DCS: F-14 Development Update - AIM-54 Phoenix Improvements & Overhaul - Guided Discussion

[WarthogOsl]

It's funny, because they fixed the issue where the missile would suddenly pull up when it was notched while on the way down (and was presumably active), but apparently the same thing does not apply when the missile is on the way up, and not active.  I have no idea what the correct behavior would be, but somehow I doubt it would be to just divert from the current arc and pull nearly vertical (especially for the C).

[Karon]

The guidance onto an extrapolated track makes little sense at the moment (they can also fly backwards towards the Tomcat).
So, yeah, there's work to do...

Nevertheless, when used correctly, they work well in the scenarios they were meant to be used.

[Gareth Barry]

Firstly, i want to thank Mr Palkovnik for his work on this- i have enjoyed being educated about nozzle exit area vs altitude and its effect on thrust and impulse. Let me also preface what i am about to say with this- there are few purchases i have ever made that i have been as happy with as Heatblur's F14. But for us nerds who like things to be as accurate as possible, even if just to understand how things really were historically, it is interesting to know where the current model is off. Can i ask for a somewhat condensed, descriptive version of Mr Palkovnik's findings versus the current model? From i can gather so far, the current DCS model is a somewhat simplified model that is sort of an 'average' across the altitude range. That is, Mr Palkovnik's model shows that the missile as currently modeled is somewhat underperforming at high altitude, and perhaps overperforming at low altitude. The motor of the phoenix is quite different in that it has pressure and nozzle exit area make its thrust quite dependant on altitude. Perhaps then, the missile matches the NASA test because that is where the current model is tuned to? As i said, im not really even asking for any changes, just trying to understand this better. And my comments/summary could be very far off.

Edited May 12, 2024 by Gareth Barry
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[Machalot]

48 minutes ago, Gareth Barry said:

Perhaps then, the missile matches the NASA test because that is where the current model is tuned to?

Way back in the pages of this thread, we discussed the fact that there was no NASA test. NASA developed a simulation based on public sources, possibly the same sources HB ended up using. To HB's credit their independent model was shown to match the NASA simulation results very closely, even though they didn't intentionally refer to the NASA model when building theirs. 

[Gareth Barry]

Shucks so there never was an actual physical test by NASA. Goodness, need to process that. Does the Heatblur model kinematically match the NASA results across a range of altitudes? Or is it specific to one altitude only? Not trying to point fingers or throw mud in any direction at all, just want to understand where we are. 

Edited May 12, 2024 by Gareth Barry
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[Gareth Barry]

Just been thinking about this, please excuse my musing- but upon further thought, if the current kinematic model of the phoenix matches the NASA simulation across a range of altitudes, then that is more than good enough for me `\/(••,)\/`

[Machalot]

18 hours ago, Gareth Barry said:

Does the Heatblur model kinematically match the NASA results across a range of altitudes? Or is it specific to one altitude only?

You could dig through this thread to find the actual posts on this topic, including screenshots of the NASA report, but there were really only a handful of trajectories published in the report, at maybe 2 or 3 altitudes and 2 or 3 Mach numbers. And only some of them have the same mass as the in-service AIM-54s.  Unfortunately it's not a data set sufficient for model validation across the flight envelope.  It's a good spot check, and the HB model passed with flying colors. 

[tavarish palkovnik]

A little bit more of mathematic ...

 

AIM-54 motor.pdf

 

I don't know what public available data were used, either by NASA or here. All I know NASA in their own handbook (Solid Rocket Motor Nozzles, page 10) gave characteristics of this motor, in very much details. Together with configuration of grain these numbers are precisely confirmed as you could find on previous page

 

 

 

Depending of temperature motor works from 20 to 30 seconds  √

Maximal chamber pressure from 1000 to 700 psi (from 69 to 48 bar)  √

Average thrust from 5000 to 1000 lbf (from 22269 to 4454 N)  √

 

Only maximal pressure of 69 bar I've got a bit higher, all right, maybe it is not +70degC but +60degC or +65degC as upper limit. When have all this, and when have basic theory about rocket propulsion everything can be calculated, it means easily and indisputably we can have thrust values of this motor in function of altitude. 

Of course, this is one pair of aces, the other pair of aces is that drag coefficient significantly increase with altitude because of friction, but this motor compared to some others gives up there quite much then friction takes.   

 

 

 

 

[Kageseigi]

On 5/12/2024 at 5:32 AM, Gareth Barry said:

Just been thinking about this, please excuse my musing- but upon further thought, if the current kinematic model of the phoenix matches the NASA simulation across a range of altitudes, then that is more than good enough for me `\/(••,)\/`

For me, at least, the issue is less with the accuracy of how the missile flies, and more with how the missile tracks (or the lack thereof). As far as I'm aware, that's an ED issue, sadly.

As was discussed earlier about third-parties, I still think that is a vital point for ED to focus on... how the different modules interact with each other. Like it or not, a big part of DCS is PVP combat. If one module's missile is realistically modeled, but another's is overperforming, that really hurts the player of the realistically modeled module.

The same can be said for any PVP game. But in most, the goal is balance. In DCS, the goal is supposed to be accuracy. But not all modules are equally accurate, unfortunately. Where the flight models of planes are concerned, you can at least voice your concerns to the specific dev team. But for missile performance, it seems ED doesn't want to allow other parties to have the control they need in order to make the changes/fixes that are needed. At least, that's what I've gathered from reading the forums. I hope some changes are made soon in that regard.

I'm not really sure of what flexibility ED allows 3rd party devs in general. The F-14 has special options to disable the burble because HB modeled its own. The Mig-21 has special options to have unrealistic tracking HUD elements, I believe. The F-86 has special options to disable automatic seat movement during takeoff/landing. Where is the limit for what a dev can allow the player to do or not to do that either ignores or overrides DCS' own systems, or even give themselves unrealistic advantages? For a single-player game, there's no real harm. But DCS is multiplayer also.

Edited May 16, 2024 by Kageseigi

[The_Tau]

5 hours ago, Kageseigi said:

For me, at least, the issue is less with the accuracy of how the missile flies, and more with how the missile tracks (or the lack thereof). As far as I'm aware, that's an ED issue, sadly.

As was discussed earlier about third-parties, I still think that is a vital point for ED to focus on... how the different modules interact with each other. Like it or not, a big part of DCS is PVP combat. If one module's missile is realistically modeled, but another's is overperforming, that really hurts the player of the realistically modeled module.

The same can be said for any PVP game. But in most, the goal is balance. In DCS, the goal is supposed to be accuracy. But not all modules are equally accurate, unfortunately. Where the flight models of planes are concerned, you can at least voice your concerns to the specific dev team. But for missile performance, it seems ED doesn't want to allow other parties to have the control they need in order to make the changes/fixes that are needed. At least, that's what I've gathered from reading the forums. I hope some changes are made soon in that regard.

I'm not really sure of what flexibility ED allows 3rd party devs in general. The F-14 has special options to disable the burble because HB modeled its own. The Mig-21 has special options to have unrealistic tracking HUD elements, I believe. The F-86 has special options to disable automatic seat movement during takeoff/landing. Where is the limit for what a dev can allow the player to do or not to do that either ignores or overrides DCS' own systems, or even give themselves unrealistic advantages? For a single-player game, there's no real harm. But DCS is multiplayer also.

 

 

For me having ED doing all the missile stuff is better than what i was before, namely for years MiG21's R3S was completely different than AIM-9B, even though one is a direct copy of another. Key problem with ED that changes and updates it make literally takes years....x

[tavarish palkovnik]

In addition after motor, to see what should be final score, what should be final velocity if motor gives this what it is gives. One example easy to calculate, horizontal flight, max altitude and max launch speed

T.pdf

Looks fair and square, total drag impulse is 137500 Ns what is 30% of thrust impulse, total additional speed 840m/s what seems as reasonable for this altitude  

By the way...with same model and if thrust force would be constant 13595 N for 27 seconds, final velocity came out as 1265m/s or 4,29M

Edited May 16, 2024 by tavarish palkovnik

[Kageseigi]

On 5/16/2024 at 5:21 AM, The_Tau said:

 

For me having ED doing all the missile stuff is better than what i was before, namely for years MiG21's R3S was completely different than AIM-9B, even though one is a direct copy of another. Key problem with ED that changes and updates it make literally takes years....x

Yes, I think ED having having control over such things is for the best so there can be consistency between the modules... but with the caveat that they make it a priority to maintain that consistency. The years between updates/changes is the only reason I'd consider that it might be better to allow other parties to make needed changes. In either case, I suppose it comes down to if/when anyone is willing to make the needed changes.

And so I can make sure I stay more on the thread topic, I do hope ED makes it a priority to get the Phoenix on a new API soon. It feels like it is unique to other FOX-3's, so it needs special attention. She's an ol... a mature girl. She needs gentle lovin' and pamperin'.

[Harlikwin]

On 5/16/2024 at 3:21 AM, The_Tau said:

 

For me having ED doing all the missile stuff is better than what i was before, namely for years MiG21's R3S was completely different than AIM-9B, even though one is a direct copy of another. Key problem with ED that changes and updates it make literally takes years....x

While I agree one party doing the modeling is better from a consistency standpoint, there are still a bunch of problems, i.e. there are 2 different magic2's in game now with different performance (and thats a recent example). Plus ED is SLOOOW to fix any missile.

And, unfortunately you are wrong on the R3S, but its an oft repeated myth, cuz its copy pasta-ed all over the web. The R3S is derived from the sidewinder but not a copy. The seeker is probably the closest part, but it has more gimbal angle IIRC, and a different track rate. The rest of the missile actually has some significant improvements. The main two are the gas generator which has a longer burn time/different composition (more flight time). And then a decently better rocket motor. So overall the missile has a decent bit more range than the 9B. 
 

Edited May 18, 2024 by Harlikwin

[tavarish palkovnik]

I’m looking for pressure-time diagram of Mk36 Mod.5 motor (Sidewinder 1C AIM-9D) or Mk50 Mod.0 (Chaparral).

Or of any other Mk36 in 6-points star configuration, preferably with composite propellant. 
So if someone has it, it would be appreciated.

There are few of such kind on dtic.mil when motor pulsing were performed in past, seams like similar but always something missing or simply is not what real Sidewinder motor should looks like

[Sindar]

I haven't read NASA's report on the AIM-54C engine. But, according to my report, I have not had a single AIM-54C defeat in DCS in the past year. Both from AI pilots and players.

[Katsu]

Working as intended? 

Edited August 21, 2024 by Katsu

[DSplayer]

17 hours ago, Katsu said:

Working as intended? 

 

Something that ED would have to change unfortunately

[Gareth Barry]

Does the missile behave differently against AI when online vs when playing single player? The reason that i ask, is that i am currently playing through 'Cage The Bear' on single player, and have got plenty of kills with the phoenix, including tonight in a pretty tough mission (mission 9, which was bugged and hence almost impossible- thankfully kaba was kind enough to send me an updated file that fixed this mission.)

Whether these are correct tactics or not i dont know, but vs fighters, it really does seem like two different missiles-when above 25000 ft, kills of around 40 miles or more seem to have a decent probability- although it does seem strange that at impact, you are pretty much within visual range of the target. At high altitudes and long ranges, i pretty much always fire in tws- keeps SA as well as options to fire another one. At low altitudes, its pretty much a 10 mile missile, and seems to have pros and cons vs the sparrow. I almost always fire from a PAL lock in these situations. This is assuming a head on target- if in a tail chase, the distances seem to be much closer (like half) in order to have enough energy. Well, thats how i use it anyway, which may or may not be correct, but seems to be working for me at least. 

[Raven (Elysian Angel)]

16 minutes ago, Gareth Barry said:

Does the missile behave differently against AI when online vs when playing single player?

Probably not, but during online play a lot depends on the quality of DCS’s network code, the ping to the server from your end, ping to the server from others’ PCs, …

It all depends on how that data is routed and synchronised.

[WarthogOsl]

6 hours ago, Gareth Barry said:

Does the missile behave differently against AI when online vs when playing single player? The reason that i ask, is that i am currently playing through 'Cage The Bear' on single player, and have got plenty of kills with the phoenix, including tonight in a pretty tough mission (mission 9, which was bugged and hence almost impossible- thankfully kaba was kind enough to send me an updated file that fixed this mission.)

Whether these are correct tactics or not i dont know, but vs fighters, it really does seem like two different missiles-when above 25000 ft, kills of around 40 miles or more seem to have a decent probability- although it does seem strange that at impact, you are pretty much within visual range of the target. At high altitudes and long ranges, i pretty much always fire in tws- keeps SA as well as options to fire another one. At low altitudes, its pretty much a 10 mile missile, and seems to have pros and cons vs the sparrow. I almost always fire from a PAL lock in these situations. This is assuming a head on target- if in a tail chase, the distances seem to be much closer (like half) in order to have enough energy. Well, thats how i use it anyway, which may or may not be correct, but seems to be working for me at least. 

40 miles is pretty close, but also, are you cranking to gimbal limits after launch, to reduce your closure to the target?

[Gareth Barry]

Generally yes- although i admit this is probably one of the many bad habits one can pick up (ie not cranking) when playing against AI red team in singlw player, who dont have fox 3s. In this scenario, they might launch a fox 1 at me, but they will eventually have to defend my fox 3, which trashes their fox 1. I usually go full burner when launching at high altitude to give the missile as much KE as possible, pull back the throttle after launch and then crank. Perhaps im not cranking enough? Anyways, im not saying that it's wrong that i seem to usually catch up with the missile- perhaps i worded that badly- it's just not how i imagined missile shots to play out. One of the main reasons i play dcs is to really educate myself on how these aircraft really work. Before DCS,  I had no idea about search bars, radar modes, doppler filters, PRF and and and....

[Flapjacks]

Hey, how does one tell when a Phoenix goes active while in STT? I read the first post and saw that it said it will go active when it should remain semi-active the whole time, I'm just not sure how to tell when it does this.

[draconus]

1 hour ago, Flapjacks said:

Hey, how does one tell when a Phoenix goes active while in STT? I read the first post and saw that it said it will go active when it should remain semi-active the whole time, I'm just not sure how to tell when it does this.

You can't tell. Only the C does that when closer than 10nmi from the target. You can force it by breaking the lock but not advisable.

[Flapjacks]

6 hours ago, draconus said:

You can't tell. Only the C does that when closer than 10nmi from the target. You can force it by breaking the lock but not advisable.

alright, thanks again!

[WarthogOsl]

16 hours ago, Flapjacks said:

Hey, how does one tell when a Phoenix goes active while in STT? I read the first post and saw that it said it will go active when it should remain semi-active the whole time, I'm just not sure how to tell when it does this.

I don't think there's any indication (and there's probably not supposed to be) in that case.  Best bet is to use the TTI timer, as I assume it will go active at 16-20 seconds to impact.  If you are able to get an external view of the missile with F8, you can usually tell by it's behavior when it has gone active.