Aim-54 going almost vertical on an STT launch

[RPY Variable]

Missiles just go way to steep until they run out of speed. One went vertical after launch. Here are the track files. It is not possible to make a long distance shoot. TWS launch works fine.

AIM54C space 2.trk AIM54C space 3.trk

[near_blind]

Okay, so a couple things. 

• Firstly, the lofting algorithm for all the AIM-54s is a WIP solution that acts as a stop gap until a version with greater fidelity can be implemented. This will require access to the new missile API and collaboration between HB and ED. There is no ETA on this. 
• The AIM-54C has the most aggressive lofting algorithm, which seeks to maximize terminal energy by taking an aggressive vertical loft to put it into the very thin atmosphere. The C however is most prone to over-lofting, taking such an aggressive loft that it stalls before it can come over the top of its arc and plunge towards the target. This is a known bug. 
• "Assisting the loft", that is pulling up your aircrafts nose to "aid" the missile in its loft greatly increases the likelihood that the missile will over loft. 

So that's the game side of the things. 

In your case. You're taking 100NM+ shots at an E-2C that's orbiting. The AIM-54 is absolutely capable of a 100 mile shot, but the presumption is the target is going to be coming towards the Tomcat at high speed. Think a transonic Badger, or a supersonic Backfire. The E-2C is slow. very slow. In fact because it's orbiting, it's going nowhere, slowly. Normally on a 100 mile shot, your missile only actually travels something like 50 miles. In this scenario, the missile has to travel the full 100 miles, and it's trying to fly a giant ballistic parabola to fly that full 100 miles.

It can't.

Try getting closer. 

 

[Spurts]

The 110nm test shot only had to travel 72.5nm

[RPY Variable]

Here is a 40.000ft level launch at 95nm to a head on 30.000ft non maneuvering E2. In the past I've done this shot multiple times with no problem.

A flight path angle of 32° at 118.000ft seems quite excessive and 1200knots a few seconds after launch already tell you that something may be wrong.

At closer ranges, like 80nm the missile may hit, it is a very inefficient trajectory because the missile arrives at a very low energy state.

The main thing that concern's me is that for a target that is at 110nm, the launch zone says it is well inside range but the missile gets not even close.

AIM54C 95nm.trk

[near_blind]

53 minutes ago, RPY Variable said:

In the past I've done this shot multiple times with no problem.

Does the past mean prior to January of 2022 when significant changes to the flight model occurred?

54 minutes ago, RPY Variable said:

The main thing that concern's me is that for a target that is at 110nm, the launch zone says it is well inside range but the missile gets not even close

DLZ calculations in the F-14, or at least this version of the F-14 are extremely rudimentary and should not be taken as the final say.

[RPY Variable]

6 hours ago, near_blind said:

Does the past mean prior to January of 2022 when significant changes to the flight model occurred?

Yes

6 hours ago, near_blind said:

DLZ calculations in the F-14, or at least this version of the F-14 are extremely rudimentary and should not be taken as the final say.

Yes I know but... is a non maneuvering target, and the launch zone mark is in the middle. In this case it (non maneuvering tgt) it should be pretty close.

[Comstedt86]

18 hours ago, RPY Variable said:

Yes

Yes I know but... is a non maneuvering target, and the launch zone mark is in the middle. In this case it (non maneuvering tgt) it should be pretty close.

Same issue with Phoenix A47 / A60? 

[Noctrach]

On 6/3/2022 at 6:05 PM, RPY Variable said:

Here is a 40.000ft level launch at 95nm to a head on 30.000ft non maneuvering E2. In the past I've done this shot multiple times with no problem.

A flight path angle of 32° at 118.000ft seems quite excessive and 1200knots a few seconds after launch already tell you that something may be wrong.

At closer ranges, like 80nm the missile may hit, it is a very inefficient trajectory because the missile arrives at a very low energy state.

The main thing that concern's me is that for a target that is at 110nm, the launch zone says it is well inside range but the missile gets not even close.

AIM54C 95nm.trk 537.71 kB · 2 downloads

Thank you for attaching tracks to your post.

I hate to say it but all of your shots are simply out of parameters. It's unfortunate that DLZ's in DCS seem to be somewhat inaccurate for most modules, as they are quite important in communicating expectations to the player before taking the shot. That said, for all AIM-54C shot above, the DLZ indicator does show your shot being very unfavourable, even if the symbology doesn't truly correspond to what's in the manual. (Ropt on the TID seems to equal Raero for the missile)

All of your tracks show you firing subsonic (<M0.8) shots at below 40,000 (you lose a lot of altitude by not controlling the nose in the first 10-15 seconds of flight) at ranges simply exceeding the max aerodynamic range for the Phoenix under those conditions. What's happening on these shots is really easy, your missile gets sent on the loft geometry that corresponds to the range you're launching at, but you do not give it the energy to be capable of executing this geometry.

If I retry the same scenarios but launch at 40,000 ft, M1.2 (similar to the reference shots exceeding 70 miles) my missiles hit absolutely fine after about 180 seconds of flight. Provided I fire them at the correct range.

This Phoenix went to space

This Phoenix hit the target

Track for above shots is attached.

Your tracks showed the dot at the end of the velocity vector indicating your target was out of range and your shot parameters were invalid.

It seems to me the reason players see this behaviour happening more often with the AIM-54C than the AIM-54Amk47, which in return shows this more than the 54Amk60, is simply because the 54C is kinematically the worst missile in the bunch (@IronMike does it have the increased Isp at this point or is it still just a heavier 54A?).

 

Quite frankly, people should stop expecting the Phoenix to be some magical physics defying death machine and learn how to employ the weapon. The reason folks managed to hit shots like this in the past is because the Phoenix was simply overperforming. It has since been fixed so will take some adjusting expectations.

MoonPhoenix_and_HitPhoenix.trk

Edited June 4, 2022 by Noctrach

[Noctrach]

On 6/3/2022 at 2:52 PM, Spurts said:

The 110nm test shot only had to travel 72.5nm

The AIM-54Cmk47 in the sim can cover about 70 (ground) miles when launched at M1.4+ before running out of energy (sub-sonic), so that seems pretty damn close. Limiting factor for 110nmi shots seems to be radar more than missile.

Edited June 4, 2022 by Noctrach

[SspectrumM]

[RPY Variable]

4 hours ago, Noctrach said:

I hate to say it but all of your shots are simply out of parameters.

Quite frankly, people should stop expecting the Phoenix to be some magical physics defying death machine and learn how to employ the weapon.

No if you ask the DDD. Look at the screenshot attached. That's from your second missile at launch. The AWG-9 is the one that need to manage it expectations.

 

5 hours ago, Noctrach said:

It's unfortunate that DLZ's in DCS seem to be somewhat inaccurate for most modules, as they are quite important in communicating expectations to the player before taking the shot. 

I find them pretty accurate on other modules. If you shot even out of parameters to a non maneuvering tgt, it will certainly hit.  At least on the F16 of M2K.
 

4 hours ago, Noctrach said:

If I retry the same scenarios but launch at 40,000 ft, M1.2 (similar to the reference shots exceeding 70 miles) my missiles hit absolutely fine after about 180 seconds of flight. Provided I fire them at the correct range.

It is not about making the shoot. Anyone can figure out that if I spawn at M2.0 at 50,000ft the missile will have better performance. And your missile didn't hit "absolutely fine", it hit a head on 30.000ft tgt on level flight with an impact speed of 650kn which is almost subsonic.

4 hours ago, Noctrach said:

The reason folks managed to hit shots like this in the past is because the Phoenix was simply overperforming.

One could argue that the missile is underperforming and and when I use to make the 40K ft subsonic 100nm shots to a orbiting target, it was performing accordingly. I'm not saying that's the case, all am saying is that if "everything is subject to change" the argument of "now is working fine, before was overperforming" is a little bit dogmatic.

[Noctrach]

8 hours ago, RPY Variable said:

One could argue that the missile is underperforming and and when I use to make the 40K ft subsonic 100nm shots to a orbiting target, it was performing accordingly. I'm not saying that's the case, all am saying is that if "everything is subject to change" the argument of "now is working fine, before was overperforming" is a little bit dogmatic.

I think this is a challenging argument to make when all the real world test shots and Heatblur's own CFD whitepaper correlate with the current kinematic profile of the missile in the sim. Could it be a little conservative in a couple areas? Sure, HB themselves have said this. But it really was overperforming significantly before the change.

To me this thread should be renamed "Phoenix DLZ does not match missile kinematics" and we'd have a very different, very constructive discussion.

[captain_dalan]

2 hours ago, Noctrach said:

I think this is a challenging argument to make when all the real world test shots and Heatblur's own CFD whitepaper correlate with the current kinematic profile of the missile in the sim.

Correct me if i'm wrong, but doesn't the CFD really only supports straight level shots? That is, no AoA, lofting, g's pulled and other drag inducing activities? 

[Noctrach]

1 hour ago, captain_dalan said:

Correct me if i'm wrong, but doesn't the CFD really only supports straight level shots? That is, no AoA, lofting, g's pulled and other drag inducing activities? 

Both straight line and loft. You can also simulate most of the testing scenarios mentioned on current patch with greater reliability than they could at the time (guidance has definitely improved even if it's nowhere near done).

Can't quite get the AI to stay at 52,000 or M1.55 to replicate the 110 mile shot, but I managed to do a 105 nmi PD-STT launch at M1.55 42,000 ft vs a M1.45 Tu-160 at 46,000 ft with the AIM-54C:

Missile was still going M2.63 upon impact after slightly over 70 miles of flight. For these conditions the AWG-9 is more of a limitation than the missile

[captain_dalan]

35 minutes ago, Noctrach said:

1. Both straight line and loft.

2. You can also simulate most of the testing scenarios mentioned on current patch with greater reliability than they could at the time (guidance has definitely improved even if it's nowhere near done).

Can't quite get the AI to stay at 52,000 or M1.55 to replicate the 110 mile shot, but I managed to do a 105 nmi PD-STT launch at M1.55 42,000 ft vs a M1.45 Tu-160 at 46,000 ft with the AIM-54C

1. Am am referring to page 8 of the white-paper here:
"We calculated the drag forces from the combined surface integral of the face-normal forces and face-shear forces on the whole missile surface. From these we calculated the drag coefficients at each altitude and fitted a curve that uses the same trajectory as the game engine does. We used this function to further calculate the the flight profile of the missile in level flight and in a loft scenario. This simulation is considerably simpler than the one used for the AIM-120, but in this case we do not have drag data for flight at AoA."

2. I actually have on multiple occasions. And the tests are..... let's say satisfactory, in that they pass the bare minimum. I'll post 10 tracks here and the mission that helped create them, to illustrate my point. What i mean by satisfactory is, the relevant tests give the adequate results, but just barely and not in a way most people think. This mission is set to recreate the 6 on 6 shootout, shooter at 28400ft mach 0.8, targets between 20000ft and 23000ft mach 0.5. Targets hot, set to non-maneuvering and now CM. The formation of targets is carefully chosen to make things as easy for the AWG9 to discriminate the targets. That is the front echelon is lower then the rear echelon, so the rear isn't in the radar shadow of the front. Targets aren't small drones but  large MiG-31's and most shots are taken closer to 50 miles. The original test requires launches from 50 to 32 miles. Thus the test is heavily rigged to succeed. And it does. The missiles score 3-6 out of 6 kills routinely, and the average being 4.5-5 out of 6. And except in one case, all the misses are a result not of the missile running out of energy, but guidance failure-loss of track by the mothership. Just like in real life. So the missile is well modelled, right? 

On the surface it seems so, if we consider the PK to be only valid metric here. Take a closer look at each missile that actually makes it to the target. Both those that hit, and the one just barely misses. At least half the missiles that make it, are barely transonic at the moment of impact. The hang around mach 0.95 and 0.98. Some are as slow as 0.90 and 0.91. That's just enough to hit the target. I have no idea who came up with the test, or what was on their mind when they did, but i would expect a wider margin of error on their part. That is, designing the test so that they give themselves a better chance to succeed.

But that's not what is puzzling me the most though. Not even close. An even closer inspection of the test results, reveals that most of the subsonic kills are achieved by the missiles that were fired from closer ranges. And against the higher flying targets - the rear echelon. So a missile fired at 50 miles against at 20000ft target has better terminal performance then 30 mile shot against a 23000ft target. A target in less dense atmosphere and closer at moment of launch. That seems very counterintuitive to me. The only obvious difference that i can spot is that the closer shots are actually steeper on both the way up and the way down, does bleeding more energy.  This makes me think one of two things may be off here:
a- The induced drag is overmodelled;
b- The lofting profile needs further work;

Or possibly c - my expectations are wrong, and intuitiveness be damned, this is indeed the desired behavior of the missile.

Sorry for the long rant, but unlike most shooters people, i was never really obsessed with the extreme shots, i've never fired a Phoenix at more then 60 miles away (at the extreme during strategic intercepts) nor do i plan to, unless the mission i fly demands me doing so. And this above mentioned behavior has really been my only chip in the shoulder since the major upgrade. In the attachments you can find my mission and the tacview files. 

Cheers and have great Sunday! 

Tacview-20220605-161933-DCS-6 on 6 test mk47.zip.acmi Tacview-20220605-162401-DCS-6 on 6 test mk47.zip.acmi Tacview-20220605-162827-DCS-6 on 6 test mk47.zip.acmi Tacview-20220605-163248-DCS-6 on 6 test mk47.zip.acmi Tacview-20220605-163657-DCS-6 on 6 test mk47.zip.acmi Tacview-20220605-164111-DCS-6 on 6 test mk47.zip.acmi Tacview-20220605-164537-DCS-6 on 6 test mk47.zip.acmi Tacview-20220605-164949-DCS-6 on 6 test mk47.zip.acmi Tacview-20220605-165355-DCS-6 on 6 test mk47.zip.acmi Tacview-20220605-165759-DCS.zip.acmi 6 on 6 test mk47.miz

[Noctrach]

27 minutes ago, captain_dalan said:

a- The induced drag is overmodelled;

b- The lofting profile needs further work;

I think it's a perhaps a tiny bit of the former but mostly the latter. If I would speculate anything it's that maybe the missile body might be contributing slightly too little to lift, putting more work (and thereby drag) on the control surfaces, but that's pure conjecture from my side. I think it's mostly related to sub-optimal loft geometry and poor terminal guidance.

If we look at the current AMRAAMs (which might be a bit a bit lacking on the induced drag), their loft generally takes them higher than the Phoenix. Though the AIM-120 is also currently quite incapable of manoeuvring with targets at higher altitudes, either due to lack of control surface authority or just really bad geometry. It just doesn't do enough turning.

The Phoenix on the other hand does way too much turning. I'm very much with you in that frustration. No matter the parameters, they will manage to bleed off more than a mach of energy in the last 7 miles almost every single time.

I see a significant discrepancy in terminal velocity of STT vs TWS shots for the AIM-54, with the latter bleeding off speed much more rapidly by aggressively compensating for any target vector change. But I believe reading that a patch for this is slated for next open beta release, so we'll see if that improves things

Edited June 5, 2022 by Noctrach

[captain_dalan]

31 minutes ago, Noctrach said:

I think it's a perhaps a tiny bit of the former but mostly the latter. If I would speculate anything it's that maybe the missile body might be contributing slightly too little to lift, putting more work (and thereby drag) on the control surfaces, but that's pure conjecture from my side. I think it's mostly related to sub-optimal loft geometry and poor terminal guidance.

If we look at the current AMRAAMs (which might be a bit a bit lacking on the induced drag), their loft generally takes them higher than the Phoenix. Though the AIM-120 is also currently quite incapable of manoeuvring with targets at higher altitudes, either due to lack of control surface authority or just really bad geometry. It just doesn't do enough turning.

The Phoenix on the other hand does way too much turning. I'm very much with you in that frustration. No matter the parameters, they will manage to bleed off more than a mach of energy in the last 7 miles almost every single time.

I see a significant discrepancy in terminal velocity of STT vs TWS shots for the AIM-54, with the latter bleeding off speed much more rapidly by aggressively compensating for any target vector change. But I believe reading that a patch for this is slated for next open beta release, so we'll see if that improves things

 

That's a very good point, and definitely a worthy subject for my next series of tests, just like the above, but in STT. Glad i am not alone in my observations here! Salute!

[RPY Variable]

On 6/4/2022 at 5:35 PM, Noctrach said:

Quite frankly, people should stop expecting the Phoenix to be some magical physics defying death machine and learn how to employ the weapon. The reason folks managed to hit shots like this in the past is because the Phoenix was simply overperforming. It has since been fixed so will take some adjusting expectations.

 

@Noctrach with the new update that:

• Reduced AIM-54 induced drag. 
• Returned to original guidance parameters thanks to a guidance fix by ED.

I test your tracks again:

Your track:
You made two shoots. One at 92nm that didn't hit, and a second one at 85nm that hit at 700kn.
The same track with the new update:
Both missiles hit, the second one, that didn't hit before, now hits with a speed of 1600kn, more than double the speed of the closest shoot before the update.

I also was able to make a 107nm shoot at M0.9 with the AIM-54A and actually hit a maneuvering target. Imagine what can be done at supersonic speeds with the MK60.

So @Noctrach are you going to make a post about the AIM-54 being broken and doing "magical physics defying death machine"? Because when I made this post, you stated, in a very condescending way, that the missile was working as the "real world test shots" and before "it was simply overperforming" and "people" (me) needed to "learn how to employ the weapon". Seems that we are back at >100nm shoots like before.

_AIM54A 107nm boom.trk

[Comstedt86]

8 hours ago, RPY Variable said:

@Noctrach with the new update that:

• Reduced AIM-54 induced drag. 
• Returned to original guidance parameters thanks to a guidance fix by ED.

I test your tracks again:

Your track:
You made two shoots. One at 92nm that didn't hit, and a second one at 85nm that hit at 700kn.
The same track with the new update:
Both missiles hit, the second one, that didn't hit before, now hits with a speed of 1600kn, more than double the speed of the closest shoot before the update.

I also was able to make a 107nm shoot at M0.9 with the AIM-54A and actually hit a maneuvering target. Imagine what can be done at supersonic speeds with the MK60.

So @Noctrach are you going to make a post about the AIM-54 being broken and doing "magical physics defying death machine"? Because when I made this post, you stated, in a very condescending way, that the missile was working as the "real world test shots" and before "it was simply overperforming" and "people" (me) needed to "learn how to employ the weapon". Seems that we are back at >100nm shoots like before.

_AIM54A 107nm boom.trk 616.46 kB · 3 downloads

Can't wait to try this, did 140nm splash before this patch