Does POS-RUK mode for HARMs work well on BMS?
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The missile must have a flight profile off the rails
If the flight profile is always without loft you will tell me that in RUK you arenunable yo hit 50nm distant threat
POS-RUK turns the seeker on while on the rail. HAS also turns the seeker on the rail and does not have STPT flight profile off the rail.
I can only reverse engineer speculate on how the RUK or HAS ranges a locked target while on the rail to create a loft.1. It uses right angel triangle trigonometry. One angel (slant angel) and one leg (altitude). Lock a target in HAS, it shows were the target is in it’s FOV.
2. The pilot determine the loft. There is no computerize loft program. I doubt irl that RUK uses a STPT. Pilot just a lines the jet with the RWR.
Sorry but the logic is pretty clear to me
You don’t understand the situation. If your current STPT is 70nm away and a SA-6 pops up 10nm off your nose you can’t hit it with POS-RUK. Does that sound like a self protect mode?
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Ok, i will try again also selecting an stp behind me, to see what happens.
By the way, when you suggested about using a markpoint, were you referring to using an OVERFLY markpoint right? I can´t imagine how to set a TGP or FCR markpoint if i don´t know the location of the SAM site, with the exception of aproximate direction.First you have to call for a “time out”. You don’t want SAM flying at you while you are trying MARK STPT with just a RWR bearing.
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POS-RUK turns the seeker on while on the rail. HAS also turns the seeker on the rail and does not have STPT flight profile off the rail.
I can only reverse engineer speculate on how the RUK or HAS ranges a locked target while on the rail to create a loft.RUK stands for “Range Unknown,” it does not range a locked target, and the seeker does not come on while on the rail. In RUK mode the seeker comes on after launch (BMS manual page 99). Record an ACMI and you can see this in action: The missile will initially steer towards STPT immediately at launch but changes direction if/when it detects the threat you handed off. RUK is also described as a “degraded state of EOM” and, EOM being STPT dependent, would explain the logic that Mav-jp is talking about.
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RUK stands for “Range Unknown,” it does not range a locked target, and the seeker does not come on while on the rail. In RUK mode the seeker comes on after launch (BMS manual page 99). Record an ACMI and you can see this in action: The missile will initially steer towards STPT immediately at launch but changes direction if/when it detects the threat you handed off. RUK is also described as a “degraded state of EOM” and, EOM being STPT dependent, would explain the logic that Mav-jp is talking about.
I believe RUK is NOT STPT dependent. That why it’s described a “degraded state of EOM”.
It also says that RUK is used for Target of Opportunity – TOO. To me that mean that the target can be off flight plan. -
I believe RUK is NOT STPT dependent. That why it’s described a “degraded state of EOM”.
It also says that RUK is used for Target of Opportunity – TOO. To me that mean that the target can be off flight plan.What you’re saying seems sensible, but here is what I don’t understand in your explaination:
@HARM:
…. In the last mode, RUK, the seeker is activated immediately after launch …
There is a certain amount of time from pickle, to launch, to the seeker going active, to seeker finding a target …. maybe the time is smaller or a bit larger depending on when the seeker finds a target. Where is the missile flying to during this time between launch and target acquisition?
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I believe RUK is NOT STPT dependent. That why it’s described a “degraded state of EOM”.
It is “degraded” because it has a wider FOV, the seeker activates immediately after launch, and range of the target is completely unknown, making it less accurate. EOM and PB are used when the target is known to be in the general vicinity of a STPT, therefore giving at least a good estimation of range. The seekers also activate much closer to the STPT/target, making them more accurate.
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I’ll try one more time. The way RUK is coded in BMS:
When the current STP is >60nm it is coded to do a loft program even when the seeker locks on a target a short range. And the HARM goes up to 30k feet or it hits behind the target.The code is real close. If the STP is <30nm from the a/c not the target(STP can be behind your a/c), the missile will fly LOS to the target.
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RUK is the same as HAS(both range unknown/target of opportunity modes). so use HAS better. u dont want the HARM to go active ASAP since it searches a larger geographical area making it susceptible to a miss or an impact somewhere within the Missile Impact Zone.
RUK is LOAL, HAS is LOBL.
POS-RUK turns the seeker on while on the rail. HAS also turns the seeker on the rail and does not have STPT flight profile off the rail.
I can only reverse engineer speculate on how the RUK or HAS ranges a locked target while on the rail to create a loft.1. It uses right angel triangle trigonometry. One angel (slant angel) and one leg (altitude). Lock a target in HAS, it shows were the target is in it’s FOV.
2. The pilot determine the loft. There is no computerize loft program. I doubt irl that RUK uses a STPT. Pilot just a lines the jet with the RWR.
You don’t understand the situation. If your current STPT is 70nm away and a SA-6 pops up 10nm off your nose you can’t hit it with POS-RUK. Does that sound like a self protect mode?
RUK is LOAL, HAS is LOBL.
RUK, PB, EOM are all three POS modes and all POS modes are steerpoint-directed in azimuth. The difference is in end game seeker activity and assumed range only. EOM and PB assume range = range to steerpoint. RUK assumes range = maximum.
EOM = point
PB = area
RUK = laneI agree. RUK is for painting a long, wide stripe of ground with HARM coverage. PB is for a floodlight on an area. EOM is a laser pointer. I tried the HARM TE with RUK against the same 56-59 STPT as the SA-3. I prepared the missile and drove into the SA-3 at medium altitude. When SA-3 launched I launched and RUK HARM were pretty bad at acquiring it and the STPT was co-located with the SA-3! BTW in RUK the steerpoint only gives direction, not range. If you fire two RUK HARM at two steerpoint both the same bearing but different range (say 10nm, 100nm) the missiles behave identically RUK is lofting for maximum area covered along a given direction.
There exist self-protect modes of HARM which are not steerpoint related, even get their threat and direction data from RWR, but not in BMS or F-16.
EDIT: Whee, I was wrong. Apparently RUK is range-to-steerpoint dependent. More testing shortly. Imagine the yellow text is strike-through. I wish this board used the tags.
Test#1: RUK against 30 and 50nm steerpoint in line, deliberately set threat to SA-6 so it wouldn’t go active on a 2-3-4 present. Farther steerpoint resulted in higher profile. Surprisingly RUK short shot seemed to run out of steam right over the near steerpoint and likely wouldn’t have been able to engage any threat significantly beyond.
Test#2: EOM short range (<10nm) at 180, 135, and 90 degrees off axis. Engaged SA-3 from limit of PPT circle with three EOM shots released approx 15,000’. None did significant turning toward EOM steerpoint. Showed “inertial, lost target” in external view label. Expected EOM to have off-axis capability easily in this scenario.
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I just did a test myself. I set STPT5 at an SA-2 site and STPT6 approx. 70nm beyond the SA-2. I called up RUK and selected the SA-2 and STPT6, put the FPM on the SA-2 site (you can see a smoke plume in my HUD shot) and fired. The HARM flew right over the SA-2 and headed direct to STPT6.
While defensive I called up RUK again, selected SA-2 and STPT5 this time. Fired and killed the Fan Song.
If the seeker activates immediately after launch and the target was well within the seeker’s FOV, why did it ignore the target right in front of it?
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RUK is LOAL, HAS is LOBL.
RUK is LOAL, HAS is LOBL.
RUK, PB, EOM are all three POS modes and all POS modes are steerpoint-directed in azimuth. The difference is in end game seeker activity and assumed range only. EOM and PB assume range = range to steerpoint. RUK assumes range = maximum.
I agree. RUK is for painting a long, wide stripe of ground with HARM coverage.
Seeker going to lose search width with loft angle. FOV is 45* (from tecref). Take your flashlight and point it up as if it is a missile in a loft profile and see how much coverage is on the floor. I doubt if RUK goes for max range via lofting.
I don’t care if RUK LOBL or LOAL a micro second after launch. I can see advantages if it did/could lock on the rail.
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Frederf, could you please tell me what “LOAL” and “LOBL” mean? I was following the discussion well and with a lot of interest but i got lost there. :(.
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i think the problem is not the avionic on the F-16, not even the symbology, i think the problem is the agm-88 itself in BMS.
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I’ll try one more time. The way RUK is coded in BMS:
When the current STP is >60nm it is coded to do a loft program even when the seeker locks on a target a short range. And the HARM goes up to 30k feet or it hits behind the target.The code is real close. If the STP is <30nm from the a/c not the target(STP can be behind your a/c), the missile will fly LOS to the target.
https://www.benchmarksims.org/forum/attachment.php?attachmentid=2185&d=1270401654&stc=1
Thanks a lot for the explanation Caper, i will try with this too. And i think it’s very important this clarification to be present on the BMS manual on the future. I would even report it, if i knew to who report it.
Now i will have to wait until tomorrow to test all explained here :(.
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Thanks a lot for the explanation Caper, i will try with this too. And i think it’s very important this clarification to be present on the BMS manual on the future. I would even report it, if i knew to who report it.
Now i will have to wait until tomorrow to test all explained here :(.
Good luck with that.
I had misses using RUK and never knew why….now I do…Thanks to this thread.
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I just did a test myself. I set STPT5 at an SA-2 site and STPT6 approx. 70nm beyond the SA-2. I called up RUK and selected the SA-2 and STPT6, put the FPM on the SA-2 site (you can see a smoke plume in my HUD shot) and fired. The HARM flew right over the SA-2 and headed direct to STPT6.
While defensive I called up RUK again, selected SA-2 and STPT5 this time. Fired and killed the Fan Song.
If the seeker activates immediately after launch and the target was well within the seeker’s FOV, why did it ignore the target right in front of it?
Are you sure you set each missile properly with threat and submode? They are individually configurable except for steerpoint. I’ll try to launch a RUK HARM over the top of a threat between me and it and see if it detects and goes terminal on the overfly threat. I’ve found launching RUK on actively engaging SA-2s to be problematic. I think in engagement the radar beam is very narrow so your RWR sees it but the HARM slightly away won’t.
Seeker going to lose search width with loft angle. FOV is 45* (from tecref). Take your flashlight and point it up as if it is a missile in a loft profile and see how much coverage is on the floor. I doubt if RUK goes for max range via lofting.
I don’t care if RUK LOBL or LOAL a micro second after launch. I can see advantages if it did/could lock on the rail.
The HARM shouldn’t even activate its seeker in EOM until it’s very close to the expected threat anyway. You should be able to fire an EOM HARM “over the shoulder” provided you’re within the MMZ and then only when in a good position and look direction activate the narrow search. Maybe I’m too close and the EOM is activating by simple proximity instead of by directional proximity? More testing required. Honestly my best off-axis shot was a RUK because of it’s early and wide seeker FOV. I really expect a 5-10nm EOM shot to be a lot more aggressive turning for off-axis.
RUK does loft but apparently proportional to the range to steerpoint. Honestly I haven’t seen much difference in profile from all 3 submodes. I’ve launched a PB, EOM, and RUK at the same steerpoint within a few seconds and they behave very similarly. As for “I could see the advantages” I could too but let’s keep it focused on what is the case, not what the designers of the weapon could have done.
Frederf, could you please tell me what “LOAL” and “LOBL” mean? I was following the discussion well and with a lot of interest but i got lost there. :(.
Lock on before/after launch. Usually pronounced “low-al” “low-boll.” Maverick is a LOBL missile. GBU-12 is a LOAL …err bomb. Hellfire can do either depending on what shape you want it to fly or if you have off-board designation. Technically AIM-9 can do either but it’s recommended to LOBL. Javelin is LOBL. Stinger is LOBL. AIM-120 is freaking complicated but generally LOAL. It’s a question of when the onboard and/or terminal seeking mechanism acquires the target before or after launch.
The HARM has INS guidance and radiation homing guidance so it’s a question of which guidance do you mean. Because we don’t have datalink control over HARMs the INS guidance is always determined before launch so that goes without saying. The radiation homing guidance varies so it’s meaningful to ask if it acquired the radiation before launch or not. Harm-as-sensor (HAS) is the only method of employment where the radiation is acquired by the missile prior to launch. It’s effectively an anti-radiation Maverick in HAS mode.
MORE TESTING!
I think EOM sucks for off axis (60 deg+). It takes its time and lazily circles around even at short ranges which takes forever so the missile times out before it can arrive. It really needs to pull more Gs trading energy for angles for shorter ranges. I know it can pull harder. I’ve seen it when it detects in RUK with the wide FOV. Predicted TOF is something like 1:05 but it’s out there for 2-3min. EOM TOF is supposed to be for current conditions (including turns) assuming within MMZ. If not in MMZ predicted TOF should be clamped to the nearest edge of MMZ envelope. PB TOF is for launch conditions which are pretty strict (±5 deg heading, within max/min toss markers).
EOM and HAD shots appear identical except HAD shots don’t show “target locked” in external view text.
I attempted to fire a RUK against a STPT beyond an SA-3 and it flew over the top in most (all? I forget now) cases. I’m not sure if SA-3 deaggregation or HARM view limits or HARM logic is to blame.
EVEN MORE TESTING!!
Fired 4 HARMs at minimum intervals at PTT57 SA-4, HARM TE. Range was at the 00:00 timer and box flash, on axis, approx 1 sec intervals. All three POS shots flew in perfect formation for most of the flight. The only differences was in terminal behavior. RUK found target first but followed similar path. Missiles differed slightly in azimuth (degree or so) but they all steered back toward target before terminal. The fourth HARM fired was a HAD shot that followed a significantly lower profile (30,000’ v 40,000’ peak altitude) but arrived nearly the same timing of launch behind the first three.
TESTING OFF-AXIS
Same as above except intentional 20 degree launch misalignment. Same initial behavior as before except RUK’s early turn to target in azimuth paid dividends for arriving first followed by PB and lastly EOM which was first to launch, last to arrive but not by much. HAD shot again flew lower than POS but also flew similarly tighter heading profile arriving at a similar time as RUK despite being the last launch. -
The HARM shouldn’t even activate its seeker in EOM until it’s very close to the expected threat anyway. You should be able to fire an EOM HARM “over the shoulder” provided you’re within the MMZ and then only when in a good position and look direction activate the narrow search. Maybe I’m too close and the EOM is activating by simple proximity instead of by directional proximity? More testing required. Honestly my best off-axis shot was a RUK because of it’s early and wide seeker FOV. I really expect a 5-10nm EOM shot to be a lot more aggressive turning for off-axis.
Don’t care about EOM. It’s OT. Thread is about RUK, a self protection and target of opportunity mode for target that are not pre-planed with a STP. However, I have killed SA-6 emitter firing when the target was just in front of my 3/9 line. <shrug>The turn radius was about 5nm, too much it took forever to hit the target. It
RUK does loft but apparently proportional to the range to steerpoint. Honestly I haven’t seen much difference in profile from all 3 submodes. I’ve launched a PB, EOM, and RUK at the same steerpoint within a few seconds and they behave very similarly. As for “I could see the advantages” I could too but let’s keep it focused on what is the case, not what the designers of the weapon could have done.
That’s the way the code works. It appears to have a loft flight profile and LOS flight profile depending on STP range.
RUK problem is if the STP range calls for the loft program it cant hit a target at short range. If this is the way it works in r/l it’s a sh*ty weapon system and it would be foolish to call RUK a “self protection” or “target of opportunity” mode.
jmfo :)</shrug> -
If this is the way it works in r/l it’s a sh*ty weapon system and it would be foolish to call RUK a “self protection” or “target of opportunity” mode.
Couldn’t agree more!
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Are you sure you set each missile properly with threat and submode?
100% positive. SA-2 was at STPT5, STPT6 was 66.1nm beyond that. Essentially the SA-2 (and STPT5) were between me and STPT6.
First shot: RUK SA-2 handoff, STPT6 selected. Fired 13.0nm from SA-2 (which was engaging me). I was at 17,600’ in a ~13* dive (as seen in the picture). When the HARM came off the rail it slowly leveled out to a 1*~2* climb and flew right over the SA-2 at 17,500’.
Second shot: RUK SA-2 handoff, STPT5 selected. Fired 9.4nm from SA-2 (which was still engaging me). I was at 12,700’ in a ~10* dive. When the HARM came off the rail it flew 5* down until about 5nm and went into a 20* dive straight for the Fan Song.
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There exists a self-projection method of employing HARMs but possibly not in F-16 and definitely not in BMS. I think real F/A-18 has such a thing. It links with onboard RWR and is left “hot” such that it auto launches. BTW “target of opportunity” is synonymous with “missile as sensor.” The reason the blue background picture shows the TOO footprint like that is because that’s what you can expect firing HAS. TOO = HAS. HAS = TOO. RUK is a submode of position-known which is not TOO. Flying around with the HARM in HAS is effectively electronic reconnaissance. To actually fire when in HAS is to fire TOO. AhhhhhhhHHHHH!!! I have to stop learning about real HARMs. BMS isn’t exact and it’s going to drive me crazy!
You know the HARM AMZ/MMZ cue should be either 80nm or 40nm depending on FCR range or if not set automatic based on other factors? The HAD footprint is just painted on when in RL it’s dynamically calculated. HARM launch isn’t inhibited properly in EOM/PB either when outside parameters.
Yeah, I was too. RUK doesn’t seem to reliable to pick up overfly threats. I’ll try some more scenarios such as overflight of an SA-2 en route to another SA-2. Try to avoid engagement situations as I think those are inherently less straightforward. Let’s try firing over yellows 2s, nothing red or flashing.
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i always thought that RUK was a ‘beam-riding’ mode like the older shrike? it finds a radar beam and then rides it down the line? if not, is there a mode like this? generally when i use HARMs i’m just using them as a PB radar killer, wiping out position-known lowblows and stuff, never used RUK though that’s what i assumed. weird that it relies on steerpoints. the HAD serves pretty well for popups, anyway. lock on with HAD point nose at target (hopefully before missile intercept) fire, then make your defensive turn when the missile approaches. HARM are autonomous, aren’t they?