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Lockheed Martin F-22A Raptor

bring_it_on

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Infrared search and track sensor (IRST) systems are considered a high-value asset to the United States Air Force. Current systems can search, track and target enemy aircraft and discriminate between multiple aircraft at intermediate to long ranges better than many traditional radar systems fielded today. The unique capabilities of IRST technology is now driving the demand to provide the same capabilities for a variety of different tactical aircraft by improving performance and reducing size, weight, and power (SWaP). A key element to this approach is to move from a steered, small focal lane array (FPA) to a staring, large-format FPA. By eliminating the requirement for bulky mechanical stabilization and pointing hardware, a high-performance, low-SWaP, flexible IRST system can be realized. The challenge to developing such a system is in performing image stabilization in the presence of full aircraft kinematic movement. Toyon in partnership with Lockheed Martin Santa Barbara Focalplane, proposes a solution that uses IMU-based stabilization and innovative infrared search and threat identification algorithms to exploit the rich capabilities of LM-SBFs latest nBn sensors. The proposed system will result in a low-SWaP, wide-field-of-view (WFOV) staring IRST capable of long-range detection and tracking of targets in cluttered environments.; BENEFIT: At the end of the Phase I effort Toyon will have developed an approach for providing non-mechanical image stabilization for a staring WFOV IRST sensor. The Phase II work will lead to the development of a prototype staring IRST sensor based on the design approach established within the Phase I effort. Such a system will result in a high-performance, low-SWaP, WFOV IRST sensor with the flexibility to be installed on a variety of different tactical aircraft. In addition to being deployed in Air Force tactical networks, the main commercial prospect is in the field of commercial surveillance.

Successful implementation of an offensive staring infrared search and track (IRST) system can potentially yield significant benefits when incorporated into a fighter aircraft fire control system. It is anticipated that this type of passive sensor will yield higher performance in a more compact, lighter weight design with greater installation flexibility. Advancements in large format two-dimensional FPAs and readout integrated circuits offer potential advantages in clutter rejection, more frequent updates, longer integration times, multi-frame detection techniques, and image stabilization. It is expected that by exploiting these advantages, an IRST can be developed that supports long range detection and tracking of targets in cluttered environments with a low false alarm rate over a large field-of-view (FOV).

By leveraging advancements in the development of large format two-dimensional FPAs for wide FOV search and track to maximize aircraft installation flexibility and yield the highest performance in the most compact and light weight design, it is preferable to eliminate all mechanical pointing and line of sight stabilization components. This is especially critical for embedded/conformal sensors on highly dynamic aircraft. It is expected that successful implementation of electronic image stabilization and exploitation of other advantages of large format arrays will result in a novel and innovative IRST. It is envisioned that such a system can be developed to support long range detection and tracking of targets along clear atmospheric paths and in cluttered environments with low false alarm rates while staring over the system FOV.

The technical focus of this topic is to explore novel techniques and sensor chip assembly design concepts that can provide rapid control of the field of view from the subpixel level to a substantial fraction of the field of view to enable fine line-of-sight stabilization in addition to image motion compensation during aircraft maneuvering. The sensor wavelength bands of interest are midwave (3.0 to 5.0 microns) and longwave (8.0 to 12.0 microns). Stabilization must occur during the integration time of the FPA and requires an appropriate bandwidth input source.

Non-mechanical stabilization techniques such as those implemented in the FPA/readout integrated circuits of the sensor are of primary interest, but other techniques shall be considered. Mechanical and non-mechanical beam steering approaches are specifically excluded from this solicitation.

Teaming/collaborating with prime contractors to develop transition approaches is encouraged.

PHASE I: Investigate component-level concepts and techniques. Perform initial component prototype development and experiments to validate concepts. Establish system design implementation and provide technical analysis that supports the proposed design and quantify expected performance. Develop business case analysis and transition plan.

PHASE II: Based on Phase I results, construct and test a prototype imaging sensor to demonstrate and evaluate the design concept. Identify and reduce the risk of the component technologies needed to perfect the design and demonstrate the approaches needed for commercialization of a flight-capable instrument. Refine business case and transition plan.

PHASE III DUAL USE APPLICATIONS: Transition the newly demonstrated design to DoD industry partners. There may be some commercial applications that could benefit from the proposed approach.
 

riggerrob

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Canada could never afford F-15 or F-22.
The RCAF struggles to keep their CF-18A fleet in the air with expensive avionics upgrades and fatiguing airframes. They recently bought a batch of C-18A from the Royal Australian Air Force. Political meddling prevented the RCAF from buying F-35 … something about a trade war with Boeing over Dash-8 sales ....
 

Purpletrouble

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IRST would be an obvious upgrade to help with confrontations with other g5 stealth fighters, and probably also the biggest bang for the buck.


Cheek radars would be lower priority so long as the US would likely retain a preponderance in both surveillance assets and networking in likely battlefield. But if it become necessary to keep assets like AWACS from battlefields due to presence of such adversaries as j-20, it might be advantageous to fit the cheek radars that f-22 was designed for.


HMS would probably be a low priority because with only 187 f-22s, it should be the American strategy to make the maximum use of the f-22 stealth and speed, and avoid at all cost dog fighting with f-22.


My own feeling is f-35 really won't cut it against j-20 and t-50, and there will be a 10 year period between 2020 and 2030 when the US would wish it had a larger force of f-22s.
Sorry, but that is nearly all wrong.

IRST is much overhyped, hardly ever used. The F35 level yes, but that is basically a Laser Designator Pod embedded. The LDP is the thing pilots want because it is cued to the radar and has definition (and ongoing development, much easier to swap out and improve) orders of magnitude over IRSTs.

Cheek radar, yes low, as the radar fit is good, although ageing, software being the key issue and the inability of hardware to take modern software.

HMS, helmet mounted sight - the one thing they desperately do want. The advantages of this are beyond just short range dogfighting and relate to vastly improved SA (and we're not talking F35 look through here, just Euro HMS style) in all missions and flights at all ranges.

F35 doesn't need to "cut it", (a) there's hordes of them vs. serviceable J-20/t-50s, (b) working as a team is what all air combat is about anyway - there is a reason they fly 4-ships all the time, and if they have to, accept a pair! Pretty much nothing would stand a 4 ship of F35s with the sharing of info in terms of ease, reliability and speed that they can.

This whole F35 thing is like looking at HMS Tiger of the 1950s and saying "what, 4 x 6" barrels, that is awwwwwful vs. the 1930s Town class with 12". Ignoring the sensors and fire control system which makes the former worth multiple of the latter (let's just ignore reliability though!).
 

BDF

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F-22 EW system includes jamming antennae?

View attachment 630940View attachment 630941

Very interesting stuff. What document is this from? If this is accurate its interesting, beyond the ECCM stuff highlighted, is that the ALR-94 covers down to the C Band but can not cover the A and B bands; i.e. VHF and UHF frequencies. I wonder if the F-35 has the same limitations? I also wounder what the Cooperative Engagement Capability arrays are? 64 element AESA arrays. I wonder if they support missile data links?
 

Ronny

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Very interesting stuff. What document is this from? If this is accurate its interesting, beyond the ECCM stuff highlighted, is that the ALR-94 covers down to the C Band but can not cover the A and B bands; i.e. VHF and UHF frequencies. I wonder if the F-35 has the same limitations? I also wounder what the Cooperative Engagement Capability arrays are? 64 element AESA arrays. I wonder if they support missile data links?
It came from this book
Capture.PNG

F-35 EW can go down to band 2, so it won't has the same limitations
f-22 ew.PNG
file.png
 

stealthflanker

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I'm curious tho if the Band 2 is really used for Emitter locating, as in F-22 antenna of similar place are listed in as Navigation, Identification and Others. It probably an IFF Interrogator.
 

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Josh_TN

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I wish I understood the various band nomenclatures more accurately. That said, isn't IFF interrogation done in around the save wavelength as common datalinks like 16? L band, to use the lettered system? I'd be surprised if a single fighter sized aircraft could resolve angle outside of a cardinal direction in that range, but given a flight of aircraft with differentiation of time of arrival, they possibly could geolocate very accurately by sharing information over the MADL.
 

Ronny

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I'm curious tho if the Band 2 is really used for Emitter locating, as in F-22 antenna of similar place are listed in as Navigation, Identification and Others. It probably an IFF Interrogator.
According to what I know, Band 2 on F-22 is used for CNI but on F-35 it is used for EW function as well.
F35-TH18-Block4.png
RclUR2V.jpg
 

Sundog

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For all of his degrees, he really doesn't know much about aircraft design. The fact is, most of the aerospace companies said designing for stealth actually aided the aerodynamic design of their vehicles. For the record, stealth does not make an airplane unstable. One can design stable stealthy stable aircraft (See the Scaled Composites Model 401 for reference). What makes an aircraft stable or unstable, if I reduce it to it's most simplistic explanation, is the position of the wing relative to it's position on the fuselage (The over all center of mass to the aerodynamic center). Also, launching a missile isn't a huge change, although the flight controls, indeed, must compensate. The empty weight of the raptor is around 43,400 lbs, so it is going to weigh more in combat when it launches the missile. An AMRAAM weighs about 335 lbs. That's .7% of the F-22's empty aircraft. The C.M. isn't moving that much. In fact, opening the missile launch doors and the trapeze ejecting the missile probably cause a greater FCS response than the missile weight change.

Also, if you bank right, the left aileron goes down, causing the wing to go up and the right aileron goes up, causing the wing to go down. Also, the flight controls as air brakes they got from the YF-23 (Not that that matters). Just saying.

Also, like he said, fighters are easy to fly. There is a fighter pilot podcast on test pilots and the test pilot that is the guest normally flew C-130's. When she went to test pilot school and finally flew a fighter she couldn't believe how easy they were to fly.

The "G-Limit Mode" was interesting. It sounds like he's talking about neutral stability, which is really cool. I also like how they use the ailerons to unload the wing while pulling Gs as well.
 

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Hmmm having actually designed for stealth, it does not aid aerodynamics unless you are starting with a corrugated shed surface and the improved smoothing does aid both! The reason for actual comparable aircraft designs it is difficult relates to apertures (inlets/outlets being very inefficient to avoid large electromagnetic returns) and the angles of curvature. We saw the 80s where Aerodynamics was king in getting superlative performing platforms (F22, Typhoon, F16, F15 etc). Vs the 2000s of electro magnetics telling us “this is the shape it has to be, make it fly ok”. It’s one reason I eventually left.

There is mass confusion on stability. It is nothing more than if you disturb something, do the changes prompted by that disturbance return it to the original condition (stable) or exacerbate the disturbance (nstable).


Wing positon is true but a bit clunky - it is simply the position of the aircraft’s Centre of Gravity (CG) vs Aerodynamic Centre (AC, point at which aerodynamic forces can be reduced to acting through). This is for longitudinal stability - lateral would be the wingspan direction offset off the two.

If the AC is in front, a disturbance (eg gust) will create more lift and pitch the aircraft up about the CG, creating yet more lift and pitch = unstable. If behind, that extra lift pitches it back down = stable.
Generally you want stable, as trying to put countering control inputs in quick enough is beyond a human/most control system responses to avoid making it worse/being ineffective. Computers and fast responding high power controls overcome that. The advantage of instability is freedom of design and for fighters, the option to reduce supersonic drag by placing the AC ahead of the CG so that when it (AC) naturally migrates rearward in supersonic flight (about the only time it moves) it actually reduces control surface deflections required to trim (especially vice the opposite) - thus significantly reducing supersonic drag and enabling supercruise on dry thrust which gives you more supersonic range and critically for operational effectiveness, the ability to make more slashing in/out attacks per sortie.

Clearly too far away makes control difficult in that your control surfaces would need to generate huge lift/moment to change direction, leading to excess drag when you do.

Most aircraft have a box in which the CG is permitted to be based on weighs, the exact point being bespoke to that airframe. Payloads and stores have additional limits in clearing them generally heavy inboard . For example Harrier couldn’t ever carry Storm Shadow because it couldn’t handle the lateral stability impact of just having one (if one fired and the other didn’t) which would lead to loss of aircraft. It also couldn’t VL with SS fitted due to the required flap setting fouling the missile but that could be avoided by land based use and RVL.


Payloads are thus best at or near the CG (lat and long) for minimal impact when dropped or not present. Weapon launched the biggest concern is where it goes due to the complex aerodynamics interacting betwen store and aircraft. This was an entire area of specialism in my firm. There is youtube footage of an F111 dropping a drop tank, it goes down, pitches up, gains lift going upwards, pitching more up gains drag goes “backwards”, taking the wing with it.

Hence why stores are forcibly pushed away from the aircraft using gas powered piston ejectors and extending frames (internal/surface mounted). Rail launched are better in that they take themselves away but then you have the fear of hang up plus they seem to come off more easily on (very) heavy landings.
Sorry rather long post!
 

Josh_TN

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The above reminded me of one of my favorite old timy youtube videos. Its not just dogs that have separation issues:

 

Josh_TN

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631054[/ATTACH]
Any idea what "Non-MADL EA Mech" refers to?
I was curious about that too. I'd think EA was electronic attack in this context, but the MADL is the LPI datalink, so I don't see how EA would be part of MADL in the first place. However the MADL system is apparently something that exists more or less as software, not a separate set of boxes or antennas. The EA system likely time shares all the various wing and stabilizer mounted antennas with the com system; the radar certainly gets employed for EA. Mech = mechanism? Perhaps some type of EA system that doesn't use the wing/stabilizer apertures?
 

bring_it_on

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I guess one could read this in two ways. One could be that communicate via MADL during Electronic Attack or have some sort of cooperative EA mode. Another could be that MADL itself is a multi-function array like the radar. It seems the AN/APG-81 is also getting all round (surface, maritime, and A/A) electronic protection upgrades and probably some EA enhancements as well.

However the MADL system is apparently something that exists more or less as software, not a separate set of boxes or antennas.
MADL has its own dedicated Ku band Antennas spread across the aircraft.

It would be interesting to do a quick survey to see how many (if any) active missiles come with a Ku band seeker which would would make a current or future - Multi-Functional MADL aperture attractive for EA in addition to comms.
 

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Josh_TN

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Thanks for that, I didn't realize MADL used dedicated antennas.
 

TomS

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It would be interesting to do a quick survey to see how many (if any) active missiles come with a Ku band seeker which would would make a current or future - Multi-Functional MADL aperture attractive for EA in addition to comms.
Seems like several, based on a pretty cursory web search. Original ASTER, Meteor, Indian Astra and Akash. I suspect there are also several Russian and Chinese missiles, but info on their seeker frequencies are less available for some reason...
 

bring_it_on

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There was an Air Force S&T project looking to develop conformal antennas that could operate with both IFDL and MADL and either switch instantly or operate across these bands concurrently. Not sure what came of it, but thinking of these antennas beyond communication also seems interesting and something that could potentially be what these types of systems evolve too eventually.

 
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BDF

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Honestly I don't know why they can't just standardize the peer to peer data link around the MADL platform. I know they've updated the IFDL several times to improve bandwidth and other improvements but given that we're on the cusp of the Raptor's MLU it just makes eminent sense to upgrade the fleet to MADL. I realize there will be interoperability problems as the fleet cycles through MLU but once done you'll have both 5th Gen fighters on that standard and potentially the B-21.
 

bring_it_on

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I think it probably helps to move towards dual and multi-band conformal arrays, space permitting, just given the long term survivability and LPI/LPD goals. The size of these apertures would probably be platfrom specific so no reason to hold the B-21 to the SWaP constraints of of the F-22 or F-35.

 

Sundog

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Hmmm having actually designed for stealth, it does not aid aerodynamics unless you are starting .....
I was referencing what I had read from the ATF designers, about how the aligned edges aided the high alpha regime, in terms of controlling the vortices being shed (You don't want a curved leading edge) and also yaw stability at higher alpha due to the sloped sides of the fuselage. As an aeronautical engineer as well, I understand everything you're saying. One of the reasons Lockheed had to redesign their original ATF submission, besides being overweight, is it didn't have enough tail volume to push the nose back down with the large area chines it had originally. Why that wasn't caught in the initial design review is beyond me, as I wasn't there, but it seems obvious to me.

Also, the store separation issue you brought up can clearly be seen in the Super Hornets outward canted pylons, which still drives me nuts (Due to the added frontal area/drag increase).
 

sferrin

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Hmmm having actually designed for stealth, it does not aid aerodynamics unless you are starting .....
I was referencing what I had read from the ATF designers, about how the aligned edges aided the high alpha regime, in terms of controlling the vortices being shed (You don't want a curved leading edge) and also yaw stability at higher alpha due to the sloped sides of the fuselage. As an aeronautical engineer as well, I understand everything you're saying. One of the reasons Lockheed had to redesign their original ATF submission, besides being overweight, is it didn't have enough tail volume to push the nose back down with the large area chines it had originally. Why that wasn't caught in the initial design review is beyond me, as I wasn't there, but it seems obvious to me.

Also, the store separation issue you brought up can clearly be seen in the Super Hornets outward canted pylons, which still drives me nuts (Due to the added frontal area/drag increase).
The Super Hornet has curved leading edges on it's strakes too. ;)
 

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I think he refers having rounded or sharp leading edge for the LERX. Sharp leads to better predictable separation.
 

Sundog

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Hmmm having actually designed for stealth, it does not aid aerodynamics unless you are starting .....
I was referencing what I had read from the ATF designers, about how the aligned edges aided the high alpha regime, in terms of controlling the vortices being shed (You don't want a curved leading edge) and also yaw stability at higher alpha due to the sloped sides of the fuselage. As an aeronautical engineer as well, I understand everything you're saying. One of the reasons Lockheed had to redesign their original ATF submission, besides being overweight, is it didn't have enough tail volume to push the nose back down with the large area chines it had originally. Why that wasn't caught in the initial design review is beyond me, as I wasn't there, but it seems obvious to me.

Also, the store separation issue you brought up can clearly be seen in the Super Hornets outward canted pylons, which still drives me nuts (Due to the added frontal area/drag increase).
The Super Hornet has curved leading edges on it's strakes too. ;)
I was referring more to the overall platform and the sharp break at the water line as opposed to a slab fuselage as on the previous generations. Regarding the leading edges, you definitely don’t want it like the North American F-X design submission or the Sukhoi T-10, unless you enjoy wing rock at moderate to high alpha. Although it did make for good looking designs.
 

BDF

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I think it probably helps to move towards dual and multi-band conformal arrays, space permitting, just given the long term survivability and LPI/LPD goals. The size of these apertures would probably be platfrom specific so no reason to hold the B-21 to the SWaP constraints of of the F-22 or F-35.

Thinking about it you're probably right, it wouldn't surprise me to find out that the B-21 will use some sort of multifunction array that can communicate with IFDL/MADL providing the array has the bandwidth to cover those two waveforms. Theoretically it would just need the software to run it assuming the array can meet those constraints.
 
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bring_it_on

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I think it probably helps to move towards dual and multi-band conformal arrays, space permitting, just given the long term survivability and LPI/LPD goals. The size of these apertures would probably be platfrom specific so no reason to hold the B-21 to the SWaP constraints of of the F-22 or F-35.

Thinking about it you're probably right, it wouldn't surprise me to find out that the B-21 will use some sort of multifunction array that can communicate with IFDL/MADL providing the array has the bandwidth to cover those two waveforms. Theoretically it would just need the software to run it assuming the array can meet those constraints.
Yes that could be the goal. As well as to incorporate future higher frequency waveforms. I posted a link to the USAF funded S&T program on the Dual Band link covering both MADL and IFDL. The leap from there to a true multi-band system (like the one First RF (also the recipient of the award for the Dual Band antenna)) for a platform that has the space for it (like a UAV or Bomber) isn't too far fetched. I think given the vast communication and networking needs of the present and future, this may actually end being a net saving as far as efficiency and cost are concerned.
 
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Josh_TN

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Does the Talon HATE pod cover both of those wave forms (IFDL/MADL)? Regardless, it seems like it wouldn't be difficult to incorporate both into a new, larger airframe. The B-21 should have plenty of antenna space.
 

BDF

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Does the Talon HATE pod cover both of those wave forms (IFDL/MADL)? Regardless, it seems like it wouldn't be difficult to incorporate both into a new, larger airframe. The B-21 should have plenty of antenna space.
I believe it only covers IFDL and Link16. I'm curious how close the Eagles have to be to the Raptors to enable high bandwidth data flow. I worry that they'll (F-15s) be vulnerable in the high end fight if they have to stay relatively close to the F-22s. Has it been determined if they're acquiring this pod in any volume?
 

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Here is an old 1 page handout/brochure that was given out when one was on dispaly at LAFB before they were deployed.
 

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bobbymike

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I always do a quick “years since cancellation X 40 F-22s/year” calculation and we’d have what 500 raptors by now :mad:

 
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uk 75

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As someone who loved the Israeli versions of hot US fighters, especially their F15s ata time when USAF ones saw no combat, I was always disqppointed not see IDF Raptors strutting their stuff like Ziva in NCIS (Sorry too much Lockdown).
Was this the reason?
 

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Firefinder

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It’d be cool to see Raptors in an aggressor scheme. Probably unlikely that they would with the special coatings and all, but a guy can dream.
I don't know about that.

The Isrealies appereantly has a camo paintjob for their F35s that works with the stealth paint.

Then you have the Russian SU57s blue paint job that's apperantly RAM like.

If all that is true we may see some interesting designs...
 

helmutkohl

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indeed.. the Israeli F-35s have the standard honkey donkey scheme


one could dream though

 
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