Dido class cruisers

[dunmunro]

Dunmunro,

Are you implying that the 5.25" gun had the same rate of fire as the 5"/38?

No, but under combat conditions, the variation in the RoF will probably be less than the stated RoF for these weapons.

[RF]

Looking at this class as warships I wonder what would have happened when HMS Scylla intercepted the blockade runner Rhatokis if instead the Rhatokis had been a fully armed hilfskreuzer, let the range close and open fire at the same time as Scylla.....

[dunmunro]

Looking at this class as warships I wonder what would have happened when HMS Scylla intercepted the blockade runner Rhatokis if instead the Rhatokis had been a fully armed hilfskreuzer, let the range close and open fire at the same time as Scylla.....

Scylla was poorly armed to engage a surface raider, but a standard Dido class CL, with 10 or 8 x 5.25" guns should have had little difficulty in destroying the raider.

[RF]

On paper, even for a standard class cruiser.

HMAS Sydney should have had a very easy job against Kormoran - which was loaded with over 300 mines - yet got sunk.

Rhatokis was fired on at close range and had it been a fully armed raider with competent gun crews - well if you were a bookie what odds would you give the raider captain - it might have been worth a punt.....

[dunmunro]

On paper, even for a standard class cruiser.

HMAS Sydney should have had a very easy job against Kormoran - which was loaded with over 300 mines - yet got sunk.

Rhatokis was fired on at close range and had it been a fully armed raider with competent gun crews - well if you were a bookie what odds would you give the raider captain - it might have been worth a punt.....

Kormoran was given every possible advantage, yet was still sunk after being hit by only 3 6" rounds. Sydney was hit by a torpedo, raked by light AA and hit many dozens of times by 15cm rounds and still took many hours to sink.

[Bgile]

Dunmunro,

Are you implying that the 5.25" gun had the same rate of fire as the 5"/38?

No, but under combat conditions, the variation in the RoF will probably be less than the stated RoF for these weapons.

Absolutely. That's pretty much true of any weapon other than fully automatic ones. Max rate of fire is normally only achieved for short periods. All kinds of things happen to cause interruptions, etc.

[RF]

dunmunro,

I agree with what you say but I think you have missed my point, which is that Scylla was on full alert (and Sydney evidently wasn't) to intercept a blockade runner - if Rhatokis was a hilfskreuzer and returned the fire of Scylla would Scylla have been sunk?

[RNfanDan]

dunmunro,

... I think you have missed my point, which is that Scylla was on full alert (and Sydney evidently wasn't)...

If I may, Sydney's guns were purportedly trained abeam, with shells breeched and ready, which speaks to a fairly advanced state of alert. The entire problem was the fatal error of judgment on the part of her CO, not the ship's readiness.

[RF]

It's difficult to comment on Sydney because there are no surviving witnesses to testify over not so much what happened as to why it happened. The only evidence we have is from the Germans, in their account of the exchange of signals as Sydney closed on Kormoran, the action of Sydney's crew in preparing to launch their seaplane and then retracting the catapault, and the opinion of Detmers that Sydney was not fully closed for action (based on the ''pantrymen'' and the AA guns and torpedo tubes not being manned).

My impression, for what its worth, is that Sydney's watch officer (I conjecture that Captain Burnett may not have initially been on the bridge) was at first taken in by Detmers reply to his questions and he thought he was dealing with the real Straat Malakka. Only when they asked for the secret call sign did they become suspicious, after approaching too close.
Had Sydney been on full alert, then the moment the Dutch flag came down the order to prepare to fire should have been given, and when Kormoran de-camourflaged Sydney should have opened fire. Kormoran's advantage in firing first would have been negated and Kormoran quickly sunk.

Coming back to the Scylla her armament was far less substantial than Sydney's largely silent guns, but they would have been firing on their target, the question is to what effect and how many hits a raider Rhatokis would have inflicted. On paper the Germans would have had a chance to sink Scylla in open battle, whereas Sydney fell victim to an ambush.

So it really comes back to my original point - could the ''toothless wonder'' be sunk in open battle by an armed merchant ship?

[dunmunro]

The biggest problem that an AMC has is the lack of armour and low speed, and it seems that KM raiders were not equipped with AP rounds for their 150mm guns. Scylla is lightly armoured, but it is sufficient to stop base fused HE rounds, and so her machinery spaces would have been almost immune to the AMC's guns, while Scylla's rapid fire 4.5" HE rounds would have been highly effective against an AMC. Baring a torpedo hit, Scylla would rapidly destroy the raider, and would not be in any danger of being sunk in return.

[dunmunro]

Transcription of an image file posted on another board:

Page 13 of (HMS) Excellent's Ro.291/K.1160/5 dated 26th July, 1939.

report of firing trials of 5.25" Pilot Equipment in HMS Iron Duke.

Appendix 1 (continued)
RATE OF FIRE TRIALS.

SERIES--1. (I think it reads series but it was hard to decipher)

(a) The following rounds were fired:-

Rounds Per Gun. Elevation(degrees). Recoil (inches). Bearing(degrees).
Left gun only.

20-----------------65 to 70-----------23.9-------------R.90


(b) The RoF was 7.5 RPG/minute

(c) The first 10 rounds were fired at 65deg elevation at which the RoF was 9.1 RPM
disregarding one long firing interval of 11.6 seconds owing to the trigger not being properly pressed.

(d) The HA hoists were used for this series.

(e) Sharp corners at the rear of the LA hoist are liable to injure the tray worker.
(See Item 54, Appendix II.)

(f) The coaming at the inboard side of the empty cylinder compartment impedes the
assistant tray worker loading cartridges at angles approaching maximum elevation.
(See Item 10(b), Appendix II.)