[RESOLVED] AIM-54 inconsistency with CFD whitepaper

[Spurts]

Oh wow!  That's great news!

[captain_dalan]

On 1/31/2022 at 3:51 PM, Skarp said:

I disagree I think the missile will still perform well as before. 70% Of my missiles miss because of bad guidance logic. Over AOA ect. Launch from low altitudes I suspect will be rough because it’s so draggy.

 

I was just taking a jab at that guy that apparently implied 35 mile shots at medium - CAP altitudes were false expectations due to years of inaccurate modeling 

1 hour ago, Cobra847 said:

Guidance changes will be introduced in a hotfix tomorrow. There should be significant improvement in the performance of the missile, though it is certainly not yet definitive. 

 

That came faster then expected! 
Apologies (from every likeminded individual) for the sleepless nights guys!

Edited February 1, 2022 by captain_dalan

[dundun92]

6 minutes ago, captain_dalan said:

I was just taking a jab at that guy that apparently implied 35 mile shots at medium - CAP altitudes were false expectations

I was actually responding to the claim that the AIM-54 kinetics at high altitude had to be made underperforming to make the low altitude, and that we therefore should expect significant boosts in kinetics at high altitude, which isnt the case from what HB has said. The guidance improvements will definitely improve energy retention for the AIM-54 for lofted shots, but its not going to fundamentally change the kinetics. 35nm shots were, and still are well within the 54s capabilities even with the broken guidance, though the terminal energy is unrealistically low from bad guidance.

[captain_dalan]

3 hours ago, dundun92 said:

 35nm shots were, and still are well within the 54s capabilities even with the broken guidance, though the terminal energy is unrealistically low from bad guidance.

Seeing how these two statements are made in the same sentence, if by "capabilities" you mean the missile is subsonic 5-10 miles short of reaching a non-maneuvering co-altitude hot target, then yes. I fully agree. I just wouldn't use the term capabilities, no more then i would use them for a plane doping out of the sky at 100 knots as part of its flight envelope  

[Prez]

41 minutes ago, captain_dalan said:

Seeing how these two statements are made in the same sentence, if by "capabilities" you mean the missile is subsonic 5-10 miles short of reaching a non-maneuvering co-altitude hot target, then yes. I fully agree. I just wouldn't use the term capabilities, no more then i would use them for a plane doping out of the sky at 100 knots as part of its flight envelope  

You simply have to baby the missile more than you are used to. It's not magic, it's physics. Regardless of the guidance issues, the missile is not smart. You have to do everything you can to improve the performance of your shots. From the short time I have been using the new missile in training, I've quickly adapted the SOP of the missile and have seen, frankly, the exact same performance at range and altitude compared to the previous iteration of the missile. A lot of people are upset with the reality of the AIM-54 because they had a year of it being the most insane thing ever, and making up for their poor employment standards.

[IVAN01rch]

Does anyone have AIM-54 CAD model?

[Strider21]

 

In the HB AIM-54 Simulation "White Paper", four known shots are referenced: High Altitude Intercept, Sea Skim Intercept, Maximum Range Intercept and Multi-Target Intercept. The source for these shots is cited as:  An Outsider’s View Of The Phoenix/AWG-9 Weapon System, Stephen Thornton Long, Naval Postgraduate School, March 1977

Is this paper available to view online anywhere? I cannot seem to find it but it seems it would be interesting to review.  

Having looked through a couple of F-14 books it appears those 4 shots are described similarly. For example, they are described in the 1985 book: "Modern Fighting Aircraft F-14" and details specifically about the target drones and RCS augmentation used. 

Searching online the only reference I can find is from an old NPS review: "Recent Naval Post Graduate School Publications June 1978". https://archive.org/details/DTIC_ADA060891/page/n1/mode/2up

It appears that the HB reference is incorrectly cited as the author in the above document appears to be P.C.C. Wang with Long as contributor. 

 

Edited February 2, 2022 by Strider21

[deathhoneybadger]

With the 4 different missile tests demonstrated in the white paper has the new drag logic been taken into account? I imagine the missile and Sim have changed a considerable amount since the white paper was published. With the current state of the missile the high alt intercept seems to be the only that continues to hit with regularity, 

The Sea skimming test does not seem to check out due to missile drag at low alt and reduced top speed of the missile down low. Hopefully a guidance logic update will solve issues with the MAX range shot, However the new drag modelling might cause an issue with the element. 

I also see an issue with the Multi target intercept with launching platform being at 28,000. It seems as is the missile does not have the kinematic performance to impact a target at 50NM fired under the parameters in the white paper. 

Is it possible to have the HB team demonstrate the new launch parameters in another White paper style document after the guidance logic has been updated with the upcoming hotfix?

[captain_dalan]

19 hours ago, Prez said:

You simply have to baby the missile more than you are used to. It's not magic, it's physics. Regardless of the guidance issues, the missile is not smart. You have to do everything you can to improve the performance of your shots. From the short time I have been using the new missile in training, I've quickly adapted the SOP of the missile and have seen, frankly, the exact same performance at range and altitude compared to the previous iteration of the missile. A lot of people are upset with the reality of the AIM-54 because they had a year of it being the most insane thing ever, and making up for their poor employment standards.

Checkout the tacview i posted in the feedback thread and PM me on your impressions. 

[Prez]

12 minutes ago, captain_dalan said:

Checkout the tacview i posted in the feedback thread and PM me on your impressions. 

You're gonna have to be more specific about that than just telling me to go look at a tacview. There are 6 pages and 150 replies to that thread. I'm not spending time sifting through it to look at something that wouldn't change my opinion. I participate in both milsim and competitive DCS, and so my opinion is such. I'm not part of the bias from either community here. 

[DSplayer]

58 minutes ago, Prez said:

You're gonna have to be more specific about that than just telling me to go look at a tacview. There are 6 pages and 150 replies to that thread. I'm not spending time sifting through it to look at something that wouldn't change my opinion. I participate in both milsim and competitive DCS, and so my opinion is such. I'm not part of the bias from either community here. 

Since I have way too much time on my hands during class.
 

[Katsu]

On 2/1/2022 at 2:17 PM, Cobra847 said:

Guidance changes will be introduced in a hotfix tomorrow. There should be significant improvement in the performance of the missile, though it is certainly not yet definitive. 

 

Hi Guys!

Did the hotfix has released? 

If not, did you guys have an estimate of when it will be released?

Thank you!

Edited February 3, 2022 by Katsu

[DSplayer]

1 hour ago, Katsu said:

Hi Guys!

Did the hotfix has released? 

If not, did you guys have an estimate of when it will be released?

Thank you!

 

TLDR: Patch might've gotten delayed. 

[Giat]

Hi everyones,
i beleive everyone here is trying to fix the AIM-54 issues and i can't wait till i'll be able to shoot down some plane 8NM in front of me without seeing my missile falling out of energy ... Yes, 8NM only ...

[near_blind]

1 hour ago, Giat said:

i can't wait till i'll be able to shoot down some plane 8NM in front of me without seeing my missile falling out of energy ... Yes, 8NM only ...

Sounds like you tried to force a bad shot and the tyranny of aerodynamic drag shut you down.

[Ikaros]

4 hours ago, Giat said:

Hi everyones,
i beleive everyone here is trying to fix the AIM-54 issues and i can't wait till i'll be able to shoot down some plane 8NM in front of me without seeing my missile falling out of energy ... Yes, 8NM only ...

Same thing happened to me last night.

[Biggus]

Cold or possibly flanking bandit roughly co-alt at low level?  8nm is marginal.  I'd be holding fire til 2nm or rethinking my missile selection.

So much of the current feedback is from people not understanding how over-modeled the old Phoenix was at lower altitudes, and it makes it hard to separate that phenomenon from actual bugs.  Tacviews would be very helpful.  

[Hardcard]

On 1/30/2022 at 7:15 PM, dundun92 said:

Unfortunately, years of the old AIM-54 have set some false expectations, which is becoming really apparent.

I'm sure that's the reason... it can't possibly be that the phoenix met the requirements to be classified as long range missile and thus people expect better than a medium range missile...

Nah, that can't be it

[The_Tau]

15 hours ago, Hardcard said:

I'm sure that's the reason... it can't possibly be that the phoenix met the requirements to be classified as long range missile and thus people expect better than a medium range missile...

Nah, that can't be it

long range missile with 1960s tech...

[DD_Fenrir]

The sheer amount of people who apparently lack the physics nous to understand the vast effect that changes in air pressure (and by direct proportion, density) play in missile performance leaves me somewhat incredulous.

Let's start with a truism:

• peak Aim-54 performance requires a supersonic launch from 30,0000 ft+ against a hot, high flying, non-manoeuvering target

At 30,000ft air pressure is going to be in the region of 25-30KPa. 

At 6,000ft it's going to be closer to 80kPa. 

That's more than 3 times the air pressure - ergo there are 3 times as many air molecules (density remember) that the missile body has to push against, 3 times as much air resistance; this slows the rate of acceleration of the missile whilst it is under power, limiting it's max achievable top speed plus it makes the missile slow down faster when it's in its glide phase.

That's already brought your theoretical range down to 35nm.

BUT THERE'S MORE!

Don't forget that the AIM-54 in those high-altitude, long-range shots lofts to >80,000ft in order to benefit from even less air resistance, in the region of only 2-3kPa! That's 1/10th of the air resistance it would have had at 30,000ft and ~1/20th of the air resistance down at 6,000ft!

But the 6,000ft shot would loft, right?

Not necessarily - given the max range the WCS may not calculate a loft profile; even if it does, it cannot possibly loft the additional 40-50,000ft that the high alt launch loft profile gives you because the motor performance suffers due to the increased low altitude air density. Ergo the loft will likely be in the 33% of that figure, and give you ~15,000ft additional loft, which would take the missile to the ~20,000ft region. That equates to roughly 40kPa.

That's still 13 times more than the air resistance at 80,000ft.

Then, have your target make even a moderate missile defence and of course it's going to be scuppered.

So, if you are:

1. Below 30,000ft
2. Under Mach 1
3. Targeting anything other than a bomber/transport that has limited evasive manoeuvring potential

Don't expect your Phoenixes to connect at anything close to 100nm. Even maintaining those launch parameters, against fighters you need to compress that timeline to 40-50nm. 

Get slower/lower and those ranges compress further. 

What's so difficult to comprehend?

 

 

 

Edited November 28, 2022 by DD_Fenrir

[WarthogOsl]

I honestly don't find being above Mach 1 to make much difference with Phoenix, and I stopped trying to get past the number when launching one a while ago.  Altitude seems to matter quite a bit more as far as the final missile interception speed goes.  I'd rather convert my speed into a bit more altitude rather then launch fast.  For the record, I'm usually launching 60-70 nm shots from 38-40k against AI fighter targets.  Against Fulcrums and Flankers I'll try to get higher...around 45k, and I still get kills on them.

F-14 pilot "Puck" Howe said that "the Sparrow likes speed, the Phoenix likes altitude."  That seems to hold true in DCS as well.