Patriot STR doesn't work properly

[Lukas2438]

Hi folks,

 

the radar set of the Patriot SAM seems to have an general issue with detecting and tracking hostile targets.

 

It won't turn it's radar part into target's direction, even with threats deep in weapon engagement area. At some point (about 50 % of max. weapon range) the launchers (LN) start turning and firing on it's own, but missiles are some kind of inaccurate (missing guidance?).

 

I have tested this both with the Patriot template and by placing separate units one by one (all in the same ground unit group), on Nevada and Mariana Islands.

AI Skill (Average, High ...) doesn't matter, at least I didn't notice any difference.

 

 

Can someone confirm this misbehavior?

[Frederf]

The Patriot's coverage is a wedge shaped zone and not a 360 sphere. Is the system oriented in the appropriate direction? Can you share a mission file which shows the system not working?

[Lukas2438]

Hi Frederf,

 

I should be able to rule out incorrect positioning or parameters since I work as a Patriot crew man in real life.

 

The attached mission contains an AI Su-25T with waypoints straight through the engagement area of the SAM site. As you will see, the RS will stay focused at 315°, while 1-2 launcher turn their platform and "track" the incoming threat.

 

 

Greetings

test-caucasus-SAM.miz

[Frederf]

I don't know much about the system. Is the MPQ-53 supposed to physically traverse during engagement?

[Lukas2438]

By default the base stays stationary but the upper part (radar itself) is supposed to rotate 160° left/right and faces directly into threat's direction.

[Lt_Jaeger]

Nah, you got a PTL and  a STL and that is it. You have to make sure the launches are in a certain area for the MSL being able to hit a "acquisition" window. That's the reason why you won't employ a lone Battery. In this regards the Russian systems are way better and supposed to be operating as you want the system to work, but they launch their msl straight up, which makes it easy easier to bring them into the "tracking window" 

[Lukas2438]

If the launched MSL would not hit this window, the missile starts self destruction.

But in DCS (at least current beta version) the LN seems to work without guidance by the STR, they start engaging threats.

Don't know if it's a feature, but in real life the STR is mandatory.

Edited August 22, 2021 by Lukas2438

[Frederf]

I think perhaps the developer thinks since the STR is an electronically scanned array the radar is able to scan the entire zone without physically rotating. I'm pretty sure that the missiles cannot engage without the STR present in DCS.

[Lukas2438]

Thing is, in older DCS versions the STR performed well, starts tracking and following enemies even a bit outside the maximum radar range, also rotating/turning and "gives" rotate commands to individual launchers (within the 120 degrees L/R limits)

And then locks on shortly before weapon engagement range is reached by the threat, followed by firing the first 1-2 missiles.

 

That's the reason I discovered this difference to previous beta releases.

Other (russian) SAM performs well, at least those I tested.

[Grimes]

The radar no longer rotates. If you need to cover more area you need to add more radars and orient them as needed. 

[Tippis]

Just looking at the sensor definition, the radar has a 360°×75° scan zone that it traverses once per second. It could simply be that the animation arguments for the STR aren't firing properly to show the tracking that it is actually doing within that volume. At the same time, though the unit definition for the STR has a ±55°×83° rotation limit on… something, which is usually just cosmetic and doesn't actually affect where it can see things.

 

But then, that's exported from an older version, and I don't have the facilities to check what a more recent dump would yield. So an immediate question would be, when did you start noticing this behaviour?

[Grimes]

ED changed it sometime in 2020 and I'm not sure when the changes were merged. Possibly with the first 2.7 patch. 

[Lukas2438]

9 hours ago, Tippis said:

though the unit definition for the STR has a ±55°×83° rotation limit on…

[...]

But then, that's exported from an older version, and I don't have the facilities to check what a more recent dump would yield. So an immediate question would be, when did you start noticing this behaviour?

In fact the STR has a search sector of 90° and a missile steering sector of 120°, the +/-55 should corrected to 60 if I understand your unit definition correct.

 

It's a bit hard to determine when I noticed this change first since I'm not using PATRIOT defence that often. When playing Through The Inferno missions, I started to deploy one group with 3-5 launchers for securing the home airfield and providing safe take-off conditions.

I'm pretty sure in early 2021 the STR worked the old (known) way.

[GumidekCZ]

On 8/24/2021 at 10:56 AM, Lukas2438 said:

In fact the STR has a search sector of 90° and a missile steering sector of 120°, the +/-55 should corrected to 60 if I understand your unit definition correct.

 

It's a bit hard to determine when I noticed this change first since I'm not using PATRIOT defence that often. When playing Through The Inferno missions, I started to deploy one group with 3-5 launchers for securing the home airfield and providing safe take-off conditions.

I'm pretty sure in early 2021 the STR worked the old (known) way.

Hi @BIGNEWY , me again ,but this time, I will stay short of any source document screens (against the forum rules).

The Patriot radar have the ability to rotate to any angle around 360° I suppose, but never to angle to put supporting units into radiation danger (50° example on picture).

I studied briefly this document and there much more about adjusting radar azimuth into the threat axis:

TM 9-1430-602-10-1 PATRIOT Operators Manual (search for "commnad fp reorientation")

My Patriot setup example with course 360° as threat axis - Primary Target Line (PTL):

TR 90°   -Search zone - correct as in DCS is

TR 110° -Tracking zone - correct as in DCS is

TR 100° -CW an CCW train azimuth limit for Secondary Target Line (STL) - missing in DCS = BUG

TR 50°   -Radiation Cut-off zone (no radiation to friendly supporting untis)

LN 10°  -Launcher able to turn 10° more CW or CCW than both STL. (Launcher azimuth +-110° = 220° in total - correct as it is in DCS) (smallest circle on picture).

 

What I didnt found source for, is if radar was able to adjust its azimuth when in process of missile guidance to target, or if oprators need to wait till no missile guided by radar. I suppose that second option is correct.
 

If needed I will try to put here more evidence material links and references.

[ngreenaway]

let me shed some light on this, if i can.

i spent 11 years working patriot as a 14E in 4 countries and two states - i worked a variety of positions from fire control operator, system maintainer, and towards the end of my career, a patriot master gunner. I am very familiar with both pac2 and pac3 systems.

 

first and foremost, in an air battle, when you have targets on scope, the radar would never slew during an engagement. in other circumstances, the radar would never slew unless it had been given orders to do so from higher up the kill chain. when it does so, it would do it to a predifined STL. normally this would be done for situations such as providing target coverage for a sister battery in the event of a system failure , pre-planned maintenance down time, et cetera, and then only if the sister battery's defended assets were a higher priority than the ones on the PTL. there are other situations, but its rare.

regarding the 100 degree cw and ccw train limit for STL, heres the thing, the radar shelter itself can rotate far more than that. Prior to radiating, one of the duties of the fire control crew is to look out at the van and physically verify that the radar is pointing where it should, because it is possible for the radar (in the event of certain system errors, its conceivable but i never saw it) to be pointing in an unintended direction - including directly back at the ECS. so what then is the true STL train limits? it really is somewhat site specific. let me explain: the system can *not* fire from a launcher outside of radar coverage. normally, launchers are placed in a fan to cover the PTL optimally, +/- a bit . when you slew a radar to one side or the other, inevitably you will have launchers fall out of coverage. if you slew too far to one side or the other , you risk having few , if any, eligible launchers to use. But wait! theres more! it *is* possible to have a remote bank of launchers. these could be attached to a CRG+AMG , or they could even be another sister battery's launchers, however theres certain constraints on what can be used as a remote bank. Along with Hawk interoperability, it was something we had the ability to do but in practice never did during my time.

the 50 degree cutoff limit is sort of a nominal thing, its given as if PTL was 0, STL1= 100 & STL2= 260 . its possible, generally theres a greater cutoff zone than that, again, thats something that both mission & site specific. 

Under no  circumstances would the radar slew to track or follow a target. there is a very simple reason for this. i dont believe its information that needs to be protected, but because i cant find an open source reference to explain why, you'll just have to take it on the basis of faith. if you saw the reason, you would understand.

as for launchers slewing its a bit complicated and perhaps confusing to someone who's never spent a lot of time with patriot, because the launchers absolutely CAN and DO slew, its part of setup (same with radar) . however, during operation, they only slew when the entire battery is commanded to aim in a different direction, however during normal operations and engagements, they do *not* slew

 

how is it supposed to work?

like i said, the launchers never slew, but theyre placed in a fan in front of the radar, with some launchers placed turned slightly to the left or right, some straight ahead. When the engagement command is given, the RWCIU (Radar/weapon control interface unit) compares the azimuth-to-target from the radar and then selects the launcher with the most favorable angle to target.

after launch, the missile does its greatest correction to target during the initial turn

 

during this whole process, neither the radar nor the launchers slew at all

here's a war-time launch. you dont see the launcher at time of motion, but just prior to launch you can see the launchers are static:

https://www.youtube.com/watch?v=K04JaCHIURM

of course, this is a pac-3 system, which we cant have with the pac 2 radar in DCS

[ngreenaway]

On 9/29/2021 at 6:55 AM, GumidekCZ said:

 

I studied briefly this document and there much more about adjusting radar azimuth into the threat axis:

TM 9-1430-602-10-1 PATRIOT Operators Manual (search for "commnad fp reorientation")

 

 

Thats one piece , but theres much more to it. Unfortunately , the icc manual is publicly available but not the ECS one which is one thats really pertinent here. In most cases they are identical , an icc is physically nearly identical to an ecs, so it stands to reason the manuals are as well, however, youre referencing the procedure for the icc to command a battery to change to another target line. The procedure to actually slew a battery is in the battery level manuals which are unclassified , yet not publicly releasable (same with the current icc manual, yet google books has the 1982 edition , if i remember correctly )

There are other considerations which are contained in crew battle drills, site setup , and air defense planning . I wish i still had my reference library , so i could point to exactly which manuals covered  what , even if they werent available for others to look at 

[GumidekCZ]

@ngreenawayis there any doc in your mind I can find for you in my library, that can help you to point at description, which can proove my point of slewing radar to STL when no missiles in the air?

Edited November 2, 2021 by GumidekCZ

[ngreenaway]

A system will slew when commanded to by the icc. It won't simply pick up an STL arbtrarily. It also won't slew with birds in the air. With targets on scope, whatever is being defended by the STL had better be more important than PTL defended assets

If you have access to a hard copy of tm 9-1430-600-10-1 or this: http://link.sfpl.org/portal/Patriot-crew-drills-for-Engagement-Control/DPpVxk7T5NU/ I may be able to point you to appropriate spots