Aim-54 track issues

[IronMike]

Ah sorry, didn't see you notified me in this thread.

[GGTharos]

I worked on the numbers a bit regarding a 120 seeker- we know it'll pick up a fighter in theory from 20+ km (around 13nm) .. with an RCS of 5m^2.

Probably around 16-18km for 3m^s (don't quote me on this, going off by memory - the above number is more solid).  Anything smaller is a cruise missile or a missile.

The 54 has a much larger antenna, so logically more power density at range but .. it's also an older analog system, so maybe it's equivalent to the 120 in terms of ranges.  I would expect the 54C to do a little better.

 

The WCS sends the missile active command based on TTI - I don't know what calculations are made, but I'll revisit the docs to see what it has to say about it.

Edited December 17, 2020 by GGTharos

[IronMike]

2 hours ago, GGTharos said:

The WCS sends the missile active command based on TTI - I don't know what calculations are made, but I'll revisit the docs to see what it has to say about it.

We just changed that GG, that was a wrong assumption on our side, based on the data we had previously. After re-investigating the TTI, SMEs pointed us in the right direction. Activation criteria is now set with the TGT size switch, that's indeed how it was irl. The TTI was a rule of thumb for crews.

[GGTharos]

59 minutes ago, IronMike said:

We just changed that GG, that was a wrong assumption on our side, based on the data we had previously. After re-investigating the TTI, SMEs pointed us in the right direction. Activation criteria is now set with the TGT size switch, that's indeed how it was irl. The TTI was a rule of thumb for crews.

 

Yup, I just read that in the weapons manual - it's just a small piece of info   Did the SMEs state that the size switch changes the activation distance?   I'll tell you why I ask, if you don't mind - I'll explain my issue with this:

 

1.  This is normally used to set fuzing parameters, IIRC

2.  Activating the seeker a little earlier for a small target doesn't really cause any problems.  Activating too early is a battery problem, maybe, but otherwise no - the missile will just go through its SARH-to-ARH routine as necessary until it picks up the target

3.  The missile doesn't send back any information to the launching aircraft, and so the activation signal can only be sent based on the TTI.  In other words, here TTI=missile range to target.   This means you have to have TTI tables and maths, and it also means that delaying turning on the seeker may not be the best thing.

(NOTE:  Also, I don't care too too much that you're using distance instead of TTI, getting TTI to be very accurate is a pain.  But if you have good TTI, this is what should trigger the go active signal, because it's the only way for the WCS to determine when the missile is close enough - this would result in realistic problems also, as target maneuvers would decrease the accuracy of the TTI as the WCS tries to keep up with it)

 

Anyway, bottom like is I wonder if the SMEs would have any comment on this. 

 

As always, great work

Edited December 18, 2020 by GGTharos

[IronMike]

29 minutes ago, GGTharos said:

 

Yup, I just read that in the weapons manual - it's just a small piece of info   Did the SMEs state that the size switch changes the activation distance?   I'll tell you why I ask, if you don't mind - I'll explain my issue with this:

 

1.  This is normally used to set fuzing parameters, IIRC

2.  Activating the seeker a little earlier for a small target doesn't really cause any problems.  Activating too early is a battery problem, maybe, but otherwise no - the missile will just go through its SARH-to-ARH routine as necessary until it picks up the target

3.  The missile doesn't send back any information to the launching aircraft, and so the activation signal can only be sent based on the TTI.  In other words, here TTI=missile range to target.   This means you have to have TTI tables and maths, and it also means that delaying turning on the seeker may not be the best thing.

(NOTE:  Also, I don't care too too much that you're using distance instead of TTI, getting TTI to be very accurate is a pain.  But if you have good TTI, this is what should trigger the go active signal, because it's the only way for the WCS to determine when the missile is close enough - this would result in realistic problems also, as target maneuvers would decrease the accuracy of the TTI as the WCS tries to keep up with it)

 

Anyway, bottom like is I wonder if the SMEs would have any comment on this. 

 

As always, great work

 

I forwarded it to Naquaii, he is better equipped to answer that than me.

[Callsign JoNay]

On 12/14/2020 at 8:18 AM, IronMike said:

This should be fixed in the next patch.

 

Just wondering if the CM rejection values of the AIM-54 we're adjusted in today's patch. I don't see it mentioned in the changelog, and the Phoenix still seems to be drawn to chaff like a moth to a flame in all my testing today post patch.

[Dudikoff]

6 hours ago, GGTharos said:

3.  The missile doesn't send back any information to the launching aircraft, and so the activation signal can only be sent based on the TTI.  In other words, here TTI=missile range to target.   This means you have to have TTI tables and maths, and it also means that delaying turning on the seeker may not be the best thing.

 

Well, yes, the WCS can't know exactly where the missile is, it can only work with where the missile should be at some point which I guess is the TTI value. But, I don't see why this would also not be mixed in with the target size switch to give the seeker a better chance for a timely lock on. E.g. for bigger targets you use a higher TTI value, for smaller ones, you use a smaller value (i.e. activate later).

 

I guess it would be interesting to know more details about it like e.g. if these TTI values are influenced by some other parameters like target range and altitude which would influence the missile speed at intercept point and thus the actual range for the given TTI value or it's more simplified and these values are fixed based on some average missile speed value.

 

IIRC, there's a similar thing with N001/N019 radars where the target illumination by the radar starts earlier or later based on the target size switch (which also influences the fuze setting on the missile).

Edited December 18, 2020 by Dudikoff

[near_blind]

21 minutes ago, Callsign JoNay said:

Just wondering if the CM rejection values of the AIM-54 we're adjusted in today's patch

 

They're still the same values. .25 for the C, .3 for the As

 

@IronMike I've noticed since the last patch there doesn't seem to be active indication for tracks that are both extrapolated and have an airborne phoenix assigned to them (numbers nor contact ever flash), and this is usually accompanied by the missile missing. I don't know if this is because the missile is activating and the target is out of the "basket" and the crew simply isn't receiving any indication, or if the missile simply isn't going active at all. If I had to speculate could this be because the active trigger and countdown are using the distance to the DCS object rather than the estimated target position? I have no evidence one way or another, that's simply a guess. 

[Callsign JoNay]

58 minutes ago, near_blind said:

 

They're still the same values. .25 for the C, .3 for the As

 

Ahh, I thought so. That's disappointing. I currently can't hit the broad side of a barn with 54s.  They get decoyed almost every time.

[GGTharos]

1 hour ago, Dudikoff said:

But, I don't see why this would also not be mixed in with the target size switch to give the seeker a better chance for a timely lock on.

 

What's the point?  The RCS isn't a fixed value IRL, and having the missile searching earlier is probably not a bad thing.   The 54 tries to get an active return when activated, if it fails it goes back to SD/A to get a new sample, then tries again.

 

1 hour ago, Dudikoff said:

I guess it would be interesting to know more details about it like e.g. if these TTI values are influenced by some other parameters like target range and altitude which would influence the missile speed at intercept point and thus the actual range for the given TTI value or it's more simplified and these values are fixed based on some average missile speed value.

 

You couldn't possibly give an accurate TTI without this.

 

1 hour ago, Dudikoff said:

IIRC, there's a similar thing with N001/N019 radars where the target illumination by the radar starts earlier or later based on the target size switch (which also influences the fuze setting on the missile).

 

Not even close    The AIM-54 will guide in SD/A or CSA from the moment of launch.  The DLZ is not even displayed if the RCS is too small for a given range AFAIK.

[Naquaii]

7 hours ago, IronMike said:

I forwarded it to Naquaii, he is better equipped to answer that than me.

 

The TGTS switch affects a lot of stuff, some of it hard to model in DCS. In fact it's more of a general setting for expected target RCS and affects amongst other things missile launch zones, tws minimum track initiation range, thresholding settings in tws as well other radar related stuff. So it very much affects both weapon launch settings as well as radar stuff.

 

The range at which the missile ATC and the activation of the AIM-54 seeker occurs seems to be mostly related to the range at which the missile seeker is expected to actually detect and track the target. I do concur that the battery life is probably not too much of a worry here as the large setting was obviously expected to work. The two reasons I can think of for not wanting to switch to active too early would be that you'd want to deny the enemy seeing the active seeker and that having activated the seeker with it not finding a target would have it switching back and forth between active and looking at SARH returns as it can't do both at the same time meaning less time in either.

 

The original intended use of the different settings, afaik, would be large for bombers, norm for fighters and small for missiles. That you have to support the missile until ATC was probably not as much as a thing IRL as you were expected to support it until a hit anyway but in DCS it will ofc be a worry for many.

 

In any case, the new information we have is quite clear, the implementation we now have is the most realistic one within the limits we have in DCS. And yes, that information do indeed confirm it being range based and not time based.

[Lurker]

The TGTS switch is located in the back-seat, on the DDD? Can we expect Jester to set it correctly & is this even modeled currently?  

[Naquaii]

Just now, Lurker said:

The TGTS switch is located in the back-seat, on the DDD? Can we expect Jester to set it correctly & is this even modeled currently?  

 

Jester does not set this automatically, he will default to norm if you don't tell him otherwise. This is more of a preference than anything but you can tell him which setting to use via the Jester-wheel as per the patch notes.

[Lurker]

Just now, Naquaii said:

 

Jester does not set this automatically, he will default to norm if you don't tell him otherwise. This is more of a preference than anything but you can tell him which setting to use via the Jester-wheel as per the patch notes.

 

Oh I missed that in the patch notes. Thanks for the quick reply! 

[Dudikoff]

1 hour ago, GGTharos said:

What's the point?  The RCS isn't a fixed value IRL, and having the missile searching earlier is probably not a bad thing.   The 54 tries to get an active return when activated, if it fails it goes back to SD/A to get a new sample, then tries again.

 

It's not fixed, but obviously there are some reasonable RCS value ranges like large for bombers, tankers, etc., medium for fighters and small for e.g. cruise missiles that both US and Soviet side would see fit to add to the WCS controls.

 

Do you have any references stating that the Phoenix would jump back and forth between active guidance and updates from the launching platform once it goes active? I'm curious how long would these cycles be in the sense that if long enough, the missile might be too late to make the turn based on updates (if e.g. the target maneuvered significantly) and then lose the chance to intercept the target.

 

One reason why the early activation might not be ideal is that the missile might pick the wrong target along the way.

 

1 hour ago, GGTharos said:

You couldn't possibly give an accurate TTI without this.

 

Yeah, come to think about it, it's pretty logical that some tables for the missile speed depending on the time of flight, launch and target parameters would be necessary to be able to determine a good enough estimate of the missile's position to be able to determine it's distance from the target and then also its remaining speed to be able to calculate the TTI.

 

1 hour ago, GGTharos said:

Not even close    The AIM-54 will guide in SD/A or CSA from the moment of launch.  The DLZ is not even displayed if the RCS is too small for a given range AFAIK.

 

You misunderstood my point. I meant similar in ways of the large/medium/small target setting influencing the guidance as well as fuzing as previously you stated that it only influences the fuzing.

Edited December 18, 2020 by Dudikoff

[Naquaii]

3 minutes ago, Dudikoff said:

 

It's not fixed, but obviously there are some reasonable RCS value ranges like large for bombers, tankers, etc., medium for fighters and small for e.g. cruise missiles that both US and Soviet side would see fit to add to the WCS controls.

 

Do you have any references stating that the Phoenix would jump back and forth between active guidance and updates from the launching platform once it goes active?

 

 

You misunderstood my point. I meant similar in ways of the large/medium/small target setting influencing the guidance as well as fuzing as previously you stated that it only influences the fuzing.

 

 

The missile will have to switch modes to again look for the semi active returns from the AWG-9 as the seeker can't do both at the same time, just as any other radar. And this is just in case it doesn't find the target ofc.

[GGTharos]

3 hours ago, Dudikoff said:

Do you have any references stating that the Phoenix would jump back and forth between active guidance and updates from the launching platform once it goes active? I'm curious how long would these cycles be in the sense that if long enough, the missile might be too late to make the turn based on updates (if e.g. the target maneuvered significantly) and then lose the chance to intercept the target.

 

Pretty fast probably, but the point was made that you want to minimize switching.  And yes, it's in the weapons manual, but the detail you're asking for is not available there.

[Skysurfer]

1 minute ago, GGTharos said:

 

Pretty fast probably, but the point was made that you want to minimize switching.  And yes, it's in the weapons manual, but the detail you're asking for is not available there.

 

So you have access to the "weapons manual"? Since you keep bringing it up.

[GGTharos]

A part of it and it says a lot.   But it doesn't answer everything - kinda like having a -34, it's very near but the extra interesting stuff is in supplements that we won't have access to.

Edited December 18, 2020 by GGTharos

[Callsign JoNay]

On 12/10/2020 at 7:47 PM, near_blind said:

 

Honestly, my experience is the opposite. I generally try to shoot high/fast around 50 miles. The AI likes to commit in the high thirties, will waste copious amounts chaff trying to decoy the missile during the fly out, and are limited in their ability to maneuver once it goes active.  I'm seeing 50% against things like Fulcrums and Flankers, and even better against Floggers. Them reducing the occurrence of track yeet in the last patch only sweetens the deal. 

 

 

50 miles? Never would've occurred to me to take a shot from there on a fighter, seeing as even shots from 35 leave the missile pretty low energy by the time they get to the terminal phase. Are you saying you have higher PK% at 50 miles than you do at 35 miles?

 

Also how do you avoid losing tracks to ground clutter and notching? I thought the purpose of the 54/AWG9 system was to engage from a lower alt than the targets and use MLC out/auto to make sure you don't get notched. You shoot from high up and then dive to a lower altitude before they start notching?

 

My PK% vs AI targets is pathetic right now. I need to figure this out.

[DarksydeRob]

@Naquaii

Is there an ETA to when the Aim-54 will use the new missile API ?

Or is it not currently planned?

Edited December 18, 2020 by DarksydeRob

[Naquaii]

1 minute ago, DarksydeRob said:

@Naquaii

Is there an ETA to when the Aim-54 will use the new missile API ?

Or is it not currently planned?

 

 

It has been since the november patch. This entails the ability for us to control seeker activation an lofting, everything else is on EDs side.

[DarksydeRob]

Just now, Naquaii said:

 

It has been since the november patch. This entails the ability for us to control seeker activation an lofting, everything else is on EDs side.

Ah I see. So its not utilizing it fully yet. Looking forward to when it uses the new FM and full Seeker logic like the Sparrow , SD-10 and AMRAAM.

[IronMike]

Just now, DarksydeRob said:

Ah I see. So its not utilizing it fully yet. Looking forward to when it uses the new FM and full Seeker logic like the Sparrow , SD-10 and AMRAAM.

There will be no new FM for the phoenix. There is nothing wrong with its FM, in fact it is one of the most accurate missile FMs in DCS. That's all in the whitepaper.

As for seeker logic, that's up to ED, not us.

[KlarSnow]

The missile has the same terminal kinematics at 60 miles as it has at 30 miles, It fully flies out its loft, and will go terminal with mach 2 plus in most cases. If you need more than that you are talking having it intercept while the motor is still burning, so short range shots. The only advantage firing it closer gives you is a shorter fly out.

 

The Aim-54A/C kinematically is plenty capable of engaging fighter or otherwise sized targets in DCS out to 60-70 miles, you just have to support it successfully.

 

If the target turns cold on the longer ranged shots, it all depends on what range he turns around, in most cases if you are high fast and shoot at long range, if he turns around at the missiles activation, it is impossible to outrun the missile. If he turns around prior to the missiles activation, different story, and that missile is probably defeated, but not necessarily. All of this is just talking about pure kinematic ability to reach the target with enough energy to successfully complete the engagement. Chaff/Notching will always be something the target can do, either at 30 miles or 60 miles to completely defeat your missile, and there is nothing you can do about that other than hope the chaff dice rolls don't go good, and hope his notch is either late or ineffective. That applies to every missile in DCS right now in varying degrees.