US 5" Mk42 Naval Gun

[JohnR]

I know that the RN evaluated the Swedish 120mm model 1950, but found it to noisy and not gas tight. Did they ever evaluate the 5"/Mk 42.

The RN was willing to change it's standard medium calibre to 5" (cruise/destroyer) so it seems like a logical step.

 

[TomS]

Sort of. Friedman covers the issue briefly in his postwar destroyers book. As he tells it, DNO wanted to standardize on the US 5-inch ammunition at least, but felt that the 5-in/54 was going to be an interim step on the way to a much higher velocity and faster-firing gun around 5-in/70. They hoped to test the Mk42 or possibly a twin version in the mid 1950s, but then decided on a 5-in/62 instead. And that got cancelled in 1953, thanks to the Korean War. There were a range of cruiser-destroyer designs based around the very fast (60 rpm) high-power 5-inch guns that were sketched in the early 1950s.

This was all just before the flirtation with the Bofors 120mm. They apparently were moderately serious about a British version with a flash/gas tight gunhouse and other improvements, for some extra weight. A single mount was also considered. (The Swedes came back to this idea a bit later, IIRC).

But after the early 1950s, 5-inch seems to have become a caliber non grata, and 4.5-inch was accepted as the only option.

 

[uk 75]

In the 1960s the Brits had the Vickers 4.5" gun under development at the same time as the 105mm Abbot SP gun and the lightweignt 105mm towed version.
The Abbot was replaced by the 155mm AS90 but the light gun serves on. Meanwhile the RN has adopted the US 5" gun for its new frigates (will the T45s get them later?)

 

[timmymagic]

(will the T45s get them later?)

Near zero chance of that. The betting at present is either on retaining 4.5 until their OSD or switching to the Mk.110 57mm gun.

 

[uk 75]

(will the T45s get them later?)

Near zero chance of that. The betting at present is either on retaining 4.5 until their OSD or switching to the Mk.110 57mm gun.

why such a small gun?

 

[TomS]

(will the T45s get them later?)

Near zero chance of that. The betting at present is either on retaining 4.5 until their OSD or switching to the Mk.110 57mm gun.

why such a small gun?

Switching to 57mm would improve defense against small boats and air targets -- drones and possibly even ASCM, depending on the available ammunition. It would also free up weight for future growth in other systems and offer commonality with the Type 31.

Switching to 127mm would add weight. It might also require more volume, depending on the specifics of how the loading rings and magazines for the 127mm gun are installed.

 

[JohnR]

I've read that BAE has received an order for 5 x 57mm and 10 x 40mm to be fitted to the Type 31, which I feel is the wrong concept. They are the low cost escort (If there is such a thing) and should be fitted with the 5"/62 for shore bombardment.

The Type 26 and Type 45 are high end escort's best used as carrier escort. I believe they should have been fitted with 76mm OTO's (or the Bofor's 57mm) like the French and Italian Horizon class, they offer better AA performance and protection against a mosquito fleet.

I also think that the Italians have the better concept; better than nearly all other navies, regarding the positioning of the gun armament, on both their Horizons and FREMM frigates they have a 76mm covering the aft arcs. Which I think is advisable for dealing with mosquito fleets.

 

[TomS]

We are getting pretty far off topic here but I think your understanding of the British fleet is wrong. The Type 31s are enhanced patrol ships, with some ability to serve as convoy escorts in moderate threat environments. They don't have the wherewithal to survive inshore to carry out NGFS against a modern anti-access defense. The Type 26s at least have the robust self-defense systems needed to give that a try. OTOH, I'm increasingly unconvinced of the feasibility of NGFS as a mission.

 

[Yellow Palace]

Switching to 127mm would add weight. It might also require more volume, depending on the specifics of how the loading rings and magazines for the 127mm gun are installed.

T45 does, or did, have space and weight margins for a gun upgrade. At time of build this was expected to be a 155mm L39 derivative, but it might (or might not) be sufficient for a 127mm L54.

This, incidentally, is to the exclusion of the additional 16 Mk 41 strike-length cells. Using the space for one upgrade denies it to the other. And it's possible that it's already been used for some other purpose.

 

[JohnR]

Switching to 127mm would add weight. It might also require more volume, depending on the specifics of how the loading rings and magazines for the 127mm gun are installed.

T45 does, or did, have space and weight margins for a gun upgrade. At time of build this was expected to be a 155mm L39 derivative, but it might (or might not) be sufficient for a 127mm L54.

This, incidentally, is to the exclusion of the additional 16 Mk 41 strike-length cells. Using the space for one upgrade denies it to the other. And it's possible that it's already been used for some other purpose.

Given that the 4.5" Mk8 and the 5"Mk45 were roughly equivalent, therefore changing the gun to the same 5"/62 as on the Type 26 should not present a problem, although the likelihood of it taking place is as likely as finding rocking horse pooh.

As for fitting the additional VLS cells, I was under the impression that they were to be fitted in the space between the existing cells; which seems a rather awkward arrangement, it would seem to me it would have been more logical to have mounted the VLS across the beam rather than lengthways, that could have left sufficient space for an extra 4 eight cell units.

 

[David N]

Switching to 127mm would add weight. It might also require more volume, depending on the specifics of how the loading rings and magazines for the 127mm gun are installed.

T45 does, or did, have space and weight margins for a gun upgrade. At time of build this was expected to be a 155mm L39 derivative, but it might (or might not) be sufficient for a 127mm L54.

This, incidentally, is to the exclusion of the additional 16 Mk 41 strike-length cells. Using the space for one upgrade denies it to the other. And it's possible that it's already been used for some other purpose.

Given that the 4.5" Mk8 and the 5"Mk45 were roughly equivalent, therefore changing the gun to the same 5"/62 as on the Type 26 should not present a problem, although the likelihood of it taking place is as likely as finding rocking horse pooh.

As for fitting the additional VLS cells, I was under the impression that they were to be fitted in the space between the existing cells; which seems a rather awkward arrangement, it would seem to me it would have been more logical to have mounted the VLS across the beam rather than lengthways, that could have left sufficient space for an extra 4 eight cell units.

I believe that in the T45s there is space between the Mk8 and the Sylver silo for Mk41s (currently used as a gym). I would like to see Sea Ceptor mushrooms put in their as the lowest cost increase in the number of SAMs on board.

 

[zen]

Ideally, it would be useful to leverage Brimstone seeker into a CAMM fusilage and thus expand the options for this system using soft launch.
An ability to add in cells holding anti-surface weapons, including those able to deal with hardened or dispersed targets.
Such is a potentially cheaper way forward when shared with the Army.

Whereas the move to 5" is more logical if we add in HVP and extended range munitions.

 

[TomS]

Ideally, it would be useful to leverage Brimstone seeker into a CAMM fusilage and thus expand the options for this system using soft launch.

CAMM already reportedly has the ability to engage small surface vessels.

 

[zen]

Ideally, it would be useful to leverage Brimstone seeker into a CAMM fusilage and thus expand the options for this system using soft launch.

CAMM already reportedly has the ability to engage small surface vessels.

So my understanding is that the Army is looking at an option of the Brimstone system repackaged into a CAMM fusilage.
What that delivers is Brimstone-like capabilities and that must obviously include a warhead of similar type.
This is quite different from Ceptor, being configured as a SAM.
Using Ceptor for the anti-surface roles seems both wasteful and inadequate for some of the likely targets.
This comes down to things like the warhead and seeker(s), motor size etc...
A VLS CAMM-AS (anti-surface), should be effective upto modern tanks and hardened shelters, and include the cooperative engagement capabilities of Brimstone in sorting ad hoc through multiple targets engaged simultaneously. It should also permit selective targeting by nearby assets via laser designation. Hence effectively a repackaged Brimstone, rather than the desperation of using Ceptor for that target set.

CAMM -AA a.k.a Ceptor should be retained for airborne targets, where it is focused in performance terms.

 

[Volkodav]

Too bad the UK didn't look at adopting the US 5" L54 ammo for the Vickers Mk8. If my understanding is correct the ammunition used in the Mk8 was different to that used in the earlier 4.5s so adopting 5" should not have been a major imposition and using common round with the US would have had their own advantages.

 

[Tony Williams]

Too bad the UK didn't look at adopting the US 5" L54 ammo for the Vickers Mk8. If my understanding is correct the ammunition used in the Mk8 was different to that used in the earlier 4.5s so adopting 5" should not have been a major imposition and using common round with the US would have had their own advantages.

I believe that the 4.5 inch Mk 8 ammo differed from the Mk 6 only in the cartridge case and projectile being fixed together rather than loaded separately, to speed up automated handling.

 

[TomS]

Too bad the UK didn't look at adopting the US 5" L54 ammo for the Vickers Mk8. If my understanding is correct the ammunition used in the Mk8 was different to that used in the earlier 4.5s so adopting 5" should not have been a major imposition and using common round with the US would have had their own advantages.

I believe that the 4.5 inch Mk 8 ammo differed from the Mk 6 only in the cartridge case and projectile being fixed together rather than loaded separately, to speed up automated handling.

The projectile weights seem to be significantly different -- 25kg for the Mk6 HE round versus 20.8 for the Mk8 equivalent. Just a generational difference?

 

[JohnR]

With the earlier moves to adopt a 5" gun, it surprises me that they did not adopt a 5" gun when the Mk8 was developed. I was always under the impression they had kept with 4.5" to use existing ammunition stocks and was surprised when I found out the ammo was different. I really would have made sense to have adopted a 5" gun, although my preference on the time frame would have been the Italian 5", not the US MK45.

 

[Tony Williams]

The projectile weights seem to be significantly different -- 25kg for the Mk6 HE round versus 20.8 for the Mk8 equivalent. Just a generational difference?

You are right - I hadn't realised that the Mk 8 projectiles were lighter. The cartridge cases are virtually identical.

 

[TomS]

With the earlier moves to adopt a 5" gun, it surprises me that they did not adopt a 5" gun when the Mk8 was developed. I was always under the impression they had kept with 4.5" to use existing ammunition stocks and was surprised when I found out the ammo was different. I really would have made sense to have adopted a 5" gun, although my preference on the time frame would have been the Italian 5", not the US MK45.

I suspect that simply buying a foreign gun was not an option at the time (pride, hard currency issues, etc.). So at best they could have adopted 5"/54 ammo. But semi-fixed ammo might interfere with the desire to achieve the fastest possible time to first shot, which Friedman reports was considered the most important parameter for the gun in self-defense AA fire. Fixed ammo would be slightly faster to load from empty chamber because it saves a step.

Possibly this is also related to the decision to scale the Abbot gun up to 114mm for the Mk8. A semi-fixed 5-inch clearly couldn't be based on that gun, but I'm not sure whether they selected fixed ammo because they wanted to use the Abbot or selected the Abbot after they made the decision to use fixed ammo.

 

[TomS]

The projectile weights seem to be significantly different -- 25kg for the Mk6 HE round versus 20.8 for the Mk8 equivalent. Just a generational difference?

You are right - I hadn't realised that the Mk 8 projectiles were lighter. The cartridge cases are virtually identical.

The Mk8 ammo is considerably faster (about 400 fps, ~15%). Lighter projectile, similar powder charge, presumably.

 

[Hood]

Just a thought, did the Type 45s receive new Mk.8 guns or were the actual guns recycled from older decommissioned ships and placed in updated mountings?

 

[timmymagic]

Just a thought, did the Type 45s receive new Mk.8 guns or were the actual guns recycled from older decommissioned ships and placed in updated mountings?

It's a good point. Never seen any speculation on that before. Given the work on TMF it would make sense that they were re-used and re-built from T42's. Given the scrapping dates of the 4 Batch 1's and first 2 Batch 2 T42's its certainly possible. There were a few Mk8 gun mounts in the yard at Gosport at one point. There will have been Mk 8 mount available from HMS Bristol as well. At the time T45 was being built they would have been the only source for them.

 

[timmymagic]

So my understanding is that the Army is looking at an option of the Brimstone system repackaged into a CAMM fusilage.
What that delivers is Brimstone-like capabilities and that must obviously include a warhead of similar type.
This is quite different from Ceptor, being configured as a SAM.
Using Ceptor for the anti-surface roles seems both wasteful and inadequate for some of the likely targets.
This comes down to things like the warhead and seeker(s), motor size etc...
A VLS CAMM-AS (anti-surface), should be effective upto modern tanks and hardened shelters, and include the cooperative engagement capabilities of Brimstone in sorting ad hoc through multiple targets engaged simultaneously. It should also permit selective targeting by nearby assets via laser designation. Hence effectively a repackaged Brimstone, rather than the desperation of using Ceptor for that target set.

CAMM -AA a.k.a Ceptor should be retained for airborne targets, where it is focused in performance terms.

Sorry off topic....

It did look initially like MBDA was proposing a Brimstone seeker on CAMM body as part of the Land Precision Fires proposal. But it turns out that the CAMM-lookalike missile body is of a higher diameter. This presumably would give a larger warhead and larger range (with a slower burning propellant than CAMM and larger casing it would be at least 60km from the ground, probably more like 80km.) There were 2 seeker heads as well. One a Brimstone seeker head with MMW (not sure if it was Dual Mode with SAL as well) and what appeared to be an E/O seeker head. It appeared to still be compatible with Land and Sea Ceptor launchers though. Here's some thoughts on its utility..

1) - Spike NLOS replacement - Probably cheaper, faster, much larger range (60km+ vs. 25km) bigger warhead. UK built. No political issues around use/deployment (Spike NLOS is Israeli). Could be added as the image suggested as a module on Boxer. The offensive capability of Strike Brigades enhanced enormously very easily. Replaces the poor trailer mounted version of Spike NLOS (that by all accounts isn't successful or suitable for peer-to-peer war).
2) - Anti-Armour Overwatch - A super Swingfire replacement. No MBT on earth could defend against a Mach 3 missile coming in near vertically, it wouldn't even need a warhead, KE alone would tear through a tanks top armour. A modern diving LOSAT. The speed of response would mean it could operate at much further range than Swingfire could and cover multiple units. Probably easiest to leave on Boxer and MAN chassis than add on to Ajax.
3) - F-35 Outer Pylon compatible - Brimstone 2/3 will never be integrated, but Asraam has (and Asraam CSP will). The combination of the Asraam form factor (albeit wider) and Brimstone seeker (as used on Spear which will be integrated) would allow a comparatively straightforward integration to F-35. Very easily you give F-35B a cheaper, faster Spear capability but in 2 forms - Dual Mode and E/O. The Dual Mode would be very useful as a SEAD/DEAD weapon for pop up targets. The E/O capability would be a new one to the F-35.
4) - Compatibility with Land Ceptor launchers.
5) - Compatibility with Sea Ceptor launchers - A big advantage. Any RN vessel (including T31 and T26, and you would hope QE eventually) would have the capability of carrying an easy to integrate missile that can deal with Fast Attack Craft in any weather conditions or provide precision strike out to 60km+. This would be a whole lot easier than integration a VL Spear missile which would require a new booster and tip over mechanism.
6) - Export sales - New Zealand, Italy, Brazil and Chile. Plus India and Australia are Asraam users. As a solution to anti-air, anti-missile, precision strike, anti-FAC it's pretty much unique.
7) - Typhoon compatible - Another string to its bow. Not sure if the air to ground aspect could be easily ported to Tranche 1's though, be interesting if it could be.
8) - Falklands - There's no real credible threat there. But sending a few down south to be launched from the Land Ceptor battery would be a useful capability for the defence forces to have.
9) - UK Land Forces get a small anti-ship missile by default.
10) - UK Industry benefits - No ITAR issues.
11) – Could be multi packed in Sylver or Mk.41/57 launchers. Or canisters can be a standalone component, you just need a rack for them.
12) – CAMM, CAMM-ER, CAMM with E/O, CAMM with DMB head…that’s a very convincing selection of weapons for any platform to be able to fire. SAM from 200 metres to c80km, strike out to 60km+. I don’t particularly favour it but a cold launched Spear with a booster for when it clears the capsule could strike out to c200km as well, if it was lengthened with increased fuel storage to take advantage of the additional space in the canister it could go out to 250km+…

This is exactly what the Complex Weapons Team initiative was about. Developing capabilities that could be ported between different systems, maximising development and sustainment funds whilst delivering greater capability.

 

[Tony Williams]

The projectile weights seem to be significantly different -- 25kg for the Mk6 HE round versus 20.8 for the Mk8 equivalent. Just a generational difference?

You are right - I hadn't realised that the Mk 8 projectiles were lighter. The cartridge cases are virtually identical.

The Mk8 ammo is considerably faster (about 400 fps, ~15%). Lighter projectile, similar powder charge, presumably.

This sparks a dim memory from a few years ago: the RN adopted a new extended-range projectile for the 4.5 inch. Possibly that is when the weight was reduced (in conjunction with a more aerodynamic shape and base-bleed).

 

[zen]

So my understanding is that the Army is looking at an option of the Brimstone system repackaged into a CAMM fusilage.
What that delivers is Brimstone-like capabilities and that must obviously include a warhead of similar type.
This is quite different from Ceptor, being configured as a SAM.
Using Ceptor for the anti-surface roles seems both wasteful and inadequate for some of the likely targets.
This comes down to things like the warhead and seeker(s), motor size etc...
A VLS CAMM-AS (anti-surface), should be effective upto modern tanks and hardened shelters, and include the cooperative engagement capabilities of Brimstone in sorting ad hoc through multiple targets engaged simultaneously. It should also permit selective targeting by nearby assets via laser designation. Hence effectively a repackaged Brimstone, rather than the desperation of using Ceptor for that target set.

CAMM -AA a.k.a Ceptor should be retained for airborne targets, where it is focused in performance terms.

Sorry off topic....

It did look initially like MBDA was proposing a Brimstone seeker on CAMM body as part of the Land Precision Fires proposal. But it turns out that the CAMM-lookalike missile body is of a higher diameter. This presumably would give a larger warhead and larger range (with a slower burning propellant than CAMM and larger casing it would be at least 60km from the ground, probably more like 80km.) There were 2 seeker heads as well. One a Brimstone seeker head with MMW (not sure if it was Dual Mode with SAL as well) and what appeared to be an E/O seeker head. It appeared to still be compatible with Land and Sea Ceptor launchers though. Here's some thoughts on its utility..

1) - Spike NLOS replacement - Probably cheaper, faster, much larger range (60km+ vs. 25km) bigger warhead. UK built. No political issues around use/deployment (Spike NLOS is Israeli). Could be added as the image suggested as a module on Boxer. The offensive capability of Strike Brigades enhanced enormously very easily. Replaces the poor trailer mounted version of Spike NLOS (that by all accounts isn't successful or suitable for peer-to-peer war).
2) - Anti-Armour Overwatch - A super Swingfire replacement. No MBT on earth could defend against a Mach 3 missile coming in near vertically, it wouldn't even need a warhead, KE alone would tear through a tanks top armour. A modern diving LOSAT. The speed of response would mean it could operate at much further range than Swingfire could and cover multiple units. Probably easiest to leave on Boxer and MAN chassis than add on to Ajax.
3) - F-35 Outer Pylon compatible - Brimstone 2/3 will never be integrated, but Asraam has (and Asraam CSP will). The combination of the Asraam form factor (albeit wider) and Brimstone seeker (as used on Spear which will be integrated) would allow a comparatively straightforward integration to F-35. Very easily you give F-35B a cheaper, faster Spear capability but in 2 forms - Dual Mode and E/O. The Dual Mode would be very useful as a SEAD/DEAD weapon for pop up targets. The E/O capability would be a new one to the F-35.
4) - Compatibility with Land Ceptor launchers.
5) - Compatibility with Sea Ceptor launchers - A big advantage. Any RN vessel (including T31 and T26, and you would hope QE eventually) would have the capability of carrying an easy to integrate missile that can deal with Fast Attack Craft in any weather conditions or provide precision strike out to 60km+. This would be a whole lot easier than integration a VL Spear missile which would require a new booster and tip over mechanism.
6) - Export sales - New Zealand, Italy, Brazil and Chile. Plus India and Australia are Asraam users. As a solution to anti-air, anti-missile, precision strike, anti-FAC it's pretty much unique.
7) - Typhoon compatible - Another string to its bow. Not sure if the air to ground aspect could be easily ported to Tranche 1's though, be interesting if it could be.
8) - Falklands - There's no real credible threat there. But sending a few down south to be launched from the Land Ceptor battery would be a useful capability for the defence forces to have.
9) - UK Land Forces get a small anti-ship missile by default.
10) - UK Industry benefits - No ITAR issues.
11) – Could be multi packed in Sylver or Mk.41/57 launchers. Or canisters can be a standalone component, you just need a rack for them.
12) – CAMM, CAMM-ER, CAMM with E/O, CAMM with DMB head…that’s a very convincing selection of weapons for any platform to be able to fire. SAM from 200 metres to c80km, strike out to 60km+. I don’t particularly favour it but a cold launched Spear with a booster for when it clears the capsule could strike out to c200km as well, if it was lengthened with increased fuel storage to take advantage of the additional space in the canister it could go out to 250km+…

This is exactly what the Complex Weapons Team initiative was about. Developing capabilities that could be ported between different systems, maximising development and sustainment funds whilst delivering greater capability.

That sound like it.
Another possibility is using this larger form (fusilage diameter) to deliver an alternative heavier SAM than currently.
So enormous possibilities here.

But what this delivers seems more scalable than the limitations of a single 5" gun, and applicable via networks to installation on even patrol ships. One gun can really only engage one target at a time.
While this sort of missile system-of-systems delivers is simultaneous engagements around a full 360 degrees.
Hence why it seems Type 31 will get a 57mm and a pair of 40mm and Type 26 a 5". The latter if it has a justification beyond psychology (must have a big gun to look the business), is limited shore bombardment, limited anti-ship and future HVP use for ATBM.
But for more substantial use, these ideas concerning CAMM and Complex Weapons is more pressing.

 

[TomS]

This sparks a dim memory from a few years ago: the RN adopted a new extended-range projectile for the 4.5 inch. Possibly that is when the weight was reduced (in conjunction with a more aerodynamic shape and base-bleed).

No, the weight differential is older than that. The weight of 20.9 kg for the Mk 8's N4A1 HE shell comes from Tony's NavWeaps site and jibes with the numbers in Fredman's 1989 World Naval Weapon Systems (the likely source?). Tony ALSO lists the HE-ER base bleed round at 20.6 kg. Both the HE and HE ER (BB) rounds have a muzzle velocity of 2850 fps, compared to 2450 fps or so for the Mk 6.

 

[Tony Williams]

This sparks a dim memory from a few years ago: the RN adopted a new extended-range projectile for the 4.5 inch. Possibly that is when the weight was reduced (in conjunction with a more aerodynamic shape and base-bleed).

No, the weight differential is older than that. The weight of 20.9 kg for the Mk 8's N4A1 HE shell comes from Tony's NavWeaps site and jibes with the numbers in Fredman's 1989 World Naval Weapon Systems (the likely source?). Tony ALSO lists the HE-ER base bleed round at 20.6 kg. Both the HE and HE ER (BB) rounds have a muzzle velocity of 2850 fps, compared to 2450 fps or so for the Mk 6.

OK, noted thanks.

 

[JohnR]

With regard to the Falklands 'requirement', isn't a number of Rapier batteries deployed to Mount Pleasant, so any Sabre's would be a one for one replacement.

 

[timmymagic]

That sound like it.
Another possibility is using this larger form (fusilage diameter) to deliver an alternative heavier SAM than currently.
So enormous possibilities here.

Last post on this, as I know we're hijacking the thread...(probably need to move this stuff to the Asraam thread). But I don't think there would be a need. CAMM-ER will cover the next range bracket and MBDA also showed (at the same time as the CAMM-Brimstone hybrid) a green painted Meteor (i.e. ground launched). There have also been some proposals from MBDA to use a Meteor variant as a SAM, specifically to counter manoevering Hypersonic Glide Vehicles. With CAMM, CAMM-ER and a Meteor variant you'd be covering 200m-200km. Not sure how it would sit in their line up alongside Aster and SAMP/T though...

 

[zen]

That sound like it.
Another possibility is using this larger form (fusilage diameter) to deliver an alternative heavier SAM than currently.
So enormous possibilities here.

Last post on this, as I know we're hijacking the thread...(probably need to move this stuff to the Asraam thread). But I don't think there would be a need. CAMM-ER will cover the next range bracket and MBDA also showed (at the same time as the CAMM-Brimstone hybrid) a green painted Meteor (i.e. ground launched). There have also been some proposals from MBDA to use a Meteor variant as a SAM, specifically to counter manoevering Hypersonic Glide Vehicles. With CAMM, CAMM-ER and a Meteor variant you'd be covering 200m-200km. Not sure how it would sit in their line up alongside Aster and SAMP/T though...

Yes I've tried to keep things in comparison to gun systems.to keep on topic. But perhaps we should move this debate over to the CAMM thread.

 

[Volkodav]

If I recall correctly the Mk-42 gun system used on the Knox Class was a lighter, less complex version of the earlier mounts. This could have been an interesting option for late build Type 12s or export Counties.

 

[TomS]

If I recall correctly the Mk-42 gun system used on the Knox Class was a lighter, less complex version of the earlier mounts. This could have been an interesting option for late build Type 12s or export Counties.

I can't find a concrete number for the difference, but it probably wasn't huge. They reduced the train and elevation rates, switched to solid-state electronics, and reduced the crew needed (including eliminating the on-mount AA director). But in the end, it still almost certainly weighed more than the Mk 6 twin 4.5-inch, which was a very efficient mount for its time.

Edit: Just to be maddening, Friedman (World Naval Weapons) gives the weight of the Mod 0 as 145,930 lbs. NavWeaps (which lists Friedman as a source) gives the exact same number as the fully loaded weight for the "lighter" Mod 9/10.

Edit 2: Norman Polmar (usually not heavy on this level of detail) has the following in the back of Ships and Aircraft of the US Fleet : ~145,000 lbs for Mod 1-6, 139,000 lbs for Mod 10. So, about 3 tons (5%) lighter.

 

[Volkodav]

If I recall correctly the Mk-42 gun system used on the Knox Class was a lighter, less complex version of the earlier mounts. This could have been an interesting option for late build Type 12s or export Counties.

I can't find a concrete number for the difference, but it probably wasn't huge. They reduced the train and elevation rates, switched to solid-state electronics, and reduced the crew needed (including eliminating the on-mount AA director). But in the end, it still almost certainly weighed more than the Mk 6 twin 4.5-inch, which was a very efficient mount for its time.

Edit: Just to be maddening, Friedman (World Naval Weapons) gives the weight of the Mod 0 as 145,930 lbs. NavWeaps (which lists Friedman as a source) gives the exact same number as the fully loaded weight for the "lighter" Mod 9/10.

Edit 2: Norman Polmar (usually not heavy on this level of detail) has the following in the back of Ships and Aircraft of the US Fleet : ~145,000 lbs for Mod 1-6, 139,000 lbs for Mod 10. So, about 3 tons (5%) lighter.

So about the same as 20 years worth of accumulated coats of paint (just guessing not stating as fact). Shame, that ideas down the gurgler then.

 

[TomS]

It occurs to me that there was one other potential option, the French twin 127mm/54 Model 1948, which was fitted on the T47s, T53s, DeGrasse, and Colbert. It fired standard USN ammo at around 30-36 (15-18 rpm per gun*) and weighed just under 50 tons, so a good 25% lighter than the Mk 42 and only a bit heavier than the British Mk 6. What I don't know is whether it was any good. It was withdrawn pretty quickly in favor of 100mm, but that may have had more to do with weight savings and the desire for commonality than any inherent flaw of the gun. Or it could have been a total dog. Information is scarce.

France 127 mm/54 (5") Model 1948 - NavWeaps

www.navweaps.com

* I think. Jane's just says 15 rpm but NavWeaps has 15-18 rpm under the "gun" section, which generally means that's the RoF per tube.

Edit: Thanks to Tony DiGuilian and John Jordani, I've learned more about this gun, and it's apparently not a very good system at all, sort of a DP rehash of a prewar 130mm gun. Scratch that from the list.

 

[JohnR]

So about the same as 20 years worth of accumulated coats of paint (just guessing not stating as fact). Shame, that ideas down the gurgler then.

As an aside, when Queen Mary was being refitted prior to going to Long Beach, as a condition of sale se had to be made unable to make any further journeys under her own power, she therefore had most of her engines scrapped. To remove the remains through the engine casing the funnels had to be removed. They were found to be rust held together by forty years of paint and collapsed on the dock.

 

[Tzoli]

Well to be precise the gun is the Mark 18, the gun mount is the Mark 42, but I wonder if the USN thought of a twin mounting for this gun?
Seems like everybody except the Soviets in cold war forget that you can mount two gun barrels in a turret not just one. Well the Italians too but the Vertically arranged 76mm/62 OTO-Melara Sovrapposto of 1952 was not successful.

Well the post WW2 USN Gun mount designations was such a mess starting with this cold war mark 42 of 1950 and reaching Mark 110 by 2000 with the Swedish-Italian 57mm/70 gun mount without the invention of almost 70 guns for the various mountings....

 

[TomS]

Well to be precise the gun is the Mark 18, the gun mount is the Mark 42, but I wonder if the USN thought of a twin mounting for this gun?
Seems like everybody except the Soviets in cold war forget that you can mount two gun barrels in a turret not just one. Well the Italians too but the Vertically arranged 76mm/62 OTO-Melara Sovrapposto of 1952 was not successful.

Yes., there was the Mk 41 a twin semi-automatic 5-inch/54 design in mid-1944 (possibly with Mk 16 rather than Mk 18 guns, but the difference is not great). Friedman talks about it in US Naval Weapons -- [Edit: it started as a twin mount for the Montana class and later evolved into] a streamlined mount with close-set guns only 26 inches apart intended to fit on the same deck opening as the twin 5-inch/38, plus on-mount gun fire control radar. RoF was to be 18 rpm per tube, using the same basic dual-hoist loading mechanism as the Mk 42 where the projectile and charge are loading into the hoist separately but after that moved together through the mechanism. Seems like the main difference was that the loader fed two breeches instead of one. It would have required 10-12 crew on the mount, less than half the number needed for the 5-in/38 twin (and 2/3 as many as the Mk 42). There was a related Mk 43 in 1947 with lowered trunnion height.

This really does seem like a missed opportunity. A twin mount might have alleviated some of the reliability issues of the Mk 42, allowing at least one tube to keep running in a casualty event. (The on-mount radar would likely have been a failure, as the same GUNAR was tried and rapidly withdrawn on the MK 42).

[Edit: Coming back late to fix something I misread in Friedman.]

Well the post WW2 USN Gun mount designations was such a mess starting with this cold war mark 42 of 1950 and reaching Mark 110 by 2000 with the Swedish-Italian 57mm/70 gun mount without the invention of almost 70 guns for the various mountings....

Oh, there actually are quite a lot of gun mounts in the unified series between the Mk 42 and the Mk 110. Most of them are relatively small-caliber mounts, things like a twin .50-cal/40mm grenade launcher protected mount for riverine LCM-6s (the Mk 50) or a gun shield for twin M60 machine guns (the Mk 78),. But there were also things like the Mk 72 mount for the Phalanx CIWS, the Mk 83 mount for the GAU-8 CIWS (more commonly referred to as EX-83) and bigger guns like three different designs of Major-Caliber Lightweight Gun (Mk 69 was an 8-in/60, Mk 70 was similar with a longer round, and then the famous Mk 71) And of course there are the quick-firing versions of the Mk45 (Mk 65 and Mk 66), but those are probably better in a separate discussion. Plus some numbers reserved for alternative designs that never got built. But Mk 110 isn't really a huge excursion. (as an aside, you'll see some references to the 57mm gun as the Mk 100, but I think they tried to assign that and discovered some obscure small-arms mount was already using that number.)

 

[Tzoli]

About this Mark 42 mount I've seen at least 3 or 4 variants:
- with bulges/domes on both side on the turret top

https://upload.wikimedia.org/wikipedia/commons/0/04/5_inch_Mark_42_on_USS_Turner_Joy_%28DD-951%29%2C_front.jpg

- with left bulge on top

https://www.seaforces.org/wpnsys/SURFACE/Mk-42-gun_DAT/Mk-42-gun-028.jpg

- with right bulge on top

https://www.seaforces.org/wpnsys/SURFACE/Mk-42-gun_DAT/Mk-42-gun-023.jpg

- maybe a test variant without any bulges/domes on top

Mk-42 5"/54 5-inches 54-caliber 127 mm naval gun system

mk-42 5/54 naval gun

www.seaforces.org

Indeed we might require a thread in the designation subforum for the USN gun turret marks

 

[Tzoli]

and

and bigger guns like three different designs of Major-Caliber Lightweight Gun (Mk 69 was an 8-in/60, Mk 70 was similar with a longer round, and then the famous Mk 71)

Can you tell me more about this 8"/60 gun? From Navweaps I only know of the Mark 28 and Mark 32 guns both /55 calibre ones for the Mark 71 mounting