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

1 минуту назад, Fri13 сказал:

 

Because in the phonebook there is one wrong number for the contact, it doesn't render all contacts informations invalid....

 

 

Well, that one isn't the only one

Nothing to do with Blue vs Red, but they need to prioritize from a buisiness standpoint. We already saw some R-27 improvements with 2.7 and
there will be more when the full fidelity MiG-29 arrives. Just like the AIM-120 improvements for the full fidelity F/A-18C and F-16C.
It's just a matter of time. However, don't expect miracles as far as performance update goes.    

The R/ER has LOAL. Thats been knows since forever. What there is no evidence for is that the T/ET have LOAL. The manufacturers website confirms the R/ER having LOAD, and the T/ET is LOBL:

R/ER:

Quote

The R-27R1 and R-27ER1 medium range air-to-air missiles with semi-active radar homing heads are designed to engage air targets by day and night, in fair and adverse weather conditions, in the front and rear hemispheres, also against diverse underlying surfaces with enemy's active evasive manoeuvring and intensive jamming.

The missiles pursue their targets in accordance with an update proportional navigation method both in the inertial/radio-corrected flight trajectory phase and in the semi-active homing phase after locking on target en route.

T/ET:

Quote

The R-27T1 and R-27ET1 medium-range air-to-air missiles with IR homing heads are designed to engage various air targets, such as highly manoeuvrable aircraft, helicopters and the like, in the front and rear hemispheres, by day and night, in spite of natural and organazed jamming, in compliance with the "fire-and-forget" principle.

The missile guidance system employs an updated proportional navigation method with the target lock-on accomplished on the suspension under the carrier.

Source
 

I wonder if Russian missiletronics designers are deliberately dissembling or if perhaps it's an engineering cultural difference.

1.  When the F-4 fires the AIM-7E, the weapon picks up CW from the wing pylons as a kind of 'tether' which provides true distance based on pulsed coding in the FMICW.  This is then compared to the returns coming in through the seeker of the missile to provide a distance from target vs. distance from launch condition to shape a proportional lead trajectory with.  It is why 25G Sparrows, when they worked in SEA, could seemingly cut square corners to pull target lead.

2.  An autopilot is not an IMU (Inertial Measurement Unit, different from an INS In the number of feeds it can take from external sensors like radar altimeters, doppler velocity sensors and AHRS) in that an autopilot steers based on perceived target/launch platform attitude and rate differences fed to it via seeker deviations whereas an IMU steers from an internal rate and angle gyro that will put the missile in a given position downrange in time+X seconds.  It is a great deal easier to do exotic homing algorithms with a 3D spatial predictive IMU than a 2D X+Y angle off predictive target lead.  Indeed, the seeker doesn't have to 'see' the target radar returns, at launch or any time before terminals, to lock it up and start homing at the endgame.  The missile simply drives itself to a point where the seeker is in-range.

3.  Early ARH datalinks were not CW (which APG-63/66/68 did not support, though AWG-9 still did) but still used imbedded radar secondary channels (AMRAAM was an 'M' band sideband) that fed range and range rate to the weapon to perform internal midcourse update corrections, based on the IMU.  This likely limited the number of missiles which could be supported to only those which were tuned to the parent jet radar at or shortly after takeoff.

AIM-120C6/7 (sources vary) added a more sophisticated, midcourse trajectory enabled, datalink which was separate from the tuned fighter radar homing to allow other aircraft to hand off midcourse data which effectively mean you were not supporting the round through seeker activation by a lead jet but could rather launch and chainsaw with the trailing aircraft using a generic waveform but missile specific encryption code to pass tracking data, easing the shooter vs. guider airframe closure issue.  I believe AIM-120C7 now uses a GPS enabled IMU which knows it's own position far more precisesly and can tell the guiding jet (parent or illuminator) it's own position as a function of shot clock TOF remaining on whatever loft it is on.  It probably also includes remaining weapon speed and offset to inform the pilot as to likely intercept SSPK but there is of course (TRD, expendable Bright Cloud, threat airframe extension etc.) guarantee on this.  The first I heard of such a capability was on Python 5 as what differentiated it from Python 4.  So if the Israelis can stuff the tech into a 6.3" diameter, 10ft long, missile, they can probably put into a 7"X12ft AMRAAM.

The important point to note here is that an R-27ER/ET with a sophisticated (silent running, encrypted MCU) could theoretically be almost as capable as a (shorter ranging) AMRAAM _if the trajectory steering midcourse guidance_ could come from an offset wingman or trailing stinger airframe.  It would certainly make sense when you hear about jets being able to 'track 20 targets and engage 4' with HDTWS off a planar array vs. an AESA/PESA electronic scan.

Such a concept may go as far back as the AIM-7MH from the 1990s era (Janes F-18 Super Hornet had these) and it would be worth noting that the avionics could shift from TWS to High Data Rate TWS and then STT to support the onset of SARH guidance as a graduated PRF step that had nothing to do with actual launch.

You fire your own weapons AFTER you guide other folk's shots, as you close up and clean up on the missed-target survivors.  Given you are another 10-20nm further behind the SARH round than the jet which shot it, as long as it doesn't need actual target illumination until the endgame (IMU vs. Autopilot difference, the latter must generate steering differentials through the seeker) and can time share with other missiles when it does go active, you can hit multiple threats which fired on the lead jets at say 30nm and Mach 1.2 (at FL300) or 50nm and Mach 1.5 (at FL450), with the threat not realizing that the actual illuminator who was responsible for the missile shots was in-trail on the lead jets which pumped off, sometime after launch.

Again, F-16s/18s actually have a named tactic for this, it's called Chainsaw, presumably as a function of the rotation of the teeth along the retreating blade.  Having remote, offboard, guidance by powerful Zhuk/Bars/Irbis radars, would change everything about DCS gameplay without necessarily requiring mirror image missile types.

Keep in mind that Russia suffered a terrible blow when she and Ukraine went their separate ways as there were a lot of shared programs whose next-gen technology development programes, including seekers, that were effectively abandoned or likely given over to the West.  Added to the budgetary woes of the corrupt Gorbachev/Yeltsin period and there was also simply no money to redevelop more advanced SEEKERS.  But not strapdown navigators.  Nor datalinks.

These are likely what is in the upgraded R-27 missiles, along with perhaps some variant of the R-27EM seeker from the Su-33.

Fun theorycrafting.   AIM-7's are limited by the DSR cue, which gets shorter and shorter as the radar gets smaller, as in the case of an F/A-18 ... sitting in trail and illuminating is highly unlikely from that perspective, as well as the fact that missiles are channel de-conflicted and there's zero indication of some form of cooperative network capability to enable all this to happen.  You could in theory do it manually, but the radar has no (known) reason to use up that channel for a missile it did not launch.  If such capabilities and tactics exist, they are hidden away in sources we have no access to, and there are no hints indicating such things are in use.

Likewise for R-27ETs, there's a reason why it's 'lock on on the rail' - random reflections of the sun from lakes, clouds and other sources can easily seduce the seeker away from its intended target.

'But it's a stealth shot!' you say.   But then, that's what counter-tactics are for.  You don't need to see the missile launch, you just have to respect the capability.

On 4/15/2021 at 2:33 PM, dundun92 said:

The R/ER has LOAL. Thats been knows since forever. What there is no evidence for is that the T/ET have LOAL.
 

The R-27T/ET is missing the M-Link hardware, and the radar does not generate an M-link for those missiles when they are launched.   So more like there is evidence to the contrary, as opposed to 'no evidence'.

PS:  So apparently I am now a successful necroposter.  I shall go burn myself.

42 minutes ago, GGTharos said:

The R-27T/ET is missing the M-Link hardware, and the radar does not generate an M-link for those missiles when they are launched.   So more like there is evidence to the contrary, as opposed to 'no evidence'.

LOL, not a necro poster (read the PS while answering).

Lots of things about medium to longer range missiles in DCS is guesswork to smaller or greater degree. So pretty much what follows is also guessing.

The R-27 (E)[R|T] missile family were supposedly modular with ability to change seeker/motor section. In case of ER/ET with only the seeker being being a difference, and I believe you are talking about missile section that was common for both ER/ET. As for the location of rear antenna, it was also probably in one of the common sections. Now if this was used for ET guidance or not I really can not tell. From what I can tell about these seekers in DCS at least, they are slaved to either: radar, EO or the HSM, so therefore chance of getting a random reflection was less, but still there remains a question weather these seekers could be cued with DL updates accurately enough to for terminal guidance when the heat signature as perceived by the missile is stronger.

Again soviet doctrine called for 2 missiles to be launched. So if ER and ET were fired at the same target, one would expect that ET would either need to have lock from the start or means to acquire lock at later time.

I think we also concluded at some prior topic that the source of power was common with non-E and E versions, thus limiting the maximal guided flight of the missile to 60 seconds. I do not know how much is this true though, since it sounds like a really stupid thing from engineering point of view but actually smart as cost reduction in production.

1 hour ago, okopanja said:

…Again soviet doctrine called for 2 missiles to be launched. So if ER and ET were fired at the same target…

I keep seeing this statement about missiles being launched in pairs—one radar homing and one IR homing—bandied about the forums. But I haven’t seen any sources. Can you point me to some?

Concerning IR lock on after launch, the Su-27 manual, at least, only refers to IR missiles locking onto the target while on the rail when the target is designated.

1 hour ago, Ironhand said:

I keep seeing this statement about missiles being launched in pairs—one radar homing and one IR homing—bandied about the forums. But I haven’t seen any sources. Can you point me to some?

 

Here is the exempt form the book:

"F-15C Eagle vs Mig-23/25 Iraq 1991",

Douglas C. Dildy & Tom Cooper,

ISBN: 978-1-47281-270-4

page 27, paragraph 4

Quote

The "Foxbat-E" Eksportnyy model's primary weapon was the huge Bisnovat R-40, which was produced in both the SAR-homing (R-40RD) and IR-guided (R-40TD) versions. The "Foxbat" carried one of each beneath each wing, with the RP-25 radar slaving the seeker heads of both missiles on that side to the same target. When R-40RD's seeker "saw" the target (actually the R-25's reflected radar energy) and the closing velocity, altitude delta (differential - in other words, how high the R-40 had to climb to reach the target), and launch aircraft G-loading were all within prescribed limits, and range to the target was withing the dynamic (flight) range of the missile, the "Ready to Launch" (in-range) cue was illuminated in the cockpit.  If fired in "salvo", the R-40TD would launch first so that it's IR seeker head would not transfer lock to the rocket plume of the other missile.

Below is the picture showing both versions of missile hanged on left side wing, R-40TD inner pylon, R-40RD external pylon. The sidenote of the picture also mentions the salvo, and provides information on ranges (dependent of aspect) for this firing mode. The source of the picture is listed as [Foxbat Files], but as far as I can tell the picture is provided on commercial basis, so I decided not to include it.

I did read in more than one places, about this practice, but I hope it is sufficient to provide one example.

I would also recommend this book to anyone interested in the history of F-15C and Mig-23/Mig-25.

2 hours ago, okopanja said:

The R-27 (E)[R|T] missile family were supposedly modular with ability to change seeker/motor section. In case of ER/ET with only the seeker being being a difference, and I believe you are talking about missile section that was common for both ER/ET. As for the location of rear antenna, it was also probably in one of the common sections.

 

The R-27 "family" is modular, but this old discussionj regarding possible DL for the T/TE is really down to a misconception  about what resides in which missile section - more to the point, that the common "autopilot" section should have something to do with INS/datalink capability.....it does not. The "autopilot" section does exactly what the name implies - i.e. it takes simple steering commands from the seekerhead and translates them into appropriate control surface deflections.

The inertial navigation system is an integrated part of the SARH radar seeker,,  while the IR seeker doesn't have one. 

1 hour ago, Ironhand said:

I keep seeing this statement about missiles being launched in pairs—one radar homing and one IR homing—bandied about the forums. But I haven’t seen any sources. Can you point me to some?

Concerning IR lock on after launch, the Su-27 manual, at least, only refers to IR missiles locking onto the target while on the rail when the target is designated.

 

 

There was such a doctrine, but it does not apply specifically to radar/IR missiles - most SAM systems as well as aircraft radar complexes were set up so that they could simultaneously guide two missiles against a target for increased PK. The only official mention of launch of an IR missile after a radar guided one, that I have seen, has to do with the need to impose a slight delay on order to avoid having the IR missile locking on to/or being distracted by the plume from the missile launched shortly before - but then that would apply regardless of whether that was radar guided or another IR missile  .

@okopanja and @Seaeagle, thank you both.

I’m aware of launching pairs of missiles—there’d be no reason for a “pairs” switch setting for A2A missiles otherwise. In fact, the Su-27 manual even refers to using that setting to launch an R/IR pair with the missile class to launch first selected manually. It was the idea that they were typically launched as one R and one IR type that I was questioning. I was also questioning the idea that the T and ET could be launched without first locking the target while still on the rails. Again, thank you both.

6 hours ago, okopanja said:

Now if this was used for ET guidance or not I really can not tell. From what I can tell about these seekers in DCS at least, they are slaved to either: radar, EO or the HSM, so therefore chance of getting a random reflection was less, but still there remains a question weather these seekers could be cued with DL updates accurately enough to for terminal guidance when the heat signature as perceived by the missile is stronger.

There's no question as to the DL operation, documents and testimony from technicians regarding this were quite clear - no M-Link for any form of R-27T, and this is why it was removed in LOMAC   This is a very old subject.

6 hours ago, okopanja said:

Again soviet doctrine called for 2 missiles to be launched. So if ER and ET were fired at the same target, one would expect that ET would either need to have lock from the start or means to acquire lock at later time.

It would have lock from the start.   The purpose of such a technique is to counter ECM since it was expected that western ECM would be effective, especially sets carried onboard bombers.  Bombers are also large enough so that you could lock IRH onto them from a larger distance.  When engaging fighters I would expect more conservative use of missiles depending on the situation, or if the 'unencumbered Pk' of the R-27 is really 0.7, then it would simply behoove one to shoot pairs.

6 hours ago, okopanja said:

I think we also concluded at some prior topic that the source of power was common with non-E and E versions, thus limiting the maximal guided flight of the missile to 60 seconds. I do not know how much is this true though, since it sounds like a really stupid thing from engineering point of view but actually smart as cost reduction in production.

The guaranteed power would last 60 sec - IRL it wasn't quite that cut-and-dry, I've seen 80 sec flight profiles ... but the idea is you cannot guarantee that.  And yes I believe the power source is a gas generator in the rocket motor section.  I don't know if ED would ever bother simulating this, and I'm not sure that it would really matter or make a difference.

On 4/15/2021 at 10:54 AM, TotenDead said:

 

Bad one

 

It could carry 4, even though it didn't become standard.

1 hour ago, 59th_Buncsi said:

It could carry 4, even though it didn't become standard.

I would presume it would not make sense since IIRC the standard MiG-29 (9.12 and 9.13) already had problems with asymmetric load when one of the two R-27 missiles was launched. Putting these heavy missiles even further away down the same wings would only make matters worse, at least without some kind of digital FCS to adapt to these configurations. I would also wager that the wings weren't designed for big loads on these outer pylons as well, especially during A2A manoeuvring.

Presuming they could withstand the load, you could launch them in pairs, perhaps, but I have a feeling the pylons were not spaced far enough by design so there's not enough side clearance between the missiles since they are launched from these rails so you'd have to fire the inner pair first which leaves you in a not ideal configuration again. 

This was of course fixed later on starting with MiG-29M/K (9.15/9.31) with stronger and wider wings which had two extra heavy pylon points plus they were 'wet' wings with a bigger fuel capacity compared to old school bags with fuel as on the initial variants.

14 minutes ago, Dudikoff said:

I would presume it would not make sense since IIRC the standard MiG-29 (9.12 and 9.13) already had problems with asymmetric load when one of the two R-27 missiles was launched. Putting these heavy missiles even further away down the same wings would only make matters worse, at least without some kind of digital FCS to adapt to these configurations. I would also wager that the wings weren't designed for big loads on these outer pylons as well, especially during A2A manoeuvring.

Presuming they could withstand the load, you could launch them in pairs, perhaps, but I have a feeling the pylons were not spaced far enough so there's not enough side clearance between the missiles since they are launched from these rails so you'd have to fire the inner pair first which leaves you in a not ideal configuration again. 

 

The picture is of a MiG-29M 9.15 prototype.... thus, digital FCS and new wing and another pylon off-picture so a different pylon arrangement a bit.... all in all, you are absolutely correct 

2 hours ago, Dudikoff said:

This was of course fixed later on starting with MiG-29M/K (9.15/9.31) with stronger and wider wings which had two extra heavy pylon points plus they were 'wet' wings with a bigger fuel capacity compared to old school bags with fuel as on the initial variants.

Yes but according the the documentation I have, even for the 9-15/9-31 there were some restrictions - i.e. it could take 4 R-27 missiles, but only 2 of those could be of the long-burn variants.

On 4/20/2023 at 3:09 PM, Seaeagle said:

Yes but according the the documentation I have, even for the 9-15/9-31 there were some restrictions - i.e. it could take 4 R-27 missiles, but only 2 of those could be of the long-burn variants.

Interesting. Even Gordon's MiG-29 book mentions only 2 ER/ETs.. Which is kind of surprising since there are shots of MiG-29M prototypes flying with four Kh-31s (I guess inert ones, not sure how heavy they are). 

This mixed seeker salvo thing, I've only seen it in old PVO docs from the 60s and 70s for certain bomber intercepts.

I wonder where this ET LOAL myth comes from, its a rather simple par for the course late 70s single colour seeker.

People struggled making more complex ones LOAL...

1 hour ago, TaxDollarsAtWork said:

This mixed seeker salvo thing, I've only seen it in old PVO docs from the 60s and 70s for certain bomber intercepts.

I wonder where this ET LOAL myth comes from, its a rather simple par for the course late 70s single colour seeker.

People struggled making more complex ones LOAL...

I think ET would need DL support to be useful in LOAL scenario and/or a seeker that actively searches for anything it can find it's gimbals limits. Under present state we have to assume the seeker remains fixed, which means FOV is narrow and therefore probability of lock is limited but not totally impossible.

Also, I read the whole topic, and it appears some confidently made statements from 2-3 years ago proved to be premature.

Just my 2 cents do not really stand great against your tax dollar.

On 4/22/2023 at 1:53 PM, Dudikoff said:

Interesting. Even Gordon's MiG-29 book mentions only 2 ER/ETs.. Which is kind of surprising since there are shots of MiG-29M prototypes flying with four Kh-31s (I guess inert ones, not sure how heavy they are). 

I don't know what exactly the issue was, but its clearly not weight related. The same documentation(and every other I have seen) states, as you said,  that four Kh-31 missiles can be carried(on the two inner wing stations) and those are *much* heavier - the long-burn R-27s are about 350 kg + launchers, while the Kh-31s are over 600 kg + launchers(which are heavier too). It doesn't matter if the photos you have seen seem to have involved inert ones - the configuration was thoroughly tested and certified with multiple test firings of live missiles.

But then I have never seen R-27s(any version) on a MiG-29(any version) with anything other than the APU-470 rail launchers, while the Kh-31s are catapult launched(by AKU-58M) so maybe that has something to do with it - i.e.  length of the R-27E missiles, rail launching, clearance to airframe/control surfaces etc.

The radio correction antennas on the R-27R/ER are mounted on the section with the wings, but their signal wires go into the radar seeker section (propably through that housing on the bottom that is only present on R/ER).

The T/ET variants lack the antennas and also the radar/radio receiver to demodulate such signal. So no DL for them.

At the risk of getting criticized for necroing this thread again, I would like clarification on the targetting done for the R27t/ET . From reading this thread, it seems that a lock is needed before missile launch (because there is no LOAL). It also seems that a lock can be passed to the missile from either the Radar or the IRST. 

The manual describes the process for getting a lock with IRST: (p123) and it is very similar to getting a lock with radar:

1) set distance,2)set azimuth3)set elevation

But the IRST is that eyeball thing on the nose. It does not have a steerable dish like radar so what is the manual talking about?

Its eyeball is steerable.

@GGTharosthanks. I should have realized even if it is not steerable, the ccd has pixels, the focal length of the lens is known, so the azimuth/elevation should be calculatable even without the pilot 'steering' the eyeball