soc.history.war.world-war-ii

wrote in message
news:390dfe37-5d40-4725-a1b4-4f2d46ea117c@f47g2000hsd.googlegroups.com...

(On RN Fire controls)

> I would like to know what this advance fire control system that was in
> service in 1940-1942 actually was.

> http://en.wikipedia.org/wiki/QF_2_pounder_naval_gun
> "An advanced weapon when introduced, by the outbreak of World War II
> advances in aircraft had effectively made it obsolete. It was intended
> that the curtain of fire it threw up would be sufficient to deter
> attacking aircraft but lack of a suitable tracer round meant that the
> barrage was unseen and so the deterrence factor was prevented from
> being effective. It had a low velocity due to the relatively short
> barrel and small charge, the fuse mechanism was unsatisfactory, the
> weapons were extremely complex and prone to jamming, and the mountings
> were enormously heavy and complicated and could not be produced
> quickly enough or fitted widely enough. When HMS Prince of Wales was
> attacked and sunk by Japanese aircraft near Singapore the subsequent
> report judged that the single 40 mm Bofors gun, mounted on the
> quarterdeck, had been a more effective anti-aircraft weapon than the
> entire battery of multiple pom-pom mounts. Nevertheless, it was a
> ubiquitous weapon that was never entirely displaced by the Bofors gun
> during World War II. Later innovations such as remote power control
> (RPC) coupled to an effective radar-equipped tachymetric (speed
> predicting) director increased the accuracy enormously, and problems
> with the fuses and reliability were also addressed. The single
> mountings received a reprieve towards the end of the war, as the 20 mm
> Oerlikon guns had insufficient stopping power to counter Japanese
> Kamikaze aircraft and there were insufficient numbers of Bofors guns
> to go round."

> So the advanced light AA was unable to do much for HMS "Prince of
> Wales" presumably because it wasn't advanced enough to make a
> difference.

The most comprehensive set of figures for naval AA
performance I can easily find is the set relating to the
USN in the period 1 October 1944 to 31 January 1945,
broken down into Kamikaze and non Kamikaze attacks, then
by 5 inch common shells, 5 inch proximity fuse, 3 inch,
40 mm, 1.1 inch, 20 mm and 0.50 inch.

The following table is weapon or shell, (kills /
ammunition use per kill for Kamikaze) / then for non
Kamikaze actions.

5 inch common / (19/1,162) / (33.5/960)
5 inch proximity / (24.5/310) / (20/624)
3 inch / (6.5/710) / (4/752)
40 mm / (114/2,272 / (46/3,361)
1.1 inch / (1/2231) / (no kills/4,764)
20 mm / (62.5/8,972) / (50.5/7,152)
0.50 inch / (2.5/28,069) / (3/15,139)

To emphasise the way these are a guide the figures also
give monthly average expenditure per kill, so for 5 inch
common in non Kamikaze actions the figures range from
748 in October to 2,601 in November 1944. The Kamikaze
actions vary even more so, minimum 493 in December 1944
and maximum 2,675 in January.

It is interesting to note the way 5 inch proximity fuses
were much better against Kamikazes nearly 4 times as good
on average than the 5 inch common but only about 1.5 times
as good for conventional attacks, showing the speed of the
Kamikaze attack was stretching the fire controls. The way
the Kamikazes came closer to the ships helps explain the
improvement in 3 inch and 40 mm kill rates, but the reverse
is true of the 20 mm and 0.50 inch presumably for the
reasons mentioned in many references, by the time the
lighter guns were in action the need was to destroy the
aircraft, not bring it down and they were too light.

The above figures do not give the other factor which is
the ratio of damaged to shot down attackers. The figures
in Mighty Eighth War Diary are a guide, though of course
the aircraft involved were much more damage resistant than
anything the Japanese had and they were much higher in the
sky, making them harder to hit. On the other hand the flak
concentrations around the oil refineries were heavy.

In the following examples I am using oil targets on days
when visual bombing was done and the bombers reported
zero or a few air to air kills.

So when 262 the 8th Air Force B-17s hit mainly oil targets
on 20 July 1944 2 were lost and 153 damaged. The raid on
Politz by 142 bombers saw 17 shot down and 106 damaged.
The raid by 209 bombers on Zeitz and Rositz lost 6 bombers
and had another 88 damaged. So AA fire was clearly hitting
many more bombers than shooting them down.

As an aside the 28 July 1944 raid on Leuna by 652 bombers
plus another 62 attacking other targets used radar bombing,
claimed 1 kill and lost 7 bombers plus 217 damaged.

Anyway with that in mind we turn to force Z versus the IJN
in December 1941. The main reference being used is
Battleship my Middlebrook and Mahoney, which uses the
Japanese official history as the source for Japanese losses.
The weather was clear, the sea calm.

8 level bombers, Prince of Wales initially plotted them at
range 16,500 yards assuming the enemy altitude was 10,000
feet and speed 200 mph, "really reliable" range at about
12,000 yards which was when firing began. The system was
the gunnery officer pressed a button and the guns were then
automatically fired at the correct time for the fuse settings.
Repulse opened up at 11,000 yards, the attack was made on
Repulse but the aircraft flew over Prince of Wales.

Prior to the attack Admiral Phillips had ordered a 30
degree turn to starboard then as the guns were firing a
50 degree turn to starboard. The result was the AA guns
on each side of the ships were able to fire, then masked
then able to fire. With gaps between masking an unmasking.
The light AA guns were not within range of the attack.

One bomb hit. 108 5.25 inch and 36 4 inch rounds were fired
hitting 5 of the 8 aircraft, two of which immediately aborted.

Second attack by 9 torpedo aircraft, initially flying at about
7,000 feet but diving, aiming for Prince of Wales, the attacks
were delivered at 150 knots and 33 metres in height. Torpedoes
released at 1,500 to 600 metres, the longer ranged ones possibly
due to HMS Express being in the way. Twelve 5.25 inch salvoes
had been fired before going over to barrage fire. The pom
poms were suffering ammunition problems, causing one to jam
12 times and another 8 times. The aircraft swept over Prince
of Wales machine gunning it. One aircraft was shot down just
after torpedo release, 3 others sustained minor damage.

Two torpedo hits, the killer was aft near the propeller shaft,
dropping speed to 15 knots and causing at least an 11.5 degree
list. With the stern now 2 feet above water level, not the
usual 24 feet. Most of the AA guns lost power for a while.

Third attack by 7 torpedo aircraft on Repulse, coming in
at over 200 knots, Repulse had the same pom pom ammunition
problems and one if its mounts had lost power because of the
bomb hit. (There is a contradiction in the records here,
the Japanese claim another 8 torpedo bombers attacked as
well but the British do not record it, this second squadron
reported no aircraft damaged for 4 hits) Also 6 level bombers
attacked, the remainder of the original bomber formation dropping
their second bomb. Two of the 7 torpedo aircraft had hang ups,
one did a lone attack to release it, four of the seven received
light damage.

All up according to Japanese sources 8 bombers and 24 torpedo
aircraft had attacked claiming some bomb and 7 torpedo hits on
Repulse for 1 aircraft lost, 2 seriously damaged and 10 slightly
damaged. So far Repulse had taken one bomb hit and Prince of
Wales two torpedo hits and men had been lost to machine gun fire.

Prince of Wales lost all power the aft part of the ship, making
the aft heavy AA guns effectively useless, the list meant the
forward heavy AA guns could be elevated but not trained.

The next attack was by 26 torpedo bombers, one squadron attacked
scoring 4 hits on Prince of Wales from 6 torpedoes fired. A second
took on Repulse scoring 1 hit and the final 9 did the best attack of the
day, losing two aircraft and scoring 3 hits on Repulse, which also
took a long range strike from one of the second squadron to attack.
All up some 2 aircraft were shot down, 3 seriously damaged and 5
slightly damaged during this attack. One of the pom pom crew
recorded the torpedoes were being launched out of effective range
of the pom poms, so they shot down the aircraft crossing the ship
instead of switching fire as per doctrine to aircraft that had not
attacked yet.

Final bombing attack 8 level bombers, target Prince of Wales,
two heavy AA turret could shoot but the their range taker had
been wounded. The second round of torpedo strikes had solved
the list problem. One bomb hit scored for 5 damaged bombers.

By the looks of things Force Z expended under 400 rounds of
heavy AA ammunition plus plenty of light AA rounds. For 3
kills, 5 heavily damaged and 20 lightly damaged. Out of 72
attacks (22 bomber, 50 torpedo) noting 6 aircraft did two
attacks, so 66 aircraft.

People can decide for themselves how good the above
results were, with the additional note as the first torpedo
strike came in Admiral Phillips was certain it was not
a torpedo strike.

One final point attacking aircraft need to be flying straight
for a time before releasing their weapon. Slips or skids will
skew the aim. Dive bombers are at a constant speed losing
height at a constant rate. Torpedo bombers want to avoid
tossing the torpedo or causing it to dive further than normal
when entering the water so try to be in level flight.

Geoffrey Sinclair
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