fixed What's up with the R27ET?

[TheFreshPrince]

I'm having problems with long range shots against hot or notching targets with the R27ET. Even though I get a launch authorization, the missile doesn't track at all afterwards. It just flies in a straight line at it's altitude, no reaction to anything. This happened on multiple occasions on multiplayer servers. Since the bandit doesn't get a warning from IR missiles, there is no real change in course from the bandit, no flares, etc.

Is this normal with long range shots and the missile is just not good? Why does it give LA then? Some kind of ECM by the bandit? Or is it a bug?

I'm adding one example from tacview. Since this is from the GS server, the file is too big to attach. But you can get it from their server, the file is called "Tacview-20221112-175935-DCS-Server_1_Operation_Urban_Thunder_V7.1.5.zip" and you can see the timeline below.

 

 

 

[TheFreshPrince]

Same Tacview file, just shortly afterwards: Again launch authorization from the R27ET, but doesn't even bother to track against this F16:

 

 

[okopanja]

Advice: add the TRK file, ideally reproduced it.

Some of mine observations.

As a primary R-27ET user, I did not notice any degradation with 2.8. However, R-27ET can go dumb on launch, if this happens it will simply does not see anything, even if it points to right direction.

Normally when you launch it with radar/EOS assistance, it will get initial guidance and will change its trajectory. With that In mind I do not recommend you to fire it without making sure that your axis points to lead intercept point. This is easy head on: place the dot into circle aim and send all your love the the receiving side. For non HOT, make lead intercept course first, level your axis with target and fire then where you judge that target will be. This way you ensure several things:

1. it will loose less energy

2. it stands the chances of acquiring the target when it comes closer!

 

 

[TheFreshPrince]

Finally managed to get it on track ;/ very difficult to reproduce against AI because I rarely get launch authorization heads if I'm not very close (very often the R27ET has the exact same range as the R73)... I don't know if that's intended.

You need to fast forward to the 3rd encounter against the F15 as I didn't get to shoot the R27ET against the first two targets (as I said, the range usually is very small if heads on against AI). Also against AI it seems to track better. In multiplayer I get to shoot it from further distances more often. So it happens more often there, but the track files are so big that I can't upload them. On tacview it's frequently observable though. But I don't get why it happens. There is no reason for the missile to go stupid. It is as if the missile fails randomly (unfortunately not very seldom).

Tacview-20221116-170020-DCS-Test.zip.acmi R27ET#1.trk

[okopanja]

40 minutes ago, TheFreshPrince said:

Finally managed to get it on track ;/ very difficult to reproduce against AI because I rarely get launch authorization heads if I'm not very close (very often the R27ET has the exact same range as the R73)... I don't know if that's intended.

You need to fast forward to the 3rd encounter against the F15 as I didn't get to shoot the R27ET against the first two targets (as I said, the range usually is very small if heads on against AI). Also against AI it seems to track better. In multiplayer I get to shoot it from further distances more often. So it happens more often there, but the track files are so big that I can't upload them. On tacview it's frequently observable though. But I don't get why it happens. There is no reason for the missile to go stupid. It is as if the missile fails randomly (unfortunately not very seldom).

Tacview-20221116-170020-DCS-Test.zip.acmi 175.12 kB · 1 download R27ET#1.trk 186.6 kB · 1 download

Did you fire with LA or with LA override?

[TheFreshPrince]

no override, just automatic LA

[okopanja]

19 minutes ago, TheFreshPrince said:

no override, just automatic LA

Well, it should have tracked. The straight flight means it stopped tracking or it never did track.

BTW: you may wish to use LA earlier if the the other guy is flying straight at you (ET will pick it up later). In this case the your regular LA will be at 8-9km, which means he will kill you like a rabbit with amraam or even sidewinder.

To me all those "off-the-rail" loses of tracking for ET, look as if some failure is simulated (e.g. missile will track or not track based on probability). Some missiles should have this modeled, e.g. AIM-7s used in Iraq had large number of engine failures on the very launch).

Look forward to see what developer comment on your track file.

[Seaeagle]

23 hours ago, TheFreshPrince said:

Finally managed to get it on track ;/ very difficult to reproduce against AI because I rarely get launch authorization heads if I'm not very close (very often the R27ET has the exact same range as the R73)... I don't know if that's intended.

It is.  Just like the R-73, the R-27ET is pure IR homing and its IR seeker needs to lock on to the target before you get launch authorisation. So the acquisition range of the IR seeker is the limiting factor and in a head-on situation, this is quite short due to the target's main heat emmission(engines) being obscurred by its airframe.  This in turn can also cause the seeker to loose its lock after launch, which may be what you are experiencing. 

Generally speaking - don't use IR missiles for straight head-on engagements

[TheFreshPrince]

Thank you guys for your time so far! To me it looks like it comes off the rail as stupid, it doesn't even track from the beginning. I posted 3 encounters, which should prove that it doesn't happen very rarely, but somewhat frequently. Although it is hard to replicate. I certainly could post many more screenshots or try to create more track files. But I think the problem is clear. 

 

Now, while one can argue here if it is realistic that it randomly fails or loses track, it is my question if this is how it's programmed in DCS. Because I don't know how it is intended to work. From my experience, it seems very random if it hits or if it doesn't. Which makes it hardly usable, except as you said against notching or cold targets, but then you still need to get rather close. But heads on, sometimes it can track at very long ranges and then again it doesn't track at all.

 

Maybe it should be more a question of why it even has such a long range if it's not usable anyway and if it should even give you a launch authorization if it doesn't track afterwards. Or if it just has a random failure programmed into it, it would be interesting to know how often it is intended to fail. 

[Seaeagle]

14 minutes ago, TheFreshPrince said:

Thank you guys for your time so far! To me it looks like it comes off the rail as stupid, it doesn't even track from the beginning. I posted 3 encounters, which should prove that it doesn't happen very rarely, but somewhat frequently. Although it is hard to replicate. I certainly could post many more screenshots or try to create more track files. But I think the problem is clear. 

Well I don't know what goes on in DCS and I would agree with you that it sounds odd if it happens consistently.

14 minutes ago, TheFreshPrince said:

Now, while one can argue here if it is realistic that it randomly fails or loses track, it is my question if this is how it's programmed in DCS. Because I don't know how it is intended to work. From my experience, it seems very random if it hits or if it doesn't. Which makes it hardly usable, except as you said against notching or cold targets, but then you still need to get rather close. But heads on, sometimes it can track at very long ranges and then again it doesn't track at all.

Well thats the question - I am also a little doubful that IR seekers are programmed with such sensitivity fidelity in DCS.

14 minutes ago, TheFreshPrince said:

Maybe it should be more a question of why it even has such a long range if it's not usable anyway..

The R-27ET is really not about range, but rather about energy. Rear aspect targets can be seen from much longer ranges by the IR seeker, while your typical IR missile(R-73 or AIM-9) doesn't have the energy to take full advantage of this if closure rate is low or negative.

14 minutes ago, TheFreshPrince said:

..and if it should even give you a launch authorization if it doesn't track afterwards.

Well like I said it can happen, but it sounds odd if it consistently goes dumb immedeatly after launch against a target that doesn't react to it.

14 minutes ago, TheFreshPrince said:

Or if it just has a random failure programmed into it, it would be interesting to know how often it is intended to fail. 

I doubt it.

[Ironhand]

4 hours ago, TheFreshPrince said:

But I think the problem is clear. 

Yes, the problem is that you occasionally get launch permission from the radar prior to the the seeker itself locking the target. The radar should not be giving you launch permission because it has no idea if the seeker has a lock.

Edited November 18, 2022 by Ironhand

[okopanja]

4 hours ago, Ironhand said:

Yes, the problem is that you occasionally get launch permission from the radar prior to the the seeker itself locking the target. The radar should not be giving you launch permission because it has no idea if the seeker has a lock.

 

I think its a deeper problem. The ET dead on rail will not acquire the target that passes right in front of it at later time. I observed this in tacviews at least 1 year ago.

Furthermore 2.8 missile/target tracking is broken, with difference between shooter's missile and respective clones in server and victim universe being so great that you do not get RWR warnings, or are getting killed by a missile which is nowhere near you, or your missile tracks "ghost" aircraft, while the real one moves on to different direction. As far as I can tell this happens with R-27 and amraam, possibly sd10 and aim54. I would expect the longer the range, the worse it is.

Edited November 18, 2022 by okopanja

[TheFreshPrince]

vor 6 Stunden schrieb Ironhand:

Yes, the problem is that you occasionally get launch permission from the radar prior to the the seeker itself locking the target. The radar should not be giving you launch permission because it has no idea if the seeker has a lock.

 

I was also thinking if this could be the problem, but then I would get LA much more often as soon as I'm in missile range, wouldn't I? But the LA range you get on the R27ET is different from the LA range on the R77. So I think it gets it LA from the IR/EO seeker and not from the radar.

[draconus]

2 hours ago, TheFreshPrince said:

I was also thinking if this could be the problem, but then I would get LA much more often as soon as I'm in missile range, wouldn't I? But the LA range you get on the R27ET is different from the LA range on the R77. So I think it gets it LA from the IR/EO seeker and not from the radar.

You can test with R-27ET where you search and lock either with radar or with EOS - then compare the LA distance. Another variable can be target using flares - you can disallow it in ME. Same with reaction to threat.

As for the long range, mind that you can also make silent long range shots with ET overriding LA directed into the intercept point or as an anti-notch surpise following the usual ER shot.

Missile random failures while cool and realistic are not implemented into DCS afaik.

[GGTharos]

In DCS there is no 'seeker feedback' from the missile on the rail to the weapons system.   As far as the WCS goes, that weapon doesn't even exist except for an 'on rail' indicator showing that the rail is occupied.

The WCS' 'LA' is always based on an educated guess regarding the missile's known capabilities instead of feedback from the missile itself, so if the missile wasn't going to track because it now models more complex behavior than the aircraft, that won't be reflected in your aircraft (this is an example, not necessarily that this is what's going on).

Corollary, 'long range shots with heaters' is sort of LOL and you're only able to do it because there is a lack of more complex seeker simulation.

[Ironhand]

9 hours ago, TheFreshPrince said:

I was also thinking if this could be the problem, but then I would get LA much more often as soon as I'm in missile range, wouldn't I? But the LA range you get on the R27ET is different from the LA range on the R77. So I think it gets it LA from the IR/EO seeker and not from the radar.

Correct as far as DCS models the interaction. That entire encounter was rather strange from start to finish. You initially got LA with the target more or less flanking in afterburner. He killed AB and turned into you and the LA remained. You were able to launch even though you shouldn’t have the authorization at that point. Finally, after you had turned away, you still had the target locked on radar even though he was to the rear your left wing.

Edited November 18, 2022 by Ironhand

[TheFreshPrince]

Am 18.11.2022 um 20:14 schrieb Ironhand:

Correct as far as DCS models the interaction. That entire encounter was rather strange from start to finish. You initially got LA with the target more or less flanking in afterburner. He killed AB and turned into you and the LA remained. You were able to launch even though you shouldn’t have the authorization at that point. Finally, after you had turned away, you still had the target locked on radar even though he was to the rear your left wing.

 

I didn't reply to your post, because in my opinion this doesn't make any sense. If the target has AB on and I get launch authorization, the missile MUST at least fly in the direction of the target and not come off the rail as stupid. Even if he turns it off and the missile loses track, there will be a good chance that it can reacquire the track closer to the target. The F15 didn't turn away. 

Secondly, turning the AB off will not leave you as a cold target instantly. Stuff needs time to cool down. I dunno how far this is modeled in DCS. But it will take at least a few seconds or even more until your IR signature is lower. 

 

That said, I have changed my use of the R27ET and it happened rarely again since then. I'm using it only in certain situations now instead of just blindly firing it. Another reason why I didn't update this topic anymore. But as the post in the SU27 forum shows, this problem hasn't been solved. So it would still be cool to get some sort of reply from someone who knows how it works in DCS.

[okopanja]

This is true ET often still goes stupid off the rail with no chance of reacquiring. In contrast ET which tracks a target, which gets killed, will reacquire with no issues(provided that there is a target in seeker FOV).

Edited January 6, 2023 by okopanja

[DukeAngus]

just for clarification when you are getting launch authorization to shoot the r27et are you using the radar or the electro optical seeker?

[TheFreshPrince]

Shooting from a radar lock. But I haven't tried, if this can happen in EO mode as well

[Ironhand]

16 hours ago, DukeAngus said:

just for clarification when you are getting launch authorization to shoot the r27et are you using the radar or the electro optical seeker?

 

8 hours ago, TheFreshPrince said:

Shooting from a radar lock. But I haven't tried, if this can happen in EO mode as well

My guess is that it’s probably due to this: 

 

[DukeAngus]

in the su27 and mig 29 manual there is a BVR section and the section that talks about the irst  explicitly says that the r27t,and r27et can be used with the irst system. the radar section does not mention the r27t or r27et. i took that as that is what you have to use to shoot the t and et missiles. there is a mode that only uses the radar (RL)  and one that is the irst (EO), there is one that uses both (EORL). i dont know how you get there ir seeker to lock on to a target any other way.

 

Missile Engagement with IRST as the Active Sensor Using the "ОЛС-27" - infrared search and track (IRST) system for long-range missile combat allows stealth attacks. The IRST is immune to active jamming, but it has much less target detection range than radar. The R-27ET, R-27T and R-73 can all be used with the IRST system.

THE R-27T/ET MEDIUM RANGE MISSILES MUST HAVE AN INFRARED SEEKER LOCK ON A TARGET BEFORE FIRING. THESE SYSTEMS ARE IR-HOMING ALL THE WAY AND DO NOT USE A DATA LINK SYSTEM

the bvr section starts on page 121 in the su-27 manual and page 83 for the mig 29. 

i find it all quite wild about all the talk on her about missiles not working on these forums. i have only been using the su27 and mig29 in single player recently to learn them and have found that if i shoot a r27er and turn the radar off the missile still guides and kills the maneuvering aircraft.  between that and all the ai that have been crashing into the ground theses days, i dont know what to think is going on.

[draconus]

4 hours ago, DukeAngus said:

have found that if i shoot a r27er and turn the radar off the missile still guides and kills the maneuvering aircraft

When the target is jamming the missile can guide on it in Home on Jam mode, that's what probably happened in DCS.

[TheFreshPrince]

It doesn't seem to matter if you shoot any missile in radar or EO lock, because a radar guided missile will automatically trigger EORL mode when launched from EO mode and IR missile shot from radar lock seem to track fine most of the time. You should only get a LA on IR missiles in radar lock if the missile seeker head sees the target, but as we can see, this is likely bugged. On the other hand, if you shoot it with launch authorization override, even beyond max range, it might still track the target if it stays nose hot. F14 are very prone to that, because they think they can push you from far ranges and stay commited, while your stealthy 27ET is already on the way.

Ironhand linked the thread with a possible explanation, but I'm not so sure about that. If you look at my tacview screenshots, they are shot with only a small offset. Likely not at the seeker limits (although I don't know what that number is).

[Seaeagle]

11 hours ago, DukeAngus said:

in the su27 and mig 29 manual there is a BVR section and the section that talks about the irst  explicitly says that the r27t,and r27et can be used with the irst system. the radar section does not mention the r27t or r27et. i took that as that is what you have to use to shoot the t and et missiles. there is a mode that only uses the radar (RL)  and one that is the irst (EO), there is one that uses both (EORL). i dont know how you get there ir seeker to lock on to a target any other way.

IR homing missiles(R-27T/ET and R-73) can be used with any sensor of the aircraft; EOS, radar or helmet sight, because all they do is to determine the location of the target and pass this information(angular coordinates)  on to the missile seekerhead, so it knows where to look for it. The seekerhead itself must lock on to the target before launch.  There is no post-launch control for IR missiles,  so using "launch override" should provide a very low probability of intercepting the target.

The semi-active radar homing variants(R-27R/ER) require the radar to operate(the seekerhead needs the radar to illuminate the target for SARH) and in normal operation you would use radar modes for engagement, since they provide the longest detection range and thus take advantage of the missile's launch range provided by its inertial navigation system + datalink control.  You can however, use the EOS to find the target instead, but when launching the missile, the radar is automatically switched on in order to provide the above mentioned support.

11 hours ago, DukeAngus said:

Missile Engagement with IRST as the Active Sensor Using the "ОЛС-27" - infrared search and track (IRST) system for long-range missile combat allows stealth attacks. The IRST is immune to active jamming, but it has much less target detection range than radar. The R-27ET, R-27T and R-73 can all be used with the IRST system.

THE R-27T/ET MEDIUM RANGE MISSILES MUST HAVE AN INFRARED SEEKER LOCK ON A TARGET BEFORE FIRING. THESE SYSTEMS ARE IR-HOMING ALL THE WAY AND DO NOT USE A DATA LINK SYSTEM

All correct.

11 hours ago, DukeAngus said:

the bvr section starts on page 121 in the su-27 manual and page 83 for the mig 29. 

i find it all quite wild about all the talk on her about missiles not working on these forums. i have only been using the su27 and mig29 in single player recently to learn them and have found that if i shoot a r27er and turn the radar off the missile still guides and kills the maneuvering aircraft.  

As mentioned already, the most likely explanation is that the R-27R/ER switches to "home-on-jam" mode because the target is using ECM.

Edited January 31, 2023 by Seaeagle