Should the Tromp be a CLAA?

[Ian R]

The Tromp was built with 6 x 150mm/L50 weapons disposed in 3 x twin turrets.

These are properly identified in the database (speaking of Scen-1) as 15cm/50 No. 11 weapons (line 1630), but they are type 18 - naval gun - not type 17, DP gun.

Janes identifies these as Bofors guns, but digging around, they were Wilton-Fijenoord manufactured weapons, under Bofors license. In the table on page 205 Janes notes them to be an AA capable mounting of the weapon. (Query devised by Bofors-Hazemeyer?) In the gunnery notes for the ship, the elevation was given as 60 degrees.

Conways also confirms the Mk 11 mountings with 60 degree elevation, but does not rate the weapons as DP.

The only comment I have seen on the internet is "A limited role as AA-weapon was envisioned as well, but the mounts proved to be too cumbersome in practice." No source is cited for that statement.

I had always thought her sister the Jacob Van Heemskerck was completed as a CLAA at Portsmouth because the RN didn't have any other suitable weapons available than the 4" HA, and no suitable fire control systems (and they needed more AAA ships), but maybe the Tromps were always intended to have a DP main armament.

Have any modders tested out a CLAA version with DP 150mm?

Incidentally, Tromp should get a 3 month refit/upgrade in October 1944 which involves installation of SC-4, SG-1 and Type 282 radars replacing the earlier types.

[inqistor]

I have changed all heavy Japanese guns to DP (Sanshikidan). It seems to seriously help with their survivability against smaller air raids. Not much more damage against planes, and it uses main guns ammo, but hit rate by planes are mostly misses.

[Ian R]

Did you experiment with the effects of rate of fire? Sid increased accuracy for the DP 6" weapon fitted to USN Worcesters post war, because its automation generated a high rate of fire.

I suspect without researching it as yet, that the Dutch 5.9", with sophisticated fire controls and a Hazermeyer mount, should probably get similar treatment - if it worked in practice.

[inqistor]

I've made some testing long ago. Doubling accuracy increase enemy loses by around 15% IIRC.

What is more important - just changing type of main Yamato battery to DP, so 3219 effect will destroy B-29 100% of the time.


My guess is, that "mount too cumbersome" means, that trailing was too slow, so mostly one shot against approaching plane. With Japanese guns using the same accuracy as naval, I get only 1 point of ammunition used in most of the air attacks.

[PaxMondo]

I did just the opposite to the IJ, removed all of the DP. the had to depress the barrel to less than 10 degrees to be able to reload, meaning the ROF was terrible. Ergo not a DP, or more accurately a single shot which can't be accurately modeled. So I took it away.

The only true DP is the 10cm/65. It is on a DD and a couple of upgrades. Sadly, not more. It was by all accounts a very nicely designed gun that worked well in practice. IJ just didn't have the industrial capability to build more of htem.

[Ian R]

There are a couple of other issues with making it a DP weapon, apart of from rate of fire that need to be addressed.

Supplies of the Tromp's 5.9" (150mm) ammunition was specially manufactured for her in the UK and later the US. Apparently this was problematical. But in a scenario-universe where real world constraints are ignored for the Japanese, that can probably be overlooked.

More interestingly, do you give those US manufactured rounds proximity fuses in 1944? Or would the Tromp receive the general allied AAA bump anyway?

[inqistor]

Seriously, you expect Dutch ship to survive Japanese planes attack? I doubt ammo supply will be problem.

I'm pretty sure I have tried to upgrade guns (as device) of Yamato, and it doesn't work. You have to make separate ship upgrade, and armament would consume lots of repair points for that one, so simulation of different ammunition is not possible under current engine. You need shipyard for that.

Now, if you want to be really specific towards ammo. US had no large HE shells for half of first year of war (Japan also have problem with delivering it for Guadalcanal), and some Battleships at Pearl Harbor had no ammo for large guns in magazines. They were actually rearming at that time, and some Captains decided to wait with loading till Monday. I am now wondering, if magazine hit use remaining ammo to evaluate possible damage.

[Big B]

Short answer - No, Tromp had the same guns as DeRuyter http://www.navweaps.com/Weapons/WNNeth_59-50_mk9.php
An anti-surface ship weapon with long range

B

[Ian R]

ORIGINAL: inqistor

Seriously, you expect Dutch ship to survive Japanese planes attack? I doubt ammo supply will be problem.

It depends - IJA level bombers, yes; the Kido Butai, no.

[Ian R]

ORIGINAL: Big B

Short answer - No, Tromp had the same guns as DeRuyter http://www.navweaps.com/Weapons/WNNeth_59-50_mk9.php
An anti-surface ship weapon with long range

B

Same guns, but different mounts. The Mk 9/10 mountings on De Rutyer dated back to the early 1930s. Query based on the Bofors M/30 mounts used on the Swedish cruiser Gotland. The Mk 11 was the precursor to the mounting used on the Tre Konor class in Sweden - automated AAA capable 6" guns in 1943.

[el cid again]

IT is arguable that ALL modern Dutch CL's are CLAA's.

However, the ROF and the rate of training and elevation for these guns
(and even 60 degrees elevation limit) are all marginal. Six inch AA
guns are barely feasible, and only late war models came close to being
truly effective. Japan fielded a mere TWO such guns (also two EIGHT INCH
guns - found in a park covered by jungle a few years ago) - and in BOTH
cases US bombers were instructed to stay out of their range. The US
Worcester class were too late to see war operations. Some other such
weapons were fielded - generally too late to see combat - by various
countries. The Dutch 5.9s are probably fine - given their rate of fire -
BUT

IF you rate a gun as DP - the way code works - the RANGE must equal the Altitude
of the shells - divided by 3 (there being 3,000 feet in 1,000 yards). That is,
you will REDUCE the effective range of the guns in a surface action. That is
likely OK - you usually miss at long range anyway.

Code says that you get FULL AA VALUE to FULL RANGE of the gun. Well - that isn't true
in ballistics. A shell at maximum range (45 degree elevation) reaches maximum altitude
at far less range than it will reach before the shell returns to Earth.

I have CONSIDERED rating the Dutch guns for AA but NEVER implemented it. I prefer to
keep the longer range for surface actions.

[Ian R]

Sid, do you count the De Rutyer as "modern"?

I have not sen any confirmation that the Mk 9/10 mountings had 60 degrees elevation. Then again, it was the only ship that used them.