AWG-9 velocity gating?

[Harlikwin]

11 minutes ago, Naquaii said:

 

Yes, and you'll will note that the whitepaper focuses on aerodynamics and flight performance, not guidance or seeker logic.

 

Yes... Though that report does touch some on the latter subjects. I mean if I'm missing some publicly available source I'd like to know. 

 

Edited March 20, 2021 by Harlikwin

[Naquaii]

The reason I'm mentioning it is that you made it sound like we're basing our entire missile modelling on that report which is far from the truth. We've been discussing the seeker and guidance logic here, not missile aerodynamics.

[Harlikwin]

1 hour ago, Naquaii said:

The reason I'm mentioning it is that you made it sound like we're basing our entire missile modelling on that report which is far from the truth. We've been discussing the seeker and guidance logic here, not missile aerodynamics.

 

Yes... Correct... I don't really see many issues with the Aero. But you're being pretty evasive as to what you did use to do the guidance logic for it.

[Naquaii]

12 minutes ago, Harlikwin said:

 

Yes... Correct... I don't really see many issues with the Aero. But you're being pretty evasive as to what you did use to do the guidance logic for it.

 

It's probably no surprise that we have manuals and information not available publicly on the internet. I expect it's the same for the other module developers.

Edited March 20, 2021 by Naquaii

[Slant]

On 3/20/2021 at 12:52 AM, Harlikwin said:

To that end, I have read that report that HB based their model on, and well, frankly, I found some of those tests that were (not counted as failures) to frankly be failures, which IMO is typical of the era and the mil-industrial complex of the time, and it lowered my opinion of the missile. Also, IIRC there were no long range engagements of maneuvering targets in that report, just the one short range engagement against the maneuvering drone, and nothing "notching" as far as I recall. I think the ultimate point is that if the A was so great against fighters, why was the C specifically designed to be "better" against fighters?

 

 

 

It's a bit of a hobby of mine to take comments like these and point this out: To be as unbalanced, overpowered and unfair as they possibly can.

 

Mind you, I'm a layman and don't know what I'm talking about, but as a layman it seems logical to me that military R&D is always trying to be better at being as unfair to the enemy as they possibly can. I'm sure they were already dreaming about the 54D when the whole program got cancelled. Military planning always seems to center around the principle of "killing them without them killing us." (simplified to a stupid degree, I'm sure), and being "better" is always just a temporary solution in that you can always be better.

 

Ie. when missiles have a 100% hit rate under any circumstance at any range (take this literally, not even a statistical possibility of a miss in a scenario where the universe is ceasing to exist and your opponent is on the other side of the universe), that's about the time when I would imagine the military development team going "Uh, yeah.. that's it, we're done. This is the last missile we design."

 

And they'd only do that to turn around and start developing a countermeasure to that, with the intended goal to induce a 100% miss rate in all incoming attacks, again, under any circumstances (ie. you standing on the runway stationairy while they shoot at you from point blank range)

Edited March 22, 2021 by Slant

[Slant]

On 3/20/2021 at 6:17 PM, Naquaii said:

 

It's probably no surprise that we have manuals and information not available publicly on the internet. I expect it's the same for the other module developers.

 

 

All I want to know, is Grumman in on this project? Would be so cool to see the Grumman logo appear. "Officially endorsed product of the Northrop Grumman Corp."

 

I don't know why, but I like stuff like that. Hehe

[GGTharos]

On 3/20/2021 at 1:07 PM, Harlikwin said:

Yes... Correct... I don't really see many issues with the Aero. But you're being pretty evasive as to what you did use to do the guidance logic for it.

 

There are documents that describe the guidance reasonably well.  They're not secret but they're also not in the public domain ... some people have them and they don't share, and that's fine - they probably paid a lot of FOIA money to get them and they can do whatever they want.

[Harlikwin]

On 3/18/2021 at 1:49 PM, Naquaii said:

 

Comparing a figher radar guiding a SARH missile to an ARH missile with it's own built in radar is not that straight forward as it might seem at first. The radar equation in regards to returned power has both the range from the transmitter to the target and the range from the target to receiver squared. This means that effect of the distance from the fighter to the missile isn't just a linear advantage in favor of the ARH missile but it's squared, in addition in an ARH missile both ranges will decrease as the missile approaches the target while with a SARH missile likely only the range from target to receiver will decrease. Or at least the range from the transmitter to the receiver will not decrease as much. This means that the fighter radar guiding the SARH missile will have to have a transmitter much more powerful than the missile to even have a received power even to the ARH missile's. Adding to that the AIM-54 has a twíce as large seeker antenna which give it an advantage over the AIM-7 even in the SARH case.

 

It is true though that the AIM-7M seeker is much newer than the AIM-54A age-wise but to hold that as an advantage we'd need to know in what ways it is better than the AIM-54A and in which situations it holds an advantage. I'd wager a guess that the advantage is little in a non-jammed advantage while it will probably be greater when in a heavy ECM environment. But as to how much anyone's guess is equally as good as long as we're only able to discuss non classified information.

 

Added to that an opponent is much more likely to have seen the STT mode of a fighter radar and been able to design ways to counter that than a missile that they've never seen used against them and thus never seen the radar of in action and how it behaves.

 

The tl:dr, at least for me, is that in regards to power a SARH missile will always be a step behind and even in the SARH case the much larger antenna in the AIM-54 is a massive advantage, esp coupled with the powerful AWG-9. The ECM and ECCM/logic discussion is kinda moot as any representation will be guesswork at best.

 

Well, respectfully, the people that did actually do the math back then, and well, it would be fair to say "wrote the book" on missile seeker design back then would say you're TLDR is not quite right... The active seeker, as you can see, is on the bottom of that heap. 

 

Edited March 24, 2021 by Harlikwin

[Naquaii]

13 minutes ago, Harlikwin said:

 

Well, respectfully, the people that did actually do the math back then, and well, it would be fair to say "wrote the book" on missile seeker design back then would say you're TLDR is not quite right... The active seeker, as you can see, is on the bottom of that heap. 

 

 

 

Not sure how that is relevant for AIM-54 versus AIM-7? What missiles are that diagram even for? What power figures is it using for the missile vs the radar and what radars are those based on? What aperture sized or antenna gains is it using and where are those from? There are a lot of factors that are not obvious from that diagram alone.

 

I'm by no means saying I'm right about ARH vs SARH in this regards but I'm having a hard time seeing where this is leading or how it has any bearing on our missile implementation as is?

Edited March 24, 2021 by Naquaii

[Harlikwin]

1 minute ago, Naquaii said:

 

Not sure how that is relevant for AIM-54 versus AIM-7? What missiles are that diagram even for? What power figures is it using for the missile vs the radar and what radars are those based on? What aperture sized or antenna gains is it using and where are those from? There are a lot of factors that are not obvious from that diagram alone.

 

Its an apples to apples comparison of seeker types from that period not specific missiles. So you are correct in the sense that the Aim54 vs Aim7 antenna would be a factor. The "document" is basically a book of missile design from the era, its very interesting in the sense its a here's how it was done before, and how it will be done in the future. Doc is from the mid 70's. And the sections on how "analog" (terrible term btw), vs "digital" will change and how are quite interesting, and at least in part is where some of my questions on the modeling lie...

 

Here is the table with the data. 

 

Edited March 24, 2021 by Harlikwin

[Looney]

It doesn't give radar power, EIRP or any other power factor to work with. Also, how do I read the graph for the Active-PD seeker? Do I read it from right to left, as would be the case since the radar actually gets closer and closer to the target, whereas the SA variants are totally dependend of the radar of the guiding aircraft. so I should read their graphs from left to right?

 

Not to be nitpicking but just post a link to the complete book instead of cherry-pciking stuff out of it without the full context, it doesn't make sense.

[Harlikwin]

26 minutes ago, Looney said:

It doesn't give radar power, EIRP or any other power factor to work with. Also, how do I read the graph for the Active-PD seeker? Do I read it from right to left, as would be the case since the radar actually gets closer and closer to the target, whereas the SA variants are totally dependend of the radar of the guiding aircraft. so I should read their graphs from left to right?

 

Not to be nitpicking but just post a link to the complete book instead of cherry-pciking stuff out of it without the full context, it doesn't make sense.

 

As I said apples to apples comparison. Its mainly concerned about clutter performance of different seeker types/implementations in this case.

Edited March 24, 2021 by Harlikwin

[dundun92]

24 minutes ago, Looney said:

link to the complete book

https://apps.dtic.mil/dtic/tr/fulltext/u2/b010399.pdf

Edited March 24, 2021 by dundun92

[Harlikwin]

8 minutes ago, dundun92 said:

https://apps.dtic.mil/dtic/tr/fulltext/u2/b010399.pdf

 

 

Yup, thats the one.  Given the overall context of the document, and who its written for I'm pretty sure the ARH performance and design has some bearing on where the phoenix was, and where it was going in the mid 70's.

 

Edited March 24, 2021 by Harlikwin

[Looney]

It goes digital with all the pros and cons we now know.

 

The book does a fine job of taking apart the modules that make up a weapon system and that's about it. How would this document contribute to the overall discussion of this thread, the fact that at a sum of ATA/TA > 55, it breaks lock?

[AH_Solid_Snake]

I think the reality is that this thread has long since been hijiacked for AIM-54 seeker head discussion, AFAIK the AWG-9 issue has already been acknowledged by @Naquaiiso if really worried about it I guess you could make a tracking thread in Bugs?

[Naquaii]

@Noctrach I unfortunately wasn't able to reproduce. I've tested multiple scenarios and am not having that issue. The only scenario I haven't really tested yet is MP.

 

I did find another issue though with the TID track itself. It seems like there is a new bug that makes the TID behave as if the STT track was lost, the STT track itself still remains but unfortunately this also seems to affect AIM-54 guidance in STT when that TID track loss occur. We're now tracking this issue and are looking at it.

 

Do you have any other information regarding your issue? Does it always happen the same way or are there certain pre-conditions or switch configurations?

[Noctrach]

1 hour ago, Naquaii said:

@Noctrach I unfortunately wasn't able to reproduce. I've tested multiple scenarios and am not having that issue. The only scenario I haven't really tested yet is MP.

 

I did find another issue though with the TID track itself. It seems like there is a new bug that makes the TID behave as if the STT track was lost, the STT track itself still remains but unfortunately this also seems to affect AIM-54 guidance in STT when that TID track loss occur. We're now tracking this issue and are looking at it.

 

Do you have any other information regarding your issue? Does it always happen the same way or are there certain pre-conditions or switch configurations?

Not gonna lie, I find this odd. I tested it again last Tuesday while I was piloting with a squadmate of mine in the back.

He also saw the PD-STT contact disappearing consistently with the parameters I mentioned.

 

Then again, the second part of your description looks very much like the issue I described.

PD-STT, either with launching or without.

Offset the antenna angle + roll the aircraft so that the combined sum of the two exceeds 55 and keep it there, you'll see the DDD contact fade out.

TID treats it as lost track [X], missiles in the air stop guiding.

 

Note that this does NOT happen in any of the TWS modes or with P-STT. Only PD-STT is affected, either from RWS or PD-SRCH.

It happens both with MLC on and off, no other switch configurations.

 

If there's anything I can do to help reproduce this I'd be happy to, as we have a 100% reproduction rate this way.

The exact same result in both singleplayer and multiplayer.

 

One thing that I did notice as a secondary issue when we were testing whether this happened in TWS as well.

Sometimes when firing AIM-54 at a two-ship, if the TWS loses one track but maintains steady lock on the other, both Phoenixes in the air will guide as if tracks are lost.

Which is to say, they will both stop steering and fly straight ahead until they go active or time out. (Which is standard behaviour we're observing for lost tracks, I think this is intended?)

I don't know exactly when this occurs since it's happening only intermittently.

 

No offense intended, but there's quite a lot of weirdness going on with the WCS right now and I don't know whether to fault the missile API or something in the AWG-9.

The issue mentioned earlier in this thread is the only one I can reproduce with absolute certainty.

Edited March 25, 2021 by Noctrach

[Naquaii]

23 minutes ago, Noctrach said:

Not gonna lie, I find this odd. I tested it again last Tuesday while I was piloting with a squadmate of mine in the back.

He also saw the PD-STT contact disappearing consistently with the parameters I mentioned.

 

Then again, the second part of your description looks very much like the issue I described.

PD-STT, either with launching or without.

Offset the antenna angle + roll the aircraft so that the combined sum of the two exceeds 55 and keep it there, you'll see the DDD contact fade out.

TID treats it as lost track [X], missiles in the air stop guiding.

 

Note that this does NOT happen in any of the TWS modes or with P-STT. Only PD-STT is affected, either from RWS or PD-SRCH.

It happens both with MLC on and off, no other switch configurations.

 

If there's anything I can do to help reproduce this I'd be happy to, as we have a 100% reproduction rate this way.

The exact same result in both singleplayer and multiplayer.

 

One thing that I did notice as a secondary issue when we were testing whether this happened in TWS as well.

Sometimes when firing AIM-54 at a two-ship, if the TWS loses one track but maintains steady lock on the other, both Phoenixes in the air will guide as if tracks are lost.

Which is to say, they will both stop steering and fly straight ahead until they go active or time out. (Which is standard behaviour we're observing for lost tracks, I think this is intended?)

I don't know exactly when this occurs since it's happening only intermittently.

 

No offense intended, but there's quite a lot of weirdness going on with the WCS right now and I don't know whether to fault the missile API or something in the AWG-9.

The issue mentioned earlier in this thread is the only one I can reproduce with absolute certainty.

 

 

It does sound similar with the difference beeing that in our case the STT itself isn't dropped, just the TID track.

 

Problem is that I'm having the exact opposite, I never get the issue you're describing. The way I'm testing it I'm just dropping into a new mission with an F-14 and a target straight ahead and then I've tried both having Jester lock it up or jumping into the back seat and steering using Iceman. Any other switch or steps you guys do in your squadron that's not normal procedure or something not set in a fresh aircraft?

 

As for the TWS cases the Phoenix should still track normally as long as the track it's guiding onto is the same, i.e. still retains the missile flight time counter. Launching in TWS against tight formations is one of the weaknesses of the AWG-9 though and that's not unrealistic afaik.

 

Edit: I also tried using PD-STT auto from TWS as I normally don't use that but that got the same result.

Edited March 25, 2021 by Naquaii

[Noctrach]

46 minutes ago, Naquaii said:

 

It does sound similar with the difference beeing that in our case the STT itself isn't dropped, just the TID track.

 

Problem is that I'm having the exact opposite, I never get the issue you're describing. The way I'm testing it I'm just dropping into a new mission with an F-14 and a target straight ahead and then I've tried both having Jester lock it up or jumping into the back seat and steering using Iceman. Any other switch or steps you guys do in your squadron that's not normal procedure or something not set in a fresh aircraft?

 

As for the TWS cases the Phoenix should still track normally as long as the track it's guiding onto is the same, i.e. still retains the missile flight time counter. Launching in TWS against tight formations is one of the weaknesses of the AWG-9 though and that's not unrealistic afaik.

 

Edit: I also tried using PD-STT auto from TWS as I normally don't use that but that got the same result.

 

That does sound identical to what I'm describing actually.

I might've not expressed this clearly but the PD-STT lock never "drops" as such. It just loses the contact return so guidance stop and the track goes into trackhold.

When I said loses contact, what I mean is that in the DDD you will see the sweep stops getting a return.

It still "treats it" like it's locked on, which makes it a bit pernicious since you won't even notice it's gone unless you're paying attention to the DDD.

 

This is with default jets in singleplayer and multiplayer. Ground-start or air-start. No mods and no special set-ups. Jester or backseater.

Always happens the same way.

 

For the TWS issue: can it be that the TID starts mixing up tracks if one of them is lost? I see it happening often after the formation has already separated.

 

E.g. two jets at about 30 miles that are far enough apart to be in separate resolution cells.

One of the two does an aggressive jink that breaks track, the other continues flying and tracks normally.

Phoenixes will behave as if they're both fired on the same track. Which of the two tracks they choose seems kinda random.

(So sometimes they both guide on the good track, sometimes they both go stupid)

I'm not comfortable turning it into a bug report though because I'm not sure what is happening exactly and whether it's intentional behaviour. It just seems rather odd.

Edited March 25, 2021 by Noctrach

[nighthawk2174]

What is the size of the AWG-9's resolution cell?

[Naquaii]

17 hours ago, Noctrach said:

That does sound identical to what I'm describing actually.

I might've not expressed this clearly but the PD-STT lock never "drops" as such. It just loses the contact return so guidance stop and the track goes into trackhold.

When I said loses contact, what I mean is that in the DDD you will see the sweep stops getting a return.

It still "treats it" like it's locked on, which makes it a bit pernicious since you won't even notice it's gone unless you're paying attention to the DDD.

 

This is with default jets in singleplayer and multiplayer. Ground-start or air-start. No mods and no special set-ups. Jester or backseater.

Always happens the same way.

 

For the TWS issue: can it be that the TID starts mixing up tracks if one of them is lost? I see it happening often after the formation has already separated.

 

E.g. two jets at about 30 miles that are far enough apart to be in separate resolution cells.

One of the two does an aggressive jink that breaks track, the other continues flying and tracks normally.

Phoenixes will behave as if they're both fired on the same track. Which of the two tracks they choose seems kinda random.

(So sometimes they both guide on the good track, sometimes they both go stupid)

I'm not comfortable turning it into a bug report though because I'm not sure what is happening exactly and whether it's intentional behaviour. It just seems rather odd.

 

 

If you're still seeing the tracking lights being on on the DDD and the STT continueing to track it's likely the same thing. Does the track return for you as well if you turn back into the track? If you do this is likely what I'm seeing as well and that is being investigated on our side as well now.

 

13 hours ago, nighthawk2174 said:

What is the size of the AWG-9's resolution cell?

 

That depends entirely on the mode used. For TWS 6nm in range and slightly above 2 degrees azimuth is about right.

[Noctrach]

1 hour ago, Naquaii said:

If you're still seeing the tracking lights being on on the DDD and the STT continueing to track it's likely the same thing. Does the track return for you as well if you turn back into the track? If you do this is likely what I'm seeing as well and that is being investigated on our side as well now.

Yep :) that's exactly it

[Lurker]

Sorry to be necroing this thread but is there any news on Noctrach's strange STT-PD disappearing (but not disappearing) track issue? Thanks in advance!