Air-to-Air Missile Discussion

[GGTharos]

First case is R-27ER suddenly not tracking?

 

I have seen this a few times, but I don't know what causes it. I will try to replicate for devs to look at.

 

Second case is some sort of network desync issue - ping doesn't really matter (but the higher, the more likely for desync to show up).

 

Missile trajectory is simulated independently on both PCs, but damage is applied from launching PC. So if it hits you on his PC, you are hit. The trick is that since the missile trajectories are simulated independently, a tiny de-sync in launch timing or parameters may cause the two trajectories to appear very different. Why the independent simulation? It saves on network bandwidth.

[blkspade]

I haven't looked at, but I assumed this was from earlier where I was sure I only got one kill on you.

[Ragnarok]

First case is R-27ER suddenly not tracking?

 

I have seen this a few times, but I don't know what causes it. I will try to replicate for devs to look at.

 

Second case is some sort of network desync issue - ping doesn't really matter (but the higher, the more likely for desync to show up).

 

Missile trajectory is simulated independently on both PCs, but damage is applied from launching PC. So if it hits you on his PC, you are hit. The trick is that since the missile trajectories are simulated independently, a tiny de-sync in launch timing or parameters may cause the two trajectories to appear very different. Why the independent simulation? It saves on network bandwidth.

 

I'm sorry because I did not keep more track file. I remember once fired six missiles, each disappearing in front of me at 1 or 2 km. It does not matter, I thought it was worth report this bugs.

 

Lately, the server 104th has big problems with the network. But I have understanding. Nothing wrong with Spade...

[Ragnarok]

First case is R-27ER suddenly not tracking?

In fact, ER disappears in the air. I forgot to say that the switch look at my nickname. That you known...

 

I haven't looked at, but I assumed this was from earlier where I was sure I only got one kill on you.

Not. something else.

[GGTharos]

That's really interesting because tacview displays it as being there!

[will-]

Second case is some sort of network desync issue - ping doesn't really matter (but the higher, the more likely for desync to show up).

 

 

I try not to play on any server with a ping over 100. Also have seen planes warp head on engagements missile will lose lock. RWR will break contact also... and easy win for opponent..

 

Not sure what i can do to help besides confirm. Hope this gets fixed (sure it all will get ironed out).

[Bacab]

Hi,

 

I was wondering if someone had already explained somewhere how does the tracking system of missiles work in DCS (what is simulated, what is not...). If it has never been explained then is it possible to have explanations ?

Thanks in advance for your answers.

[flankerted]

First case is R-27ER suddenly not tracking?

 

I have seen this a few times, but I don't know what causes it. I will try to replicate for devs to look at.

 

Second case is some sort of network desync issue - ping doesn't really matter (but the higher, the more likely for desync to show up).

 

Missile trajectory is simulated independently on both PCs, but damage is applied from launching PC. So if it hits you on his PC, you are hit. The trick is that since the missile trajectories are simulated independently, a tiny de-sync in launch timing or parameters may cause the two trajectories to appear very different. Why the independent simulation? It saves on network bandwidth.

 

Hi,

 

I was wondering whether the second case caused by some sort of network desync issue could be sovled and could save network bandwidth in the same time. Since it often happens and annoys me:doh:

[Sceptre]

Hi,

 

I was wondering whether the second case caused by some sort of network desync issue could be sovled and could save network bandwidth in the same time. Since it often happens and annoys me:doh:

 

I normally play with around a 400 ping to European/American servers and experience no lag. I have compared it with Australian servers with less than 60 ping for me, and there was no noticeable difference, other than the load time to get into the server. The missiles behaved the same from what I could tell, and the other clients' planes were smooth and not teleporting around like you'd think they would with a high latency.

[FUgaijin]

Is it just me or are the 120's completely nerfed? Correct me if i am wrong but if you fire a 120 from 15nm at say a 27 with both altitudes being equal once it goes pit bull it should be game over. I can understand notching an AIM 7 but if you have no idea a 120 is inbound until the last 6 sec, your not out running/turning that missile. At any rate it seems DCS has set the F-15 at a huge disadvantage when compared to the 27, 33, or even the 29. While the 15 AFM is nice it really sucks in ACM against the russian birds that are not. sorry i am venting but man is it frustrating knowing that a superior Missile (120) has an ~ 60% fail rate where russian birds are able to dodge a pitbulled 120 while maintaining a solid lock guiding their ER straight into the cockpit.

[Pilotasso]

It's an old issue being worked on. The old seeker algorithm and the new missile flight model seem not to agree with each other.

[IASGATG]

AIM-120C-5 Performance Assessment

 

Hello wonderful DCS community. We've had this document written up for about the past nine months now and we've debating what we want to do with it. Finally we came to the conclusion that we'd just post it to the community so that way any questions people have regarding the most current (at time of writing) information regarding the missile can be easily accessed.

 

If there is anything in this document that is incorrect, the email at the top would love to hear it so that way improvements can be made accordingly.

 

Cheers!

AIM120C5 Performance Assessment rev2.pdf

[SFJackBauer]

Hello wonderful DCS community. We've had this document written up for about the past nine months now and we've debating what we want to do with it. Finally we came to the conclusion that we'd just post it to the community so that way any questions people have regarding the most current (at time of writing) information regarding the missile can be easily accessed.

 

If there is anything in this document that is incorrect, the email at the top would love to hear it so that way improvements can be made accordingly.

 

Cheers!

 

Impressive! I think it deserved its own thread due to the quality of the work.

 

If only you guys could re-run the simulation using a 0-0 launch parameter, so we could compare with the NASAMS/SL-AMRAAM performance (although I suspect the ground launched variant is the C-7).

[IASGATG]

It did have its own thread and suddenly it ended up here.

 

As for a 0-0 launch, well from a CFD point of view we wont be doing that. As for the missile used, the C-5 and C-7 have the same kinematic profile so it wont make a difference; same body, same motor.

Edited September 7, 2014 by IASGATG

[Bacab]

Is it just me or are the 120's completely nerfed? Correct me if i am wrong but if you fire a 120 from 15nm at say a 27 with both altitudes being equal once it goes pit bull it should be game over. I can understand notching an AIM 7 but if you have no idea a 120 is inbound until the last 6 sec, your not out running/turning that missile. At any rate it seems DCS has set the F-15 at a huge disadvantage when compared to the 27, 33, or even the 29. While the 15 AFM is nice it really sucks in ACM against the russian birds that are not. sorry i am venting but man is it frustrating knowing that a superior Missile (120) has an ~ 60% fail rate where russian birds are able to dodge a pitbulled 120 while maintaining a solid lock guiding their ER straight into the cockpit.

I assume that it must be very difficult for the dev' team to correctly balance missile. There are so many unknown data ! It is nearly impossible to really estimate the efficacy of a missile: no one who has the data will tell the truth because the stakes are too high.

 

Remember that it is not certain that the 120 behaves IRL better than a SARHM. I know the RAF has compared the efficiency of the 120 against the old Skyflash (not sure of the last name) and said that without the update target coordinates during the missile flight the 120 was worst than the Skyflash.

Edited September 8, 2014 by Bacab

[AFAlinebacker42]

"On the missiles topic, we need a new guidance system. - Blaze"

 

^^^ IASGATG, Tharos... :3 Yes!!! SOMEONE GETS IT!

 

Also, 16 nm shot, 5nm intercept, thats what like a 3 second flight time? Is that too long for you? Is the AIM-120 too slow? ;)

[Ragnarok]

Also, 16 nm shot, 5nm intercept, thats what like a 3 second flight time? Is that too long for you? Is the AIM-120 too slow? ;)

 

You that did not understand. The moment of launch 16nm distance between the attacker and the target. After that, the missile guidance, planes are closer to each other. At the moment of impact, the distance between them planes is 5nm. Should be noted that this was the first version AIM-120C.

 

I just want to say, kill ratio is not indication of how it should be programmed AMRAAM. Must be a science and logic. We live in a time of fierce propaganda of the time, where everything should be taken with a grain of salt. Regardless of the side.

Edited September 9, 2014 by Ragnarok

[GGTharos]

Hit/Kill ratio tells you how it compares to other missiles overall. For determining flight characteristics other methods must be used, and science is exactly how the graph was done.

 

As for the 120 shot you described, it's very thin on information, and it was more along the lines of 14nm to 8nm, not 16 to 5.

[TAW_Blaze]

"On the missiles topic, we need a new guidance system. - Blaze"

 

^^^ IASGATG, Tharos... :3 Yes!!! SOMEONE GETS IT!

 

Also, 16 nm shot, 5nm intercept, thats what like a 3 second flight time? Is that too long for you? Is the AIM-120 too slow? ;)

 

Unfortunely none of them have to do anything with it, they are both working on the kinematics part. I'm not too sure if there's anyone to point at to do it.

 

Maybe me in a decade or two. I'm about to jump into the radar technology department. I mean if I have the luck to get to the jump. It'll be fixed by that time though, probably. Or not. :megalol:

Edited September 9, 2014 by <Blaze>

[Ragnarok]

As for the 120 shot you described, it's very thin on information, and it was more along the lines of 14nm to 8nm, not 16 to 5.

It is said Jeff Hwang. Comparing the Serbian story, all agree. But I do not believe everything. Maybe the pilot slightly altered intentionally. Especially the implications of the dynamics of the missile. Maybe 14-8 more logical, but here the target is moved from 16L to 14R.

 

Perhaps this is a little off topic but I think it is of interest to see and compare the occurrence of DCS simulator.

 

On 26th March 1999, TJ"

[AFAlinebacker42]

Ragnarok, we understand perfectly. A ~10 to 15 mile shot in fighters, will typically have a closure rate of 800 - 1200 kts, and if a missile is going to be fired, gives a very high Pk with very low survivability on both sides of the merge.

 

457FS Spads got the first US viper kill and first AIM-120 kill. It wasn't even about the jets - just the luck and the tactics. Here:

 

Blaze, keep us posted as you learn more about radar and missile guidance, and hopefully the stuff WILL be able to contribute to making the sim more realistic!

[GGTharos]

Do you guys have anything useful to offer?

[Ragnarok]

Do you guys have anything useful to offer?

Remove all unnecessary posts. Politely was the answer from my side.

[GGTharos]

I have no argument with what you posted Ragnarok, it was at least a good attempt to interpret some known data.

 

Mostly I want to know what people's objection to the PDF is.

 

I will try to summarise what the PDF means in my opinion:

 

1. This PDF is a calculation of the AIM-120 drag profile via CFD

 

2. This dag profile corresponds with real life drag profile for a very similar missile (testbed for AIM-120 prototype), for which we have data from real shots, not computations/projections

 

3. The result means that both the CFD is good, AND that ED's missile physics engine can reproduce the performance with reasonable accuracy at least for the simple case (non-maneuvering missile) - so the in-game missile physics, while not perfect, are pretty good. IMHO.

 

4. We also have AIM-9L (real shot) data, and this data is already used in the game for AIM-9. As in, you this in the game right now.

 

 

Generally speaking, AIM-9 drag profile represents IRH missile drag profile, and AIM-120 drag profile from CFD represents radar-guided missile drag profile. Why? Because supersonic drag is driven by nose shape. This is very very basic, simplified missile physics, but it works just like that. Yes, fin types, flared tails/bodies can make a difference too.

 

So, in conclusion, IMHO radar guided missiles in-game should have a drag profile that looks more what is presented in the PDF (probably a little more drag, because like it or not, AIM-120 is seriously slick), but right now they look a bit more like IRH missiles in terms of drag.

 

 

EDIT: No one is concerned with guidance in this work. This work is sticty about the flight physics. Guidance is its own huge topic.

Edited September 10, 2014 by GGTharos

[GGTharos]

I have cleaned up the thread a little.

 

What IASGATG presented is a piece of science.

 

Many people collaborated for it, including people for the Russian side of the forum, even if they don't know about it. In other words, they provided some sources which are publically accessibe, and they contain the propellant weight for some USAF missiles.

 

Other sources include studies of AIM-9L and a physics testbed for AIM-120, which gives us an RL speed-g available-time graph for these missiles from real test shots.

 

The data isn't perfect knowledge, but it is very good.

 

If you want to dispute the presented paper, come up with something that's science.