Royal New Zealand Navy Discussions and Updates

Shanesworld

Active Member
I suspect that there would be a bit more to it than that. Consider that a late model Mk 15 Phalanx (Block 1B) has a displacement of ~6.2 tonnes, when kitted out with the M61 Vulcan with a 2 m barrel.

Then consider the impact of replacing the 20 mm M61 Vulcan rotary cannon with the 30 mm GAU-8 Avenger rotary cannon (normally found in the A-10 Warthog...)

Given that the basic rotary cannon weapon is both larger and heavier when switching from 20 mm to 30 mm, the entire Mk 15 Phalanx mounting would likely need to be redesigned. Also due to the greater recoil forces involved in the upsize from 20 mm to 30 mm. the structure of the Mk 15 would likely require some sort of recoil dampener and/or reinforcement. All of this would likely drive the weight of the finished product beyond the current ~6 tonnes for a Mk 15.

Another thing to consider is the Goalkeeper 30 mm CIWS, which already uses the GAU-8 Avenger rotary cannon... A major difference between Goalkeeper and Phalanx aside from calibre is that Phalanx is non-deck penetrating while Goalkeeper is deck penetrating.

My interpretation of the above facts is that, short of a new rotary cannon being designed in 25 mm or 30 mm that has a similar size footprint and recoil forces as the M61 Vulcan, weapons system designers are not exactly spoiled with viable options to replace the M61 in the Phalanx.
General dynamics did experiment with sea vulcan 25. GAU 12 25mm (5 barrel) fitted to a similar chassis to vulcan minus the radar and was remotely operated rather than automatically directed. Intended for surface action rather than true ciws. But 540 rnds rather than 1000 ish of 20mm. No takers at the time.
 

ngatimozart

Super Moderator
Staff member
Verified Defense Pro
There is the 3 barrelled 30 mm gun used on the AH-64D Apache and I think that the 25 mm gun is 3 barrelled as well.
 

alexsa

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Staff member
Verified Defense Pro
I
There is the 3 barrelled 30 mm gun used on the AH-64D Apache and I think that the 25 mm gun is 3 barrelled as well.
I thought the Apache had the M230 chain gun as opposed to a rotating cannon. The viper has a three barrelled cannon but it is the M197. The only rotary cannon outside the GAU-8 avenger appears to be the GAU-22 Enforcer used on the F-35. It fires 3300 rpm. The M61 Vulcan is capable of selectable rates of fire 4000 and 6000 rpm but the Mk 15 uses a rate of fire at 3,000 or 4,500 rpm so the GAU-22 may not be able to hit the same max rate (and there will be less ammunition unless the magazine can be expanded.

As indicated by Tod, I suspect this is not that easy.

 

ngatimozart

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Staff member
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I

I thought the Apache had the M230 chain gun as opposed to a rotating cannon. The viper has a three barrelled cannon but it is the M197. The only rotary cannon outside the GAU-8 avenger appears to be the GAU-22 Enforcer used on the F-35. It fires 3300 rpm. The M61 Vulcan is capable of selectable rates of fire 4000 and 6000 rpm but the Mk 15 uses a rate of fire at 3,000 or 4,500 rpm so the GAU-22 may not be able to hit the same max rate (and there will be less ammunition unless the magazine can be expanded.

As indicated by Tod, I suspect this is not that easy.
Yeah, it's looking complicated. Bugger. Still the rate of fire of the GAU-22 is still relatively high. The magazine is not a problem because that was determined by space availability in the aircraft. For a ship a larger magazine could be developed. Would it require to penetrate the deck? If designed right I don't think so as long as the load forces and recoil forces are sufficiently allowed for.
 

Shanesworld

Active Member
Goal keeper uses 30 x 173. Apache uses 30x113. Difference is about 200 ms or slightly less. Big difference in recoil. Gau22 and gau12 are same family and there is a 3 barrel for the kai Ta50 but not sure if that is in that family or separate development.
These systems like long bursts too at high speeds. As during the slow down there are unused rnds that go back into the magazine. So lots of short burst leaves more unused rnds in the drum.
 

Todjaeger

Potstirrer
Yeah, it's looking complicated. Bugger. Still the rate of fire of the GAU-22 is still relatively high. The magazine is not a problem because that was determined by space availability in the aircraft. For a ship a larger magazine could be developed. Would it require to penetrate the deck? If designed right I don't think so as long as the load forces and recoil forces are sufficiently allowed for.
The GAU-22 does have a ROF which is ~2/3rds that of Block 1B Phalanx. There are a few major differences between the two guns which would need to be taken into account when designing/redesigning. A Mk 15 Phalanx Block 1B has a 1,550 round magazine, which permits ~21 seconds for full rate fire before the magazine is exhausted. The GAU-22 in use with the F-35 comes with either a 180 round or 220 round magazine, depending on F-35 model and mounting, which would permit only 4 seconds of full ROF before the magazine was exhausted, which basically means that a new and significantly larger magazine would be required.

The other major consideration has to do with the projectile weight, with the GAU-22's 25 mm projectile having slightly more than twice the mass of the 20 mm projectiles. That becomes important because because the recoil forces are going to be greater for 25 mm gun.

Now me being me, since the Goalkeeper itself seems to be a CIWS dead-end, I see little point in trying to develop another rotary cannon with a similar calibre round to get a large volume of munitions airborne as a CIWS. If one wants a fairly easily added or removed CIWS which could be part of a pool (one of the things a Goalkeeper or other deck penetrating CIWS has problems doing) but with superior range/reach than a Mk 15, I would suggest following a different path. Instead I would go with a single or twin, non-deck penetrating gun. in the 30 mm to 40 mm range, and use appropriate submunition rounds like AHEAD. Granted, such systems would require connections into a vessel's own sensors and CMS as opposed to the independent/stand-alone capability that Phalanx has, but so far there does not seem to be a single CIWS which meets all requirements.
 

Albedo

Member
It seems like the 6-barrel 20 mm M61 weighs 202-248 pounds depending on variant with up to 3,200 pounds of recoil. The 4-barrel 25 mm GAU-22 weighs 230 pounds with 3,700 pounds of recoil and a 3300 rpm while the 6-barrel 25 mm GAU-12 weighs 270 pounds with 5,000 pounds of recoil at 4200 rpm. So the GAU-22 is comparable to the M61 weight-wise and the recoil increase seems fairly modest so a M61 to GAU-22 swap is probably a viable upgrade path. The issue is whether a 25 mm GAU-22 Phalanx that provides a modest increase in range but, as pointed out, likely significantly reduced rate of fire (could be 2475 rpm if same ratio as 6000 rpm M61 to 4500 rpm Phalanx) yields any increase in overall CIWS effectiveness?

The latest modifications being tested for Phalanx reduce weapon weight by 180 pounds. Perhaps that weight savings can be put toward modifications to accommodate the weight and recoil of the 6-barrel 25 mm GAU-12 whose higher rate of fire (perhaps 3150 rpm using the M61 to Phalanx ratio) over the GAU-22 is likely needed to provide a tangible Phalanx upgrade. This might no longer be a low-cost upgrade to make the effort viable though.

EDIT:
Just wanted to add for comparison that the 30 mm GAU-8 in the Goalkeeper is 620 pounds with 10,000 pounds of recoil at 4200 rpm so is in a completely different league to the 20 mm and 25mm gatlings.
 
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JohnJT

Member
Phalanx is just so convenient being a self-contained system that requires no deck penetration and can engage both surface and air-threats. Longer range CIWS options have compromises like the Millennium Gun requiring an external fire control system with external radar and/or EO while SeaRAM, if I'm not mistaken, doesn't incorporate an anti-surface capability.
SeaRAM does have an anti-surface capability:
The missile is continually improved to stay ahead of the ever-evolving threat of anti-ship missiles, helicopters, aircraft and surface craft.
HAS (Helicopter, Aircraft, and Surface) mode was introduced after 1998 to allow the missile to engage more ship threat types, not just anti-ship missiles.
 
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Albedo

Member
SeaRAM does have an anti-surface capability:
HAS (Helicopter, Aircraft, and Surface) mode was introduced after 1998 to allow the missile to engage more ship threat types, not just anti-ship missiles.
Ah, you're right. A gun-based Phalanx upgrade doesn't seem needed then since SeaRAM can fulfill the same feature-set. I'd imagine cost is higher due to missile pricing but can be justified since longer engagement range is increasingly necessary.
 

ngatimozart

Super Moderator
Staff member
Verified Defense Pro
The Millennium Gun requires shipboard sensor input and it's 35 mm. Also it doesn't penetrate the deck and uses the AHEAD ammo. I have always liked the Millennium gun and I don't necessarily see it's dependence upon shipboard sensors as a weakness because it usually has 180°+ training across the bow or the stern, depending upon the ship and where it's located on the ship. Problem that I see from a RNZN POV is that the gun and hence its ammo is not used by allies and partners, so we would have to ensure that we always carried extensive supplies of it, which unfortunately NZ governments are loathe to pay for.
 

Shanesworld

Active Member
The GAU-22 does have a ROF which is ~2/3rds that of Block 1B Phalanx. There are a few major differences between the two guns which would need to be taken into account when designing/redesigning. A Mk 15 Phalanx Block 1B has a 1,550 round magazine, which permits ~21 seconds for full rate fire before the magazine is exhausted. The GAU-22 in use with the F-35 comes with either a 180 round or 220 round magazine, depending on F-35 model and mounting, which would permit only 4 seconds of full ROF before the magazine was exhausted, which basically means that a new and significantly larger magazine would be required.

The other major consideration has to do with the projectile weight, with the GAU-22's 25 mm projectile having slightly more than twice the mass of the 20 mm projectiles. That becomes important because because the recoil forces are going to be greater for 25 mm gun.

Now me being me, since the Goalkeeper itself seems to be a CIWS dead-end, I see little point in trying to develop another rotary cannon with a similar calibre round to get a large volume of munitions airborne as a CIWS. If one wants a fairly easily added or removed CIWS which could be part of a pool (one of the things a Goalkeeper or other deck penetrating CIWS has problems doing) but with superior range/reach than a Mk 15, I would suggest following a different path. Instead I would go with a single or twin, non-deck penetrating gun. in the 30 mm to 40 mm range, and use appropriate submunition rounds like AHEAD. Granted, such systems would require connections into a vessel's own sensors and CMS as opposed to the independent/stand-alone capability that Phalanx has, but so far there does not seem to be a single CIWS which meets all requirements.
Oto malera have a new 40mm non deck penetrating system and I saw something about a similar 76mm system proposed for ppa.
 

Albedo

Member
The Millennium Gun requires shipboard sensor input and it's 35 mm. Also it doesn't penetrate the deck and uses the AHEAD ammo. I have always liked the Millennium gun and I don't necessarily see it's dependence upon shipboard sensors as a weakness because it usually has 180°+ training across the bow or the stern, depending upon the ship and where it's located on the ship. Problem that I see from a RNZN POV is that the gun and hence its ammo is not used by allies and partners, so we would have to ensure that we always carried extensive supplies of it, which unfortunately NZ governments are loathe to pay for.
Using shipboard sensors with the Millennium Gun is less of an issue on larger warships that already have the required sensor fits, but can be limiting for auxiliaries or smaller ships that only have surface surveillance radars with limited air search capability and that may lack gun fire support tracking or that just have navigation radars. Having to add and integrate a surface/air fire control radar in addition to the Millennium Gun would be an added expense and complexity compared just placing a SeaRAM or Phalanx. EO fire control systems seem lighter and cheaper to add, but are they effective at directing guns against supersonic missiles?
 

JohnJT

Member
Ah, you're right. A gun-based Phalanx upgrade doesn't seem needed then since SeaRAM can fulfill the same feature-set. I'd imagine cost is higher due to missile pricing but can be justified since longer engagement range is increasingly necessary.
It could be an option for HMNZS Aotearoa.
Another option could be the MBDA SPIMM, which is specifically designed for support ship defense:

The SPIMM module consists of a SIMBAD-RC automated naval turret equipped with two ready-to-fire Mistral missiles and a 360° infrared panoramic system to detect and track air and surface threats. The system is entirely controlled by two operators located in a shelter inside the module, which is also used to store four additional missiles. This ISO standard “allin-one” module, 10 feet long and weighing some 7 tons, can be easily positioned on the deck of a ship using a crane, and requires just a standard electrical connection. Designed to protect surface vessels against most conventional airborne threats (anti-ship missiles, combat aircraft, helicopters and UAVs), the SIMBAD-RC and Mistral demonstrated, at the end of last year, its ability to neutralise asymmetric threats such as Fast Inshore Attack Craft (FIAC) by day and by night.
This has the advantage of using the Mistral missile already in service with the NZ Army. It's capable against anti-ship missiles, combat aircraft, helicopters, UAVs and surface craft, and is lighter than SeaRAM.

Here it is taking out a surface craft:
 
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Nighthawk.NZ

Active Member
This has the advantage of using the Mistral missile already in service with the NZ Army.
I am pretty sure the Mistral missile in the "NZ Army" are in storage and not really used in training anymore, and would not surprise me if they get rid of them.
 
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John Fedup

The Bunker Group
The Millennium Gun requires shipboard sensor input and it's 35 mm. Also it doesn't penetrate the deck and uses the AHEAD ammo. I have always liked the Millennium gun and I don't necessarily see it's dependence upon shipboard sensors as a weakness because it usually has 180°+ training across the bow or the stern, depending upon the ship and where it's located on the ship. Problem that I see from a RNZN POV is that the gun and hence its ammo is not used by allies and partners, so we would have to ensure that we always carried extensive supplies of it, which unfortunately NZ governments are loathe to pay for.
A Millennium gun with AHEAD ammo works for me, certainly for larger vessels like T26.
 

alexsa

Super Moderator
Staff member
Verified Defense Pro
Ah, you're right. A gun-based Phalanx upgrade doesn't seem needed then since SeaRAM can fulfill the same feature-set. I'd imagine cost is higher due to missile pricing but can be justified since longer engagement range is increasingly necessary.
I have always liked the SeaRAM as an option for vessel designed to take a Mk15 ...minimum pain, some real advantages and no significant changes required to the vessel. Folk often underestimate the impact of providing services (power and interfaces) and weight and space for new systems. Most CIWS are mounted high on the vessel and will have an impact on CoG.

Personally I would like to see this system on the RAN LHD's, AOR's and LHA. For the Hunter Class we should have ESSM Block II (which, combined with the SAAB/AEGIS combat system, will provide a very capable anti missile defence) by then. In this case the the current Mk 15 may provide a surface engagement capability (noting these vessels also have 30mm autocannons) and a Hail Mary back up to the internal system.

As a side issue, noting the Mk15 provides a CRAM capability ashore, it is not beyond the realms of possibility that these vessel may have to defend against similar threats in the littoral operations (i.e supporting a landing) and may still have a place as a stand alone system.

In the NZ AOR context (trying to get back on the thread) it 'may' be an option for the AOR. However, this is all speculation and would be subject to political will and in the current climate I suspect the Mk15 (FFBNW) is the only option on the table. I could be wrong and would pleased if I was.
 

MickB

Active Member
Another option could be the MBDA SPIMM, which is specifically designed for support ship defense:
The advantage of this system would not be in arming naval aux vessels but quickly adding self protection to merchant vessels operating in a conflict zone. Think Atlantic Conveyor or similar.
 
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