British 4.5"/45 (11.4 cm) vs American 5"/38 (12.7 cm) Mark 12

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wmh829386
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Re: British 4.5"/45 (11.4 cm) vs American 5"/38 (12.7 cm) Mark 12

Post by wmh829386 »

dunmunro wrote: Wed Oct 13, 2021 10:25 pm
GRU/GRUB (Naval Weapons of WW2):
GRUB enabled the observed angle of
presentation and target ground speed to be
applied to the HA table, whether the
observed values were from GRU or control
officer's estimates. Under windless con-
ditions and with GRUB controlling, any
form of spotting correction was far more
likely to do harm than good, but GRUB
had no wind corrector and the control
officer might have to override.
He also had
to inform the GRUB operators of any
observed alteration of target's course,
warning them that a new setting of the
presentation follow up handwheel was
necessary.

If the target was seen to climb or dive,
continuous operation of presentation
follow up and target speed handwheels was
ordered by the control officer. The design
of GRUB assumed straight and level flight
and it could generate fresh rates auto-
matically only as long as level flight was
maintained. GRU could still measure
vertical and lateral rates if the target was
not in level flight and GRUB could be set
to give these rates by fictitious speed and
target plan inclination. These in turn gave
deflections acceptable for small angles of
climb and dive.
Apparently Friedman is not the only source.
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Re: British 4.5"/45 (11.4 cm) vs American 5"/38 (12.7 cm) Mark 12

Post by dunmunro »

wmh829386 wrote: Sun Jan 16, 2022 3:05 am

You are quoting AFCC manual, but the data flow diagram from Tribals shows the FKC directly generate gun elevation order, bypassing AFCC. There is no wind input at the FKC so elevation is not corrected. You might want to check it again.
https://www.kbismarck.org/forum/downloa ... hp?id=3921

There's three inputs:

Gun deflection = wind input
Gun elevation
Gun range = Wind input. Gun range is a modifier to gun elevation.
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Re: British 4.5"/45 (11.4 cm) vs American 5"/38 (12.7 cm) Mark 12

Post by dunmunro »

wmh829386 wrote: Sun Jan 16, 2022 3:14 am
dunmunro wrote: Wed Oct 13, 2021 10:25 pm
GRU/GRUB (Naval Weapons of WW2):
GRUB enabled the observed angle of
presentation and target ground speed to be
applied to the HA table, whether the
observed values were from GRU or control
officer's estimates. Under windless con-
ditions and with GRUB controlling, any
form of spotting correction was far more
likely to do harm than good, but GRUB
had no wind corrector and the control
officer might have to override.
He also had
to inform the GRUB operators of any
observed alteration of target's course,
warning them that a new setting of the
presentation follow up handwheel was
necessary.

If the target was seen to climb or dive,
continuous operation of presentation
follow up and target speed handwheels was
ordered by the control officer. The design
of GRUB assumed straight and level flight
and it could generate fresh rates auto-
matically only as long as level flight was
maintained. GRU could still measure
vertical and lateral rates if the target was
not in level flight and GRUB could be set
to give these rates by fictitious speed and
target plan inclination. These in turn gave
deflections acceptable for small angles of
climb and dive.
Apparently Friedman is not the only source.
GRU/GRUB was designed for short range accuracy where wind effects were minimal, similar to Mk51.

Also GRUB used an alternate set of projected light strips on the deflection display, not the crosswires normally used by HACS.
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Re: British 4.5"/45 (11.4 cm) vs American 5"/38 (12.7 cm) Mark 12

Post by Steve Crandell »

Could GRUB be linked to the HAA like Mark 51?

Were there British ships with Mark 51?
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Re: British 4.5"/45 (11.4 cm) vs American 5"/38 (12.7 cm) Mark 12

Post by dunmunro »

Steve Crandell wrote: Sun Jan 16, 2022 2:16 pm Could GRUB be linked to the HAA like Mark 51?

Were there British ships with Mark 51?
GRUB was linked to the same guns as HACS or FKC.

The RN used some lendlease Mk51s, and some UK built Simple Tachymetric Directors (Friedman calls these Standard Tachymetric Directors), which had the same functionality. They also employed the Mk IV Pom-pom director.

Campbell:
Owing to an inadequate supply of Mk
51, a British version was produced. It wa
known as the Simple Tachymetric
Director (STD) Mk I, or as the 'Austerity
Director. This was first indended for the
Mk XI Bofors gun in the twin RP 50 MkV
mounting, but could be used with any
mounting with RPC and/or Magslip re
ceivers. The Mk 14 sight was soon super-
seded by the British Type 6 Mk II, with
maximum deflection reduced from 24° to
11%%°. Wind corrections could be made at
the price of doubling the crew to two.
Weight, with Type 6 sight, was 11201
(508kg). The overall performance was con-
sidered to be about the same as or a little
better than the Mk IV pom-pom director
and 1945 policy was for it to replace the
latter as opportunity occurred.
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Re: British 4.5"/45 (11.4 cm) vs American 5"/38 (12.7 cm) Mark 12

Post by Steve Crandell »

I believe the Mark 51 required that the guns had RPC. Was that true of GRUB? Which British HAA had RPC? You said GRUB controlled the same guns as HACS or FKC, so does that mean one GRUB would control ALL HAA by switch transfer? Each Mark 51 was only connected to 5" mounts which could bear on the same target as the Mark 51, and it was switched between that and Mark 37.
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Re: British 4.5"/45 (11.4 cm) vs American 5"/38 (12.7 cm) Mark 12

Post by dunmunro »

Some notes on prewar RN drone trials.

The RN used 'innocuous' shells against drone targets. These shells had special low power, black powder bursters, designed to create a visible smoke cloud whilst minimizing the fragmentation effect. Therefore they had a lower kill probability than a service shell. Early drone trials also used the powder fuze MT fuzes (~.6sec error) whilst later trials and WW2 service shells used a clockwork MT fuze (.15sec error)
~
Friedman:
Work on radio-controlled targets seems not to have resumed until about 1930. In 1932 the RAF
modified three standard fleet floatplanes (Fairey IIIFs called Fairey Queens) into radio-controlled
drones. The first two were damaged beyond repair while being catapulted by the battleship Valiant,
but the third was successfully launched in the autumn. It made a short trial flight, which demonstrated
that it could be controlled in the air and landed on its float. Arrangements were made to use it as a
Home Fleet target off Gibraltar during the 1933 Spring Cruise, and plans were made to develop a
smaller and less expensive drone which could be maintained by RAF and Fleet Air Arm personnel.
The cruiser Sussex shot down the sole Fairey Queen late in May 1933 on the ninth salvo of Run
2. The ship had 48 per cent of her bursts within 100 yds during Run 1 and 59 per cent during Run 2
(100 yds was considered satisfactory). As a result of the Fairey Queen trials, the Air Ministry carried
out further trials with radio-controlled De Havilland Moths which were called Queen Bees. Four
were to be made available to the Mediterranean Fleet in June 1934, and four more to the Home Fleet
in the autumn of that year. Unfortunately these targets could not simulate dive bombing.
Initial experiments showed that anti-aircraft effectiveness was much less than had been
imagined. Reporting on Queen Bee firings in the Mediterranean, Vice Admiral 1st Battle Squadron
pointed out that the standard of placing rounds within 100 yds of a target was misleading. In one
exercise, although 59 per cent were within 100 yds, only 1.56 per cent would have scored actual hits.
No more than a quarter of 4in shells within 100 yds would cause damage to an aircraft, and the other
three-quarters should be scored as close misses. The fleet commander agreed; probably only 1/30th
of these shells would damage an aircraft. Experiments by the all-service Ordnance Committee
showed that a 4in HE shell had to burst within 70ft to cause decisive damage, and outside 140ft there
would probably be no damage at all. The 100 yd standard had been adopted because it was
impossible to determine the position of a shell burst any more accurately – the percentage within 100
yds was really no more than a way of assessing accuracy.
A contemporary account states 100ft rather than 100yds as the desired standard of accuracy.

More info on the Sussex drone kill:
Fisher to Chatfield
[CHT/4/5] Malta, 29 May [1933]
Sussex will tackle the High bombing mission.
Revenge " " " Medium height ".
R.[oyal] Sov[ereign] " " " Mark M. Pom-pom
I am satisfied that the ships have been well trained – but to produce hits
with such a small volume of fire as is given by a pair of guns only in the
bombing runs may prove difficult. If we can’t I think that we shall
probably be able to say that it is not the system which is at fault but the
inadequate number of guns...
Just back from Fairey Queen trials. Started off at 8.30 but low cloud &
then no wind prevented a start. At last at 2.30 p.m. the conditions became
well nigh ideal & to our relief. London shot the F.Q. off & she sailed away
without a falter. An hour after she had climbed as high as they could get
her but it was short of 10,000 ft. (nearer 9000 I believe) and Run 1 was
started, F.Q. coming in at roughly right angles from the port beam of
Sussex.
She managed to pick her way through all the bursts the first run which
was average shooting, not more than that, 1 or 2 very close but not
consistent fine [?] rate of fire. The 2nd run started about 10 mins. later
and I think Sussex had got over stage fright for the bursts were close from
the start and before it was 1∕3 over the F.Q. was hit, threw her nose up into
the air, altered course right round & came spinning down into the water.
I’m afraid she sank before anyone could get to her. The Sussex’s gave a
great cheer but the R. Sov.s and Revenges were very glum about being
baulked of their go at her. One can’t help feeling glad that she only lasted
about 3 minutes altogether (this is a guess only, I not sure really[?]) and
at the same time sorry that so splendid a target couldn’t have had more
ships firing at it...

Fisher to Chatfield
[CHT/4/5] Queen Elizabeth, Alexandria
25 October 1935
...We keep up our programmes of exercise and firings at sea just as if we
were at Malta. Every day & most nights squadrons or flotillas are at sea
and so far we have managed to get in and out of this congested harbour
without incident. Yesterday I counted 84 ships or vessels under my orders
here in Alexandria alone.
Air attacks on the Fleet in harbour & at sea day & night all days except
Sat. & Sun.
The H.A. fire is variable. I saw the 1st B.S. fire the other day at a sleeve
[target], single ships & then massed firing. No formation could have
survived either. Later I saw the 8″ cruisers who had previously been better
than battleships and was very disappointed. But a very big target is I feel
sure going to be very different from the generally almost invisible sleeve.
I am satisfied that we are getting better & that an occasional shoot is not
a bad thing if only to avoid complacency...

Fisher to Chatfield.
[CHT/4/5] Commander-in-Chief, Mediterranean Station.
Alexandria, 25 February [1936]
...We have started our Queen Bee1 firings. Going slow with the attack on
them so as to preserve their lives, but despite firing one gun at a time with
[black-DM]powder filled shell, we have shot down 3 out of the four at 8000′.
Coventry has not got going properly yet & Curlew has only just arrived,
but both ships are pretty keen...


Commander-in-Chief, Mediterranean Station
H.M.S. Queen Elizabeth, Alexandria
6 March [1936]

...We have had some splendid clear days with the Queen Bees and some
with crossing clouds. I have seen most of them myself and believe it is
not an exaggeration to say that given an uninterrupted view and the Q.B.
steering a steady course the majority of ships if they use H.E. will hit it
in the first run. But when bursts are close the Q.B. is made to jink. This
saves her if only one ship is firing. Neither she nor a formation could
bomb accurately under those circumstances. [Added in margin] A big
formation of S.81s approaching to bomb the Fleet and keeping together,
as they should do, is now a pleasant dream, certainly not a nightmare...

...Pound to Chatfield.
[CHT/4/10] Commander-in-Chief, Mediterranean Station
31 March [1936]
We had completed the Queen Bee firings just before I took over and as
this was a kind of peak of an intensive exercise programme lasting over
several months I have given the Fleet a fortnight off these weekly
programmes before commencing them again...


Memorandum by Admiral Sir William W. Fisher1
[CAB 16/147] n.d. [29 June 1936]
SECRET.
My Flag has been flying with one brief interlude for the last five years
in the Mediterranean and I have, therefore, been in a position to watch the
progress made in the H.A. fire of the Fleet since this was first seriously
tackled by my predecessor in Chief Command, the present First Sea Lord.
2. In August of last year a period of danger supervened and since that
date A.A. training has been intensive in all units of the Fleet resulting in
the doubling of the rate of fire of the 4-inch gun (now 16 to 20 rounds per
minute) and an increase in effective accuracy that is difficult to measure
but very obvious to see.
3. Being well aware that the principal menace to the Mediterranean
Fleet lay with submarines and aircraft, it was natural that every important
exercise set to combat these should have been witnessed by me. In the
last six months I saw over 100 runs by ‘Queen Bees’ and many hundreds
of runs with the sleeve target. The defence of the Fleet in an open
anchorage has been frequently practiced and those factors making for
combined A.A. defence by ships and shore batteries have been exercised
and developed at Malta, Haifa and Alexandria daily and nightly, excepting
Saturdays and Sundays. The appointment of an Air Defence Officer in
each ship and the inclusion of a Senior Officer on my Staff as Fleet Air
Defence Officer has led to an all-round improvement in control,
communications, lookouts and loading.
4. As regards the Fleet’s main base – Alexandria – we had to guard
against long-range bomber attack from Libya and attack by flying boats
from the Dodecanese. When the situation warranted two arcs of sea patrols
at radii of about 75 and 150 miles were arranged for (and exercised) in
addition to the military shore look-outs in the Western desert. I counted
on getting sufficient warning by telephone or W/T to man all guns, and
lights, both afloat and ashore, and to have fighters in the air to intercept.
I mention this as being a typical state of affairs applicable to almost any
harbour that the Fleet might be using. With all the Fleet in Alexandria I
calculated that from 40 to 80 H.A. guns (4-inch and above) could be
brought to bear on an enemy formation depending on the direction from
which it approached.
5. The defence of the Fleet at sea depends on the suitability of the
‘Cruising order’ which was such as to give the greatest chance of early
warning of the approach of enemy aircraft and the development of
maximum gunfire as soon as they came in range.
6. The result of the intensive training was that instead of being
extremely apprehensive of what might happen were the Fleet attacked in
harbour or at sea, I became tolerably sure that the enemy, and not we,
would suffer most. No Fleet could, however, be expected to resist repeated
attacks such as might have been possible if a base closer than Alexandria
to Italian shore-based aircraft had been used or if the Fleet had
continuously cruised in waters within easy striking distance of them.
7. The small ‘Queen Bee’ target provided our most realistic test. I
expected a single well-trained ship firing two gun salvoes to be on the
target in under 30 seconds after her first shell had burst. With a larger
target to observe on (such as an S.81) and still more with a formation,
effective fire should occur earlier and if instead of one ship a squadron is
firing I am sure a formation would be broken up and receive many
casualties

Halperen, The Mediterranean Fleet 1930-39
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Re: British 4.5"/45 (11.4 cm) vs American 5"/38 (12.7 cm) Mark 12

Post by dunmunro »

Steve Crandell wrote: Sun Jan 16, 2022 4:57 pm I believe the Mark 51 required that the guns had RPC. Was that true of GRUB? Which British HAA had RPC? You said GRUB controlled the same guns as HACS or FKC, so does that mean one GRUB would control ALL HAA by switch transfer? Each Mark 51 was only connected to 5" mounts which could bear on the same target as the Mark 51, and it was switched between that and Mark 37.

IIRC, MK51 controlled 5in guns via FtP control. GRU/GRUB was incorporated into the HADT (GRU)/HA Transmitting Station (GRUB). it sent gun mount control signals through the regular FC circuits and could control either RPC or FtP mounts and could be connected to any or all HA mount as required via change over switches, The theory of operation of Mk51 and GRU was similar in that they measured target motion via gyro gunsights, and used a simple computer to calculate and transmit the needed gun orders.
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Re: British 4.5"/45 (11.4 cm) vs American 5"/38 (12.7 cm) Mark 12

Post by Steve Crandell »

Doesn't sound like someone who thinks HA fire is useless. Presumably his thinking changed at some point, since you have determined that HA fire doesn't do very much.
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Re: British 4.5"/45 (11.4 cm) vs American 5"/38 (12.7 cm) Mark 12

Post by Steve Crandell »

Steve Crandell wrote: Sun Jan 16, 2022 6:43 pm Doesn't sound like someone who thinks HA fire is useless. Presumably his thinking changed at some point, since you have determined that HA fire doesn't do very much.

edit: was referring to the Halpern quote.
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Re: British 4.5"/45 (11.4 cm) vs American 5"/38 (12.7 cm) Mark 12

Post by wmh829386 »

Steve Crandell wrote: Sun Jan 16, 2022 2:16 pm Could GRUB be linked to the HAA like Mark 51?

Were there British ships with Mark 51?
GRU is a rate measurement device. It has its own stabilised sight so operator use joystick to follow the target. It function even on unstablised platform (pom pom director mkIV).

GRUDOU combined the rates from GRU and range to produce gun deflection. Basically GRU with GRUDOU functions as a gyro-sight operated by joystick. With radar ranging, it should behave like Mk52 director. It is used for HAA exclusively as far as I know. No RPC is required.

I have mentioned how GRU with GRUB works. Human lag is introduced and suffers from assumption in the HACT.

Use of GRU on LAA is quite early in pom pom director mkIV, but in a rather absurd form from hindsight. The rates are manually followed and input into Automatic Control Officer’s Forward Area Sight (AUTOCOFAS), which is also stabilised.

The problem is the number of crew required. A fully crewed pom pom director mklV includes.

Gunnery officer (shooting through AUTOCOFAS)
GRU operator (measuring rates)
Elevation rate follower
Bearing rate follower
Range rate follower
range finder operator (he is a backup)
Trainer
Layer (yes, the whole contraption need to be slew around)
+
Type 282 operator below deck

Friedman claims RPC is installed for pom pom paired with MkIV director.

If everyone did their job correctly and if radar is working , it is very capable and entered service in 1941. But we now know it can be cut to 1~3 officer in late war system.

The whole reasoning for implementation like GRUB in HACS and pom pom director is to treat new technologies as add-ons to existing systems. So that
1. It still works to some degree of the new part fails.
2. Allow retrofitting of existing systems.
But as everyone can tell, the result is definitely not the most efficient implementation.
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Re: British 4.5"/45 (11.4 cm) vs American 5"/38 (12.7 cm) Mark 12

Post by dunmunro »

Steve Crandell wrote: Sun Jan 16, 2022 6:44 pm
Steve Crandell wrote: Sun Jan 16, 2022 6:43 pm Doesn't sound like someone who thinks HA fire is useless. Presumably his thinking changed at some point, since you have determined that HA fire doesn't do very much.

edit: was referring to the Halpern quote.
I think the salient points are that there was over 100 observed runs and only a few drones (6 IIRC) were shot down. There probably was a tendency to overestimate the potential kill rate of service ammo vs actual targets, especially given the low speed (~100 knots) of the Queen Bee drone and the relatively low altitude (~8000ft). OTOH, if we add radar ranging, improved HACS, and VT ammo we should see a pretty good kill rate, against a TD2C drone at 130-150 knots. PoW did quite well against level bombers at ~9000ft (IIRC) using radar, even with a substantial list and half her 5.25in armament OOCS
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Re: British 4.5"/45 (11.4 cm) vs American 5"/38 (12.7 cm) Mark 12

Post by Steve Crandell »

dunmunro wrote: Sun Jan 16, 2022 7:23 pm
Steve Crandell wrote: Sun Jan 16, 2022 6:44 pm
Steve Crandell wrote: Sun Jan 16, 2022 6:43 pm Doesn't sound like someone who thinks HA fire is useless. Presumably his thinking changed at some point, since you have determined that HA fire doesn't do very much.

edit: was referring to the Halpern quote.
I think the salient points are that there was over 100 observed runs and only a few drones (6 IIRC) were shot down. There probably was a tendency to overestimate the potential kill rate of service ammo vs actual targets, especially given the low speed (~100 knots) of the Queen Bee drone and the relatively low altitude (~8000ft). OTOH, if we add radar ranging, improved HACS, and VT ammo we should see a pretty good kill rate, against a TD2C drone at 130-150 knots. PoW did quite well against level bombers at ~9000ft (IIRC) using radar, even with a substantial list and half her 5.25in armament OOCS
As I understand this post, you believe that it is actually possible for shipborne HAA to shoot down aircraft, as long as they approach in a formation on a predictable course and speed. That makes sense. Do you think a US ship might also be able to do this with Mark 37?

Unfortunately the IJN usually didn't use level bombing against naval targets, with the attack on anchored ships in Pearl Harbor a notable exception.
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Re: British 4.5"/45 (11.4 cm) vs American 5"/38 (12.7 cm) Mark 12

Post by dunmunro »

Some notes on USN prewar drone trials:
A study of the results of antiaircraft firings by the ships of the Fleet,
from July 1, 1938 to June 30, 1940, gave little cause for cheer or hope for
solution in this area. This study showed that in 307 firing runs by 1.1",
3", and 5" antiaircraft guns against high-altitude, horizontal-bombing
drone aircraft, dive-bombing drone aircraft, and low-altitude, horizontal-
bombing drone aircraft, only 5% of the drone target aircraft had been
hit seriously enough to stop the bombing attack and only 17% hit at all.""
(Dyer. On the Treadmill to Pearl Harbor)
Friedman:
Up to 1939 all conclusions had been based on towed targets. During the 1938–9 gunnery year,
however, drones (converted obsolete aircraft) were introduced, the first practices being flown in
March 1939. Drones made ten diving attacks on the gunnery experimental ship Utah, which fired her
1.1in battery at them. A drone simulated a plane passing over the screen; firing began after it passed
overhead and continued as it flew towards its objective. Drones attacking the destroyers Cushing,
Reid and Patterson made standard S runs simulating bombers approaching the force screened. Not
only could drones act as dive bombers; they could also manoeuvre freely.72 They were generally
controlled by other aircraft, flying from land bases and returning to them.
The results must have been shocking. Methods useful against sleeves failed. The volume of 5in
fire was inadequate, because guns frequently checked fire for spotting and for refining rangekeeper
solutions. Even when shells burst near a drone, it often seemed to emerge unscathed (although there
were spectacular drone crashes). Even a good fire-control solution might not be nearly enough, unless
many shells were brought into the proper range and burst properly. That was bad enough, but the
existing drones were far slower than modern aircraft. CinCUS considered the horizontal bombing
approaches unrealistically easy for the ships.73
The new realistic drone exercises highlighted fire-control alternatives. Directors could be set
for either automatic or manual rate control. In automatic control, moving the director sights (to stay on
the target) automatically corrected the set-up. In manual rate control, the operators changed the set-up
themselves, estimating how far off it had been.74 Gunners could either correct fire until they thought
they would hit, or they could fire ladders or boxes in hopes that by trying alternatives around the
expected target position they could get at least one shell within lethal range. Exercises showed many
variations of the ladder, including a ‘mechanical fuse ladder’ in which fuse settings were
systematically varied.
The rub was that individual shells were not lethal enough. Again and again, drones came back to
base with numerous holes in them. That should not have been too surprising. Tests of 5in shell
fragmentation against an obsolete aircraft (an F7B) showed that the fragments were generally about
the size of a 0.50-calibre bullet. Earlier analysis of the 0.50 vs the 1.1in gun (see above) showed that
a 0.50 would be lethal only if it hit a vital spot. The larger impact-fused shell of the 1.1in was
considerably more lethal. The fleet was unhappy; it wanted larger fragments. BuOrd replied that the
larger the fragments, the smaller the volume they would cover, because there would be fewer of them,
and also because they would be given lower velocities...

...The exercises showed that even the best anti-aircraft batteries were unable to hit manoeuvring
drones even though their manoeuvres were not radical. The volume of fire brought to bear against
high-altitude bombers was unacceptably small. The exercises did show that a longer-base stereo
rangefinder (an 8.2m instrument was tested) could help...

...The future was bleak. The maximum speed of aircraft flying below 45,000ft was expected to be
450kts. That would make anti-aircraft fire, in relation to target manoeuvres, nearly analogous to
torpedo fire – the dead time and time of flight of the projectile corresponded to the running time of the
torpedo. They had to be reduced to a minimum, and this minimum would set an upper limit on the
effectiveness of an otherwise perfect battery and fire-control system. Dead time could be reduced by
developing fuses and fuse-setters which operate during ramming. Time of flight could be reduced
either by increasing initial velocity or by increasing calibre to 6in (to decrease the effect of air
resistance). The destroyer force commander, an ordnance officer (Rear Admiral Sexton), considered
the present trend of design, including more accurate rangefinders, two-speed remote controlled fuse
setting, and mechanical time fuses, is in the right direction. The technique of firing at a manoeuvring
aircraft was closely related to the technique of manoeuvre to avoid hits. Evasive manoeuvres should
be tested in drone firings.
The manoeuvring drone experience opened a debate within the fleet. It was difficult to imagine
that any fire-control operator could anticipate target manoeuvres in three dimensions. The aircraft
would always be about 20 seconds ahead of the rangekeeper solution, since the last shell fired would
take about that long (including dead time) to get to wherever it was sent. One possibility was to keep
trying to aim for the aircraft, over-correcting for any observed manoeuvre to place bursts ahead of the
aircraft. A pilot could evade such bursts by manoeuvring (and not by much) every time a gun fired.
A second possibility was to try to bracket the aircraft, to cover its possible manoeuvres. That
required considerable skill. Worse, it would place very few bursts close enough to damage the
aircraft.
So prewar (before Dec 1941) the USN really struggled with drone targets and overall results certainly do not appear to have been better than RN drone trials. Yet when war started BuOrd reported kill rates against real maneuvering targets that were far higher than the drone trials indicated. Lundstrom's analysis seems to indicate actual AA kill rates similar to those indicated in the drone trials.
Last edited by dunmunro on Sun Jan 16, 2022 8:18 pm, edited 1 time in total.
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Re: British 4.5"/45 (11.4 cm) vs American 5"/38 (12.7 cm) Mark 12

Post by dunmunro »

D.P.
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