Vympel R-27 guidance doubt

I think this is not correct when talking about loosing a radarlock for a second or more. When pilot turns the aircraft and radar away from the target, he looses a radar lock as well as the missile, there is no chance to regain the missile back. Therefore pilots are strictly instructed to hold the target circle within the HUD frame and keep illuminating. Written in combat employment and pilot instruction manuals.

How MISSILE can be lost? If radar briefely losses target tack for whatever reason it doesnt mean it also losses missile. There is the problem however – if radar losses track than reaquiring it might take too much time. Even several seconds might be too much, especeally when missile is close to target.

so the platform can lose lock, and regain it, missile can still hit in that kind of scenario, just the PK drops down.

I think this is not correct when talking about loosing a radarlock for a second or more. When pilot turns the aircraft and radar away from the target, he looses a radar lock as well as the missile, there is no chance to regain the missile back. Therefore pilots are strictly instructed to hold the target circle within the HUD frame and keep illuminating. Written in combat employment and pilot instruction manuals.

Yes, the ER has IN and MCCU. It has a datalink, and it works just as i described, so the platform can lose lock, and regain it, missile can still hit in that kind of scenario, just the PK drops down.

The ET has no MCCU, no datalink. It requires a positive lock before launch. It’s ideal for high-speed tailchases against afterburning targets, where the R-73 range drops down to couple of km’s. If the target is breaking away with high transsonic speeds, and you’re following it, R-27ET rmax should be around 15 km’s or so.

Garry, you mistake R-27ER for R-27ET. First is semi-active radar version and have INS, MCCU, and LO after Launch since very beginning.

Sorry… was confusing myself…

The SARH models of the R-27 do have inertial navigation to fly toward what the Soviets describe as mathematical targets till the launch aircraft paints the target and the missile homes on the reflected energy.
That means they are lock on after launch and fly towards a point in the sky where the target is calculated to be when the missile gets there.
The IR models don’t have INS systems and require lock on before launch. The inertial guidance period of the R-27R and ER is described as being up to 60% of its flight trajectory. (Note for the R-24R that figure is given as 20%). The R-77 is 80% and has Lock on after launch capability.

I had a book from Milparade that had an article written by MiG that was describing the R-27E missiles in comparison to the Sparrow and it mentioned that one of its advantages was a lofted trajectory that would allow it to reach targets more quickly (and with more terminal energy).

Regarding the original question, no. The R-27R and R-27ER are lock on before launch and as far as I know have no capability to reaquire a target in flight.

Garry, you mistake R-27ER for R-27ET. First is semi-active radar version and have INS, MCCU, and LO after Launch since very beginning.

Garry, i think you’re wrong on this one. For LOBL, seekerhead needs to acquire the contact upon launch, and it’s impossible for the R-27ER seeker to do that from, let’s say 80 km distance. Even the R-37 seeker, 40 kg heavy and 38 centimeters in diameter, does 70km against 5m2 RCS.

According to the makers of the missile it does not have a datalink.

Remember what aircraft is carrying the R-27T and R-27ET is the Su-27. Th early Mig-29s couldn’t carry it. Look at that chart for the Su-35BM and you will see even that aircraft can only carry two R-27ETs. The later model Mig-29UBs could carry two R-27ETs and 4 R-73s due to their lack of radar making R models pointless.

For exceptional engagements the ET can be used to near max range against targets like the SR-71.. ie high and fast and hot aircraft. For most of the rest of the time they will be fired together with SARH missiles at moderate ranges to improve kill probability and complicating the defensive task of the target.

THe Mig-29 would be directed to the optimum launch position and then it would fire and guide its R-27ERs. The time it would take for two seperate launches would mean the R-73s would be used in any ensuing dogfight.

The Su-27 on the other hand might have closing or receding targets at high or low altitudes at high or low speeds. At low altitudes a missile like R-27ET will have a range of about 20km in clear weather… which is about 10 times the range of a sidewinder in similar conditions. More often than not the R-27ET will be a chase down weapon as receeding targets have very short radar tracking ranges in comparison with closing targets.

Thats what got me as well; i mean whats the point in having a max range of 120 odd km if the blasted missile has to lock on before launch?

No Alamo I know of has a range of 120km. IR versions of Alamo have a max launch at ideal target of 80kms in ideal conditions… ie closing target high and fast launch platform… non manouvering target.
The Alamo has the same seeker as fitted to the R-73 but the larger diameter tube means -+55 degrees look angle. It does not however have thrust vector capability and can engage targets doing up to 7g evasive turns.

This is very shortsighted thinking. First – IR R-27 is likely to be used in a tailchase engagement. Missile ranges are much shorter in tailchase as they must overtake the target.

Also, the engagement might be lower altitude, which reduces missile range further.

R-27T range in such conditions might only be 10km or so, well within lockon range. R-27ET range would be substantially longer.

R-27R does lock on after launch, by design. However, R-27ER typical max range is 65km, not 120km.

Garry, i think you’re wrong on this one. For LOBL, seekerhead needs to acquire the contact upon launch, and it’s impossible for the R-27ER seeker to do that from, let’s say 80 km distance. Even the R-37 seeker, 40 kg heavy and 38 centimeters in diameter, does 70km against 5m2 RCS.

Thats what got me as well; i mean whats the point in having a max range of 120 odd km if the blasted missile has to lock on before launch? It’s tiny seeker’s never going to lock on @ such ranges, the russians can’t be that daft – build a whopper of a missile with a kinematic range in excess of 100kms only to have the need for LOBL, which probly is not possible for distances above 15-25 km! or were they? 😮 i’m talking mainly of the IR version here (not the SARH).

Regards,
USS.

The R-27R and R-27ER are lock on before launch and as far as I know have no capability to reaquire a target in flight.

Garry, i think you’re wrong on this one. For LOBL, seekerhead needs to acquire the contact upon launch, and it’s impossible for the R-27ER seeker to do that from, let’s say 80 km distance. Even the R-37 seeker, 40 kg heavy and 38 centimeters in diameter, does 70km against 5m2 RCS.

R-27R(ER) uses MCCU and IN for the stages until the seeker picks up bounced radar beams. And, the answer is yes, if the Su-27 lost contact on initial stages, the missile will lose MCCU and go for IN regime. Depending on the timeframe of reacquiring, the missile will see the contact once again, if it’s far away, the platform will start sending MCCU again, and correct the trajectory, if it’s near, seeker will just pick up beams and go in SARH. It’s also possible for the R-27ER to reacquire contact even if the contact got lost in final stages. Everything depends on the N001, missile is timed to selfdestruct at 60 seconds (or something similiar), it’ll always listen to MCCU and contact from the seekerhead. Missiles will guide themselves just on information of N001/equipment that belongs to platform that launched them (coded pulses).

In any case, every contact loss reduces PK. Especially in terminal mode, where the missile is working on the semi-active radar regime.

Do you have a source for the R-27R/Er not having a lofted trajectory ?

I had a book from Milparade that had an article written by MiG that was describing the R-27E missiles in comparison to the Sparrow and it mentioned that one of its advantages was a lofted trajectory that would allow it to reach targets more quickly (and with more terminal energy).

Regarding the original question, no. The R-27R and R-27ER are lock on before launch and as far as I know have no capability to reaquire a target in flight.

loft or not?

Do you have a source for the R-27R/Er not having a lofted trajectory ?

Longburn ALAMO have better RAero than R-77, althorugh the flight trajectory isn’t as advanced (non-lofted against lofted).

There was active ALAMO project (K-27A) it was cancelled in the late 80 along improved SARH homer for anti sea-skiming performance (K-27EM)

Pit

Sorry for my ignorance, but what model R-27P1/EP1 is?
As far as I know there is just R-27R/ER (SARH) and R-27T/ET (IR) isn’t it?

Thanks

P/EP is a passive radar homing version. To the best of my rather limited knowledge it is basically an air to air anti radiation missile.

Correct me if I am wrong but I was under the impression that one of the reasons that the Alamo was still around was becouse it had better range than Adder? Was there ever an active radar homing version?

Pit

Sorry for my ignorance, but what model R-27P1/EP1 is?
As far as I know there is just R-27R/ER (SARH) and R-27T/ET (IR) isn’t it?

Thanks

I don’t think so, after comercialization abroad of R-27P1/EP1 (export versions), Vympel is not really interested on the ALAMO any more.

R-27T didnt run with MCGU, it’s LOBL. MICA IR did receives MCGU so it could be a LOAL weapon.

Thanks Pit, do they have any plans of getting MCGU with alamo versions? It would make it a fearsome beast esp. if they added an IIR seeker.

Regards,
USS.

R-27T didnt run with MCGU, it’s LOBL. MICA IR did receives MCGU so it could be a LOAL weapon.

While we are on the topic of alamos, I was wondering how is the guidance of a Mica IR different from the IR version of the alamo (R27 T1)? Would they both use inertial guidance/datalinks until the seeker goes active?

Regards,
USS.