| Notes:
1) The following description is adapted
from "Naval Weapons of World War Two.
Propellant bags were transported
from their storage locations in the magazines on roller chutes into hydraulically
operated cages that raised them to the handling room. A and B mountings
had four cages, but Y turret had two. Y turret had two double-door
scuttles in place of the other two hoists, primarily because of the reduced
vertical spacing for this mounting. In the handling rooms, bags were
manually rolled or slid over to open waiting trays from which they were
then manually carried to cordite hoppers. There was one hopper per
gun on a circular platform connected to the hoist trunk. Power-rotated
scuttles and chain rammers transferred the bags to the lower hoist cage.
This cage had two compartments which each held two propellant bags (half
charge).
Projectiles were moved from the shell rooms
by overhead trolleys and then rammed over hinged shell trays through openings
normally closed by watertight doors to the revolving shell ring in the
shell handling room. The shell rings for the quad mountings held
16 trays in four groups spaced 90 degrees apart while the twin mounting
had 8 trays in four groups spaced 90 degrees apart. The shell room
ring could either be coupled to the ship or to the revolving stalk.
When coupled to the ship, the shell ring was driven by a 24 bhp hydraulic
engine that was connected via a flexible coupling, friction clutch, worm
gear and pinions with allowance for eccentricity and a rise and fall of
up to 1 inch (25 mm) of the ring in relationship to the mounting.
When coupled to the stalk, a similar hydraulic engine was used but the
connection to the shell ring did not have any provision for eccentricity
or relative motion. [Editor's note: This ring proved not to be flexible
enough to withstand the twisting of the ship as it moved through the waves
or made sharp maneuvers and was a source of jamming] Projectiles
were rammed into the upper hoist cage when the ring was coupled to the
stalk.
The lower hoists were operated by winches
having two reel drums of different diameters on the same shaft which meant
that the propellant and shell cages arrived together at the working chamber
below the gunhouse. Projectiles and propellant bags were rammed from
the cages into traverses which ran on rails across the chamber to the gun
loading hoist cage. This was a three level container with the shell
on top and half charges in each of the two lower compartments. The
hoist then ran up to the gunhouse at a slant such that the loading cages
were at the +5 degree loading angle when they reached the gun breeches.
After the shell was rammed, the cage incremented upwards twice as the half
charges were rammed.
Magazines were located below the shell
rooms.
2) Training was by one of two swashplate engines,
160 bhp in the quads and 70 bhp in the twin, which drove the turrets via
a worm gear. Elevation was by hydraulic cylinder and piston connected
to the rear of the cradle and run out was via compressed air. RPC
equipment was never fitted to any of these ships, they used "follow the
pointer" style control throughout their careers.
3) These mountings had very elaborate flash
precautions, perhaps overly so given the problems encountered during World
War II.
4) "The Big Gun" states that the quadruple
mounting had over 3,000 working parts.
5) These turrets had a vertical roller
race similar to the ones added to the Nelson and Rodney in the 1930s.
These were located just below the main horizontal roller races.
6) The gun axes were 96 in (244 cm) apart
in both the twin and the quad mountings.
7) Rangefinders in A and X turrets had
a baselength of 41 feet (12.5m) while the rangefinder in B turret had a
baselength of 30 feet (9.10 m).
8) Some details of the problems found in
action with these mountings during the 1941 battles: Prince of Wales
fired only 55 out of a possible 74 shells during her action with Bismarck.
Her problems included jammed shell rings and associated fittings.
King George V fired 339 shells during her engagement with Bismarck compared
to 380 fired by Rodney.
9) The following description of the problems
encountered by King George V is taken from "The Final Action: The
Sinking of Bismarck, 27 May 1941" by John Roberts:
"Initially she did well achieving
1.7 salvoes per minute while employing radar control but she began to suffer
severe problems from 0920 onward [Note: King George V had opened
fire at 0850 - TD]. 'A' turret was completely out of action for 30
minutes, after firing about 23 rounds per gun, due to a jam between the
fixed and revolving structure in the shell room and Y turret was out of
action for 7 minutes due to drill errors. . . Both guns in B turret, guns
2 and 4 in A turret and gun 2 in Y turret were put out of action by jams
and remained so until after the action - 5 guns out of 10! There
were a multitude of other problems with mechanical failures and drill errors
that caused delays and missed salvoes. There were also some misfires
- one gun (3 of A turret) misfired twice and was out of action for 30 minutes
before it was considered safe to open the breech."
[Editor's Note: The ellipsis in this
paragraph is to omit what I believe is actually a reference to the performance
of Rodney's 16"
(40.6 cm) guns which was mistakenly included in this description]
Admiral Sir John C. Tovey, C-in-C Home
Fleet, commented upon some of these problems in his after-action report
PRO Adm 234/509:
"Comparatively little experience
had previously been gained of the reliability of the turrets. The
prolonged practice firing for the King George V had been carried out only
in one turret. It was fortunate that the action [against Bismarck]
was not prolonged, because the 25 rounds per gun practice previously planned
would not have shown up so many of the defects."
10) Following the Bismarck battles, King George
V and Prince of Wales had numerous modifications made to their ammunition
supply safety interlock system; the watertightness of the mantlet plates
was improved; and the existing drains in the shell rooms were enlarged
and additional drains fitted. These changes were incorporated into
the rest of the class as they were being built.
11) During her battle with Scharnhorst
at North Cape, Duke of York was shooting for a total of two hours.
Mechanical problems suffered included failures of the bridge flash tubes
in the working chambers to close completely, the collapse of shell arresters
in the lower hoists and a shell-cage defect in A turret, all of which caused
some guns to drop out of firing opportunities. All guns suffered
at least some failures to fire, with B1 gun being the most reliable, having
missed only three out of the 77 broadsides. Notable among these missed
salvos: Poor loading drill put A3 gun out of action for 71 of the
77 broadsides. Three guns in Y turret were unable to fire for a 15
minute period, causing them to miss 17 broadsides.
12) Some comments from William Jurens regarding
the vertical face plates of these turrets.
"The reason for sloped turret
faces is primarily geometric. For normal trunnion locations, if the
turret face is not sloped back, then for large angles of [gun] elevation,
as in post-1930 ships, the gunports get very large and start to eat away
at the turret roof. If the angle of elevation is small as on older
ships, [then the] angles of fall [of shells fired by enemy ships] would
be equally small, so a slanted faceplate which would deflect rounds upward
makes sense. If the angle of elevation is large and a vertical front
plate is seen to be desirable, as in KGV etc., then one answer to avoiding
cutting long slots in the roofplates is to move the trunnions far forward.
This makes the overall rotating structure and the guns themselves harder
to balance and complicates gun elevation mechanisms. On KGV a compromise
was made; the trunnions were moved as far forward as possible, and the
front plate was moved BACK as far as was feasible. Even so, the maximum
angle of elevation was limited to 40 degrees. There is little saving
in weight in moving to a vertical faceplate, in some cases less than none.
. . . moving from a sloped to a vertical
faceplate is usually nearly weight-neutral, although some savings can be
achieved by thinning the vertical face somewhat as it is now much more
oblique to incoming (long-range only) fire than a sloped face is.
Several problems remain. On KGV, moving the face back left an inconvenient
"D" shaped portion of the top of the barbette uncovered forward of the
faceplate, a situation aggravated by the probability that long range fire,
even if deflected, would be channeled downwards into the "D". On
KGV, this "D" underneath the gun chases was about 115 ft2 (10.7
m2) in area, which needed to be protected at least as well as
the turret roof. This added protection would weigh about 13 additional
tons. A final problem lies in the construction of the face plate
itself. Such a plate is much stronger if it can be made in one piece
with two, three, or four (as required) vertical slots cut into it for gunports.
This in turn requires at least a thin band of material above and below
the port openings to hold the whole thing together. Because the slots
are quite problematical in a vertical plate to begin with, there is a tendency
to revert to installing a number of smaller plates joined together, which
is not as strong, though arguably cheaper to manufacture.
Overall, I suspect that vertical faceplates
create more problems than they solve, and their advantages (if any) are
marginal, which is likely why so few ships ever adopted them."
As can be seen in the photographs above, the
quad turrets on the King George V class have a semi-circular plate of armor
attached to the lower front plate of the turret. This plate protects
the top of the barbette.
13) Two guns were mounted at Dover in 1940,
one in No. 26 Proof Structure and the other in a 18"/40
(45.7 cm) mounting removed from a monitor.
14) Armor thickness for both twin and quad
mountings as given in "Naval Weapons of World War Two" by John Campbell:
Face: 12.74 in
(32.4 cm)
Fore Sides: 8.82
in (22.4 cm)
Rear Sides: 6.86
in (17.4 cm)
Rear: 6.86 in
(17.4 cm)
Roof: 5.88 in
(14.9 cm) |
