27ER + IRST passive lock

Hi. If I press the 'O' key to turn on IRST passive lock. And then lock onto an enemy. Can I fire a radar missile (27ER) and will it hit the target?

Without turning on radar (I) key.

I think yes, once you launch it, the radar turns itself on to guide the missile to the target.

Hi. If I press the 'O' key to turn on IRST passive lock. And then lock onto an enemy. Can I fire a radar missile (27ER) and will it hit the target?

Without turning on radar (I) key.

It depends. The optical and radar suites work together and what happens depends on the type of missile (IR or SARH) you have selected. When the optical suite has the target locked, it "tells" the radar where to look for the target. If you have a SARH missile selected, press and hold the launch key, the radar will attempt an SST lock. If it's successful, the radar will become the primary suite, you will receive the launch cue, and the missile will leave the rail. If the radar is unable to lock the target, of course, none of that will happen.

Do I need to maintain an IRST lock until the missile, (27ER), hits the target?

+ in the manual it says with a radar missile, 27ER, you need to maintain a radar lock until the missile hits target.

The ER is radar guided. Keeping an EO lock is not needed, or does nothing to the missile anyway.

You need to keep the radar locked onto the target until impact.

IRST does nothing for R-27ER.

IRST lock will cue the radar to the target when the radar is switched on.

When locking with IRST only and you then fire an R-27ER the radar will switch on automatically and try and aquire radar lock.

If the radar is not able to achieve lock due to notching etc. you will remain with IRST lock and the missile will not track.

Check the symbology on the left side of the HUD in EOS mode, with English cockpit EO is IRST and EORL is both IRST and radar.

It is interesting to note that it can guide a R-27R/R-27ER in real life without a radar track. I’m sure it’s becuase of the simple systems model that we can’t do it, and it might be a separate mode in the real thing that isn’t simulated, I’m sure someone will correct me. The idea is that the IRST cues the radar and even if it can’t be tracked with radar(such as notch or stealth), if there is enough reflection it should still guide a R-27R/R-27ER. Who knows how well that actually works, but it is an interesting real life feature that is most likely possible under the right conditions

I’m sure Ironhand will post. He has a manual I believe. It was mentioned recently I believe when we were helping FightingFalcon

It is interesting to note that it can guide a R-27R/R-27ER in real life without a radar track. I’m sure it’s becuase of the simple systems model that we can’t do it, and it might be a separate mode in the real thing that isn’t simulated, I’m sure someone will correct me. The idea is that the IRST cues the radar and even if it can’t be tracked with radar(such as notch or stealth), if there is enough reflection it should still guide a R-27R/R-27ER. Who knows how well that actually works, but it is an interesting real life feature that is most likely possible under the right conditions

In a word, "no". Or, more precisely, there is no such mode described in the materials I have. When slaved to OLS (EOS as primary), the radar operates in КВази Обзора (КВО) or Quasi-Survey (Search) mode. After locking the target with the Optical Tracking System, the Search and Track Radar System is used to intermittently and briefly illuminate the target and provide range information (which is displayed on the HUD). This is accomplished by moving the EMIT switch from the DISABLED to the EMIT position. This slaved range support begins after a 5 second delay.

Other than that, all other radar modes used to put SARH missiles into the air--СНП (sort of like the Western TWS), РНП or Continuous Bearng Mode (STT), and ДНП (Discrete-Continuous Illumination)--require the radar itself to be tracking the target. The latter mode, Discrete-Continuous Illumination, in case you're wondering, is where the radar tracks and illuminates the target under attack and periodically sends single-use (guidance) command information [разовые команды (РК)] via the update link to the radar-guided missile (РГС).

Ah I was wrong, wonder where I heard that, thank you

Ah I was wrong, wonder where I heard that, thank you

:) Not saying you're wrong. I'm only saying that it's a statement I can't support given what I've read. I am not omniscient.

It would be a bit like FLOOD mode. The missile would be launched without initial target data that should be fed by the radar, assuming the WCS can do that - this would cause the seeker's own search to be unconstrained and thus it could easily lock onto something you don't want ... like chaff, the ground, etc.

But what if the missile was launched with radar lock, then the target notches and it switches to EOS backup. Would the real Su-27 still emitt the radar pulses with the radar antenna slaved to the EOS direction, so that the R-27R/ER can keep tracking the target (especially when it comes from a different angle where the target is not notching)?

yes, basically more focus and targeted FLOOD-ish mode... basically if in EO range you should not be able to easily notch the Flanker and Fulcrum...

Should be easy to notch AIM-120B/C against ground clutter with chaff as well. ED like to make Su-27/33 realistic but nothing else :)

Depends on a bunch of circumstances - in theory, if the radar set (aircraft or missile) is capable, it can track through the notch if the target can compete with the background (but also you lose doppler discrimination vs chaff here ... lots of competing circumstances).

But yep in the strict case you posit I imagine the missile itself would track ok since it's already flying with a locked target.

Lots of 'it depends' sort of stuff in there - is the radar to EOS track smooth - did the EOS just lock a flare, etc. Putting the attacking platform on the 3-9 is probably one of the main drivers of Pk reduction for a whole bunch of reasons - and any time you need to use some sort of back-up, Pk goes down.

Most of the interesting stuff isn't modeled in the game.

But what if the missile was launched with radar lock, then the target notches and it switches to EOS backup. Would the real Su-27 still emitt the radar pulses with the radar antenna slaved to the EOS direction, so that the R-27R/ER can keep tracking the target (especially when it comes from a different angle where the target is not notching)?

But what if the missile was launched with radar lock, then the target notches and it switches to EOS backup. Would the real Su-27 still emitt the radar pulses with the radar antenna slaved to the EOS direction, so that the R-27R/ER can keep tracking the target (especially when it comes from a different angle where the target is not notching)?

I guess the question is, what does the radar complex do, when tracking is lost and EOS isn't involved? It's my understanding (though I have no supporting technical reference) the the radar continues in РНП (STT) for several seconds guiding along the projected track. As an aside, that's what you are seeing in the sim, when the Launch Authorized (ПР) symbol starts flashing--it means the actual lock has been lost and you are guiding along the projected track. About 3 seconds later, the track is dropped, unless the radar complex has reaquired the target.

When EOS is tracking the target, it sends the radar complex the angular coordinates of the target. That's all. I have read nothing in the manual which indicates that there is a special mode wherein EOS also tells the radar to remain in STT mode longer than it otherwise would. That's only doing to happen if that's what the radar already does when EOS is not involved. In other words, if the radar remains in STT without EOS until the pilot hits a button or switch, then that's what it'll do when EOS is feeding the radar the target's coordinates. If not, then not.

That's my take on it, anyway. As far as the sim goes, I'll enjoy it either way. If that function should be there, then I wish someone would provide the technical reference.