FLIR , IRST in air to air mission

Cockpit, radar, helmet-mounted display, and other avionics
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by ricnunes » 03 Jun 2020, 19:51

BDF wrote:I'm well aware that the Chinese have struggled to master high end military turbo fan manufacturing. That is an entirely separate engineering discipline than airframe manufacture or systems integration for example.


And my point was that it's far more complicated to master stealth airframe manufacturing than it is to master turbofan jet engine manufacturing and the evidence of this is that only the USA really masters the former while several countries besides the USA (such as the UK, France, Russia and Canada) masters the later.
So if you can't master a simpler and far well known aerospace engineering field how would you expect to master a far more complicated aerospace engineering field which only one country really masters?


BDF wrote:Look, its obvious that we're simply going to go around and around on this. We'll have to agree to disagree. I hope you're right and that I'm wrong, but I'm not convinced that is the case. I'll bow out now, Regards...


Here, I agree with you and because this discussion is really getting "off topic".
“Active stealth” is what the ignorant nay sayers call EW and pretend like it’s new.


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by disconnectedradical » 04 Jun 2020, 15:32

zero-one wrote:The 3rd disadvantage listed is very interesting for me. If I'm understanding this correctly you can only configure it for high lift or low drag but not both.

The EF Typhoon's design seem to be high lift and simply uses brute power to compensate for the drag.


Wrong, if you actually read it, it's only referring to induced drag curve, i.e. drag induced from lift, which is dominant at low speeds or when turning, not in level flight. In level flight and cruise, parasitic drag, and at supersonic speeds, wave drag are the dominant ones. Delta wings tend to do well in wave drag, why a lot of early supersonic fighters are pure delta. It's saying that canard aircraft can configure for CLmax or induced drag, which means it can either optimize for max instantaneous turn rate or good sustained turn rate, but having good values for both is much harder.


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by disconnectedradical » 04 Jun 2020, 15:38

ricnunes wrote:And my point was that it's far more complicated to master stealth airframe manufacturing than it is to master turbofan jet engine manufacturing and the evidence of this is that only the USA really masters the former while several countries besides the USA (such as the UK, France, Russia and Canada) masters the later.
So if you can't master a simpler and far well known aerospace engineering field how would you expect to master a far more complicated aerospace engineering field which only one country really masters?

How are you making this claim? That's not really how it works, specifically in terms of jet engines a lot of it is backed by institutional knowledge, so not mastering that part doesn't mean you're not formidable in other aspects of aerospace engineering. For example even though Soviet Union was way behind in gas turbines, it was way ahead of US in ox-rich staged combustion rocket engine, because of experience and institutional knowledge.

Even Japan, a technologically advanced country which is a front runner in engineering of composite materials, struggles with engine technology. Because they don't have the kind of institutional knowledge US or even Russia has.


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by zhangmdev » 04 Jun 2020, 21:32

US rocket engineers thought oxygen-rich staged combustion engine is basically impossible, so why bother? They went down a different path. I think F-22 doesn't have something like Rafale's Front Sector Optronics for the same reason: the benefit isn't worth the effort.

With enough computing power, one can assemble an aircraft virtually, down to every single fastener, fine-tuning the manufacturing process repeatedly without physically making anything. Things went like that since the days of Boeing 777 development. And computers improved a lot since then. One cannot do that to jet engine development. Computer simulation can only help some part of it, like aerodynamics around the blade, combustion in the chamber. Computers cannot simulate the whole thing. That is too complicated even for today's computers. To prove any design change works, one must physically make the component, sometimes the whole engine, and run it. Making physical things are way more difficult and expensive and time-consuming than tweaking parameters in some computer software.


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by ricnunes » 08 Jun 2020, 16:28

disconnectedradical wrote:How are you making this claim? That's not really how it works, specifically in terms of jet engines a lot of it is backed by institutional knowledge, so not mastering that part doesn't mean you're not formidable in other aspects of aerospace engineering. For example even though Soviet Union was way behind in gas turbines, it was way ahead of US in ox-rich staged combustion rocket engine, because of experience and institutional knowledge.

Even Japan, a technologically advanced country which is a front runner in engineering of composite materials, struggles with engine technology. Because they don't have the kind of institutional knowledge US or even Russia has.


The above basically concurs with my point.
If mastering well known technologies worldwide (such as jet engines) is very/extremely hard then imagine what would take to master a technology (such as Stealth) which only one country (USA) really masters.

Speaking about "experience and institutional knowledge" I would say that China is probably one of the countries (among the most powerful ones in the world) that have the "lowest level of that" when it comes to Stealth technology.
“Active stealth” is what the ignorant nay sayers call EW and pretend like it’s new.


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by marauder2048 » 11 Jun 2020, 19:08

hornetfinn mentioned it upthread but the positive and negative contrast that imagers use to locate
targets against backgrounds needed an illustration that I couldn't find in the open literature until now.

from "Reconstruction of the 3D Temperature and Species Concentration Spatial Distribution of a Jet Engine Exhaust Plume Using an Infrared Fourier Transform Spectrometer Hyperspectral Imager" by Mason D. Paulec.

https://scholar.afit.edu/etd/1953/
Attachments
f-15-imagery.png


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by falcon.16 » 28 Jun 2021, 20:53

How much is the scanning rate (FPS) on an IRST?
https://aeropathfinder.blogspot.com/


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by doge » 01 Jul 2021, 05:11

falcon.16 wrote:How much is the scanning rate (FPS) on an IRST?

Is this related to scan speed ? :roll:
I am not familiar with scanning or EOTS at all. :doh: (Apology in advance. :notworthy: )
EOTS1.gif
EOTS1.gif (2.23 MiB) Viewed 6886 times
EOTS2.gif
EOTS2.gif (1.85 MiB) Viewed 6886 times

@3:15~ 8) Spaz's video.
https://www.youtube.com/watch?v=-sNlDgnRzm8

@0:58~
https://www.youtube.com/watch?v=xAvgnMPANeE


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by falcon.16 » 01 Jul 2021, 09:36

doge wrote:
falcon.16 wrote:How much is the scanning rate (FPS) on an IRST?

Is this related to scan speed ? :roll:
I am not familiar with scanning or EOTS at all. :doh: (Apology in advance. :notworthy: )
EOTS1.gif
EOTS2.gif



Thanks, gimball is fast, but i am talking about scanning. You can be fast moving optics, but slow scanning when your field of view is 1-3º. I think is around 30fps, maybe 60 fps most modern systems.
https://aeropathfinder.blogspot.com/


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by hornetfinn » 09 Aug 2021, 09:54

falcon.16 wrote:
doge wrote:
falcon.16 wrote:How much is the scanning rate (FPS) on an IRST?

Is this related to scan speed ? :roll:
I am not familiar with scanning or EOTS at all. :doh: (Apology in advance. :notworthy: )
EOTS1.gif
EOTS2.gif



Thanks, gimball is fast, but i am talking about scanning. You can be fast moving optics, but slow scanning when your field of view is 1-3º. I think is around 30fps, maybe 60 fps most modern systems.


Most thermal imaging systems (including IRST and FLIR) are either 30fps or 60fps. There are some high-speed thermal imaging systems, but they have not been suitable for military roles due to many reasons like resolution, cost, weight/volume, data volume (processing and data transfer requirements) and maintenance needs. For most purposes 30 fps is good enough if resolution can be kept high enough and other parameters good enough.

FoV is usually variable and for search purposes it's usually more like 5-20 degrees in most systems. 1-3º (or even less) is usually used to single target tracking and identification purposes. Many IRST systems don't necessarily even have that narrow FoV available as they don't have enough volume for required optics. F-35 is pretty unique that it always carries combined IRST and FLIR/targeting system with both functions and having much superior narrow FoV to other current IRST systems.


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by falcon.16 » 09 Aug 2021, 18:00

hornetfinn wrote:
falcon.16 wrote:
Thanks, gimball is fast, but i am talking about scanning. You can be fast moving optics, but slow scanning when your field of view is 1-3º. I think is around 30fps, maybe 60 fps most modern systems.


Most thermal imaging systems (including IRST and FLIR) are either 30fps or 60fps. There are some high-speed thermal imaging systems, but they have not been suitable for military roles due to many reasons like resolution, cost, weight/volume, data volume (processing and data transfer requirements) and maintenance needs. For most purposes 30 fps is good enough if resolution can be kept high enough and other parameters good enough.

FoV is usually variable and for search purposes it's usually more like 5-20 degrees in most systems. 1-3º (or even less) is usually used to single target tracking and identification purposes. Many IRST systems don't necessarily even have that narrow FoV available as they don't have enough volume for required optics. F-35 is pretty unique that it always carries combined IRST and FLIR/targeting system with both functions and having much superior narrow FoV to other current IRST systems.



Yes, i was reading and for example new Skyward Irst (evolution from Pirate) in narrow field of view is 8º*6.4º and in wide Field of view 30º*24º. They have a medium field of view 16º*12.8º

I think when they need to scanning and dont have support from radar, need search on WFoV, due to slow scanning rate. But on this case, detection range drop quite a bit compared to NFoV.

Flir in EOTS will be of great help in identification tasks with a maybe 1º*1º, but of course nned to be slave to radar.

Scanning rate of 30 FPS can be ok in medium and wide field of view, but i dont think same with Narrow field of view. Only if you know exactly point where you need look, you need a principal sensor telling you that.
https://aeropathfinder.blogspot.com/


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by hornetfinn » 10 Aug 2021, 09:15

falcon.16 wrote:Yes, i was reading and for example new Skyward Irst (evolution from Pirate) in narrow field of view is 8º*6.4º and in wide Field of view 30º*24º. They have a medium field of view 16º*12.8º

I think when they need to scanning and dont have support from radar, need search on WFoV, due to slow scanning rate. But on this case, detection range drop quite a bit compared to NFoV.

Flir in EOTS will be of great help in identification tasks with a maybe 1º*1º, but of course nned to be slave to radar.

Scanning rate of 30 FPS can be ok in medium and wide field of view, but i dont think same with Narrow field of view. Only if you know exactly point where you need look, you need a principal sensor telling you that.


Yes, that is totally true. However I can see several situations where NFoV search could be very useful. Especially so in F-35, which has fully automated and networked sensor fusion engine. In 4th gen fighters some of these would not be possible as they lack both of these features. The difference get larger and larger in more complex and target-rich situations

1. F-35 radar is used to search for targets and then further ID'd with EOTS NFoV imagery. Radar could be in the same F-35 or in some other F-35 within the network.
2. Some off-board sensor like surveillance radar detects and tracks a target and target location is well known. Basically the same as first one but with different source sensor
3. AN/ASQ-239 detects some emissions. It also has high angular resolution, so a NFoV EOTS search could be used to determine what was the source for that emission. EOTS has the advantage of being able to quickly look to the sides and even back without turning the whole aircraft around.
4. EO DAS detects a missile launch (AAM, SAM or BM). It also has high angular resolution and thus EOTS NFoV search can be used to determine what launched that missile or even track the missile itself depending on situation.
5. EOTS WFoV search detects some new blip, which is not detected with other sensors. Sensor fusion would likely do a quick NFoV search with EOTS until it could track and then ID the blip or discard it as an anomaly.

IRST systems do have to compromise between angular coverage and range. So especially in 4th gen aircraft they would be supporting system to radar for searching and tracking. They do have the advantage of having superior angular resolution and being totally passive. However latest thermal detectors with very high resolution and sensitivity would allow quite long detection distances against most targets even with relatively wide FoV. That would mitigate some of the problems associated with those systems. For example next gen EO DAS for F-35 will give quite significant improvement for spherical IRST capabilities and Advanced EOTS will give improved long distance detection/tracking/ID capabilities for it.


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by ricnunes » 16 Aug 2021, 11:15

hornetfinn wrote:However latest thermal detectors with very high resolution and sensitivity would allow quite long detection distances against most targets even with relatively wide FoV.


And that if there aren't any obscurants between the IRST and the target like for example a cloud or if the target doesn't have any IR signature reduction measures (something that the F-35 for instance has). :wink:
“Active stealth” is what the ignorant nay sayers call EW and pretend like it’s new.


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by hornetfinn » 16 Aug 2021, 12:07

ricnunes wrote:
hornetfinn wrote:However latest thermal detectors with very high resolution and sensitivity would allow quite long detection distances against most targets even with relatively wide FoV.


And that if there aren't any obscurants between the IRST and the target like for example a cloud or if the target doesn't have any IR signature reduction measures (something that the F-35 for instance has). :wink:


IR systems are good in clear conditions and it can see through clouds/fog better than visible light systems or naked eye can see. However radar systems are vastly superior seeing through fog/smoke/clouds but have their own restrictions. Of course best is to do what F-35 does and use the strengths of each system to the fullest with networked and automated sensor fusion system.


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by ricnunes » 16 Aug 2021, 12:27

hornetfinn wrote:IR systems are good in clear conditions and it can see through clouds/fog better than visible light systems or naked eye can see. However radar systems are vastly superior seeing through fog/smoke/clouds but have their own restrictions. Of course best is to do what F-35 does and use the strengths of each system to the fullest with networked and automated sensor fusion system.


Yes, I believe that IR system may or can see through (very) thin clouds/fog. But I believe that they cannot see thru thick or considerably thick clouds/fog, correct?
“Active stealth” is what the ignorant nay sayers call EW and pretend like it’s new.


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