CIWS Logic/Angle Limits

[Exorcet]

Ship CIWS logic might need some tuning. I've noticed at times the CIWS pointing itself at the ship it's defending in an attempt to lead incoming missiles. This obviously isn't helpful as any shots fired will just hit the ship.

CIWS also don't consider other friendly ships in the area. If ships are close enough CIWS will try to intercept missiles even if the missiles are aimed at another ship, but often times the friendly ship ends up taking cannon fire.

Track attached.

CIWS and Group Attack.trk

[Exorcet]

Bumping this since no response in over a year, it's still an issue:

And it's impacting more than carriers:

https://forum.dcs.world/topic/335872-c-ram-bad-target-prioritization/

[Viper 13]

When a Phalanx is installed on a ship, a series of hard stops are used to limit the firing arcs to prevent rounds hitting the ship’s decks or superstructure.

However CIWS have fired at friendly ships in real life!
During the first Gulf war in 1991, the Phalanx onboard USS Jarret in automatic mode fired at a chaff cloud launched by USS Missouri in response to an attack by an Iraqi Silkworm missile. Several rounds hit USS Missouri

[Northstar98]

Even without additional stops, the maximum train angles are somewhere around ±150°, so that should be the maximum train angles in any case.

But as for firing at other ships, this has indeed happened IRL - I'm not aware of any system to prevent friendly fire as Phalanx systems (at least in their automatic mode) will fire at anything meeting certain criteria (so it shouldn't be firing at targets whose range is opening).

In addition to Viper 13's example of the Gulf War when a Phalanx system mistakenly engaged chaff, but there has also been an accident against target drones where rounds hit nearby vessels. In 1996, a JMSDF Phalanx system also mistakenly engaged a USN A-6 Intruder instead of the target it was towing

The best thing to do here is to ensure that ships are adequately spaced apart. I'm not sure on the specifics but unlike what's often seen in DCS with tightly bunched formations, it's more realistic to have several miles between ships.

Edited January 16, 2024 by Northstar98
Addendum - other examples of Phalanx either engaging friendlies or firing rounds that struck them

[Exorcet]

Thanks for the added info, I was unsure about any safeguard in place for automatic CIWS to protect against friendly fire, I'll have to note that there isn't such a thing. However as far as I know the ship crew should have the ability to disable CIWS manually if necessary. If that's the case, could that functionality be used to prevent, or reduce the chance of, friendly fire? Or is the system designed in such a way that that would be impractical? In that case it wouldn't be part of the CIWS systems modeling as much as ship crew modeling, but externally the result should be similar.

Either way, the bigger issue for me is that CIWS turns around too far and gives incoming missiles opportunities to get through while it's facing the wrong direction.

  

4 hours ago, Northstar98 said:

The best thing to do here is to ensure that ships are adequately spaced apart. I'm not sure on the specifics but unlike what's often seen in DCS with tightly bunched formations, it's more realistic to have several miles between ships.

Indeed, carrier fleets and their supporting ships in real life can be many miles apart, though as highlighted by the examples above, ships can also be in close proximity at times. Also, to provide some backstory, the reason that I stumbled upon this issue was that I was doing tests on ship formations in DCS for the purpose of defending against anti ship missiles. The best defense is putting Ticonderogas or similar in the way of attacking planes before they can get close to the carrier, but the further you place them from the carrier, the easier it is to leave gaps for planes to get through, especially when you don't know exactly from what direction they will come. DCS maps may also have limited water area, which can force ships to be close. I found that placing one or two ships near the carrier for last ditch defense helps. The close escort ships can also be offset away from the carrier, but the ability of the SM-2's to intercept incoming missiles is greatly increased by having them in the path of said missiles instead of the sides.

Edited January 16, 2024 by Exorcet

[Northstar98]

Just now, Exorcet said:

However as far as I know the ship crew should have the ability to disable CIWS manually if necessary.

Yes, there absolutely is. The Stark's Phalanx was famously left in a standby mode when it was attacked by 2 AM39 Exocets.

And as it will engage just about anything (including on one occasion, a friendly aircraft, see my edit above), you need to be able to switch it off when friendly aircraft are expected in its engagment envelope (and for maintenance etc).

The local control panel for Phalanx also has buttons for "HOLD FIRE" (which AFAIK, removes consent to engage targets) and "BREAK ENGAGE" (which AFAIK manually terminates an engagement in progress).

Just note that in DCS, the Phalanx behaves no differently to really any AI gun (though they might now differentiate between radar guided and manually directed) so it will never fire at friendlies unless they're in the line of fire.

21 minutes ago, Exorcet said:

Either way, the bigger issue for me is that CIWS turns around too far and gives incoming missiles opportunities to get through while it's facing the wrong direction.

Yeah, at a maximum it can only train ±150° at a maximum and -25° to +85° in elevation, that should definitely be fixed.

[Northstar98]

On 1/16/2024 at 2:19 PM, Exorcet said:

 The best defense is putting Ticonderogas or similar in the way of attacking planes before they can get close to the carrier, but the further you place them from the carrier, the easier it is to leave gaps for planes to get through, especially when you don't know exactly from what direction they will come.

True, though this is an issue faced in real life, of course sometimes you've got restricted operating areas and sometimes not many escorts, but then this is why a layered defense is employed.

One thing made worse in DCS that isn't just the maps, is that the Arleigh Burke and Ticonderoga should have access to much longer-ranged missiles (RIM-156A SM-2ER Block IV for the latter, RIM-174A ERAM for the former), which would partially counteract this problem.

SM-2MR in DCS also behaves like an SM-1MR and doesn't fly a trajectory optimised for engaging low-flying threats at longer ranges.

The other thing is that ships won't manoeuvre to adapt to a changing threat axis, not will they manoeuvre defensively at all.

All this however, is probably going further and further off-topic, so I'll cut it off here.

Edited August 9, 2024 by Northstar98
Correction - can't find evidence for the SM-2ER being employed on Arleigh Burkes

[Raisuli]

35 minutes ago, Northstar98 said:

Yes, there absolutely is. The Stark's Phalanx was famously left in a standby mode when it was attacked by 2 AM39 Exocets.

 

That was normal in those days.  Back when we splashed around in that bathtub the R2D2s were pretty much always in standby, or just flat out turned off.  Those things have a mind of their own and the first thing on their mind is not always the promotion path of the commanding officer, which runs counter to the purpose of a Naval vessel in those days.

The scuttlebutt was nobody felt comfortable leaving them turned on lest something career limiting happen. 

[Yoda967]

On 1/16/2024 at 3:35 PM, Raisuli said:

That was normal in those days.  Back when we splashed around in that bathtub the R2D2s were pretty much always in standby, or just flat out turned off.  Those things have a mind of their own and the first thing on their mind is not always the promotion path of the commanding officer, which runs counter to the purpose of a Naval vessel in those days.

The scuttlebutt was nobody felt comfortable leaving them turned on lest something career limiting happen. 

Having been a CIWS tech during its earliest days in the fleet, I can attest to this being the mindset at the time. As a former CIWS instructor, I can say that no, they do not have a "mind of their own", they operate exactly how they were designed to (barring a failure -- more about that in a moment). The biggest operational problem with them was that many COs did not understand them. I will add that in my experience, military decision-makers tend to be risk-averse, especially when there are systems involved that are poorly understood. That was most certainly the case in the 80s, and made the bogus "meaning" of the acronym ("Captain, It Won't Shoot") that much more insulting to those of us who maintained and operated it. 

In STARK's case, the CIWS was not operating because they were running electrical power-affecting engineering drills at the time. According to an old CO of mine who had commanded an FFG in the Gulf during the Iran/Iraq War, it was commonplace for Iraqi F-1s to overfly US warships on their way to their targets. It may seem hard to believe now, but Iraq was considered an ally at the time, so such overflights were accepted, even if they weren't particularly comfortable. 

The JARRETT/MISSOURI friendly-fire incident didn't do much to assuage concerns. Eventually, the Navy developed doctrine that was effective in preventing issues like these, which is why we're not talking about similar incidents in the last 30-odd years. 

Now, a sea-story involving a failure: This happened during a firing exercise being conducted to impress some distinguished visitors with the power of our Phalanx systems. I was at the local control panel, and would be firing the gun from my position after being cleared by the skipper. The procedure was 1) receive clearance while gun was in stowed position, 2) energize the gun mount and move it to the pre-assigned firing bearing off the port beam at 45 degrees elevation, 3) fire a 100-round burst. What happened was: 1) I received clearance to fire, 2) I energized the gun and set it to move to the firing bearing and elevation, 3) the rate integrating gyro failed, causing the gun to slew to the physical stops aft of the port beam at 45 degrees elevation -- which left the visitors and the skipper in his whites standing on the port bridgewing staring directly into the muzzle of the gun and diving for the deck, and 4) yours truly recognizing the error and powering the mount down where it was. (It is worth noting that the PHYSICAL mount stops are outside the ELECTRICAL firing circuit stops. The gun was not going to fire because the firing circuit gets broken if the gun is pointed at any part of the ship's structure. I shut it down because the gun hadn't gone where I expected it to.)   

As @Northstar98 rightly points out, RL screen formations look nothing like the close-in stuff you typically see in DCS missions and cinematics, though this is not entirely because of CIWS. It's mostly a safety of navigation issue. Look up the MELBOURNE/EVANS incident, in which an Aussie carrier collided with a US destroyer. CO's Standing Orders on the cruiser I served in were to remain at a safe distance from the carrier at all times (1 mile if astern of the carrier, 2 miles if abeam of the carrier, 3 miles if ahead of the carrier), going closer only with the CO's express permission, such as taking station as CV Shotgun or plane guard. The CO who wrote those orders went on to be a Carrier Group commander and after a destroyer maneuvered too close to the carrier, he summoned the destroyer's CO to the carrier and fired him on the spot.