Sukhoi PAK FA

[bhramos]

Chinese experts explain why India and Russia jointly develop FGFA | Russia & India Report

 

[bhramos]

http://indrus.in/articles/2011/10/1...ia_and_russia_jointly_develop_fgfa_13132.html

 

[bhramos]

Is the above image PS???

 

[Anshu Attri]

^^^^^^yes......

 

[Anshu Attri]

 

[Drsomnath999]

 

[Anshu Attri]

 

[Galaxy]

FGFA – what sort of plane is it?


December 19, 2011


The information about fifth-generation jet fighter is partially disclosed.

Hindustan Aeronautics plane maker has posted on its website some of the specifications of the FGFA model, thus raising the curtain over the future jet fighter created by Russian and Indian developers on the basis of Russia's PAK FA.

While some of the disclosed figures are quite predictable, some others are truly puzzling, if we believe everything that the Indian developer has to say. However, many of the basic parameters of the future jet fighter still remain undisclosed.

The Fifth Generation Fighter Aircraft (FGFA) is an Indian fighter being developed by India's Hindustan Aeronautics Limited (HAL) and Russia's Sukhoi based on the T-50 aircraft (PAK FA). Russia and India signed a contract for the creation of the concept and technical design on 21 December 2010, the amount of transaction being $295 million. It was planned that front-end engineering would take 18 months. During this phase, Sukhoi will account for 80% of the total volume of work. The Russian side has not yet disclosed the T-50 characteristics.

According to the description available on the Hindustan Aeronautics website, the proposed FGFA will have air combat superiority and media exchange systems to communicate with similar aircraft in conditions of poor communication support. They do not specify what "poor communication" stands for. HAL must be referring to jamming. It is also noted that the FGFA has a network centric warfare capability by getting access to the Indian Defence Ministry's database. (In mid-October 2010, India launched AFNET digital information grid, aiming at centralising the command of the country's Air Force. AFNET will later be combined with information grids of the Defence Ministry, the Navy and the Army. As a result of this centralisation effort, the Indian Armed Forces will coordinate their activities via a single data management and exchange system).

Other characteristics mentioned by the Indian developer include increased stealth, cruise at speeds well above Mach, and supersonic manoeuvring capability. The last feature is not specified, because "manoeuvring" can mean both aerobatic manoeuvres, which envisage a colossal impact of G forces on the pilot at supersonic speeds, and regular changes in the height and direction.

The length of the Indian fighter is 22.6 meters, its height is 5.9 meters, and its maximum takeoff weight is 34 metric tons. With a maximum speed of 2 Mach (2,300 kilometres per hour), the jet fighter will have a range of 3,880 kilometres.

The FGFA will feature two jet engines and have thrust vector control, with jet nozzle angle of +/-150. HAL does not mention in the description whether the FGFA will get all-aspect thrust vectoring, but it seems it will, because the Russian T-50 (PAK FA) will have all-aspect thrust-vector control.

According to HAL, each engine will reach a thrust of 1,400 kgf (13.7 kN). This one is a puzzling characteristic, because this thrust will clearly be insufficient for a heavy fighter. To compare: Indian heavy fighter Su-30MKI is powered by two Al-31FP turbofans, each producing 7,670 kgf dry and 12,500 kgf in afterburner.

The Indian specialists must have lost a zero somewhere – a thrust of 14,000 kgf looks suitable for the FGFA.

In September 2011, Indian Air Force Chief Norman Anil Kumar Browne said the military had chosen the engine that would be installed in the FGFA. The power plant will be introduced in two phases, following the T-50 patters. The Al-41F1C will likely become the engine of the first stage, whereas the one selected by the Indian Air Force will be used for the second stage. There is no information about the latter yet, except for the fact that it will produce more power than that to be installed in the T-50.

According to the description on the HAL website, the FGFA will have a maximum internal weapon load of 2.25 tons and external weapon load of 5.75 tons. The FGFA weapon load will therefore total 8 tons. The fighter is still at the design stage, so the reported figures are not final and will probably be adjusted after the prototype is created. The FGFA is expected to make its first flight in 2015 and go into service in India in 2017 or 2018.

In early October 2011, Browne said the Indian Air Force would procure 214 FGFA planes in addition to the 272 Su-30MKI that it already has. Previously, Indian Defence Minister Arackaparambil Kurien Antony said some $25-30 billion would be spent on new fighters. Browne added that 166 single-seat FGFA models would be purchased, while the remaining 48 fighters would be two-seaters, although the original plan was to buy only two-seaters.

Soon after India announced its plans to buy new jet fighters, some experts said single-seat FGFA would likely be different from the T-50 in the way that the Su-30MKI is different from the Su-30 of the Russian Air Force. In February 2011, HAL Finance Director D. Shivamurti said the FGFA development project would cost a total of $6 billion, and the Indian side would account for 35%-40% of the work. Specifically, Indian specialists will be developing an onboard computer, navigation system, data displays in the cockpit and the plane's self-protection system.

The two-seater will have more serious distinctions than just a larger cockpit. HAL Chairman of the Board Ashok Baweja said that the two-seater would have wings, fins, rudders and electronics different from those of the T-50. Also, the design of the Indian fighter must account for the use of Indian-made weapons, including Astra air-to-air missiles or Nirbhay cruise missiles.

http://indrus.in/articles/2011/12/19/fgfa_what_sort_of_plane_is_it_14029.html

 

[Anshu Attri]

To replace the Tu-160


I need to read the rules.ВЗГЛЯД / На смену Ту-160

By 2025, the Air Force should adopt a critical development until the designated abbreviation PAK DA (prospective aviation complex long-range aircraft). Now this is the role of the world's largest supersonic strategic bombers Tu-160. However, according to the terms of reference, certain parameters of the new aircraft will give the old one.

Command-range aviation of Russia issued the military-industrial complex tactical and technical requirements for the development of long-term strategic bomber the next generation, received the code name PAK DA. This was stated by the Commander-range aviation Maj. Gen. Anatoly Zhikharev.

"We would like to see this aircraft with a brand new sighting and navigation system, communications, reconnaissance, electronic warfare systems. He must use all the weapons that now exist and which will in the future armed with long-range aviation. The new aircraft is to be created using the technology of invisibility ", - said Anatoly Zhikharev.????

# {Weapon} According to him, in 2012, industry will present a preliminary design for approval by the forward-looking aircraft. The first prototype will be ready by 2020 and in 2025 a new long-range bomber entered service. Incoming PAK DA for service is determined by the completion of the resource challenges armed with long-range aviation bombers Tu-160 Blackjack and Tu-95. And this is approximately 2025-2030 years. Funding for development is within the state armaments program through 2020.
Top of the Russian program to develop PAK DA is a response to begun in the 1990s in the U.S. research project related to the creation of long-term air combat complex U.S. Strategic Air Command. This aircraft is designed to replace currently used strategic bombers B-52, B-1 and B-2, complete removal of the weapons with which to take place in 2037. The last program of its development is considered to NGB (Next Generation Bomber). According to the plans, design bomber runs until 2015 and conclude with the adoption of the concept of the aircraft. No later than 2020 to be held bomber selection of a specific project, and in 2035 - started its commercial production.
On Russia's new car is known very little. According to former Chief of Armaments of the Ministry of Defense Vladimir Popovkin, PAK DA should be the arithmetic mean between the two main Russian bombers - supersonic Tu-160 and subsonic turboprop Tu-95.
"If a supersonic aircraft, then it will not replace these two planes, if subsonic, then we lose something, but the aircraft will replace the two planes at once. Here, the simple answer is no, "- vaguely informed about the PAK DA Popovkin.
General uncertainty due to the fact that to date not fully decided how it should be promising bomber and what kind of tasks he has to solve. For example, the Tu-160 (development started in 1981, adopted in 1987) was created as a means of destruction of nuclear and conventional weapons the most important sites in remote geographical areas and in the rear of continental theaters of war.
Due to the speed of 2000 km / h and it could quickly fly anywhere in the world, where would cause air strikes on enemy territory. And to break the defense, escape from enemy fighters Tu-160 can climb into the stratosphere (the crew before the flight wearing almost the same suits as the astronauts), where his "normal" dual-mode rocket engine begins to run is a rocket.
The two compartments vnutrifyuzelyazhnyh he placed ammunition weighing 45 tons, strategic cruise missile Kh-55 (12 units) and hypersonic missiles aeroballistic X-15 (24 units). To hit small targets of tactical aircraft can be equipped with adjustable aviation bombs caliber from 250 to 1500 kg. All of them were created by the use of nuclear warheads. So he and a bomber, and its impact tools have a very weak sighting systems. Nuclear warhead blunder in 50 kilometers from the target is irrelevant.
Recently, however, the requirements for the aircraft has significantly changed. The Tu-160 was to be used not only as a means of nuclear deterrence potential enemy, but as usual bomber. In particular to counter the terrorists. As part of this machine has a new sighting system, new high-precision long-range cruise missiles - X-101 and X-555. Both were created in the DB "Rainbow".
X-101 has a mass of 2400 kg, warhead weight - 400 kg. Range of its flight - 5500 km. The missile flies in a complex profile - constantly changing altitude and flight path from 30 to 6000 meters above the ground. Maximum speed - 270 meters per second - making it virtually neperehvatyvaemoy for air defense missile-. Machine is equipped with electro-optical system of the flight path correction, as well as a television guidance system in the terminal phase of flight. This ensures the accuracy of hitting 12-20 m. X-555 is flying at a distance of 2.5 thousand kilometers. Target takes its satellite navigation system. For the TU-160 designed and guided aerial bombs KAB new-1500.
The only "but" all of this upgrade is that the "chase" supersonic bomber in the solution of the "local" problems economically disadvantageous. It is better to have approached the subsonic Tu-95. But these machines are in operation since 1956. Of course, they have been modernized. Can use the full range of high-precision weapons. Yet in the long term should leave the scene. Infinitely perfect one and the same aircraft is physically impossible. Looking for modern technological solutions. This is what is dictated by the need for a new bomber.
According to some reports, there are at least 10 different options for arranging car of the future. The most promising is the option of a subsonic bomber on a "flying wing", based on studies for long-range anti-aircraft theme 80s Tu-202. In the bomber has one bomb bay, which should accommodate Multi-ejection unit for six cruise missiles X-101 or X-555 weighing 16 tons. The range of the aircraft must be at least 7 thousand km. Given the range of the missiles hit targets should bomber at a distance of 13.5 kilometers.

Purge the project model 80s - antisubmarine aircraft TU-202. Perhaps it will take as the basis for the development of PAK DA (photo: vesti.ru)
Presumably, the propulsion system for the bomber is created on the basis of long-term engine "117S" "Saturn". This became the base engine - the engine of the "first stage" for a fighter of 5th generation of the T-50 with which the machine will go to the army in 2017. On the basis of the same engine creates so-called engine of the "second stage". Its distinguishing feature will be increased thrust, an opportunity to make cruising flight at supersonic speeds. At PAK DA suggest to put four of these motors.
Technology stealth, to which the general Zhikharev, is likely to be borrowed from the fighter T-50. For example, in the design of fighter aircraft for the first time used a range of advanced carbon fiber polymer. They are two times lighter than aluminum of comparable strength, and in four or five times - began, half the weight of titanium. New materials make up 70 percent coverage of the fighter. His weight was four times less compared with the plane, collected from conventional materials.
In CB "Dry" suggests that the use of new materials has resulted in "unprecedented low" level of radar, optical and infrared signature machine. Thus, the effective area of "‹"‹the reflecting surface of the T-50 is 0.5 square meters. m (the Su-30MKI - 20 square meters. m). This means that if the radar of Su-30MKI is seen as a metal object the size of 5 to 4 m, the reflection of T-50 - 40 times less. This ensures that the machine is not only low profile, but also greatly complicates the guidance of her high-precision weapons.
One of the most difficult parts of the project will be e-filling. In the Tu-160 is more than 100 computers. Probably, at the level of modern technology in their PAK DA is significantly less. But that's just their performance should be higher. For example, the assurances of developers, the T-50 - almost a robot. Around the fuselage fighter deployed dozens of different sensors that will not only monitor the situation around the car, but also to exchange data in real time how land-management systems, and with vnutriaviatsionnoy group. "E-pilot", self-analyzing a situation, the pilot offers a real range of options. For bomber similar requirements will be even greater.
It is curious that began development in the 90s, Americans are waiting for real results not previously in 2035. The Russian version - PAK DA - DB "Tupolev" is from 2008. His Adopting a plan tentatively in 2025-2030's. But, as expected, the rate of creation of PAK DA is unlikely to be "Stakhanovite". The reason for this - the lack of urgency in his appearance and huge costs of the project. In the U.S. only for development work on Next Generation Bomber plan to spend at least $ 10 billion How much will the program end up in the United States did not undertake to judge. Our development is estimated at $ 35 billion
Moreover, given the unreality of a military conflict between Moscow and Washington, Russia is unlikely to force the allocation of money to the PAC YES. As they say the military, combat potential of Tu-160 is now used only by 60 percent. American bomber B-52 are in service since 1955, although the shape and out of date, but after a series of upgrades (full replacement of electronics, engines, weapons systems), will serve another 40 years.
Most likely, the same path planning to go and our military. A PAK DA will be created with an eye to the United States. This will not only save money by not repeating the mistakes of others, but also make the car more modern. Using the fact that she was born later. Similarly, as is currently happening with the fighters of 5th generation. The Americans withdrew from the production its F-22, but we have not yet put in a series of his T-50. But even declare that he is the best.
Text: Denis Kovalenko

 

[indian_sukhoi]

Look at the engine body of PAKFA and F-22. It seems Russians didnt made any efforts to reduce heat signature from the engine.

Raptors are designed to reduce its infrared signal too.

 

[Twinblade]

Look at the engine body of PAKFA and F-22. It seems Russians didnt made any efforts to reduce heat signature from the engine.

Raptors are designed to reduce its infrared signal too.

The definitive engine for Pak-Fa enters testing around 2015(rumored). To spend money on signal management of non definitive engines is wasteful.

 

[Austin]

They can always go for Seratted Nozzle of F-35 type with Round Nozzle to give it stealth.

And you cannot reduce heat signature to the extent that it is usable in any Stealth Fighter , unless you to to some extreme length like using non-after burner engine and careful placing of engine mixes with cool air and other thing like B-2 does which needs size , the idea of using Serrated Nozzle or Flat Nozzle on fighter is to reduce Radar Signature and not heat.

 

[Twinblade]

They can always go for Seratted Nozzle of F-35 type with Round Nozzle to give it stealth.

And you cannot reduce heat signature to the extent that it is usable in any Stealth Fighter , unless you to to some extreme length like using non-after burner engine and careful placing of engine mixes with cool air and other thing like B-2 does which needs size , the idea of using Serrated Nozzle or Flat Nozzle on fighter is to reduce Radar Signature and not heat.

Nozzle design helps in reducing the thermal bloom as well. Flying at 60,000 feet, the exhaust plume of a jet engine makes a stark contrast with the ambient temperature. The plume of a regular jet nozzle is of conical shape, what the flat nozzles manage to achieve is pressing the exhaust plume into a sheet, similar to what happens when you squeeze your gardening hose end and water spreads into a sheet instead of a circular cross section. Due to this, the surface area of plume in contact with freezing air increases several times as compared to your regular jet nozzle, the cooling is more rapid and the exhaust plume as visible in the IRST shrinks several time (some rumours quote 4-5 times reduction in size). This achievement comes at the cost of reduced thrust. Serrations on the nozzle help achieve lower RCS and also create ripples on the surface of plume that increases its surface area (though not as much as a flat nozzle). The idea of using flat nozzles is also used in hairdryers, where an excessively hot plume used to damage the hair, flattening the nozzle made the temperature of hot air a little more homogenous

PS: If you can get hold of an IR camera, you can observe the exhaust of hair dryers with regular round nozzle and flat nozzle

 

[p2prada]

The biggest problem when it comes to RCS on engines is Carbon deposition on the nozzles.

 

[p2prada]

Saturn's flat nozzles.

saturn flat nozzle patent(2008) - YouTube

However Salyut has been chosen for Type 30 engine.

 

[Twinblade]

Saturn's flat nozzles.

saturn flat nozzle patent(2008) - YouTube

However Salyut has been chosen for Type 30 engine.

Saturn and Salyut are working together for the definitive engine.

 

[p2prada]

Yeah! Seems like Saturn won 54% while Salyut will work on 46% of the engine. Maybe.

Design and building the first few prototypes is apparently done. So, what remains is testing. I wonder if this is true.

 

[Austin]

Nozzle design helps in reducing the thermal bloom as well. Flying at 60,000 feet, the exhaust plume of a jet engine makes a stark contrast with the ambient temperature. The plume of a regular jet nozzle is of conical shape, what the flat nozzles manage to achieve is pressing the exhaust plume into a sheet, similar to what happens when you squeeze your gardening hose end and water spreads into a sheet instead of a circular cross section. Due to this, the surface area of plume in contact with freezing air increases several times as compared to your regular jet nozzle, the cooling is more rapid and the exhaust plume as visible in the IRST shrinks several time (some rumours quote 4-5 times reduction in size). This achievement comes at the cost of reduced thrust. Serrations on the nozzle help achieve lower RCS and also create ripples on the surface of plume that increases its surface area (though not as much as a flat nozzle). The idea of using flat nozzles is also used in hairdryers, where an excessively hot plume used to damage the hair, flattening the nozzle made the temperature of hot air a little more homogenous

PS: If you can get hold of an IR camera, you can observe the exhaust of hair dryers with regular round nozzle and flat nozzle

All that is cool and can be considered a nice scientific argument , if you fly at 60 thousand feet the radar will any way detect you and most modern radar are designed to detect small RCS target at sufficiently long range ( and dont tell me stealth is invisible )

For modern IR sensors seeker that are cooled at below zero degrees , they can even detect a small match stick flare at long distance , even if they manage to reduce Thermal Signature many fold with Flat Nozzle , the nozzle it self is sufficiently hot and the plume is enough to get a sweet IR spot for any decent single or two color IR seeker that looks at 2 different IR frequency.

Now if you add FPA type array that actually images the entire target and not just sweet hot spots , your flat nozzle wont help you much in IR spectrum.

If you recollect in one of the Franborough air show were the Rapier IR system detected a B-2 flying and created a controversy , you would have realised the B-2 did not create any engine signature but still the IR system could see the aircraft and image it. Now only if that was a missile nose it would have hit that bird.

The problem with IR system is how to cue it to the right place and for that you need a radar , if you can sufficiently be less visible to the radar you are in a way beating the IR system , but for any modern AAM like Python-5 ,RVV-MD and similar type finding a target like F-22 or PAK-FA wont be a challange if you are in a WVR duel with it.

Nozzle is that much better becuase you can exploit the 3 D TVC to enhance your manouveribility over a just 2D type nozzle that is what you will get with Flat Nozzle.

 

[Twinblade]

All that is cool and can be considered a nice scientific argument , if you fly at 60 thousand feet the radar will any way detect you and most modern radar are designed to detect small RCS target at sufficiently long range ( and dont tell me stealth is invisible )

Nope, I don't think that stealth is a magic bullet, its far from it. But I would also take SAM radar manufacturers claims with a pinch of salt. The fact that there is one stealth fighter flying around, 3 in prototype stages and 3 on drawing boards suggest that the advantage of a low RCS is undeniable. How long do you think before vlo planes get jammers with processors strong enough to counter frequency hopping and frequency modulation for dozens of channels ? There is a limit for application of LPI modes before it gets prohibitive for 1500 i/p o/p channels (assuming al T/x modules can operate independently and are not bunched together in large numbers), of which only a small fraction will be dedicated per target which will enable 5th gen platforms to come closer to LPI radars with minimal risk of being targeted than ever before ?

For modern IR sensors seeker that are cooled at below zero degrees , they can even detect a small match stick flare at long distance , even if they manage to reduce Thermal Signature many fold with Flat Nozzle , the nozzle it self is sufficiently hot and the plume is enough to get a sweet IR spot for any decent single or two color IR seeker that looks at 2 different IR frequency.

Now if you add FPA type array that actually images the entire target and not just sweet hot spots , your flat nozzle wont help you much in IR spectrum.

If you recollect in one of the Franborough air show were the Rapier IR system detected a B-2 flying and created a controversy , you would have realised the B-2 did not create any engine signature but still the IR system could see the aircraft and image it. Now only if that was a missile nose it would have hit that bird.

The problem with IR system is how to cue it to the right place and for that you need a radar , if you can sufficiently be less visible to the radar you are in a way beating the IR system , but for any modern AAM like Python-5 ,RVV-MD and similar type finding a target like F-22 or PAK-FA wont be a challange if you are in a WVR duel with it.

The jet nozzles, if made of proper material, would not be glowing hot (I am just talking about outer view of nozzles, not the plume or rear view looking into exhausts)

^This is the substance used on the outer surface of space shuttles, developed in the 60's. Its ability to maintain high temperature gradient enables one side to be as hot as 3000 degree celcius and other side cold enough to be held in hand without being too uncomfortable. Raptor's nozzles use a more durable material like this, both in form of lining and forming sawtooth edges. Even MiG 1.44 was supposed to use ceramic lining in the nozzles.

I, agree, when looking from rear hemisphere, any engine with any kind of signature management available today, should be visible at a long distance on any decent IRST, but from frontal hemisphere, with plume being rapidly cooled and the hottest core of the exhaust being obfuscated by the airframe itself, I'd dare say that a VLO platform can come very close despite IRST being focussed directly on it.

Nozzle is that much better becuase you can exploit the 3 D TVC to enhance your manouveribility over a just 2D type nozzle that is what you will get with Flat Nozzle.

One can design a 3D nozzle with petals but that would lead to terrible nozzle efficiency (although it will be squeezing plume into 3 planes instead of one and lead to a greater reduction in heat signature).

The Japanese are going for 3D petals placed over a regular nozzle (like x-31) but I doubt that it would be shaping the exhaust plumes much.

Edit: Another possibility about 3D thrust vectoring that I read (somewhere I can't put a finger on), was using regular 3 d nozzles with ovular exhaust instead of circular one, thereby increasing the plume surface area and still having 3D vectoring.

 

[Austin]

Nope, I don't think that stealth is a magic bullet, its far from it. But I would also take SAM radar manufacturers claims with a pinch of salt. The fact that there is one stealth fighter flying around, 3 in prototype stages and 3 on drawing boards suggest that the advantage of a low RCS is undeniable. How long do you think before vlo planes get jammers with processors strong enough to counter frequency hopping and frequency modulation for dozens of channels ? There is a limit for application of LPI modes before it gets prohibitive for 1500 i/p o/p channels (assuming al T/x modules can operate independently and are not bunched together in large numbers), of which only a small fraction will be dedicated per target which will enable 5th gen platforms to come closer to LPI radars with minimal risk of being targeted than ever before ?

Ofcourse where did i ever say Stealth was useless , far from it it gives you a killer advantage when combined with Super Cruise and Super Manouveribility over conventional 4th gen fighter that lack these qualities.

All wars so far both in 1991 where F-117 were used and 1999 Kosovo conflict where F-117 and B-2 were used was that they needed strong jammer support and/or enemy Radar was substantially degraded during their mission , Stealth without jammer support is a very risky proposition with high probability of being shot down when facing modern SAM , one of the reason why the F-117 have been claimed to have been shot was due to lack of jammer in the area on that day and it was shot with a 60's sam ( SA-3 ) using 60's radar.

The jet nozzles, if made of proper material, would not be glowing hot (I am just talking about outer view of nozzles, not the plume or rear view looking into exhausts)

^This is the substance used on the outer surface of space shuttles, developed in the 60's. Its ability to maintain high temperature gradient enables one side to be as hot as 3000 degree celcius and other side cold enough to be held in hand without being too uncomfortable. Raptor's nozzles use a more durable material like this, both in form of lining and forming sawtooth edges. Even MiG 1.44 was supposed to use ceramic lining in the nozzles.

Ceramics are used to reduce reduce the heat thats true and you can see the white coating even on PAK-FA nozzle but those gains are not substantial to reduce its effectiveness against modern 2 color Seeker or FPA array.

If you want to reduce the heat completely then you need more than Ceramics , mixing the hot gas with cold air and other classified technique is used on B-2 and for that you need space too something only bombers seems to have done so far like B-2.

If you check the IR image of Space Shuttle in space and after landing , you would see post landing the base area which uses ceramics still has the heat that IR detects look at the contrast when view through camera , not just becuase you can hold it in your hand does not mean IR will have problem detecting it.

http://nycaviation.com/newspage/wp-...06/endeavour-ir-landing-sts134big-300x234.jpg

Similarly looks at Space Shuttle IR view in relatively cold space

Spaceflight Now | STS-107 | Infrared images of space shuttle Columbia in orbit

Dont the SM-3 seeker uses 2 colour IR seeker in its kill vehical to hit a Warhead in cold space , see no reason why a more sophisticated FPA array or even a 2 color seeker would have any problems dealing with a hot nozzle or even the aircraft in normal atmosphere where the contrast in heat due to friction generated by speed and lack of B-2 like sophisticated cooling techniques on F-22 , JSF or PAK-FA would be any problem for modern IR seeker.

The Flat Nozzle is to reduce the RF signature of the aircraft when viewed from back or from ground based radar ( in X/S band ) , for modern IR seeker it wont be any great challenge to deal with.