FCR ACM Mechanization
-
I’ve noticed that Falcon’s manner of ACM radar mode and DCS Viper’s manner are different in a few places. I’m curious which are correct if any or both. The question led to reading more closely the infamous GR -34 and I found it inconclusive with ACM description most resembling DCS and TMS function in ACM as most resembling Falcon. There are other details like the boresight mode cross remaining displayed post-lock in DCS while it disappears in Falcon.
Falcon features the 30x20 non-radiating mode more prominently allowing a return to this state by TMS aft from any radiating mode. DCS does no such thing with aft always selecting 10x60 and no-radiation not possible to reenter by TMS. There’s also a weird mention of “ACM-RWR”, a name that suggests some kind of locking pattern directed against an RWR threat, something I’ve never heard mention of until today.
I ask for those with access to BMS, DCS, and whatever manuals might be consulted or simply anyone with insight to help me better understand the landscape.
-
ACM/RWR (AKA RWR Slave) is a v5 feature (so upgraded block 40s, with the v1 radar, miss out).
The modes for the v5 are 30x20, 10x60, Boresight, Slewable, and RWR Slave. 30x20 is the default, and is not selectable hands-on with a v5 radar. It is selectable hands on with the v1 radar! It tries to lock up the closest contact inside the HUD FOV inside 10 miles. Body referenced scan pattern. Boresight is a nonscanning, body referenced mode - intended to allow the pilot to select a specific visual contact. TMS FWD and hold inhibits acquisition, releasing TMS starts acquisition. TMS FWD and hold, plus slewing allows the BORE cross and scan pattern to be slewed around the HUD to aid target acquisition. TMS right to slave the BORE pattern to the TGP if the TGP is in A-A mode. In BORE, acquisition of targets up to 40 miles is supported. 10x60 works as in BMS. Slew as in BMS.
in ACM with no target, TMS right selects RWR Slave. In RWR Slave, the RWR only allows airborne emitters to be the priority thread (diamond). When RWR Slave is selected, the FCR selects the smallest ACM mode that covers the RWR priority threat azimuth of uncertainty and emits, controlling the scan elevation automatically. If a contact is detected by the ACM mode, its automatically locked, much as ACM normally works. If a contact is not detected after 6 seconds of search, the radar changes modes automatically, to try and gain information about contacts which might be outside 10 miles. If it can detect such a target, it tries to track it until its within 10 miles, at which point it switches automatically to the boresight ACM mode and attempts to enter STT as normal. If Boresight is unable to track the detected target, it switches to 30x20 to improve the chance of detection. If it was unable to detect a target at range, it returns to selecting the appropriate ACM mode and searching - the same as it was doing when RWR Slave was first entered, and the process repeats.
Normally, the FCR displays the priority threat diamond at the base of the FCR display. TMS up on the diamond in CRM modes selects RWR Slave.
Additionally, there is the ACM Merge mode. In STT entered from ACM, a short TMS right will enter ACM Merge. The FCR remembers the current location of the target and spends one search cycle of a 60x20 scan looking for a target near the current locked target. If a target is detected, it is automatically locked instead of the current target. Targets too close to the original target are ignored (to avoid locking the same target by accident). TMS inputs during the scan cancel the scan, and enter the appropriate ACM mode instead (TMS up for BORE, etc). AMRAAM data links are dropped if ACM Merge mode is entered.
-
Blu,
Is this explanation you gave one that is real-life and is actually in BMS 4.34,or just a real life?
-
Quite the info dump. DCS claims v5 simulation. The '97 manual is probably PXII which is v7. I’m trying to square its description with BMS or DCS or is this hopeless? MLU3 doc also describes stuff but I’m unsure how later -66 compares to -68 with its bore non-radiating.
Is there any way to hands on select a non-radiating mode with v5? I see in BMS documentation now there’s a difference between FCR-SOI and HUD-SOI. Anyway BMS selects non-radiating 30x20 on TMS aft which according to what you’re saying shouldn’t be. If you look at the '97 manual in the section describing TMS operation, ACM is exactly what happens in BMS. If you look in the same manual under FCR ACM, it says 10x60 selected directly from any other pattern which is not what happens in BMS.
In DCS, TMS forward, right, aft gives you bore, 30x20, 10x60 and that’s it. It starts in 30x20 non-radiating as expected. Any lock when the three directions of TMS are pressed is dropped and it re-enters one of those three modes, scans again, and locks the first thing it sees. There is no effect of holding down any TMS direction except for HMCS slaving. Radar is always emitting when a TMS direction is held. DCS manual describes returning to non-radiating by TMS aft and even 20nm acquisition in bore (although no mention if that’s normal bore or some kind of TGP or CRM transition) which isn’t the case.
-
Well, which F-16? The ACM hands on selections depend on what tape and what radar… a block 40 CM should have different hands on controls to a block 50 CM, which is possibly different again to a PXII jet…
You should need to TMS aft first to drop a STT lock. ACM is consistent in that with a locked target, it tries to keep that target.
Blu,
Is this explanation you gave one that is real-life and is actually in BMS 4.34,or just a real life?
If you try to enter RWR Slave or ACM Merge in 4.34, you will be disappointed.
-
They say 4.2 v5 block 50 USAF which is as far as I know BMS except I don’t know the OFP for BMS.
So if TMS aft is required to drop lock then in theory one can switch ACM modes bore, 20, slew while maintaining lock? What I wonder is how can you select 10x60 since it’s TMS aft and that would drop lock.
-
The mode is ACM STT if you have a lock. TMS aft drops the lock, leaving STT.
-
BMS uses tape 5.1
If you are in NO RAD, TMS AFT commands 10x60
If you are in BORE,SLEW or ACM20 with no lock, TMS AFT commands ACM 20 NO RAD. A second TMS AFT commands 10x60
In any ACM mode with a lock, TMS AFT drops the track and commands ACM20 NO RAD. A second TMS AFT commands 10x60
TMS Right commands ACM20
Cursor slew commands slew mode. -
Ive not flown much 4.34, and still not explored the radar modes - does it support DTT now?
If so, that would mean BMS would be doing a fair job simulating the v1 (block 40) radar with 5.1
Is there any way to hands on select a non-radiating mode with v5?
First TMS Aft commands 30x20 NO RAD unless already in 30x20 NO RAD, in which case it commands 10x60.
Falcon features the 30x20 non-radiating mode more prominently allowing a return to this state by TMS aft from any radiating mode.
This is the case for both v1 and v5 radars. With the v1 radar, TMS right selects 30x20 radiating. With the v5 radar, TMS right selects RWR Slave (ACM/RWR). TMS aft from any ACM mode (including ACM STT) returns to 30x20 NO RAD.
-
Well aware of how BMS works. You think OFP 4.2 and DCS’s version should be the same? Is the HAF v7 manual description consistent with BMS in this regard?
-
Differences between V1 and V5 :
V1 : if not in STT, TMS-Right commands ACM 30*20
V5 :- if not in STT, TMS-Right commands ACM-RWR, aka the radar is commanded to search near the priority RWR threat (not simulated in BMS).
- ACM 30x20, radiating, cannot be entered hand-on. It is entered by pressing OSB 2 on the FCR page from any other ACM mode.
The rest is the same :
- in STT, you can return to ACM-NO RAD with TMS aft
- if not in STT :
–> TMS aft selects 10*60
–> TMS forward selects boresight
–> cursor motion selects ACM-Slew
If DCS selects 10*60 with a single TMS aft from STT, that’s not correct in either v1 and v5.
-
One other minor v5 difference to note: If the TGP is tracking in A-A and the aircraft is in ACM NO RAD, TMS right commands the radar to track the TGP target.