Missile Dynamics - A discussion

[Exorcet]

Last I checked, yes.

[RIPTIDE]

given how low the PK the Slammer has ingame, the phoenix wouldnt make no difference on a head on shot but it might make a world of difference in a chase, and a high speed chase is what I see most of the time. People cant turn much then. ;)

Quick, timely pull of the stick, AIM-54 wasted. Ironically, it's active seeker makes it easier. Now.... fire 2 or 3 of them in close succession.... that's a different story. :P

[MaverickF22]

The last time I flew a Su-27 online, I went head to head with an Eagle, dodged two BVR AIM-120's and flew into visual range before I was shot down with a AIM-7.

 

The 120 is certainly not unstoppable.

 

Man..., from what range had those AIM-120's been fired at you? 10-15nm? Of course it won't reach you before it's engine is stopped (it also depends on the speed of both you and that Eagle, but more on altitude i'd say, rather then the closure speed) and if you've done proper evasive manoeuvres or at least did some barrel rolls along your path to make the missile bleed airspeed..., then you won and outmanoeuvred it, not a surprise to me eighter! I've tested this enough too, and if the Aim-120 has less than 1000kts airspeed you may out turn it or outrun it(which is the only certain way possible to get rid of it so far)! If that missile is fired at you from closer than 5-7nm let's say on head-on..., you are dead whatever you'd try..., it is 100% chaff resistent and 100% resistent for not breaking lock no matter how close to the ground you are, which is bullshit, especially for a missile that has it's own, smaller and much weaker radar on which it can barely lock a target up at a maximum of 8nm on a clear day! Because even the firing aircraft's radar looses lock on a target flying as low as 3-5m above the ground due to clutter or signal waves bounce, not to mention the missile's radar that is even weaker! The missile might only be able to maintain a lock on it's target flying so low, if the missile would be just close enough to have a stronger and less breakable signal!

 

So this the most annoying thing at this missile, at least for me, not to mention that it has the longest legs between all the missiles, even greater than the R-27C and D, don't know why because the difference should be huge, but the fact that it has an unbeatable lock to fight with..., no beam manoeuvering, chaff crap, nor anything works! Only the drag and lift coefficients due to alpha seem to be fine for it and nothing else!

 

The only chance, cause there is one..., is to stay away off of it's lethal firing range (depends on closure aspect between firing aircraft and target and their particular altitudes) and to start descending (to conserve as much airspeed as possible) while running away from it (keeping it at 6 o clock) and doing loaded barrel rolls (don't do it at more than 6-7G's, in order to conserve some airspeed) just enough to make the missile deplete it's own airspeed/energy quick as it tries to constantly intercept you..., and the lower the missile gets,the thicker the air and the faster it's speed will drop while following you through the rolling manoeuvre..., and so when it's below 1000kts airspeed, you may out turn it by pulling towards maximum G if it gets too close and it will pass beneath your belly and fly away, or by outrunning it if you continue trough the rolls...! I hope i had given some advices in how to use the strongest technique in order to evade any type of missile which doesn't break lock on you, not only the AIM-120 crapram, which i won't allow anyone to use on my server, to be honest, as long as they won't nerf it's locking ability and use a more realistic one!

Edited January 28, 2013 by MaverickF22

[GGTharos]

resistent for not breaking lock no matter how close to the ground you are, which is bullshit,

 

You're doing it wrong.

 

I hope i had given some advices in how to use the strongest technique in order to evade any type of missile which doesn't break lock on you, not only the AIM-120 crapram, which i won't allow anyone to use on my server, to be honest, as long as they won't nerf it's locking ability and use a more realistic one!

 

... because, let's be honest, if you knew how to perform an actual beam to the notch you wouldn't be having this rant :)

[Teknetinium]

Man..., from what range had those AIM-120's been fired at you? 10-15nm? Of course it won't reach you before it's engine is stopped (it also depends on the speed of both you and that Eagle, but more on altitude i'd say, rather then the closure speed) and if you've done proper evasive manoeuvres or at least did some barrel rolls along your path to make the missile bleed airspeed..., then you won and outmanoeuvred it, not a surprise to me eighter! I've tested this enough too, and if the Aim-120 has less than 1000kts airspeed you may out turn it or outrun it(which is the only certain way possible to get rid of it so far)! If that missile is fired at you from closer than 5-7nm let's say on head-on..., you are dead whatever you'd try..., it is 100% chaff resistent and 100% resistent for not breaking lock no matter how close to the ground you are, which is bullshit, especially for a missile that has it's own, smaller and much weaker radar on which it can barely lock a target up at a maximum of 8nm on a clear day! Because even the firing aircraft's radar looses lock on a target flying as low as 3-5m above the ground due to clutter or signal waves bounce, not to mention the missile's radar that is even weaker! The missile might only be able to maintain a lock on it's target flying so low, if the missile would be just close enough to have a stronger and less breakable signal!

 

So this the most annoying thing at this missile, at least for me, not to mention that it has the longest legs between all the missiles, even greater than the R-27C and D, don't know why because the difference should be huge, but the fact that it has an unbeatable lock to fight with..., no beam manoeuvering, chaff crap, nor anything works! Only the drag and lift coefficients due to alpha seem to be fine for it and nothing else!

 

The only chance, cause there is one..., is to stay away off of it's lethal firing range (depends on closure aspect between firing aircraft and target and their particular altitudes) and to start descending (to conserve as much airspeed as possible) while running away from it (keeping it at 6 o clock) and doing loaded barrel rolls (don't do it at more than 6-7G's, in order to conserve some airspeed) just enough to make the missile deplete it's own airspeed/energy quick as it tries to constantly intercept you..., and the lower the missile gets,the thicker the air and the faster it's speed will drop while following you through the rolling manoeuvre..., and so when it's below 1000kts airspeed, you may out turn it by pulling towards maximum G if it gets too close and it will pass beneath your belly and fly away, or by outrunning it if you continue trough the rolls...! I hope i had given some advices in how to use the strongest technique in order to evade any type of missile which doesn't break lock on you, not only the AIM-120 crapram, which i won't allow anyone to use on my server, to be honest, as long as they won't nerf it's locking ability and use a more realistic one!

 

Agree, for some reason even in FC3 aircraft can lose lock from 15km but Aim-120 will not, When AIm-120 has you in FC3 it will never lose track, you can only make it miss by notching or extending. I would be happy if someone could prove to me that aim-120 tracks as good as F-15s radar from 15km. We can start whit giving me information about aim-120s power output :)

Edited January 28, 2013 by Teknetinium

[blkspade]

The AIM-120 is not 100% chaff resistant, it really an issue of technique. With some idea of the angle that the missile is approaching you, you can spoof it with chaff. It doesn't work by randomly spitting out chaff, though you may get lucky that way. Specific maneuvers, that present chaff at specific angles are what works.

[GGTharos]

Agree, for some reason even in FC3 aircraft can lose lock from 15km but Aim-120 will not,

 

Yes it will.

 

When AIm-120 has you in FC3 it will never lose track, you can only make it miss by notching or extending.

You can only make an aircraft radar lose track by notching as well at that range, or if you manage to get zero-doppler ... which cannot physically happen to a missile that's got enough energy to intercept.

 

I would be happy if someone could prove to me that aim-120 tracks as good as F-15s radar from 15km.

Why wouldn't it? Prove that it can't. 'Power output' isn't proof of anything :) The publicly stated acquisition ranges for 120's are around 13nm for fighter-sized targets.

 

But wait, it gets better. You whine about AIM-120, but the truth is, while there are effects that could cause missiles not to pick up a target at those ranges, they are not modeled for any missile in the game. So please tell me how you find it logical to whine about a single missile in this game when the effect is quite general.

[Exorcet]

Man..., from what range had those AIM-120's been fired at you? 10-15nm? Of course it won't reach you before it's engine is stopped (it also depends on the speed of both you and that Eagle, but more on altitude i'd say, rather then the closure speed) and if you've done proper evasive manoeuvres or at least did some barrel rolls along your path to make the missile bleed airspeed..., then you won and outmanoeuvred it, not a surprise to me eighter! I've tested this enough too, and if the Aim-120 has less than 1000kts airspeed you may out turn it or outrun it(which is the only certain way possible to get rid of it so far)! If that missile is fired at you from closer than 5-7nm let's say on head-on..., you are dead whatever you'd try..., it is 100% chaff resistent and 100% resistent for not breaking lock no matter how close to the ground you are, which is bullshit, especially for a missile that has it's own, smaller and much weaker radar on which it can barely lock a target up at a maximum of 8nm on a clear day! Because even the firing aircraft's radar looses lock on a target flying as low as 3-5m above the ground due to clutter or signal waves bounce, not to mention the missile's radar that is even weaker! The missile might only be able to maintain a lock on it's target flying so low, if the missile would be just close enough to have a stronger and less breakable signal!

 

I could only wish my 120's were fool proof. I'm never guaranteed a hit at any range. I usually fire the first missile at 12-15 nm, and if a second one is required, it's usually launched from 5-10 nm. The second missile will fail as often as the first, and the opposing aircraft has no need to turn around and run. The missile simply gives up and losing the target.

 

Likewise in the case that I referred to before where I was flying the Su, I did not need to turn around, high energy maneuvering and using ground clutter is what allowed me to get around the AMRAAM's and into WVR.

 

So this the most annoying thing at this missile, at least for me, not to mention that it has the longest legs between all the missiles, even greater than the R-27C and D, don't know why because the difference should be huge, but the fact that it has an unbeatable lock to fight with..., no beam manoeuvering, chaff crap, nor anything works! Only the drag and lift coefficients due to alpha seem to be fine for it and nothing else!

The 120 seems no more resistant to CM than the R-77. If I fail to notch the 77 probably, I can dump all of the Eagle's 120 chaff and it will still hold a lock.

 

The only chance, cause there is one..., is to stay away off of it's lethal firing range (depends on closure aspect between firing aircraft and target and their particular altitudes) and to start descending (to conserve as much airspeed as possible) while running away from it (keeping it at 6 o clock) and doing loaded barrel rolls (don't do it at more than 6-7G's, in order to conserve some airspeed) just enough to make the missile deplete it's own airspeed/energy quick as it tries to constantly intercept you..., and the lower the missile gets,the thicker the air and the faster it's speed will drop while following you through the rolling manoeuvre..., and so when it's below 1000kts airspeed, you may out turn it by pulling towards maximum G if it gets too close and it will pass beneath your belly and fly away, or by outrunning it if you continue trough the rolls...! I hope i had given some advices in how to use the strongest technique in order to evade any type of missile which doesn't break lock on you, not only the AIM-120 crapram, which i won't allow anyone to use on my server, to be honest, as long as they won't nerf it's locking ability and use a more realistic one!

This just sounds like a good way to get an enemy fighter on your tail. Your only option would be to RTB, and you wouldn't exactly be getting things done, at least not in the typical 1 v 1 online. Team tactics might make it effective, unless of course the entire flight starts running.

 

You're better off notching the 120 and then pressing to make your own shot. If you don't put pressure on the F-15 you will either die or burn all your fuel going back to where you started.

[falcon_120]

Right now the AIM 120 as well as the others CAN BE spoofed with a bit of notching and a very quick sequence of 7-8 chaffs.Please try it yourself against the AI as close as 12 mn or even less.No need to complain about something is not really true.

[blkspade]

Right now the AIM 120 as well as the others CAN BE spoofed with a bit of notching and a very quick sequence of 7-8 chaffs.Please try it yourself against the AI as close as 12 mn or even less.No need to complain about something is not really true.

 

I have a tacview track saved, that has a guy spoofing 2 of my 120s with a single chaff..

[Exorcet]

Come to think of it, I posted this a little while ago. 3 AMRAAM's, 3 missiles failing to track.

 

http://forums.eagle.ru/showthread.php?t=100683

[Frostie]

Network lag shouldn't be discounted, I've seen guys stutter so much that their nose bounces up and down greatly while they fly in a straight line so the missile follows these stutters, bleeds speed and can sometimes lose track with the simplest of moves.

[Crescendo]

I have two questions regarding NATO ait-to-air missiles in 1.2.2.

 

First question:

 

1. Why does the AIM-120 have a 'loft' trajectory, while the AIM-7 does not? This significantly reduces the Rmax range of an AIM-7 compared to the Rmax range of an AIM-120.

 

I have attached two Tacview recordings. "Recording 1" shows an AIM-7 launch at 25nm, and "Recording 2" shows an AIM-120 launch at 25nm. All other variables are essentially identical. Note how the AIM-7 falls well short of the target while the AIM-120 only barely misses — this is the energy difference between a non-lofted and lofted missile shot (discounting the kinemtatic range difference between the actual missiles themselves of course). I can't see any reason why the AIM-7 shouldn't have this lofting profile too. I understand that the AIM-120 is a more sophisticated missile with better software, but I find it difficult to believe that the AIM-7 doesn't at least attempt a similar sort of loft trajectory in real life. Perhaps ED has decided to simulate the advantages of the AIM-120 by giving it—and only it—access to a lofted trajectory, but I think this is a mistake because it disproportionally undermodels the AIM-7, and because the current lofting logic in-game is very rudimentary anyway.

 

This brings me to my second question:

 

2. Why is the loft trajectory of the AIM-120 so inefficient? Specifically, why does the missile perform such a high-g pull down maneuvor (up to 22g according to Tacview) at the apex of the trajectory? This high-g maneuvor is inefficient and costs a signficant amount of energy — energy that could have been used to extend the range of an Rmax missile shot if it hadn't been 'spent' so wastefully. This inefficiency can easily be seen in "Recording 2".

 

Regarding question 2, I don't pretend to understand the complexity of ED's missile code, but wouldn't this be a simple matter of g-limiting the AIM-120 to say 10g for a few seconds after it goes active? (I am assuming that the reason the AIM-120 pulls 22g at apex is because this is the point at which it goes active and starts intercepting the target. If this is the case, the apex of the loft trajectory is a direct result of the missile going active, not any real lofting logic at all.)

 

Naturally this g-limiting idea would negatively affect AIM-120 missile shots near Rmin, because in that situation you need the missile to pull max-G immediately to intercept the target. However, couldn't this be solved by implementing some sort of simple logic condition such as 'if range to target is less than 13nm (or whatever) upon launch, the missile will not impose a 10g limit for x seconds upon going active'?

 

To sum up: I think that the AIM-7 needs a loft trajectory, and that the lofting logic is flawed and needs to be improved (which I, perhaps naively, think should be easy to do).

Tacview recordings.zip

[falcon_120]

I have two questions regarding NATO ait-to-air missiles in 1.2.2.

 

First question:

 

 

 

2. Why is the loft trajectory of the AIM-120 so inefficient? Specifically, why does the missile perform such a high-g pull down maneuvor (up to 22g according to Tacview) at the apex of the trajectory? This high-g maneuvor is inefficient and costs a signficant amount of energy — energy that could have been used to extend the range of an Rmax missile shot if it hadn't been 'spent' so wastefully. This inefficiency can easily be seen in "Recording 2".

 

 

It is a known issue and has been said it's being worked.The new AFM of the missiles still need quite a bit of tweaking to get it right.

[karambiatos]

my question is, is the aim120 suppose to be better than the aim9 in dogfights, because it currently is, your chances of hitting the enemy with an aim120 in are much larger with the aim120 than the aim9

[Exorcet]

Lofting and general missile performance (like terrible AIM-9 range and agility) are being addressed in the next patch.

 

Basically, the parameters for a lot of stuff is currently wrong.

[Crescendo]

OK, I didn't know that the weird AIM-120 lofting behaviour was a known issue that is actively being addressed. Thanks all.

 

What about the AIM-7 and other SARH missiles? Surely they must loft in real life to some degree also?

[GGTharos]

I have two questions regarding NATO ait-to-air missiles in 1.2.2.

 

First question:

 

1. Why does the AIM-120 have a 'loft' trajectory, while the AIM-7 does not? This significantly reduces the Rmax range of an AIM-7 compared to the Rmax range of an AIM-120.

 

The real AIM-7M(F-1/H)/P does have it, but it was a user-selectable setting and was to be used under particular circumstances which we're not well versed in (Also, the manual I have it from '88/'89, things may have changed since).

 

Going straight gets you there faster, too.

 

I can't see any reason why the AIM-7 shouldn't have this lofting profile too. I understand that the AIM-120 is a more sophisticated missile with better software, but I find it difficult to believe that the AIM-7 doesn't at least attempt a similar sort of loft trajectory in real life.

Then push the 'I believe' button, because that's the way it is :)

We had similar adventures with R-27T/ET's having data-link in game because well, 'it made sense' ... but the real deal doesn't have that.

 

2. Why is the loft trajectory of the AIM-120 so inefficient?

Because programming efficient loft trajectories (or any trajectories) is in fact difficult. It will happen, but when ... that's anyone's guess.

 

 

but wouldn't this be a simple matter of g-limiting the AIM-120 to say 10g for a few seconds after it goes active?

.... [snip]

 

Naturally this g-limiting idea would negatively affect AIM-120 missile shots near Rmin, because in that situation you need the missile to pull max-G immediately to intercept the target. However, couldn't this be solved by implementing some sort of simple logic condition such as 'if range to target is less than 13nm (or whatever) upon launch, the missile will not impose a 10g limit for x seconds upon going active'?

Sure, anything can be implemented. It's all a matter of time and resources to make things happen.

 

To sum up: I think that the AIM-7 needs a loft trajectory, and that the lofting logic is flawed and needs to be improved (which I, perhaps naively, think should be easy to do).

The AIM-7 doesn't need anything in the scope of air to air missiles as they are modeled right now.

 

As for the rest, the scope of work is large, and there's no benefit for throwing a few if-then's just for the 120. The missile guidance model simply needs a lot of work, and it has a lot of needed components both on the missile side and the carrier avionics side.

[GGTharos]

It shouldn't be better; that's being worked on. Newer 120's though are pretty good at dogfights anyway, but they're not a substitute for the 9 (M or X, depending).

 

my question is, is the aim120 suppose to be better than the aim9 in dogfights, because it currently is, your chances of hitting the enemy with an aim120 in are much larger with the aim120 than the aim9

[Crescendo]

Then push the 'I believe' button, because that's the way it is :)

 

...programming efficient loft trajectories (or any trajectories) is in fact difficult. It will happen, but when ... that's anyone's guess.

 

As for the rest, the scope of work is large, and there's no benefit for throwing a few if-then's just for the 120. The missile guidance model simply needs a lot of work, and it has a lot of needed components both on the missile side and the carrier avionics side.

 

Regarding my thoughts about AIM-7 loft trajectory, I take your point that certain kinds of people will argue something to death because they "believe" it to be the case (you see that all the time on these forums). I am not one of those people; I can be perusaded otherwise by someone more knowledgable in the subject. ;)

 

I do understand that programming efficient non-terminal trajectories and loft trajectories is very difficult, especially if you are trying to program them to be as efficient as possible in all circumstances. There are so many variables and situations to consider that you just have to feel bad for the person attempting the task. However, my thought was to implement some simple if-then logic that might get you, say, 75% of the way there with a really simple tweak, as opposed to coding a complete and highly complicated trajectory system that would cover 100% of situations. This would be sort of a 'good enough for now' stop-gap solution.

 

For this reason I would like to question you saying that "there's no benefit for throwing a few if-then's just for the 120." I would point out that the AIM-120 already is special: it's currently the only missile with any loft at all (AFAIK), so obviously ED is enthusiastic about having AIM-120 lofting in the game right now and is willing to accept its current substandard performance. If AIM-120 lofting needs to be in the game, why not implement a simpler stop-gap logic tweak instead of waiting for the complete overhaul of the missile system? That, or remove the AIM-120 loft entirely until it meets ED's usual standards.

 

Again, I don't purport to know anything about game design and the practicalities of making feature decisions and allotting time for coding etc. :blush:

Edited January 29, 2013 by Crescendo

[GGTharos]

However, my thought was to implement some simple if-then logic that might get you, say, 75% of the way there with a really simple tweak, as opposed to coding a complete and highly complicated trajectory system that would cover 100% of situations. This would be sort of a 'good enough for now' stop-gap solution.

 

If-then logic not only sucks, it's also (per your suggestion) specific to a particular missile. Not only is this tweak not necessarily simple (missiles are goverened by a template/standard guidance model) but may also be the epitomy of in-efficient programming in this case.

 

For this reason I would like to question you saying that "there's no benefit for throwing a few if-then's just for the 120." I would point out that the AIM-120 already is special: it's currently the only missile with any loft at all (AFAIK), so obviously ED is enthusiastic about having AIM-120 lofting in the game right now and is willing to accept its current substandard performance. If AIM-120 lofting needs to be in the game, why not implement a simpler stop-gap logic tweak instead of waiting for the complete overhaul of the missile system? That, or remove the AIM-120 loft entirely until it meets ED's usual standards.

 

Stop-gap logic is okay in some cases, and a waste of time in other cases. I believe it to be the latter in this case, but the devs are better able to quantify such a thing than I am. The missile guidance model needs a general overhaul, with big benefits in realism and variety overall.

[EtherealN]

What you are describing is essentially a "hack" in the sense of a "quick and dirty fix". These are not good to have if they can be avoided, since they make the code complex and dirty: in large software, it is a good idea to make sure standards are followed in how functions are implemented, and you don't want to have postits all over the office about code you should rip out because it's bad. It sets you up for epic chaos in maintaining the code later on.

 

Much better to do it right, and remember: FC3, which currently contains the relevant flyable, is not yet complete and relesed it's a pre-purchase beta. Thus, no need for temporary hacks, much better to just do it right.

[Crescendo]

OK, all good points. Thanks for the replies.:)

[Exorcet]

All active missiles loft by the way, including the R-77.

 

Also, one large problem with restricting the g load as described is WVR combat.

[Oberst Zeisig]

I´ve read very many of the last posts of this thread. I´m now playing FC2 in the latest version for about half year with simulator experience in advance. In my opinion its quite obvious that the 120 is by far the best missile in the game regarding to range and hitting precision. Having read all the Information fererring to real life experience and data I also doubt this is very realistic. But don´t mind, it´s just a simulation where You con play with certain parameters. I prefer flying the MIg29s und Su27 as I like the System-Handling more and don´t just take the F15 for its obvious better Missiles. I´ve tried this notch beaming several times with little success, perhaps need some more practise. Some times You can lose a 120 with a bundle auf chaffs, but I think this is not affected by the aspect to missle. Regarding to my experience mostly in multiplayer You have to choose when the distance is still far enough to bleed the missiles energy through maneouvering or You can just out run it or perhaps hide behind a mountain or You have to face and dodge it. The last I tried also many times in a self edited mission su27 vs 2 or 4 F15 and referring to my experience its actually surely possible to just kinetically doge 120s. But has to be done very exactly at speed about 800-1000 k/ps i an angle quite directly towards and 9g turn towards missile at distance about 0.8 nm. Has to be timed about +- 0.1 sec. (So very exactly) If You can conserve enough energy this can work with 2-3 120s. (Or a group of several 120s togeher).

Now question what about these vids of dodging 120s just by smooth barrel roling for a few secs like:

 

 

in my experience this doesnt work anymore as You got to time the dodge of each missile very exact. Do these vids refer to older versions of fc where the missile ki was worse? So You can forget about training vids about barrel roling?