several IR signature reduction measures. The nozzle is quite well hidden and It seems to have ceramic coatings that likely has low thermal conductivity to keep nozzle relatively cool. There are indications that there is exhaust cooling system, probably using engine by-pass air. It's likely that there is cooling systems to cool the hot exterior parts. I think it's likely that F-35 will be significantly more difficult to detect with IRST systems than 4th generation fighters. How much more is difficult to say.

[sprstdlyscottsmn]

if you watch the IR SU-35S display, it's mil power looks like the F-22 with the AB lit, and when the Su-35S had the AB lit it was just a huge flare.

[castlebravo]

IR stealth is definitely not impossible and I'm sure most modern 4+ generation fighter aircraft do have some IR reduction measures. F-35 and F-22 seems to have more extensive measures to reduce the IR signature. Of course totally hiding IR signature is impossible but there are many ways to reduce the signature. Just like radar stealth, the aim is to reduce detection and tracking range and increase the effectiveness of countermeasures (like flares, DIRCM systems). A close range high end thermal camera will see stealth aircraft just as well as non-stealth ones as there is more than enough radiated energy available to it.

Basically IR stealth can be achieved by reducing the amount of radiated infrared energy through masking and cooling. F-35 engine is well buried inside the aircraft and nozzle seems to have several IR signature reduction measures. The nozzle is quite well hidden and It seems to have ceramic coatings that likely has low thermal conductivity to keep nozzle relatively cool. There are indications that there is exhaust cooling system, probably using engine by-pass air. It's likely that there is cooling systems to cool the hot exterior parts. I think it's likely that F-35 will be significantly more difficult to detect with IRST systems than 4th generation fighters. How much more is difficult to say.

Another possibility is to use materials that have significantly reduced emissivity in the wavelengths that the Earth's atmosphere is transparent to. That won't help you much in the WVR fight, but could severely restrict the range that an IRST is effective against you.

[av111]

The advancement of technology has changed the game and its important to be ahead of the game dictating the terms. In terms of building a fighter for BVR or WVR, you would elect for BVR. If I flip the scenario and said Russia had dominant BVR aircraft and the US had dominant WVR aircraft you would feel extremely exposed.

Well actually the idea is to be domminant in all forms of combat.

No one wants to design a fighter that would compromise WVR in order to emphasize BVR or vise-versa,

Even the Russians dont want this, they are doing everything they can to make their fighters as effective in BVR as possible, investing in Ram-jet powered weapons, AESA radars for fighter and missiles.

The requirement for the F-22 was to be uncompromising in its close combat WVR capability even though most people believed it would never need this.

Plus when it comes to WVR, the US still has many advantages, one of which is training, American pilots spend around 300 hours a year in training while Russians only spend 100-150 hours.

So in combat, the US will not fight BVR while the Russians fight WVR, its going to be a mixed fight, both sides fighting long and close range. and today fighters are being designed to fight both types of fights as effectively as possible

In an ideal world you want to be dominant in everything, but the question is more along the lines of which is more important.

As you mention Russia are developing their own advanced radar and medium to long range missiles so the actions of the enemy give you an idea of where future air combat is heading.

Also like you say WVR pilot training and strategy is hugely important. In truth if the F22, F35, Typhoon, Rafale, Sukois and Migs met each other in the air WVR then the pilots of each plane no matter which one you flew would start to sweat harder because the dominance of the aircraft is not decisive. To some extent developing an aircraft for manoeuvrability WVR has gone as far as it needs to go.

However by building an aircraft that focusses more on BVR fighting this on the other hand will allow you to tip the balance more decisively for air superiority. If you build an aircraft that focusses on this sphere there is a greater reward to be gained in terms of dominating the skies.

[count_to_10]

Another possibility is to use materials that have significantly reduced emissivity in the wavelengths that the Earth's atmosphere is transparent to. That won't help you much in the WVR fight, but could severely restrict the range that an IRST is effective against you.

Ideally, you would like to transfer heat to as much air as possible (that T^4 pretty much dominates every other consideration), but if you could arrange to have a coating that had nice tall emission peaks in the absorption bands of O2 and N2, that would definitely help. H2O and CO2 are probably easier to do, but there isn't that much CO2 in the air, and the amount of H2O varies a lot.

[XanderCrews]

Finding a needle in a haystack isn't any easier even if it glows.