R-23, R-24 & R-27 AAM

[overscan (PaulMM)]

Image from PVO museum- allegedly an R-27R seeker

 

[overscan (PaulMM)]

Re: R-27 AAM

Same source

 

[overscan (PaulMM)]

Re: R-27 AAM

From MrDetonator

Phase mono-pulse antenna system for tracking targets in azimuth and elevation (two planes). Each antenna has its own transmitter. In operation one antenna works in transmit mode, three others in receive mode. The target signal received ís fed to "phase detectors", where formation of azimuth and elevation correction signals take place. If the phase sum is zero, the target is straight ahead. If the target is above/below or left/right, correction signals created in the "phase detectors" are used to control the missile flight direction.

source: RADIOLOCATION: Sluchevskyi.B.F.

 

[Dilbert]

Re: R-27 AAM

Well, there's another surprise!

So, what's this thing?

There was one just like it in a "Russia's Arms Catalog" a few years ago, I thought it was labeled "9B-1101K". ???

Source:
- Y. Gordon et al., MiG-29, Polygon, Moscow, 1998

 

[overscan (PaulMM)]

Re: R-27 AAM

I'm not sure! It seems odd that the aircraft radars couldn't have planar array antennas due to manufacturing and performance issues, yet the missile seeker could. A phase comparison antenna like this would be cheaper.

The Phazotron museum has the same seeker, labelled as ПАРГС 9Б-1101К, Р-27Р1 и Р-27РЭ1

Are you sure you aren't mixing up the seekers?

9B-1101 - Semi-active monopulse seeker from R-27R/ER
9B-1101K - export version of above?
9B-1103M - Active radar seeker for R-27 upgrade

Picture from Russia's Arms Catalog 2000

 

[Dilbert]

Re: R-27 AAM

Yes! that's probably the one, thank goodness you have that document too? I was looking everywhere for my download, seems I deleted it. Ok one mystery solved, thanks! Next question:

What business does any SARH seeker have, operating in "transmit" mode? ???

 

[Pit]

Re: R-27 AAM

Hello everybody

First post here, nice to see this forum running good !.

For the russian speaking troop, this fragments came from a NICE article from Istoria Aviatsia magazine, an article called "Metamorphosis of the Combat Preparation of Soviet Air Force on air to air fights of the post-war period" by Petr Chernich.

It have some interesting information (as I was commented) on R-27 tests by Soviet Air Force. Sadly the way the article is scanned/photographed made too much harm on my OCR software and can't translate it, so if anybody speak russian good enough for that, I would be more than happy and guess some other guys too!.

I have the whole article on request (14 pages), and the topic seems worth a discussion somewhere! .







Source:
- Istoria Aviatsii magazine, June 2004 edition.

 

[overscan (PaulMM)]

Re: R-27 AAM

I don't think it does operate in transmit mode.

Its simply 4 receivers for the same radar signal, all offset slightly. This allows phase monopulse homing; by comparing the phase received left/right and up/down, you know the direction to the target. In fact, can't you sum/difference the signals and get steering commands directly?

 

[mrdetonator]

Re: R-27 AAM

Damn, you fast guys..... But wait,there's more headache for you...

What business does any SARH seeker have, operating in "transmit" mode?

Who told you that is a SARH seeker?

 

[overscan (PaulMM)]

Re: R-27 AAM

The system mrdetonator describes is active. I believe the seeker head we have the picture of is SARH, but clearly working on similar principles.

 

[mrdetonator]

Re: R-27 AAM

I think it wouldn`t work when all four antennas were passive. There has to be at least one transmitter on the board. The phase mono-pulse principle assumes that you have transmitter/receiver on the same place. If the aircraft radar was used for illuminating the target, those four antennas on the missile would receive "incorrect" phase signals to track the target.

 

[crossiathh]

Re: R-27 AAM

I think it wouldn`t work when all four antennas were passive. There has to be at least one transmitter on the board. The phase mono-pulse principle assumes that you have transmitter/receiver on the same place. If the aircraft radar was used for illuminating the target, those four antennas on the missile would receive "incorrect" phase signals to track the target.

Regarding SARH:
Talking about the predecessor (R-23R/R-24R), also having a mono-pulse seeker with four receivers in the antenna, you have a fifth receiver directed backwards receiving the "original" signal from the aircraft's radar. This signal was used as reference to compare the phase, enabling the extraction of the doppler shift.

I wonder if this would'nt be true for SARH type seeker of the R-27.

 

[overscan (PaulMM)]

Re: R-27 AAM

Hmmm.

Interesting!

Need to read some more Stimson I think.

 

[mrdetonator]

Re: R-27 AAM

Regarding SARH:
you have a fifth receiver directed backwards receiving the "original" signal from the aircraft's radar. This signal was used as reference to compare the phase, enabling the extraction of the doppler shift.

That`s exactly my problem, I know it could work this way but I haven`t found a single prove for that. Those supposed "receivers directed backwards" are totally omited from my sources. ??? I did a close detail of those, I`ll post it here later.

 

[Dilbert]

Re: R-27 AAM

I don't think you'll find this one in Stimson. The use of "backwards-directed receivers" seems to be part of "inverse-processing" and is pretty standard on SARH missiles including AIM-7 (that was even using conical scan instead of monopulse). I always thought it was used mainly for Doppler comparison and shoot-down capability, not for monopulse. For example, an anti-radiation missile needs a monopulse seeker to measure direction to a transmitter, but doesn't need those backwards-looking antennas AFAIK, because it doesn't measure Doppler. It's purely passive and it still works. I never before heard the idea that you need a transmitter in the same place as the receiver, for monopulse direction-finding to work.

Two "backward-directed receivers" can be found on R-27R mounted just behind the moving butterfly control surfaces. They are absent on R-27T, which is one way that we know that the heat-seeker doesn't have a datalink.

What system is Sluchevskiy describing, if not 9B-1101K?

 

[mrdetonator]

Re: R-27 AAM

I genuinely apologize for that misunderstanding, you right, it just compares the phase difference of returned signal between two(more) antennas. So, it doesn`t matter if the trasmitter is not on the board. The book is describing amplitude, phase and sum/difference signal processing mono-pulse systems, no details where is used.

 

[crossiathh]

Re: R-27 AAM

... I always thought it was used mainly for Doppler comparison and shoot-down capability, not for monopulse ... They are absent on R-27T, which is one way that we know that the heat-seeker doesn't have a datalink.

Exactly. The "backwards-directed receivers" are use to compare doppler-shift to enable shoot-down-capability. In case of the R-23R/24R there is no datalink available.

 

[mrdetonator]

Re: R-27 AAM

Regarding SARH: Talking about the predecessor (R-23R/R-24R), also having a mono-pulse seeker with four receivers in the antenna

The monopulse tracking system relies on the pulse radar design. It measures the angular position (elevation,azimyth) of the target from two pulses being received simultaneously. In case of the R-27 I wouldn`t dare that it uses monopulse homing seeker, active or passive one.
But the R-23R SARH seeker uses the continual wave(CW) beam provided by the KNP transmitter of the Sapfir-23E radar. AFAIK only the Sapfir radar itself uses a monopulse system to track target in space, but when the missile has to be prepared for launch, the radar switches to CW.
How would you call the R-23R seeker then, a mono-pulse continual wave?
Also please explain to me why would a missile seeker need doppler for homing on to a low-flying target or better, why is doppler needed for missile homing? The only one application for doppler on SAHR missiles I see in the radio proximity fuse. It compares the frequencies of the outgoing to the incoming waves and uses the doppler to determine the range to the target.
thanks

 

[Dilbert]

Re: R-27 AAM

In case of the R-27 I wouldn`t dare that it uses monopulse homing seeker, active or passive one.

I don't understand the above sentence.

But the R-23R SARH seeker uses the continual wave(CW) beam provided by the KNP transmitter of the Sapfir-23E radar. AFAIK only the Sapfir radar itself uses a monopulse system to track target in space, but when the missile has to be prepared for launch, the radar switches to CW.
How would you call the R-23R seeker then, a mono-pulse continual wave?

The defining feature of a monopulse seeker is the ability to follow a jamming signal, regardless if it's pulsed or CW. Of course for normal operation, CW illumination is always the best, but it's not required by the monopulse seeker as it is for a conical-scan seeker.

Also please explain to me why would a missile seeker need doppler for homing on to a low-flying target or better, why is doppler needed for missile homing? The only one application for doppler on SAHR missiles I see in the radio proximity fuse. It compares the frequencies of the outgoing to the incoming waves and uses the doppler to determine the range to the target.

In the look-down situation, Doppler has the same function for the missile seeker as for the aircraft radar, to distinguish the target from the reflections of the earth.

 

[mrdetonator]

Re: R-27 AAM

I don't understand the above sentence.

I thought the missile homing principle depends on shooter`s radar. The Sparrow is to be said to have either Cw or monopulse seeker (pulse illumination). In first case the shooter`s radar had to be equiped with a cwi trasmitter when homing the old Aim-7F. The upgraded Aim-7M features inverse monopulse seeker, because the illumination is done via pulse-doppler radar (STT mode). I`m not aware whether modern airborne radars have cw illuminators for homing SAHR missile.

I`m still not clear why the doppler is used for homing on the target and saying it is used the same way as in airborne radars seems rather a simplification. While the airborne radar uses the doppler-shift for searching a target on earth backround, uses doppler bank filters to suppress ground clutter, where the doppler causes a lot of problems, e.g. blind speeds, target moving perpendicular or manuevering, so the doppler-shift may vary in wide range. The Sapfir-23 radars have overcomed those problems by changing PRF during each scan lines, using multiply doppler filters, etc... but weighting more than 500kg.
The SAHR seeker only needs angular possition of the target, it is homed on the reflected radar beam, nothing more. At the moment I see more troubles than benefits when using doppler.

 

[crossiathh]

Re: R-27 AAM

@mrdetonator
You are right about the KNP transmitter which provides a continuous wave signal, but the RGS-23 "Topas" seeker of the R-23R is a mono-puls type seeker, taking doppler shift into account as already described. This is usefull to enable the RGS-23 seeker detecting targets above the surface.

Right before launch, the R-23 still on the APU-23M missile rail, the weapon system provides a bunch of information to the R-23R. The proximity fuse "Tschaika" receives information about when to activate and the approach rate. The autopilot receives information about the direction for the initial flight (passing aircraft's radar) guiding the missile . Lock-on after launch is used because of the needed Doppler information which only can be extracted receiving the cw-signal from the KNP of the aircraft's radar as reference. The RGS seeker's frequency oscillator will be tuned on the velocity of the target by the radar via the RBS module before launch. The doppler shift's bandwith which will be searched after launch is 60Hz. The missile "knows" what kind of targets (speed range) it is looking for.
Please double-check with your sources.

 

[overscan (PaulMM)]

Re: R-27 AAM

The seeker head needs doppler processing because you want it to home on the signals bouncing from the aircraft, and not the signals bouncing off the ground, surely?

 

[Dilbert]

Re: R-27 AAM

The doppler shift's bandwith which will be searched after launch is 60Hz.

Whoa!

I agree with everything else above, but - 60 Hz?!? From a carrier frequency of 10 GHz? So if the target changes its closing speed by as little as, e.g. 10 km/h, the missile can't see it?!

This could help explain why Russian radar AAMs never seemed to hit very much in all of human history - but I nevertheless think I simply misunderstood something. Does R-27R have a similar Doppler gate? Interesting source of information, whatever it is.

 

[crossiathh]

Re: R-27 AAM

I agree with everything else above, but - 60 Hz?!? From a carrier frequency of 10 GHz? So if the target changes its closing speed by as little as, e.g. 10 km/h, the missile can't see it?!

:-\ You are absolutly right ... this was a write error. 60kHz is the correct value. While we getting a little bit off-topic we should probably switch this discussion to a separate topic about the R-23/24.

 

[Dilbert]

Re: R-27 AAM

What a roller-coaster this forum is!

I thought the missile homing principle depends on shooter`s radar. The Sparrow is to be said to have either Cw or monopulse seeker (pulse illumination).

More precisely, the seeker is either monopulse or conical scan. Monopulse can work with any kind of target illlumination, while conical scan requires CW illumination.

The upgraded Aim-7M features inverse monopulse seeker, because the illumination is done via pulse-doppler radar (STT mode).

It's the other way around - the illumination is not longer required to be CW, because the seeker is monopulse.

 

[Pit]

Re: R-27 AAM

Dilbert, while you're correct ConScan must need a CWI for working, how did this works with R-33 and Zaslon, bearing in mind that R-33's seaker is Inv ConScan and not InvMonopulse like the others one ???...

BTW, R-33 also receives reference signal from Zaslon radar in a backward pointed aerial...you mentioned two aerials (close to the buterfly wings), one of that is for reference signal and the other one for MCGU?...didn't know that R-27R used reference signal from main radar like R-23R/R-33...

 

[overscan (PaulMM)]

Re: R-27 AAM

I find it odd that Vympel would use inverse conical scan for the R-33 seeker, given it is more easily jammed, and it is more recent than the R-23 in design.

I can only imagine some feature of the Zaslon radar made a monopulse seeker unusable.

 

[Dilbert]

Re: R-27 AAM

I saw one source that said RVV-AE seeker was monopulse and another (Military Parade!) that said it was conical scan. I think this is another one of those situations where some authors don't know what they are saying. I agree with overscan, they are both almost certainly monopulse.

 

[mrdetonator]

Re: R-27 AAM

Right before launch, the R-23 still on the APU-23M missile rail, the weapon system provides a bunch of information to the R-23R. The proximity fuse "Tschaika" receives information about when to activate and the approach rate.

Hmm, does it mean that both seeker and proximity fuse are measuring doppler of the target? Why would the Tchaika proximity fuse need the information about the target approach rate before launch?. When activated (after launch 2-24sec) it works in centimeter wave band comparing of transmitted/received signal, so it is doing the doppler itself. The time after launch prior to proximity fuse activation depends on target type and target distance/aspect.

The RGS seeker's frequency oscillator will be tuned on the velocity of the target by the radar via the RBS module before launch.

The RGS is tuned on the litera(frequency) of the KNP transmitter. You are saying something different that it is tuned on the velocity of target (returned cw frenquency, which varies due to doppler.?????)

Lock-on after launch is used.......

At last I agree with that, the LOCK-ON is achieved after launch for the RGS and before launch for TGS. That`s exactly what the source is saying.

 

[overscan (PaulMM)]

Re: R-27 AAM

The time after launch prior to proximity fuse activation depends on target type and target distance/aspect.

Yes, but the optimal distance to detonate the proximity fuse differs depending on engagement type (headon/tailchase), target size, and possibly even speed? The host aircraft can supply this information.

 

[mrdetonator]

Re: R-27 AAM

The time after launch prior to proximity fuse activation depends on target type and target distance/aspect.

Yes, but the optimal distance to detonate the proximity fuse differs depending on engagement type (headon/tailchase), target size, and possibly even speed? The host aircraft can supply this information.

The AVM-23 supplies the "expected missile flight time" information when the launch button is pressed. The information is used to initiate the proximity fuse. That` what source is saying.
My point is why the "Tchaika" is measuring doppler(closure rate) if the seeker is doing the same as well? The information from the seeker could be used to detonate the warhead when close to the target. The Tchaika proximity fuse then seems to be useless.

 

[overscan (PaulMM)]

Re: R-27 AAM

OK- then perhaps "initiate" means "turn on".

That way the proximity fuse isn't armed until its well away from you and your wingmen, reducing the chance of fratricide.

 

[mrdetonator]

Re: R-27 AAM

OK- then perhaps "initiate" means "turn on".

That way the proximity fuse isn't armed until its well away from you and your wingmen, reducing the chance of fratricide.

at least we concur that "to initiate" means "turn on" .... ;D But that does not explain my question.

 

[crossiathh]

Re: R-27 AAM

My point is why the "Tchaika" is measuring doppler(closure rate) if the seeker is doing the same as well? The information from the seeker could be used to detonate the warhead when close to the target. The Tchaika proximity fuse then seems to be useless.

I agree that the Tschaika proximity fuse is doppler type. But this is independent to the seeker. Keep in mind that Tschaika uses doppler to measure closure speed, while the RGS seeker additionally needs doppler to identify and track the target. BTW, Tschaika is used with the R-23T too, where the seeker doesn't provide doppler information.
I will try to double check these points ...

I recommend to transfer the discussion to a separate topic, e.g. "R-23/24 AAM"

 

[overscan (PaulMM)]

OK- back to the R-27 seeker.

I checked Janes Air Launched Weapons 2001 and found a picture of exactly the same seeker, from a trade show display.

My guess is the flat plate antenna is the R-27EA seeker.

 

[Vadifon]

Re: R-27 AAM

Regarding SARH:
Talking about the predecessor (R-23R/R-24R), also having a mono-pulse seeker with four receivers in the antenna, you have a fifth receiver directed backwards receiving the "original" signal from the aircraft's radar. This signal was used as reference to compare the phase, enabling the extraction of the doppler shift.

(R-23R/R-24R) don't have radiocorrection datalink.

The defining feature of a monopulse seeker is the ability to follow a jamming signal, regardless if it's pulsed or CW. Of course for normal operation, CW illumination is always the best, but it's not required by the monopulse seeker as it is for a conical-scan seeker.

: if "CW illumination is always the best for a conical-scan seeker" could you tell me the other modes of illuminations?

I have read everyting but my English isn't good enough to react so fast.
re. mentioned above:
R-23 is the first missile with monopulse CW seeker (SHOU method) in the world. This missile has capability of lock target after lounching (without datalink).
R-24. Algorithm of inertial homing is pretty improved (lock target after lounching without datalink).
R-24M can homing low and slowly target (helicopter) (lock target after lounching without datalink).
R-33 cone-scan CW seeker (lock target after lounching without datalink).
R-27 monopulse CW seeker (SHOU method, lock target after lounching, datalink).

re. CW:
after lounching a missile STT mode and CW mode are working by turne. Thus CW mode is called ДНП (Discretely continuously illumination ) in Russian aircraft.

 

[overscan (PaulMM)]

Hi Vadifon.

R-23/24 do not have radiocorrection datalink. They do have receivers facing backwards which receive the radar signal from the aircraft, which is used to compare with the signal from the target.

 

[airsande]

R-23R/T (K-23, izdeliye 340/360)
Basic weapons of the MiG-23M consisted of two R-23R or R-23T Beyond Visual Range (BVR) missiles. However, the aircraft was limited to carry only one R-23 variant in a single mission, as each variant required different black boxes for the fire control system.
The R-23, initially known as the K-23, was developed by Factory No.134 by a design team led by V.A. Pustyakov. The design requirements called for a missile capable of destroying bomber-size targets at a maximum distance of 18 nm (9.8 nm) which can fly fly up to 4,000 (12,800 ft) above the launch platform (snap-up capability). Initially, it was planed the missile to be equipped with dual-sensor seeker that combines both SARH and IR guidance in a single device. However, it proved difficult to be developed and in the end, it was decided the K-23 to be built in two versions – the first one equipped with SARH seeker (izdeliye 340) and the second one with IR seeker (izdeliye 360).
K-23’s initial test firings were carried out in early 1967, initially from a specially-modified MiG-21 testbed and later on from the ‘23-11’ prototypes, in both guided and unguided (seeker inoperative) modes. The IR-version development and testing proved to be relatively straightforward but the SARH version was quite troublesome and required considerable redesign. The updated K-23 SARH version, tested for the first time in 1970 featured initial autonomous guidance for a duration of three seconds after the launch in order to avoid interference from launch platform’s radar side lobes to the K-23’s SARH seeker.
Both the K-23’s variants were fitted an unified with expanding-rod warhead weighting 26 kg (57.2 lb) and with lethal radius of 8 m (17.6 lb). The SARH version was said to have boasted a fairly good degree of ECM resistance compared to the F-4E’s AIM-7E-2 thanks to its monopulse seeker. The IR derivative of the K-23 employed a seeker with liquid nitrogen-cooled detector which required lock-on before launch. The IR seeker head could be slaved onto the target by the radar or IRST sensor; there was also an option for boresight aiming by the pilot (through the ASM-23M sight/HUD) by manoeuvring the aircraft and positioning the nose toward the target (Fi-zero launch mode). ‘Brochure’ Probability of Kill (PoK) was 0.8-0.9.

 

[Vadifon]

Hi Vadifon.

R-23/24 do not have radiocorrection datalink. They do have receivers facing backwards which receive the radar signal from the aircraft, which is used to compare with the signal from the target.

Hi .
It is interesting. Whether there is an information on the Internet?

 

[mrdetonator]

Привет Vadifon, просто отвечай на русском, молодци будут переводить русско-английским транслейтором. У меня тоже плохо с англицким языком, но нельзя писать на другом, я тоже не русский.... :-[