A Gimbal Glare Explainer

Mick West

Administrator
Staff member
FLIR is not a glare right? It's an IR signature of a physical object.
"IR signature of a physical object" is perhaps a poor descriptor. If you point a camera at a jet then what you see is the IR signature. A glare is arguably the IR signature, within the limitations of the camera system. And idealized IR signature would basically be a crystal clear image of the jet and the exhaust in the MWIR spectrum.

The FLIR1 video starts out as glare.


Later in IR though there's very little glare, and we are probably seeing something more like the true shape

2022-02-12_16-36-17.jpg

I've argued that there's a glare on the right side, and that you can even see it rotate during the gimbal roll, but it's a hard sell at this resolution.

My suspicion is that it's a plane more tail-on at the start, hence the glare, and then it turns more to the left. Like a much less extreme version of this:
 

dimebag2

Active Member
Are there IR video examples of "steps" in a Gimbal rotation? Or evidence this is typical of a pod rotation ? Mick you already explained me that this is to avoid long periods of rotation, but seeing it would be so compelling.

And an example of an IR glare that perfectly keep its shape during a rotation ? I looked at examples from other threads but they often seem to be less constant in shape.

If I see that I'd be 99% sold.
 

Mick West

Administrator
Staff member
Are there IR video examples of "steps" in a Gimbal rotation? Or evidence this is typical of a pod rotation ? Mick you already explained me that this is to avoid long periods of rotation, but seeing it would be so compelling.

And an example of an IR glare that perfectly keep its shape during a rotation ? I looked at examples from other threads but they often seem to be less constant in shape.

If I see that I'd be 99% sold.
Unfortunately there's very little targeting pod footage out there.

This one does show both of what you ask for to some degree. Notice you can see the rotation of the pod (when zoomed out and you can see the black edges of the image) AND the rotation of the glare at the same time - particularly after 1:46. then we see the glare rotate in steps after 3:40. It keeps its shape, but is pointier (the more streaked the glass in front of a camera, the larger the points)

 

jarlrmai

Senior Member
Are there IR video examples of "steps" in a Gimbal rotation? Or evidence this is typical of a pod rotation ? Mick you already explained me that this is to avoid long periods of rotation, but seeing it would be so compelling.

And an example of an IR glare that perfectly keep its shape during a rotation ? I looked at examples from other threads but they often seem to be less constant in shape.

If I see that I'd be 99% sold.
Part of the problem with these videos is uncropped, extended plain reference footage from ATFLIRs and other pods in operation for comparison is very, very limited. These 3 videos are some of the best public footage there is of ATFLIR in operation and especially in A/A mode as most other cockpit videos seem to be A/G mode.

Here's a nice one I found that shows you a bit what it would have been like from the cockpit looking at the MFD.

Source: https://youtu.be/G2JHHC4G5jI?t=89


If there was identical reference footage we'd probably not have been having threads about this for the last few years.
 

dimebag2

Active Member
It's different because it coincides with the jet banking angle going clockwise. Background rotates when the jet rolls (i.e. a change in bank angle), the glare rotates when the pod head rolls relative to the pod body.

There's a long smooth rotation here partly because it's at the steepest part of the curve, but also because of the jet rotation clockwise which has the effect of making the curve steeper (try toggling "Use real bank angle" to see the effect) and also rotating the background in the same direction.

Please let me know if I get that right :

- the fact that the glare does not rotate with the horizon (jet banking) is inconsistent with a physical object, but consistent with a glare.

- we see it when the plane banks at various points of the video. The glare does not rotate.
https://www.metabunk.org/threads/do...bunk-the-claim-that-the-object-rotates.12068/

- at 0'30 the plane makes the most important change in banking. This would be the most clear evidence that the object is a glare, because it should not rotate with the background (that clearly does at this moment).

- but because the pod head also rolls at the same moment, the glare actually rotates, and it does it a little more than the background (meaning the head roll compensates for the non-rotation, plus adds some additional rotation to the glare).

- the pod head rolls in "steps" before and after the plane banks, but it rolls smoothly when the plane banks, "hiding" what would be a dead giveaway for the object being a glare, because it would not rotate with the background if the pod head was not rolling. Or it would but with a step (unlike the background), if the pod head was rolling with a step like before and after.

So here we have a pod that makes steps in its rotation, but just not when it would make it obvious the object is not part of the image, but is a glare. This is unfortunate.

And thanks to you and @jarlrmai for the examples of IR videos.
 

markus

Active Member
I think the system moves in "steps" for small corrections only, likely because static friction is greater than kinetic friction (or play in gears, etc.).

It's also worth noting that in the first 20 seconds of the video the change in bank happens to supply approximately the small amount of roll required to track the target. But the roll at 30 seconds is quite large and the F-18 would need to roll inverted to keep the pod from rotating then.
 

Mick West

Administrator
Staff member
Yeah that's Marik, he contacted [a Raytheon engineer], whose name is on one of the patents and asked him some narrow questions about the patents, and then declared the entire rotating theory debunked because the patents don't say you can use the internal mirrors to avoid roll in a more general situation.

I emailed [the Raytheon engineer], he strongly disagrees with Marik's characterization of this, and denies he gave him permission to share anything. He is constrained to only discuss things that are public knowledge. So he can't actually address any of the theorising about the ATFLIR system.
 
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jarlrmai

Senior Member
Unfortunately not (I asked). But Marik has seen it, and will not dispute it.
I think I asked this before, do you envisage that a time will come when people like [the Raytheon engineer] will be able to become involved fully? Or is it likely to remain NDA's for the foreseeable future?
 
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Mick West

Administrator
Staff member
I think I asked this before, do you envisage that a time will come when people like [the Raytheon engineer] will be able to become involved fully? Or is it likely to remain NDA's for the foreseeable future?
It will be years. Someone told me ATFLIR is being phased out, as it's not very good. So eventually it will be old tech. But probably not declassified for 10-20 years. It's just a "why take a chance" situation. Secrecy is the safe default.
 
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Mick West

Administrator
Staff member
I've redacted the name of the Raytheon engineer, above, as he made it very clear to Marik that he wanted no part of this. Marik has deleted the tweets and moved on to other quibbles.
 

Agent K

Senior Member
It will be years. Someone told me ATFLIR is being phased out, as it's not very good. So eventually it will be old tech. But probably not declassified for 10-20 years. It's just a "why take a chance" situation. Secrecy is the safe default.
Who says it's not very good? Compared to what, Litening?

I don't think the detailed proprietary, Export Controlled technical data will ever be made public, any more than it was for old pods like Nite Hawk and LANTIRN.
 

CeruleanBlu

Senior Member.
Who says it's not very good? Compared to what, Litening?

I don't think the detailed proprietary, Export Controlled technical data will ever be made public, any more than it was for old pods like Nite Hawk and LANTIRN.

While in itself it's not evidence that it's "not very good", the Navy was seeking to obtain 250 new or upgraded units in the next 7 years, which causes lots of tight lips when multi-million dollar contracts are in play, especially from Raytheon.

REQUEST FOR INFORMATION (RFI) - Electro Optic/Infrared (EO/IR) Targeting Pod

The Naval Air Systems Command, Patuxent River, Maryland is seeking qualified sources that can provide an Electro Optic/Infrared (EO/IR) air-to-air and air-to-surface targeting pod capability focused on reducing the overall operating and support cost. In an effort to enhance sustainment capabilities while lowering life cycle and ownership cost, the F/A-18 & EA-18G Program Office (PMA265) is exploring Non-Developmental Item (NDI) procurement options to either augment or replace the existing Advanced Targeting Forward Looking Infrared (ATFLIR) pod inventory. The NDI system must be currently fielded on tactical strike/fighter aircraft within the Department of Defense (DoD) portfolio and must have an active production line or the ability to establish one with limited to no startup costs and capacity to support production of 250 Pods FY22-FY29.
Content from External Source
ISSUE/FOCUS AREA - Future sustainment of the capability provided by the currently fielded EO/IR Targeting Pod on the F/A-18E/F Super Hornet is of concern to the Government. Without significant investment in component obsolescence redesign, readiness is projected to decrease as sustainment costs continue to increase. Top focus elements of this RFI are: Material Availability, Operational Availability, Reliability, Maintainability, and Operating and Support (O&S) Costs. Elements related to procurement and capability should also be included, but should not be the primary focus of the RFI response.
Content from External Source
 

DavidB66

Active Member
A diffraction spike is the light you see extend from a star in your astro-images. A diffraction spike is caused by how light bends or diffracts around an object or in this case the support beams in your secondary mirror in reflecting telescopes. This spike isn’t present with refractors as it doesn’t have a secondary mirror.

I noticed a new video by astrophysicist Dr Becky Smethurst, which includes an explanation of diffraction spikes in images from the James Webb Telescope. I don't think she says anything beyond what is discussed above. but her video could be useful as a reference:

Source: https://www.youtube.com/watch?v=9SyvpSe4F4k
 
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