F-22/F-35 vulnerability to IR detection?

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posted on Apr, 27 2006 @ 06:05 PM
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With the best will in the world, jet engines kick out a lot of hot air out the tail end.

In many low-observable designs an attempt to reduce the intensity of this is made by:
1. Not using afterburners (yes the F-22 follows this concept)
2. Having a long narrow exhaust to even out exhaust and reduce “hot spot”, usually with an elongated jet pipe.
3. Mixing the exhaust with cold air before it exits the aircraft.
4. Masking by tail etc.

But the F-22 and F-35 do not do #2 and probably not #3. Both of those features reduce the thrust which is negative to performance.

The square exhausts and worse round exhaust of the F-35 is likely to produce a hot spot much like conventional fighters. And that is before airframe heating.


How susceptible to IR/visual detection are these jets?

Mod Edit: Image Size – Please Review This Link.


[edit on 11/5/2006 by Mirthful Me]




posted on Apr, 27 2006 @ 06:15 PM
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my own thought on this is that these aircraft are only vulnerable in this respect from the rear and as long as they are attampting a BVR engagement whilst flying parallel with the FEBA, or even approaching it, it wont be a problem.

This however is a textbook interpretation of the mission and real life rarely follows the textbook, however, if the enemy is behind, stealth is irrelevant anyway and they have a real fight on their hands. In this situation I consider the Raptor to have a decent chance of engaging the enemy and winning while the F-35, although hardly as good as dead, has much less of a chance as its prime mission is bomb truck rather than fighter.



posted on Apr, 27 2006 @ 06:26 PM
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What about "all-aspect" IR seekers. The "top gun" seeker is apparently the Python-5. This is some propaganda but is generally factual:

Conventional air-to-air missiles see targets as dots - a fact which makes it hard for the missile to tell between true or false targets .The Python 5's head seeker literally sees a clear image of the target and background, giving it an incredible advantage over other missiles by authenticating the target, thus reducing the chance of being mislead by counter measures. Using this technology allows the luxury of locking on a target after the launch. The transition to this unique technology required a development by RAFAEL, which exists in only several countries in the world. Using an electro-optical head seeker also makes it easier to locate and lock on low-heat signature aircrafts such as UAVs, helicopters or even cruise missiles. These aircrafts can fly very close to the ground and can be very hard to detect using regular head seekers. The Python 5 with the electro-optical head can easily accomplish that, by creating a sharp target image and locking on it. In order to achieve perfect performance and tracking ability, the engineers at RAFAEL tested the Python 5 against all advanced counter measures. Usually this is a tough challenge, as the missile would have to handle counter measures in the future. But that was not an impossible challenge to RAFAEL, which also develops the future counter measures. The unique head-seeker also extends the lethality of the missile by aiming it to the target's most vulnerable areas. Most heat seeking missiles tend to home on the hottest spot of the aircraft which is normally the rear exhaust system. In modern combat history, some aircrafts that were hit by a missile in that area, managed to survive the flight until the landing. The Python 5, which acquires a sharp image of the target can home on the most critical areas of the aircraft, such as the cockpit or the central area, and significantly improve the chances for a shot down.

www.israeli-weapons.com...

Clearly the air behind the aircraft will be several degrees hotter than the surrounding air so if the IR detector is sensitive enough...


mod edit to include ex tags

[edit on 27-4-2006 by masqua]



posted on Apr, 28 2006 @ 04:47 AM
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For somebody that has manufactured an image of seemingly knowing a bit, that obvious and simple fact never occurred to me. My excuse is that I dashed off a quick reply before going to bed


I can see where measures have been taken in the Raptor to minimize the heat signature, the nozzles themselves are quite deep and partially shielded for instance, but as you say, if the seeker is sensitive enough? I rememebr reading that the PIRATE sensor on the Typhoon can detect and track an aircraft merely from the kinetic heating of its skin, that being the case I shouldn't think picking up an engine signature would be too much of a problem for any half decent IR missile.

The odd thing to me is that the F-35 design appears to have made no attempt whatsoever in this respect and appears to be no more stealthy at the back end than any afterburning jet ever built.



posted on Apr, 28 2006 @ 04:52 AM
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Planeman,

At range, even an imaging seeker 'only sees a dot'. The question then being whether tracking said dot can derive sufficient range rate and angle rate (intensity) driven trajectory prediction as to make a missile midcourse workable.

IMO, the answer is no. Because even a 6" round just doesn't have the motor umph to get the job done and a 20-25km seeker (which is only 11-13nm people) is probably not going to be able to effectively negate any but the last shots in a BVR dominated game which STARTS at 60-80km. And may well be broken off by 40.

That said, there is no reason not to put a dual spectrum seeker on an AAM where the value of the target dictates the expense. Indeed JCM, 'as a technical to tank killer', has a trimode seeker and most of the new generation ARM and AShM are also trending towards this.

At which point, the question becomes that of scaling vs. firing opportunity, both of which favor an 8-10" airframe solution _compatible with airframe mounted or aerostat lofted_ IRST.

Because PIRATE/EUROFIRST and OSF both have claimed detection thresholds of 60+km or 27nm, FQ, which would enable the ability to fire a heavier weapon like a wireguided torpedo to the point at which it's own seeker could take over a practical solution. And one which could even be 'two level' cued as a function of another set of (invisible or too cheap to suppress/counter) forward placed optics or even acoustics which detected the aircraft as it flew by.

................................10" motor = 70nm F-Pole|.............................................
Parent Fighter>>>>>>>>>|IRST Detection Threshold..................................
...........................................Missile>>>>|Seeker A-Pole Detection Threshold..
...................Aerosonde 1 [Bubble]................................................................
.......................................................Aerosonde 2 [Bubble]............................
....................................................................................Aerosonde 3[Bubble]
..................................................................................................................
...................AIM-120D SSC E-Pole|



posted on Apr, 28 2006 @ 05:17 AM
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Planeman,

The F-14D has tracked F-117's (which have quite a bit of dedicated IR stealth modification) with it's AAS-42. 'Within Phoenix Envelope' (say 12-40nm).

F-15's as long ago as 1977 were forced to engage in 'sprint to coast' (greatly exceeding 500 knots and then throttling back to hit the merge at optimum energy AND 'maximum cool' factored initial turn performance) fighting against adversary F-5E's in AIMVAL/ACEVAL. The latter having had a habit of using their AIM-9Ls (even as 'Concept C', fixed boresight) to track them coming in for their preferred vertical-conversion perch fighters and nailing them as high-hot targets.

It was from this that _the Lima_ was first revealed to be capable of 'tracking glint from the airframe' as well as plume. With the nominal suggestion being that the missile could use the former to adjust relative aspect and airframe deflection calculation of angular moment against the latter in adjusting it's proportional lead intercept.

Myself, I believe that most people continue to buy into the utter BS of 'must VID to kill, must close to guide, must fire at half the missiles true kinematic range' argument.

Such having simply NEVER been true except as falsely illustrated by the 'Vietnam Scenario' and LBJ dictated ROE/targeting.

Indeed, the basis of all ACMT is, IMO, far more likely to revolve back towards (1960s and onwards) _intercept_ training in that you steer the dot, max the Q, max the Pole and fire-fire-thru. He who get's the first kill _lives to leave_ the fight.

The only real change being that we no longer have analog SARH channel stacking to worry about so that one aircraft can guide another's shots into autonomy from 10-20-50nm to the rear or sides of the optimized intercept vector.

With NCTR and netcentric historicalism shooter-eyeball is thus reversed. And the first man to light up is NOT the first man to get smoked. Because the victim sees the illuminator as a search light on the horizon. While he KNOWS that, long before he can close to chuck a spear at cyclops, he is being painted for a ninja-kill at anything from knife to sword to longbow (time of flight as a functional variable of missile terminal energy) distances.

Fighter Tactics: _60-80km, next to no G on the airframe_
www.janes.com...


KPl.

[edit on 28-4-2006 by ch1466]



posted on Apr, 28 2006 @ 05:51 AM
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I haven't read your posts guys... so sorry if I repeat what you have said... I'am in a hurry...

The problem with 2 is that a long exhaust makes the plane less manouverable... Or at least slower when it comes to reactions in the air...

The cold air thing again (no idea) but I do think it would make the system to complicated... of course it could be adapted... But it wouldn't give as much as it would take... If you get my point...



posted on Apr, 28 2006 @ 05:59 AM
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Isn't this why the Raptor has supercruise capability (to fly supersonic without using afterburners)?

As planeman points out, it's hard to pick up an IR signal from great distances, so over enemy territory a supercruising F-22 would be very hard to pick up. Mixing the exhaust with cold air will create some extra drag, that's why it's better to have supercruising capability instead.

The F-117 can mix it's exhaust with cold air because it's only a subsonic plane anyway.



posted on Apr, 28 2006 @ 08:30 AM
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The F-22 uses the fuel to cool the wing leading edges, this heat is then vented (and the fuel cooled again) through a heat exhanger located about half way down the fuselage on the upper surface.

So from above the F-22 would have a significant heat signature, but from ahead and below it would be quite low (at least, thats the design intention
).



posted on Apr, 28 2006 @ 08:40 AM
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zion, even wih supercruise the air coming out of the back is hot, its just that afterburning makes it much hotter, thats what I was getting at when I raised the point about kinetic skin heating being detectable, no kind of jet engine blows out cold air, the closest to a genuine type I am aware of is the Harriers Pegasus where the hot efflux of the rear nozzles is mixed with the cold air that comes out of the front pair,



posted on Apr, 28 2006 @ 08:59 AM
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My thinking is that all A/C are dectecable Via IR.
F-22
F-117
JSF
B2
even a 172 should be picked up by sophisticated enough equiptment



posted on Apr, 28 2006 @ 09:00 AM
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Yeah, on non afterburning, I'd reckon the F-22 is pumping the air out the back at around 800-1000 deg C.

Aterburning that will rise to around 2300 deg C, maybe more



posted on Apr, 28 2006 @ 10:06 AM
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I hear certain camoflauge schemes can break IR locks but bvr ebgagement ebvelopes should increase with longer range AAM's. Not to mention the airplane can just slow down its speed to reduce its signature on IR. Not to mention Ir is hard to use at long range especially with the target supercruising at mach 1.7. I know the JSf is more vulnerable to IR than the Raptor and a subsonic plane like the X 45 or X 47 should b even lower.



posted on Apr, 28 2006 @ 10:26 AM
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It's a given that efforts have been made to REDUCE IR signiture comparable to similar aircraft on the F-22. These make it HARDER to get a lock.

But, is it still a combat practicality to get a lock? Even without afterburning, the jets are kicking out air at about 1000 degrees C. The surrounding air temperature is probably at -10~-50 degrees C at 30,000ft. So the higher the F-22 flies, the greater the heat contrast will be.



posted on Apr, 28 2006 @ 11:56 AM
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I may be all wet, but I was taught a long time ago that most modern IR missile seekers don not track "heat plumes" and "jet exhausts". Rather, the most accurate seekers home on the heat emissions of the super-heated exhaust hardware of jet engines themselves. The metal on jet engines emit a very narrow IR signature, which is much easier to home on, and is much harder to dublicate in the form of persistent flares and decoys.

The best IR countermeasures and decoys emulate the exact IR range of these metal parts, somehwere in the single-digit micron range.

I have also heard somewhere that the F-22 may use special composites in its exhaust system that emit a lower heat signature, in a non-standard range, making it harder to hit with anything but the latest IR seekers.



posted on Apr, 28 2006 @ 12:16 PM
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Originally posted by Pyros
I have also heard somewhere that the F-22 may use special composites in its exhaust system that emit a lower heat signature, in a non-standard range, making it harder to hit with anything but the latest IR seekers.


I've been told direct that the nozzles/exhaust have not been designed with IR signatures in mind.


I would also have serious doubts over the use of composites in an exhaust as the resin would have to be seriously good (and damn hard to work with) to resist temperatures of 2500+ deg.

More likely to use something like Silicon Carbide.



posted on Apr, 28 2006 @ 03:54 PM
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no kilcoo its ceramic titanium and it's good at cooling the nozzles giving you significanly reduced signatures. The best IR missiles dont have range that radar guided ones do. The amraam will shoot he Ac out of the sky well before coming into range and it will turn away at mach1.7 supercruise to make sure the enemy doesnt catch up at all. they will run out of fuel chasing it . And amraams will knock them out well before coming into range with Ir. Weather also affects IR.



posted on Apr, 28 2006 @ 04:55 PM
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Originally posted by urmomma158
no kilcoo its ceramic titanium and it's good at cooling the nozzles giving you significanly reduced signatures. The best IR missiles dont have range that radar guided ones do. The amraam will shoot he Ac out of the sky well before coming into range and it will turn away at mach1.7 supercruise to make sure the enemy doesnt catch up at all. they will run out of fuel chasing it . And amraams will knock them out well before coming into range with Ir. Weather also affects IR.
In an ideal world I agree, but much of the time the F-22s will be over enemy territory. Re IR missile ranges. The Russians have long since deployed longer ranged IR missiles, from the Acrid, Apex and of course Alamo. The R-27T Alamo is particularly relevant because it is still widely deployed, not least by China. It has a 32km launch range.
Here it is on a Chinese Flanker:

The seeker of the standard R-27T is probably less capable than those of the latest generation SRAAMs but those too are getting ever longer ranged.

And then there are advanced IR SAM systems, such as the Israeli SPYDER system which includes ground-launched Python-5 missiles which can probably reach altitudes of about 20,000ft.

[edit on 28-4-2006 by planeman]

[edit on 28-4-2006 by planeman]



posted on Apr, 28 2006 @ 08:27 PM
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The F/A 22 cruises at 50,000 feet and anyways who says the ranges on the heat seeking missiles will be the same they'll obviously be shortended especially with the Raptor fighting at BVR.



posted on Apr, 29 2006 @ 10:23 AM
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Originally posted by urmomma158
The F/A 22 cruises at 50,000 feet and anyways who says the ranges on the heat seeking missiles will be the same they'll obviously be shortended especially with the Raptor fighting at BVR.

Why would they be shortened and why ASSUME that the F-22 only flies at 50,000ft.

My point isn't that there are off the shelf missiles that can shoot down the F-22 with ease, but rather that the technology exists to make anti-F22 weapons systems reasonably quickly, such as combining latest generation IIR (Imaging Infra Red) seekers with medium/long range AAMs/SAMs.

Say the F-22 is launching an AMRAAM at an upgraded Su-30MK? Flanker from say 60km range. The upgraded Flanker could detect the incomming AMRAAM at say 30km (if not greater) and by doing a quick radar scan in that secto determine that it probably came from a stealthy launch platform. By firing a long ranged IIR seeking missile down the reverse path in a LOAL (Lock On After Launch) mode they at least get a IIR weapon into the general ball park of the F-22. If the F-22 is at about 50,000ft, where the air temperature is about -70degreesC(?) and the jet plume is up to +1000degreesC, finding it shouldn't be hard. A datalink between the missile and the Flanker and/or a ground control unit would further assist follow-up shots. Remember that the AMRAAM and its planned upgrades are far from the longest ranged AAMs - the various Russian K-172 and European Meteor WAAAYYYY out range it.





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