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R-27T/ET Lock-on After Launch?


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After reading the (en) wikipedia article on the R-27 series of missiles, my interest was piqued by a rather poorly written paragraph about the R-27T/ET under the 'variants' header which appears to suggest LOAL capability for the missile's T/ET variants.

 

It references the manual for the Su-27SK export model, and sure enough, after cross-referencing what little I could, various essential pieces of information seemed to correspond. Specifically, the terms 'ППС', 'Р-27ЭТ1(Р-27Т1)' and finally '15 degrees'. That's about all I could translate if you want to call it that.

 

 

Here are two snippets from Wikipedia and the manual. Hopefully not stepping on any server rules with this one:

 

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Wikipedia:

https://en.wikipedia.org/wiki/R-27_(air-to-air_missile)

Img1.JPG.7ab5c08ec29d3b99a9c606f3a31a5590.JPG

 

 

Manual:

Img2.JPG.ea250d172c1ead36915f826a8a52b6cf.JPG

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Firstly, I can't read Russian beyond recognizing the characters, so it would be nice to know if the manual does indeed align with the Wikipedia article.

 

Secondly, am I correct in understanding that this suggests, with a hard-lock, in PPS mode, with no seeker lock or 'LA', you may fire a T/ET missile in the target's general direction (+- 15 degrees) and expect a LOAL?

 

Finally, does any of this work in DCS? As far as I'm aware, it doesn't.

 

EDIT:

- Fixed link


Edited by Cheetah7798
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You can use yandex with OCR to easily translate scanned/photographed documents:

https://translate.yandex.com/ocr

 

These 15° in the manual are something different than described in the Wikipedia article:

You don't want the target aircraft pointed directly towards you, but at least 15° away from you (can be up/down/left/right) for a better missile lock.

 

Propably because then because the aircraft exhaust is not covered by the fuselage that much.

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As far as DCS goes, you can lock your target with radar and then fire R27T/ET using launch override even without launch authorization. I don't really know what goes on under the hood, but it seems that the missile will fly some kind of datalink intercept course and when close to the target acquire by itself and hit. It looks like the intercept course is only calculated on launch and not updated during flight though (?)

It needs more investigation...

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You can do LOAL launches with the R-27T/ET but you have to be very, very careful because the missile receives no mid-course guidance and will lock on to anything it detects - no IFF involved.

 

Can be useful for really long range head-on shots (f-pole) or an extending range tail chase shot but again you have to be really careful with possible target deconfliction. Ask me how I know :doh:

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As far as DCS goes, you can lock your target with radar and then fire R27T/ET using launch override even without launch authorization. I don't really know what goes on under the hood, but it seems that the missile will fly some kind of datalink intercept course and when close to the target acquire by itself and hit. It looks like the intercept course is only calculated on launch and not updated during flight though (?)

It needs more investigation...

 

If it does any turn to target without the seeker being locked on, that's wrong.

 

The launch override for these missiles is meant to jettison the missiles, not launch them at targets. Your seeker might not even be cooled, and you can't guarantee what it'll lock on to - you're just lucky in DCS that other than aircraft, it can only lock onto the sun (And flares) but no cloud/water/other reflections or heat sources.

 

There is ZERO LOAL capability for these missiles IRL. They are meant to be launched with lock on the rail and AFAIK the WCS provides zero guidance to the missile other than to slave the seeker to EOS/Radar.

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After testing, it seems that R-27T/ET missiles will get course updates just like the R/ERs. Launches of T/ET missiles without a seeker lock, in weapon launch override mode will guide them out to the target until the seeker becomes active.

 

This is inconsistent with what is stated on the Wikipedia page (And, I assume, the Su-27SK manual).

 

This begs the question, does the T/ET have a datalink with the firing aircraft?

 

According to this article by Air Power Australia, it appears to suggest that the Datalink is purely associated with the R/ER variants.

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https://www.ausairpower.net/APA-Rus-BVR-AAM.html

 

Img3.JPG.3c02101bd9f50540f124c7286bd29278.JPG

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There is zero mid course update for R-27T/ET in DCS.

 

All it knows is the target position during the launch, and it turns roughly towards that position using INS. From that point it is flying straight. If the target happens to be within the narrow seeker FOV at some point within the necessary range for a lock, then the missile will start tracking.

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All it knows is the target position during the launch, and it turns roughly towards that position using INS. From that point it is flying straight. If the target happens to be within the narrow seeker FOV at some point within the necessary range for a lock, then the missile will start tracking.

 

AFAIK, it doesn't have an INS, as it has an IR seeker with no LOAL capability. If the seeker has no lock before launch, it has no knowledge of any targets and it can't be launched, except in a case of emergency because it can't be jettisoned like e.g. the radar variants on the AKU pylons.

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If it does any turn to target without the seeker being locked on, that's wrong.

 

The launch override for these missiles is meant to jettison the missiles, not launch them at targets. Your seeker might not even be cooled, and you can't guarantee what it'll lock on to - you're just lucky in DCS that other than aircraft, it can only lock onto the sun (And flares) but no cloud/water/other reflections or heat sources.

 

There is ZERO LOAL capability for these missiles IRL. They are meant to be launched with lock on the rail and AFAIK the WCS provides zero guidance to the missile other than to slave the seeker to EOS/Radar.

I am of course talking about DCS only. I have absolutely no data on how it works IRL.

But are you sure the LA override is there to jettison the missile? I was under the impression, that it is there for you to be able to launch the missile if you are not in range (for whatever tactical reason).

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After testing, it seems that R-27T/ET missiles will get course updates just like the R/ERs. Launches of T/ET missiles without a seeker lock, in weapon launch override mode will guide them out to the target until the seeker becomes active.

 

This is inconsistent with what is stated on the Wikipedia page (And, I assume, the Su-27SK manual).

 

This begs the question, does the T/ET have a datalink with the firing aircraft?

 

No - the IR homing variants have no INS and no datalink for course updates.

 

According to this article by Air Power Australia, it appears to suggest that the Datalink is purely associated with the R/ER variants.

 

Correct.

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I am of course talking about DCS only. I have absolutely no data on how it works IRL.

But are you sure the LA override is there to jettison the missile? I was under the impression, that it is there for you to be able to launch the missile if you are not in range (for whatever tactical reason).

 

It's there to jettison the missile, yep. I suppose you could abuse it but it's not designed to be used that way. Maybe it works, maybe not.

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It's there to jettison the missile, yep. I suppose you could abuse it but it's not designed to be used that way. Maybe it works, maybe not.

Well if they intended it that way, that is quite a waste of a tactical tool.

 

And not giving the ET datalink (if it is true) - that is even bigger waste.

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I think ET is intended for ECM environment, datalink could be jammed. Plus for tailchase engagements, at those ranges you will always have seeker lock from the rail.

yes that is true. but imagine having the ability to guide it without any launch warning to the target until impact. all the necessary technology is already in the ER. the only warning would be the smoketrail, but I dont know how visible it would be at 50-60km IRL. in DCS you can always cheat by zoomin in...

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yes that is true. but imagine having the ability to guide it without any launch warning to the target until impact. all the necessary technology is already in the ER. the only warning would be the smoketrail, but I dont know how visible it would be at 50-60km IRL. in DCS you can always cheat by zoomin in...

 

And just how would you track the target at that distance in the first place without a radar to be able to calculate the intercept course and guide the missile there to its seeker range? Besides, the mid-course updates for R/ER missiles are also transmitted via radar signals.

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Well if a such a system existed, I assume the same way the radar does ranging for EOS beyond laser range

 

There's a big difference between simple pulse ranging and actually tracking the target to be able to calculate the intercept course for the missile and then sending these updates to the missile somehow, especially since the context is attacking the target undetected.

 

Even the former (simple ranging) is detectable, let alone the latter.


Edited by Dudikoff

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And just how would you track the target at that distance in the first place without a radar to be able to calculate the intercept course and guide the missile there to its seeker range? Besides, the mid-course updates for R/ER missiles are also transmitted via radar signals.

notice that i didn't say without radar lock - just without launch warning.

you would of course have to radar-lock the target in STT and guide your ET via datalink until it acquires IR lock itself. sadly no datalink for ET's in DCS....or in reality. (?)

 

 

 

In DCS it works exactly like in that snippet from wikipedia that Cheetah7798 posted at the beginning of the thread.

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notice that i didn't say without radar lock - just without launch warning.

you would of course have to radar-lock the target in STT and guide your ET via datalink until it acquires IR lock itself. sadly no datalink for ET's in DCS....or in reality. (?)

 

Hmm, that's true. But, there's no immediate launch warning for the R-27R/ER missiles either unless the target is within seeker range on launch (as this is when the target starts getting illuminated by the radar roughly).

 

Otherwise, there is only mid-course updates signal (apart from the STT lock), but of course, those could technically be detectable by RWR and classified as such.

 

So, there's no big gain there if T/ET missiles would be used in such a way, with a huge issue of not really knowing which target it would get locked to once its seeker goes active.


Edited by Dudikoff

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notice that i didn't say without radar lock - just without launch warning.

you would of course have to radar-lock the target in STT and guide your ET via datalink until it acquires IR lock itself.

 

In which case there would be zero to gain in terms of surprise attack.

 

When you lock up a target in STT, the target's RWR of will alert the pilot that he is being singled out for an attack. Moreover, some RWRs can detect when your radar is starting to transmit course corrections to the in-flight missile.

 

In other words, you would be providing the exact same information for the enemy RWR to pick up as if you had been using the SARH variant.

 

sadly no datalink for ET's in DCS....or in reality. (?)

 

Nope.

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Hmm, that's true. But, there's no immediate launch warning for the R-27R/ER missiles either unless the target is within seeker range on launch (as this is when the target starts getting illuminated by the radar roughly).

 

Otherwise, there is only mid-course updates signal (apart from the STT lock), but of course, those could technically be detectable by RWR and classified as such.

 

So, there's no big gain there if T/ET missiles would be used in such a way, with a huge issue of not really knowing which target it would get locked to once its seeker goes active.

Well I have no idea how ER's work in real world, but in DCS, the opponent gets RWR warning when you lock them in STT and different RWR warning when you start guiding the missile...which is the exact same second as the missile leaves the rail (that is usually when they start paying attention).

 

 

If you shoot ET's in STT radar lock, your target has no idea that there is missile inbound (provided they don't see the smoke trail).

 

 

But if you do this from 60km away, the IR sensor won't see its target and your ET will fly straight ahead where you pointed it until it establishes IR lock itself.

It works beautifully, but your target must stay in quite narrow seeker-head cone. That's where datalink updates would help greatly - your ET would be able to intercept even maneuvering targets.

Otherwise its a game of guessing where your opponent will be, when the ET is about 10km from him - in other words, you have to guess the intercept course yourself.

 

Again I have to stress I'm talking about DCS - no idea how it works IRL.

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In which case there would be zero to gain in terms of surprise attack.

 

When you lock up a target in STT, the target's RWR of will alert the pilot that he is being singled out for an attack. Moreover, some RWRs can detect when your radar is starting to transmit course corrections to the in-flight missile.

 

In other words, you would be providing the exact same information for the enemy RWR to pick up as if you had been using the SARH variant.

 

sadly no datalink for ET's in DCS....or in reality. (?)

 

Nope.

You are exactly right if we are talking about 1v1 environment. But in really messy situations your RWR is flooded by many lock signals from any radar locking anyone if you happen to be on its LOS.

So there is massive difference between painting your opponent by STT vs painting him by guidance beam. I don't know if you happen to fly multiplayer, but 99% pilots pretty much ignore lock tones and start paying attention only if you actually shoot at them.

At least that applies to western pilots - flanker pilots will react to pretty much any RWR signal, because of the pesky TWS amraam shots.

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Well I have no idea how ER's work in real world, but in DCS, the opponent gets RWR warning when you lock them in STT and different RWR warning when you start guiding the missile...which is the exact same second as the missile leaves the rail (that is usually when they start paying attention).

 

AFAIK thats also how it works IRL. The R-27R/ER uses pulse dopler for target illumination(SARH operation), where the aircraft radar alternates between pulses for its own target tracking and target illumination for the missile's SARH seeker + transmitting course corrections. I could be wrong, but I don't think the system takes seeker acquistion range into consideration, but starts this procedure as soon as the M-link is established - i.e. at the point of launch.

 

If you shoot ET's in STT radar lock, your target has no idea that there is missile inbound (provided they don't see the smoke trail).
Well an STT lock will nevertheless warn the opponent to expect an imminent missile launch - I mean thats pretty much the reason for tracking someone in STT :) . Anyway, the point is that the procedure that provides course corrections(datalink) for the in-flight -R/ER is linked to the target illumination, so if you were to get that for the -T/ET, you would also get the same warning on RWR.

 

But if you do this from 60km away, the IR sensor won't see its target and your ET will fly straight ahead where you pointed it until it establishes IR lock itself.
Which is why such a procedure would be highly inefficient and should be considered sort of a "last ditch" attempt if no other means are available.

 

It works beautifully, but your target must stay in quite narrow seeker-head cone.
This is where I think there is a problem between the sim and reality :) . The IR seeker's immediate FOW is very narrow(a few degrees) not to be confused with its gimbal limits. Since you cannot control where the IR seeker is looking after launch, the seeker will be looking straight ahead and only be able to lock on to anything that might pass through this narrow FOW....and only if it emits enough thermal energy for the purpose.

 

That's where datalink updates would help greatly - your ET would be able to intercept even maneuvering targets.
Considering what I wrote above and that the datalink doesn't provide particulary accurate intercept course, I doubt it would help much. As far as I can tell, IR seekers in DCS don't have moving sensors, but will just "see" anything within full gimbal limits, which could explain why you can get good results with launch overriding the R-27ET.
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AFAIK thats also how it works IRL. The R-27R/ER uses pulse dopler for target illumination(SARH operation), where the aircraft radar alternates between pulses for its own target tracking and target illumination for the missile's SARH seeker + transmitting course corrections. I could be wrong, but I don't think the system takes seeker acquistion range into consideration, but starts this procedure as soon as the M-link is established - i.e. at the point of launch.

 

Well an STT lock will nevertheless warn the opponent to expect an imminent missile launch - I mean thats pretty much the reason for tracking someone in STT :) . Anyway, the point is that the procedure that provides course corrections(datalink) for the in-flight -R/ER is linked to the target illumination, so if you were to get that for the -T/ET, you would also get the same warning on RWR.

 

Which is why such a procedure would be highly inefficient and should be considered sort of a "last ditch" attempt if no other means are available.

 

This is where I think there is a problem between the sim and reality :) . The IR seeker's immediate FOW is very narrow(a few degrees) not to be confused with its gimbal limits. Since you cannot control where the IR seeker is looking after launch, the seeker will be looking straight ahead and only be able to lock on to anything that might pass through this narrow FOW....and only if it emits enough thermal energy for the purpose.

 

Considering what I wrote above and that the datalink doesn't provide particulary accurate intercept course, I doubt it would help much. As far as I can tell, IR seekers in DCS don't have moving sensors, but will just "see" anything within full gimbal limits, which could explain why you can get good results with launch overriding the R-27ET.

I pretty much agree with all you have said.

 

 

I may slightly disagree only with last paragraph: I am getting quite a good kill ratio with long range-head on shots with the ET, particularly in crowded airspace situations, with high altitude/high speed incoming formations.

The fact that they are locked in STT by me doesn't bother them - they are STT locked by many other radars, including SAMs. Datalink updates would make shots like that even more deadly.

 

 

Anyways, back to topic: I found DCS to work roughly like in that wikipedia snippet at the beginning of this thread. No idea how true that snippet is though.

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