Missile guidance while notching (R-27ER)

[Kenan]

Quick question: So if I launch an R-27ER and immediately go into a notch (maximum radar gimbal limits, while maintaining lock with the bandit), would my missile loose guidance from the onboard radar? How does the whole thing work? I presume the missile is not "riding" the radar beam (as in older fighters like MiG-21) or is it? Or is it getting target information different way?

Thanks.

[falcon_120]

If you put your radar in his gimbal limit you are cranking not notching. Notching means flying perpendicular to the radar source painting you, this way your closure rate with respect to anything on the ground appears to be almost zero and the radar of the enemy plane filters you out.

It's not exactly like this, just to make you an idea.

[Zabuzard]

The R-27 is a passive radar missile meaning it needs radar information from YOUR radar because it has no own like the american variant. If you loose radar lock to the enemy the missile will just fly straight ahead being dumb. In this mode the missile will steer to the last known position of the enemy and if it sees an aircraft there it will explode, even if the aircraft is a friendly one.

 

So being short: The R-27 is useless if loosing radar lock, keep the lock the whole flight of the R-27 if you want a hit.

 

If you can hold the lock while flying such maneuvers the missile will fly with the help of your radar to the enemy. If your flying at the maximal radar limits the radar points on the enemy anyway so theres no difference for the missile.

[Sceptre]

If you lose the radar lock while an R-27ER is in flight and then regain the lock, will the missile continue tracking normally?

[FLANKERATOR]

AFAIK, radar lock can be broken for several reasons, but not for reaching gimbal limits.

 

A SARH missile doesn't emit, it only has a passive detector that receives reflection from the target. The radar signal is provided by an external source, the aircraft radar in the case of the R-27.

[Maximus_Lazarus]

If you lose the radar lock while an R-27ER is in flight and then regain the lock, will the missile continue tracking normally?

 

I am not sure, i would guess yes.

 

But it's easy to test in mission editor is it not ?

[Zabuzard]

It will continue the flight but in most cases the interruption will cause the missile to not hit because the enemy airplane made a maneuver which the missile couldn't regognize during lock loose.

[Kenan]

Guys, I'm not talking about losing a lock but keeping it at the gimbal limits.

So, in that scenario, missile (in this case R-27ER) should still be receiving target data from the onboard radar?

[Robin_Hood]

Guys, I'm not talking about losing a lock but keeping it at the gimbal limits.

So, in that scenario, missile (in this case R-27ER) should still be receiving target data from the onboard radar?

 

Sure it will. And no, it's not a beam-riding (unlike the Vikhr), it has a radar receiver that will pick up the reflected radar energy from your own radar as long as you have the lock. Basically.

 

And I'm almost sure it won't resume guidance if you lose the lock and re-acquire. Might warrant some testing to confirm.

[Zabuzard]

The missile doesn't care if you're flying at the radar limits or not as long as it gets radar information from your aircraft. IRL the information might be more accurate if not flying at the very very end of the limit but I don't think they modelled such things in DCS. The missile won't care as long as you maintain the lock.

[Alfa]

Quick question: So if I launch an R-27ER and immediately go into a notch (maximum radar gimbal limits, while maintaining lock with the bandit), would my missile loose guidance from the onboard radar? How does the whole thing work? I presume the missile is not "riding" the radar beam (as in older fighters like MiG-21) or is it? Or is it getting target information different way?

Thanks.

 

No the R-27R/ER is not "beam riding". Its true that early SARH missiles employed such a method for midcourse guidance, but the R-27R/ER was developed later and its 9B1101K seekerhead has an INS(Inertial Navigation System).

 

Prior to launch the aircraft radar feeds it with a target fix - after launch during initial stage of flight, the INS steers the missile into general direction of the target(using proportional navigation), while the aircraft radar transmits updated target information to it via radio(known as "radio correction" or "datalink") .

 

At terminal stage of engagement, the seeker switches to semi-active radar homing(SARH).

[Alfa]

The R-27 is a passive radar missile..

 

No its not - its a semi-active radar missile.

 

A SARH seeker works in much the same way as an ARH - it just doesn't have its own onboard emitter and therefore relies on the aircraft radar to "ping" the target and thereby provide the reflected energy required for target processing - hence "semi-active".

 

Passive radar homing is something else - it has to do with the detection of the target's radar emissions and homing directly on that.

[Alfa]

If you lose the radar lock while an R-27ER is in flight and then regain the lock, will the missile continue tracking normally?

 

Good question - if the target is still within the gimbal limits of the seeker antenna, it should be possible to get it to re-acquire.

 

The question is really down to the workings of the aircraft WCS/radar - i.e. whether the missile link is maintained or just dropped as soon as target lock is broken....probably the latter.

[NoJoe]

It might be worth it to mention here:

 

Semi-Active Radar Homing (SARH): The missile has no radar of its own. The launching aircraft illuminates the target with its radar, and the missile tracks that energy reflecting off the target. Think of the launching aircraft as having a really big spotlight that shines on the target, and the missile "sees" the reflection from that.

 

Active Radar Homing (ARH): The missile has its own on-board radar that can illuminate the target. This is like the missile having its own small flashlight to track the target once it gets close enough for the small size of the radar to be effective.

 

The R-27 family and AIM-7 are examples of SARH, and the AIM-120 and R-77 are examples of ARH. :thumbup:

 

(there are of course other types of guidance, but these are probably the most common for air-to-air missiles).

[GGTharos]

 

The question is really down to the workings of the aircraft WCS/radar - i.e. whether the missile link is maintained or just dropped as soon as target lock is broken....probably the latter.

 

If there's is a radar memory feature, mlink should typically continue to be broadcast until the target track expires.

 

For the f15, mlink for amraam is operated for 80 second after the track is lost, but 120s always occupy a unique mlink channel under normal operation.

[Alfa]

Perhaps a case of nitpicking, but...

 

Semi-Active Radar Homing (SARH): The missile has no radar of its own. The launching aircraft illuminates the target with its radar, and the missile tracks that energy reflecting off the target. Think of the launching aircraft as having a really big spotlight that shines on the target, and the missile "sees" the reflection from that.

 

A SARH seeker doesn't just "see" the reflection - it recieves and processes radar returns based on which it calculates intercept point and steers the missile towards it in the same way as an ARH seeker.

 

It simply lacks the emitter component and therefore relies on the aircraft radar to provide that aspect - so it does have a radar ...or "half a radar" of its own :) .

Edited June 8, 2014 by Alfa

[Alfa]

If there's is a radar memory feature, mlink should typically continue to be broadcast until the target track expires.

 

For the f15, mlink for amraam is operated for 80 second after the track is lost, but 120s always occupy a unique mlink channel under normal operation.

 

Exactly - the question being whether the radars(N019/N001) associated with the R-27R/ER have such a track memory - taking age as well as type of weapon into consideration :) .

[GGTharos]

It does, AFAIK, and it's similar to the memory in the APG-63's STT track memory. They rely on the same principles, and I don't know the differences - basically if the target is lost, keep the mlink going, mini-raster the expected target location for some number of seconds based on range to target, and either re-acquire or give up after that given time. In the game, this time is 4 seconds.

 

There is no radar memory for TWS modes in-game. (TWS track timeout is much longer usually).

[NoJoe]

Perhaps a case of nitpicking, but...

 

 

 

A SARH seeker doesn't just "see" the reflection - it recieves and processes radar returns based on which it calculates intercept point and steers the missile towards it in the same way as an ARH seeker.

 

It simply lacks the emitter component and therefore relies on the aircraft radar to provide that aspect - so it does have a radar ...or "half a radar" of its own :) .

 

Ah, thanks for nitpicking, good detail! :thumbup:

[Alfa]

It does, AFAIK, and it's similar to the memory in the APG-63's STT track memory. They rely on the same principles, and I don't know the differences - basically if the target is lost, keep the mlink going, mini-raster the expected target location for some number of seconds based on range to target, and either re-acquire or give up after that given time. In the game, this time is 4 seconds.

 

Ok didn't know that - it makes sense.

 

There is no radar memory for TWS modes in-game. (TWS track timeout is much longer usually).

 

No but then that wouldn't apply to the R-27R/ER anyway.

[Bimbac]

It does, AFAIK, and it's similar to the memory in the APG-63's STT track memory. They rely on the same principles, and I don't know the differences - basically if the target is lost, keep the mlink going, mini-raster the expected target location for some number of seconds based on range to target, and either re-acquire or give up after that given time. In the game, this time is 4 seconds.

 

There is no radar memory for TWS modes in-game. (TWS track timeout is much longer usually).

 

Is there any chance that these features will be implemented in DCS anytime soon? Especially the TWS Memory track and m-link, both for Russian and American aircraft?

[GGTharos]

I really don't know.

[SDsc0rch]

sure would be cool......