<s>
Ship	B-Application
gun	I-Application
fire-control	I-Application
systems	I-Application
(	O
GFCS	B-Application
)	O
are	O
analogue	O
fire-control	B-Application
systems	I-Application
that	O
were	O
used	O
aboard	O
naval	O
warships	O
prior	O
to	O
modern	O
electronic	O
computerized	O
systems	O
,	O
to	O
control	O
targeting	O
of	O
guns	O
against	O
surface	O
ships	O
,	O
aircraft	O
,	O
and	O
shore	O
targets	O
,	O
with	O
either	O
optical	O
or	O
radar	B-Application
sighting	O
.	O
</s>
<s>
Most	O
US	O
ships	O
that	O
are	O
destroyers	O
or	O
larger	O
(	O
but	O
not	O
destroyer	O
escorts	O
except	O
Brooke	O
class	O
DEG	O
's	O
later	O
designated	O
FFG	O
's	O
or	O
escort	O
carriers	O
)	O
employed	O
gun	O
fire-control	B-Application
systems	I-Application
for	O
and	O
larger	O
guns	O
,	O
up	O
to	O
battleships	B-Application
,	O
such	O
as	O
.	O
</s>
<s>
systems	O
that	O
were	O
controlled	O
by	O
electronic	O
computers	O
,	O
which	O
were	O
integrated	O
with	O
the	O
ship	O
's	O
missile	O
fire-control	B-Application
systems	I-Application
and	O
other	O
ship	O
sensors	O
.	O
</s>
<s>
The	O
major	O
components	O
of	O
a	O
gun	O
fire-control	B-Application
system	I-Application
are	O
a	O
human-controlled	O
director	O
,	O
along	O
with	O
or	O
later	O
replaced	O
by	O
radar	B-Application
or	O
television	O
camera	O
,	O
a	O
computer	O
,	O
stabilizing	O
device	O
or	O
gyro	O
,	O
and	O
equipment	O
in	O
a	O
plotting	O
room	O
.	O
</s>
<s>
For	O
the	O
US	O
Navy	O
,	O
the	O
most	O
prevalent	O
gunnery	O
computer	O
was	O
the	O
Ford	O
Mark	O
1	O
,	O
later	O
the	O
Mark	B-Device
1A	I-Device
Fire	I-Device
Control	I-Device
Computer	I-Device
,	O
which	O
was	O
an	O
electro-mechanical	O
analog	O
ballistic	O
computer	O
that	O
provided	O
accurate	O
firing	B-Application
solutions	I-Application
and	O
could	O
automatically	O
control	O
one	O
or	O
more	O
gun	O
mounts	O
against	O
stationary	O
or	O
moving	O
targets	O
on	O
the	O
surface	O
or	O
in	O
the	O
air	O
.	O
</s>
<s>
This	O
gave	O
American	O
forces	O
a	O
technological	O
advantage	O
in	O
World	O
War	O
II	O
against	O
the	O
Japanese	O
,	O
who	O
did	O
not	O
develop	O
remote	O
power	O
control	O
for	O
their	O
guns	O
;	O
both	O
the	O
US	O
Navy	O
and	O
Japanese	O
Navy	O
used	O
visual	O
correction	O
of	O
shots	O
using	O
shell	O
splashes	O
or	O
air	O
bursts	O
,	O
while	O
the	O
US	O
Navy	O
augmented	O
visual	O
spotting	O
with	O
radar	B-Application
.	O
</s>
<s>
Digital	O
computers	O
would	O
not	O
be	O
adopted	O
for	O
this	O
purpose	O
by	O
the	O
US	O
until	O
the	O
mid-1970s	O
;	O
however	O
,	O
it	O
must	O
be	O
emphasized	O
that	O
all	O
analog	O
anti-aircraft	O
fire	B-Application
control	I-Application
systems	I-Application
had	O
severe	O
limitations	O
,	O
and	O
even	O
the	O
US	O
Navy	O
's	O
Mark	O
37	O
system	O
required	O
nearly	O
1000	O
rounds	O
of	O
mechanical	O
fuze	O
ammunition	O
per	O
kill	O
,	O
even	O
in	O
late	O
1944	O
.	O
</s>
<s>
The	O
Mark	O
37	O
Gun	O
Fire	B-Application
Control	I-Application
System	I-Application
incorporated	O
the	O
Mark	O
1	O
computer	O
,	O
the	O
Mark	O
37	O
director	O
,	O
a	O
gyroscopic	O
stable	O
element	O
along	O
with	O
automatic	O
gun	O
control	O
,	O
and	O
was	O
the	O
first	O
US	O
Navy	O
dual-purpose	O
GFCS	B-Application
to	O
separate	O
the	O
computer	O
from	O
the	O
director	O
.	O
</s>
<s>
The	O
director	O
system	O
of	O
fire	O
control	O
was	O
incorporated	O
first	O
into	O
battleship	B-Application
designs	O
by	O
the	O
Royal	O
Navy	O
in	O
1912	O
.	O
</s>
<s>
The	O
director	O
became	O
a	O
design	O
feature	O
of	O
battleships	B-Application
,	O
with	O
Japanese	O
"	O
Pagoda-style	O
"	O
masts	O
designed	O
to	O
maximize	O
the	O
view	O
of	O
the	O
director	O
over	O
long	O
ranges	O
.	O
</s>
<s>
Coordinated	O
gunfire	O
from	O
a	O
formation	O
of	O
ships	O
at	O
a	O
single	O
target	O
was	O
a	O
focus	O
of	O
battleship	B-Application
fleet	O
operations	O
.	O
</s>
<s>
Corrections	O
can	O
be	O
made	O
for	O
surface	O
wind	O
velocity	O
,	O
roll	O
and	O
pitch	O
of	O
the	O
firing	O
ship	O
,	O
powder	O
magazine	O
temperature	O
,	O
drift	O
of	O
rifled	O
projectiles	O
,	O
individual	O
gun	O
bore	O
diameter	O
adjusted	O
for	O
shot-to-shot	O
enlargement	O
,	O
and	O
rate-of-change	O
of	O
range	O
with	O
additional	O
modifications	O
to	O
the	O
firing	B-Application
solution	I-Application
based	O
upon	O
the	O
observation	O
of	O
preceding	O
shots	O
.	O
</s>
<s>
More	O
sophisticated	O
fire	B-Application
control	I-Application
systems	I-Application
consider	O
more	O
of	O
these	O
factors	O
rather	O
than	O
relying	O
on	O
simple	O
correction	O
of	O
observed	O
fall	O
of	O
shot	O
.	O
</s>
<s>
The	O
Royal	O
Navy	O
considered	O
Russia	O
a	O
potential	O
adversary	O
through	O
The	O
Great	O
Game	O
,	O
and	O
sent	O
Lieutenant	O
Walter	O
Lake	O
of	O
the	O
Navy	O
Gunnery	O
Division	O
and	O
Commander	O
Walter	O
Hugh	O
Thring	O
of	O
the	O
Coastguard	O
and	O
Reserves	O
,	O
the	O
latter	O
with	O
an	O
early	O
example	O
of	O
Dumaresq	B-Device
,	O
to	O
Japan	O
during	O
the	O
Russo-Japanese	O
War	O
.	O
</s>
<s>
During	O
the	O
10	O
August	O
1904	O
Battle	O
of	O
the	O
Yellow	O
Sea	O
against	O
the	O
Russian	O
Pacific	O
Fleet	O
,	O
the	O
British-built	O
IJN	O
battleship	B-Application
Asahi	O
and	O
her	O
sister	O
ship	O
,	O
the	O
fleet	O
flagship	O
Mikasa	O
,	O
were	O
equipped	O
with	O
the	O
latest	O
Barr	O
and	O
Stroud	O
range	O
finders	O
on	O
the	O
bridge	O
,	O
but	O
the	O
ships	O
were	O
not	O
designed	O
for	O
coordinated	O
aiming	O
and	O
firing	O
.	O
</s>
<s>
Centralized	O
naval	O
fire	B-Application
control	I-Application
systems	I-Application
were	O
first	O
developed	O
around	O
the	O
time	O
of	O
World	O
War	O
I	O
.	O
</s>
<s>
The	O
Dreyer	O
Table	O
was	O
to	O
be	O
improved	O
and	O
served	O
into	O
the	O
interwar	O
period	O
at	O
which	O
point	O
it	O
was	O
superseded	O
in	O
new	O
and	O
reconstructed	O
ships	O
by	O
the	O
Admiralty	B-Device
Fire	I-Device
Control	I-Device
Table	I-Device
.	O
</s>
<s>
The	O
use	O
of	O
Director-controlled	O
firing	O
together	O
with	O
the	O
fire	B-Application
control	I-Application
computer	I-Application
moved	O
the	O
control	O
of	O
the	O
gun	O
laying	O
from	O
the	O
individual	O
turrets	O
to	O
a	O
central	O
position	O
(	O
usually	O
in	O
a	O
plotting	O
room	O
protected	O
below	O
armor	O
)	O
,	O
although	O
individual	O
gun	O
mounts	O
and	O
multi-gun	O
turrets	O
could	O
retain	O
a	O
local	O
control	O
option	O
for	O
use	O
when	O
battle	O
damage	O
prevented	O
the	O
director	O
setting	O
the	O
guns	O
.	O
</s>
<s>
Visual	O
range	O
measurement	O
(	O
of	O
both	O
target	O
and	O
shell	O
splashes	O
)	O
was	O
difficult	O
prior	O
to	O
availability	O
of	O
radar	B-Application
.	O
</s>
<s>
During	O
the	O
Battle	O
of	O
Jutland	O
,	O
while	O
the	O
British	O
were	O
thought	O
by	O
some	O
to	O
have	O
the	O
finest	O
fire	B-Application
control	I-Application
system	I-Application
in	O
the	O
world	O
at	O
that	O
time	O
,	O
only	O
three	O
percent	O
of	O
their	O
shots	O
actually	O
struck	O
their	O
targets	O
.	O
</s>
<s>
At	O
that	O
time	O
,	O
the	O
British	O
primarily	O
used	O
a	O
manual	O
fire	B-Application
control	I-Application
system	I-Application
.	O
</s>
<s>
This	O
experience	O
contributed	O
to	O
computing	O
rangekeepers	B-Device
becoming	O
standard	O
issue	O
.	O
</s>
<s>
The	O
US	O
Navy	O
's	O
first	O
deployment	O
of	O
a	O
rangekeeper	B-Device
was	O
on	O
in	O
1916	O
.	O
</s>
<s>
Because	O
of	O
the	O
limitations	O
of	O
the	O
technology	O
at	O
that	O
time	O
,	O
the	O
initial	O
rangekeepers	B-Device
were	O
crude	O
.	O
</s>
<s>
For	O
example	O
,	O
during	O
World	O
War	O
I	O
the	O
rangekeepers	B-Device
would	O
generate	O
the	O
necessary	O
angles	O
automatically	O
but	O
sailors	O
had	O
to	O
manually	O
follow	O
the	O
directions	O
of	O
the	O
rangekeepers	B-Device
.	O
</s>
<s>
During	O
World	O
War	O
II	O
,	O
servomechanisms	O
(	O
called	O
"	O
power	O
drives	O
"	O
in	O
the	O
US	O
Navy	O
)	O
were	O
developed	O
that	O
allowed	O
the	O
guns	O
to	O
automatically	O
steer	O
to	O
the	O
rangekeeper	B-Device
's	O
commands	O
with	O
no	O
manual	O
intervention	O
,	O
though	O
pointers	O
still	O
worked	O
even	O
if	O
automatic	O
control	O
was	O
lost	O
.	O
</s>
<s>
During	O
their	O
long	O
service	O
life	O
,	O
rangekeepers	B-Device
were	O
updated	O
often	O
as	O
technology	O
advanced	O
and	O
by	O
World	O
War	O
II	O
they	O
were	O
a	O
critical	O
part	O
of	O
an	O
integrated	O
fire	B-Application
control	I-Application
system	I-Application
.	O
</s>
<s>
The	O
incorporation	O
of	O
radar	B-Application
into	O
the	O
fire	B-Application
control	I-Application
system	I-Application
early	O
in	O
World	O
War	O
II	O
provided	O
ships	O
with	O
the	O
ability	O
to	O
conduct	O
effective	O
gunfire	O
operations	O
at	O
long	O
range	O
in	O
poor	O
weather	O
and	O
at	O
night	O
.	O
</s>
<s>
In	O
a	O
typical	O
World	O
War	O
II	O
British	O
ship	O
the	O
fire	B-Application
control	I-Application
system	I-Application
connected	O
the	O
individual	O
gun	O
turrets	O
to	O
the	O
director	O
tower	O
(	O
where	O
the	O
sighting	O
instruments	O
were	O
)	O
and	O
the	O
analogue	O
computer	O
in	O
the	O
heart	O
of	O
the	O
ship	O
.	O
</s>
<s>
The	O
US	O
Navy	O
Rangekeeper	B-Device
and	O
the	O
Mark	O
38	O
GFCS	B-Application
had	O
an	O
edge	O
over	O
Imperial	O
Japanese	O
Navy	O
systems	O
in	O
operability	O
and	O
flexibility	O
.	O
</s>
<s>
In	O
contrast	O
to	O
US	O
radar	B-Application
aided	O
system	O
,	O
the	O
Japanese	O
relied	O
on	O
averaging	O
optical	O
rangefinders	O
,	O
lacked	O
gyros	O
to	O
sense	O
the	O
horizon	O
,	O
and	O
required	O
manual	O
handling	O
of	O
follow-ups	O
on	O
the	O
Sokutekiban	O
,	O
Shagekiban	O
,	O
Hoiban	O
as	O
well	O
as	O
guns	O
themselves	O
.	O
</s>
<s>
This	O
could	O
have	O
played	O
a	O
role	O
in	O
Center	O
Force	O
's	O
battleships	B-Application
 '	O
dismal	O
performance	O
in	O
the	O
Battle	O
off	O
Samar	O
in	O
October	O
1944	O
.	O
</s>
<s>
In	O
that	O
action	O
,	O
American	O
destroyers	O
pitted	O
against	O
the	O
world	O
's	O
largest	O
armored	O
battleships	B-Application
and	O
cruisers	O
dodged	O
shells	O
for	O
long	O
enough	O
to	O
close	O
to	O
within	O
torpedo	O
firing	O
range	O
,	O
while	O
lobbing	O
hundreds	O
of	O
accurate	O
automatically	O
aimed	O
rounds	O
on	O
target	O
.	O
</s>
<s>
The	O
earlier	O
Battle	O
of	O
Surigao	O
Strait	O
had	O
established	O
the	O
clear	O
superiority	O
of	O
US	O
radar-assisted	O
systems	O
at	O
night	O
.	O
</s>
<s>
The	O
rangekeeper	B-Device
's	O
target	O
position	O
prediction	O
characteristics	O
could	O
be	O
used	O
to	O
defeat	O
the	O
rangekeeper	B-Device
.	O
</s>
<s>
Because	O
the	O
rangekeepers	B-Device
are	O
constantly	O
predicting	O
new	O
positions	O
for	O
the	O
target	O
,	O
it	O
is	O
unlikely	O
that	O
subsequent	O
salvos	O
will	O
strike	O
the	O
position	O
of	O
the	O
previous	O
salvo	O
.	O
</s>
<s>
Practical	O
rangekeepers	B-Device
had	O
to	O
assume	O
that	O
targets	O
were	O
moving	O
in	O
a	O
straight-line	O
path	O
at	O
a	O
constant	O
speed	O
,	O
to	O
keep	O
complexity	O
to	O
acceptable	O
limits	O
.	O
</s>
<s>
A	O
sonar	O
rangekeeper	B-Device
was	O
built	O
to	O
include	O
a	O
target	O
circling	O
at	O
a	O
constant	O
radius	O
of	O
turn	O
,	O
but	O
that	O
function	O
had	O
been	O
disabled	O
.	O
</s>
<s>
Only	O
the	O
RN	O
and	O
USN	O
achieved	O
'	O
blindfire	O
 '	O
radar	B-Application
fire-control	B-Application
,	O
with	O
no	O
need	O
to	O
visually	O
acquire	O
the	O
opposing	O
vessel	O
.	O
</s>
<s>
Classes	O
such	O
as	O
Iowa	O
and	O
South	O
Dakota	O
battleships	B-Application
could	O
lob	O
shells	O
over	O
visual	O
horizon	O
,	O
in	O
darkness	O
,	O
through	O
smoke	O
or	O
weather	O
.	O
</s>
<s>
By	O
the	O
start	O
of	O
World	O
War	O
II	O
British	O
,	O
German	O
and	O
American	O
warships	O
could	O
both	O
shoot	O
and	O
maneuver	O
using	O
sophisticated	O
analog	O
fire-control	B-Application
computers	I-Application
that	O
incorporated	O
gyro	O
compass	O
and	O
gyro	O
Level	O
inputs	O
.	O
</s>
<s>
In	O
the	O
Battle	O
of	O
Cape	O
Matapan	O
the	O
British	O
Mediterranean	O
Fleet	O
using	O
radar	B-Application
ambushed	O
and	O
mauled	O
an	O
Italian	O
fleet	O
,	O
although	O
actual	O
fire	O
was	O
under	O
optical	O
control	O
using	O
starshell	O
illumination	O
.	O
</s>
<s>
At	O
the	O
Naval	O
Battle	O
of	O
Guadalcanal	O
,	O
in	O
complete	O
darkness	O
,	O
inflicted	O
fatal	O
damage	O
at	O
close	O
range	O
on	O
the	O
battleship	B-Application
using	O
a	O
combination	O
of	O
optical	O
and	O
radar	B-Application
fire-control	B-Application
;	O
comparisons	O
between	O
optical	O
and	O
radar	B-Application
tracking	O
,	O
during	O
the	O
battle	O
,	O
showed	O
that	O
radar	B-Application
tracking	O
matched	O
optical	O
tracking	O
in	O
accuracy	O
,	O
while	O
radar	B-Application
ranges	O
were	O
used	O
throughout	O
the	O
battle	O
.	O
</s>
<s>
The	O
last	O
combat	O
action	O
for	O
the	O
analog	O
rangekeepers	B-Device
,	O
at	O
least	O
for	O
the	O
US	O
Navy	O
,	O
was	O
in	O
the	O
1991	O
Persian	B-Application
Gulf	I-Application
War	I-Application
when	O
the	O
rangekeepers	B-Device
on	O
the	O
s	O
directed	O
their	O
last	O
rounds	O
in	O
combat	O
.	O
</s>
<s>
Ferranti	O
Computer	O
Systems	O
developed	O
the	O
GSA4	O
digital	O
computerised	O
gunnery	O
fire	B-Application
control	I-Application
system	I-Application
that	O
was	O
deployed	O
on	O
HMS	O
Amazon	O
(	O
Type	O
21	O
frigate	O
commissioned	O
in	O
1974	O
)	O
as	O
part	O
of	O
the	O
WAS4	O
(	O
Weapon	O
Systems	O
Automation	O
-	O
4	O
)	O
system	O
.	O
</s>
<s>
The	O
Mark	O
33	O
GFCS	B-Application
was	O
a	O
power-driven	O
fire	O
control	O
director	O
,	O
less	O
advanced	O
than	O
the	O
Mark	O
37	O
.	O
</s>
<s>
The	O
Mark	O
33	O
GFCS	B-Application
used	O
a	O
Mark	O
10	O
Rangekeeper	B-Device
,	O
analog	O
fire-control	B-Application
computer	I-Application
.	O
</s>
<s>
The	O
entire	O
rangekeeper	B-Device
was	O
mounted	O
in	O
an	O
open	O
director	O
rather	O
than	O
in	O
a	O
separate	O
plotting	O
room	O
as	O
in	O
the	O
RN	O
HACS	B-Device
,	O
or	O
the	O
later	O
Mark	O
37	O
GFCS	B-Application
,	O
and	O
this	O
made	O
it	O
difficult	O
to	O
upgrade	O
the	O
Mark	O
33	O
GFCS	B-Application
.	O
</s>
<s>
It	O
could	O
compute	O
firing	B-Application
solutions	I-Application
for	O
targets	O
moving	O
at	O
up	O
to	O
320	O
knots	O
,	O
or	O
400	O
knots	O
in	O
a	O
dive	O
.	O
</s>
<s>
They	O
had	O
no	O
fire-control	B-Application
radar	B-Application
initially	O
,	O
and	O
were	O
aimed	O
only	O
by	O
sight	O
.	O
</s>
<s>
After	O
1942	O
,	O
some	O
of	O
these	O
directors	O
were	O
enclosed	O
and	O
had	O
a	O
Mark	O
4	O
fire-control	B-Application
radar	B-Application
added	O
to	O
the	O
roof	O
of	O
the	O
director	O
,	O
while	O
others	O
had	O
a	O
Mark	O
4	O
radar	B-Application
added	O
over	O
the	O
open	O
director	O
.	O
</s>
<s>
With	O
radar	B-Application
,	O
targets	O
could	O
be	O
seen	O
and	O
hit	O
accurately	O
at	O
night	O
,	O
and	O
through	O
weather	O
.	O
</s>
<s>
The	O
Mark	O
33	O
and	O
37	O
systems	O
used	O
tachymetric	B-Device
target	O
motion	O
prediction	O
.	O
</s>
<s>
The	O
design	O
provided	O
for	O
the	O
ultimate	O
addition	O
of	O
radar	B-Application
,	O
which	O
later	O
permitted	O
blind	O
firing	O
with	O
the	O
director	O
.	O
</s>
<s>
Destroyers	O
,	O
cruisers	O
,	O
battleships	B-Application
,	O
carriers	O
,	O
and	O
many	O
auxiliaries	O
used	O
the	O
directors	O
,	O
with	O
individual	O
installations	O
varying	O
from	O
one	O
aboard	O
destroyers	O
to	O
four	O
on	O
each	O
battleship	B-Application
.	O
</s>
<s>
Destroyers	O
starting	O
with	O
the	O
employed	O
one	O
of	O
these	O
computers	O
,	O
battleships	B-Application
up	O
to	O
four	O
.	O
</s>
<s>
To	O
do	O
this	O
,	O
it	O
had	O
optical	O
sights	O
(	O
the	O
rectangular	O
windows	O
or	O
hatches	O
on	O
the	O
front	O
)	O
,	O
an	O
optical	O
rangefinder	O
(	O
the	O
tubes	O
or	O
ears	O
sticking	O
out	O
each	O
side	O
)	O
,	O
and	O
later	O
models	O
,	O
fire	O
control	O
radar	B-Application
antennas	O
.	O
</s>
<s>
The	O
rectangular	O
antenna	O
is	O
for	O
the	O
Mark	O
12	O
FC	O
radar	B-Application
,	O
and	O
the	O
parabolic	O
antenna	O
on	O
the	O
left	O
(	O
"	O
orange	O
peel	O
"	O
)	O
is	O
for	O
the	O
Mark	O
22	O
FC	O
radar	B-Application
.	O
</s>
<s>
The	O
director	O
was	O
manned	O
by	O
a	O
crew	O
of	O
6	O
:	O
Director	O
Officer	O
,	O
Assistant	O
Control	O
Officer	O
,	O
Pointer	O
,	O
Trainer	O
,	O
Range	O
Finder	O
Operator	O
and	O
Radar	B-Application
Operator	O
.	O
</s>
<s>
Up	O
to	O
four	O
Mark	O
37	O
Gun	B-Application
Fire	I-Application
Control	I-Application
Systems	I-Application
were	O
installed	O
on	O
battleships	B-Application
.	O
</s>
<s>
On	O
a	O
battleship	B-Application
,	O
the	O
director	O
was	O
protected	O
by	O
of	O
armor	O
,	O
and	O
weighs	O
21	O
tons	O
.	O
</s>
<s>
Stabilizing	O
signals	O
from	O
the	O
Stable	O
Element	O
kept	O
the	O
optical	O
sight	O
telescopes	O
,	O
rangefinder	O
,	O
and	O
radar	B-Application
antenna	O
free	O
from	O
the	O
effects	O
of	O
deck	O
tilt	O
.	O
</s>
<s>
To	O
do	O
so	O
,	O
accurately	O
,	O
when	O
the	O
fire	B-Application
control	I-Application
system	I-Application
was	O
initially	O
installed	O
,	O
a	O
surveyor	O
,	O
working	O
in	O
several	O
stages	O
,	O
transferred	O
the	O
position	O
of	O
the	O
gun	O
director	O
into	O
Plot	O
so	O
the	O
stable	O
element	O
's	O
own	O
internal	O
mechanism	O
was	O
properly	O
aligned	O
to	O
the	O
director	O
.	O
</s>
<s>
In	O
battleships	B-Application
,	O
the	O
Secondary	O
Battery	O
Plotting	O
Rooms	O
were	O
down	O
below	O
the	O
waterline	O
and	O
inside	O
the	O
armor	O
belt	O
.	O
</s>
<s>
They	O
contained	O
four	O
complete	O
sets	O
of	O
the	O
fire	B-Application
control	I-Application
equipment	I-Application
needed	O
to	O
aim	O
and	O
shoot	O
at	O
four	O
targets	O
.	O
</s>
<s>
Each	O
set	O
included	O
a	O
Mark	O
1A	O
computer	O
,	O
a	O
Mark	O
6	O
Stable	O
Element	O
,	O
FC	O
radar	B-Application
controls	O
and	O
displays	O
,	O
parallax	B-Device
correctors	O
,	O
a	O
switchboard	O
,	O
and	O
people	O
to	O
operate	O
it	O
all	O
.	O
</s>
<s>
As	O
well	O
,	O
the	O
Mark	O
8	O
Rangekeeper	B-Device
included	O
a	O
plotter	O
.	O
</s>
<s>
The	O
distinctive	O
name	O
for	O
the	O
fire-control	B-Application
equipment	I-Application
room	O
took	O
root	O
,	O
and	O
persisted	O
even	O
when	O
there	O
were	O
no	O
plotters	O
.	O
)	O
</s>
<s>
The	O
Mark	B-Device
1A	I-Device
Fire	I-Device
Control	I-Device
Computer	I-Device
was	O
an	O
electro-mechanical	O
analog	O
ballistic	O
computer	O
.	O
</s>
<s>
The	O
Mark	O
1A	O
appeared	O
post	O
World	O
War	O
II	O
and	O
may	O
have	O
incorporated	O
technology	O
developed	O
for	O
the	O
Bell	O
Labs	O
Mark	B-Device
8	I-Device
,	I-Device
Fire	I-Device
Control	I-Device
Computer	I-Device
.	O
</s>
<s>
Almost	O
all	O
of	O
the	O
computer	O
's	O
inputs	O
and	O
outputs	O
were	O
by	O
synchro	B-Algorithm
torque	O
transmitters	O
and	O
receivers	O
.	O
</s>
<s>
This	O
is	O
the	O
same	O
function	O
as	O
the	O
main	O
battery	O
's	O
Mark	O
8	O
Rangekeeper	B-Device
used	O
in	O
the	O
Mark	O
38	O
GFCS	B-Application
except	O
that	O
some	O
of	O
the	O
targets	O
the	O
Mark	O
1A	O
had	O
to	O
deal	O
with	O
also	O
moved	O
in	O
elevation	O
—	O
and	O
much	O
faster	O
.	O
</s>
<s>
Digital	O
fire	B-Application
control	I-Application
computers	I-Application
were	O
not	O
introduced	O
into	O
service	O
until	O
the	O
mid-1970s	O
.	O
</s>
<s>
Central	O
aiming	O
from	O
a	O
gun	O
director	O
has	O
a	O
minor	O
complication	O
in	O
that	O
the	O
guns	O
are	O
often	O
far	O
enough	O
away	O
from	O
the	O
director	O
to	O
require	O
parallax	B-Device
correction	O
so	O
they	O
aim	O
correctly	O
.	O
</s>
<s>
In	O
the	O
Mark	O
37	O
GFCS	B-Application
,	O
the	O
Mark	O
1/1A	O
sent	O
parallax	B-Device
data	O
to	O
all	O
gun	O
mounts	O
;	O
each	O
mount	O
had	O
its	O
own	O
scale	O
factor	O
(	O
and	O
"	O
polarity	O
"	O
)	O
set	O
inside	O
the	O
train	O
(	O
bearing	O
)	O
power	O
drive	O
(	O
servo	O
)	O
receiver-regulator	O
(	O
controller	O
)	O
.	O
</s>
<s>
The	O
function	O
of	O
the	O
Mark	O
6	O
Stable	O
Element	O
(	O
pictured	O
)	O
in	O
this	O
fire	B-Application
control	I-Application
system	I-Application
is	O
the	O
same	O
as	O
the	O
function	O
of	O
the	O
Mark	O
41	O
Stable	O
Vertical	O
in	O
the	O
main	O
battery	O
system	O
.	O
</s>
<s>
The	O
weight	O
,	O
its	O
scale	O
,	O
and	O
frame	O
are	O
mounted	O
on	O
the	O
shaft	O
of	O
a	O
synchro	B-Algorithm
torque	O
receiver	O
fed	O
with	O
ship	O
's	O
course	O
data	O
from	O
the	O
gyro	O
compass	O
,	O
and	O
compensated	O
by	O
a	O
differential	O
synchro	B-Algorithm
driven	O
by	O
the	O
housing-rotator	O
motor	O
.	O
</s>
<s>
(	O
The	O
sonar	O
fire-control	B-Application
computer	I-Application
aboard	O
some	O
destroyers	O
of	O
the	O
late	O
1950s	O
required	O
roll	O
and	O
pitch	O
signals	O
for	O
stabilizing	O
,	O
so	O
a	O
coordinate	O
converter	O
containing	O
synchros	O
,	O
resolvers	O
,	O
and	O
servos	O
calculated	O
the	O
latter	O
from	O
gun	O
director	O
bearing	O
,	O
level	O
,	O
and	O
crosslevel	O
.	O
)	O
</s>
<s>
The	O
fire-control	B-Application
radar	B-Application
used	O
on	O
the	O
Mark	O
37	O
GFCS	B-Application
has	O
evolved	O
.	O
</s>
<s>
In	O
the	O
1930s	O
,	O
the	O
Mark	O
33	O
Director	O
did	O
not	O
have	O
a	O
radar	B-Application
antenna	O
.	O
</s>
<s>
The	O
Tizard	O
Mission	O
to	O
the	O
United	O
States	O
provided	O
the	O
USN	O
with	O
crucial	O
data	O
on	O
UK	O
and	O
Royal	O
Navy	O
radar	B-Application
technology	O
and	O
fire-control	B-Application
radar	B-Application
systems	I-Application
.	O
</s>
<s>
In	O
September	O
1941	O
,	O
the	O
first	O
rectangular	O
Mark	O
4	O
Fire-control	B-Application
radar	B-Application
antenna	O
was	O
mounted	O
on	O
a	O
Mark	O
37	O
Director	O
,	O
and	O
became	O
a	O
common	O
feature	O
on	O
USN	O
Directors	O
by	O
mid	O
1942	O
.	O
</s>
<s>
Soon	O
aircraft	O
flew	O
faster	O
,	O
and	O
in	O
c1944	O
to	O
increase	O
speed	O
and	O
accuracy	O
the	O
Mark	O
4	O
was	O
replaced	O
by	O
a	O
combination	O
of	O
the	O
Mark	O
12	O
(	O
rectangular	O
antenna	O
)	O
and	O
Mark	O
22	O
(	O
parabolic	O
antenna	O
)	O
"	O
orange	O
peel	O
"	O
radars	B-Application
.	O
</s>
<s>
(	O
pictured	O
)	O
in	O
the	O
late	O
1950s	O
,	O
Mark	O
37	O
directors	O
had	O
Western	O
Electric	O
Mark	O
25	O
X-band	O
conical-scan	O
radars	B-Application
with	O
round	O
,	O
perforated	O
dishes	O
.	O
</s>
<s>
The	O
Mark	O
38	O
Gun	O
Fire	B-Application
Control	I-Application
System	I-Application
(	O
GFCS	B-Application
)	O
controlled	O
the	O
large	O
main	O
battery	O
guns	O
of	O
Iowa-class	O
battleships	B-Application
.	O
</s>
<s>
The	O
radar	B-Application
systems	I-Application
used	O
by	O
the	O
Mark	O
38	O
GFCS	B-Application
were	O
far	O
more	O
advanced	O
than	O
the	O
primitive	O
radar	B-Application
sets	O
used	O
by	O
the	O
Japanese	O
in	O
World	O
War	O
II	O
.	O
</s>
<s>
The	O
director	O
was	O
equipped	O
with	O
optical	O
sights	O
,	O
optical	O
Mark	O
48	O
Rangefinder	O
(	O
the	O
long	O
thin	O
boxes	O
sticking	O
out	O
each	O
side	O
)	O
,	O
and	O
a	O
Mark	O
13	O
Fire	O
Control	O
Radar	B-Application
antenna	O
(	O
the	O
rectangular	O
shape	O
sitting	O
on	O
top	O
)	O
.	O
</s>
<s>
This	O
could	O
be	O
done	O
optically	O
with	O
the	O
men	O
inside	O
using	O
the	O
sights	O
and	O
Rangefinder	O
,	O
or	O
electronically	O
with	O
the	O
radar	B-Application
.	O
</s>
<s>
(	O
The	O
fire	O
control	O
radar	B-Application
was	O
the	O
preferred	O
method	O
.	O
)	O
</s>
<s>
The	O
present	O
position	O
of	O
the	O
target	O
was	O
called	O
the	O
Line-Of-Sight	O
(	O
LOS	O
)	O
,	O
and	O
it	O
was	O
continuously	O
sent	O
down	O
to	O
the	O
plotting	O
room	O
by	O
synchro	B-Algorithm
motors	I-Algorithm
.	O
</s>
<s>
When	O
not	O
using	O
the	O
radar	B-Application
's	O
display	O
to	O
determine	O
Spots	O
,	O
the	O
director	O
was	O
the	O
optical	O
spotting	O
station	O
.	O
</s>
<s>
It	O
housed	O
the	O
forward	O
system	O
's	O
Mark	O
8	O
Rangekeeper	B-Device
,	O
Mark	O
41	O
Stable	O
Vertical	O
,	O
Mark	O
13	O
FC	O
Radar	B-Application
controls	O
and	O
displays	O
,	O
Parallax	B-Device
Correctors	O
,	O
Fire	O
Control	O
Switchboard	O
,	O
battle	O
telephone	O
switchboard	O
,	O
battery	O
status	O
indicators	O
,	O
assistant	O
Gunnery	O
Officers	O
,	O
and	O
Fire	O
Controlmen	O
(	O
FC	O
's	O
)	O
(	O
between	O
1954	O
and	O
1982	O
,	O
FC	O
's	O
were	O
designated	O
as	O
Fire	O
Control	O
Technicians	O
(	O
FT	O
's	O
)	O
)	O
.	O
</s>
<s>
The	O
Mark	O
8	O
Rangekeeper	B-Device
was	O
an	O
electromechanical	O
analog	O
computer	O
whose	O
function	O
was	O
to	O
continuously	O
calculate	O
the	O
gun	O
's	O
bearing	O
and	O
elevation	O
,	O
Line-Of-Fire	O
(	O
LOF	O
)	O
,	O
to	O
hit	O
a	O
future	O
position	O
of	O
the	O
target	O
.	O
</s>
<s>
It	O
did	O
this	O
by	O
automatically	O
receiving	O
information	O
from	O
the	O
director	O
(	O
LOS	O
)	O
,	O
the	O
FC	O
Radar	B-Application
(	O
range	O
)	O
,	O
the	O
ship	O
's	O
gyrocompass	O
(	O
true	O
ship	O
's	O
course	O
)	O
,	O
the	O
ships	O
Pitometer	O
log	O
(	O
ship	O
's	O
speed	O
)	O
,	O
the	O
Stable	O
Vertical	O
(	O
ship	O
's	O
deck	O
tilt	O
,	O
sensed	O
as	O
level	O
and	O
crosslevel	O
)	O
,	O
and	O
the	O
ship	O
's	O
anemometer	O
(	O
relative	O
wind	O
speed	O
and	O
direction	O
)	O
.	O
</s>
<s>
With	O
all	O
this	O
information	O
,	O
the	O
rangekeeper	B-Device
calculated	O
the	O
relative	O
motion	O
between	O
its	O
ship	O
and	O
the	O
target	O
.	O
</s>
<s>
The	O
Mark	O
13	O
FC	O
Radar	B-Application
supplied	O
present	O
target	O
range	O
,	O
and	O
it	O
showed	O
the	O
fall	O
of	O
shot	O
around	O
the	O
target	O
so	O
the	O
Gunnery	O
Officer	O
could	O
correct	O
the	O
system	O
's	O
aim	O
with	O
range	O
and	O
deflection	O
spots	O
put	O
into	O
the	O
rangekeeper	B-Device
.	O
</s>
<s>
Because	O
of	O
radar	B-Application
,	O
Fire	B-Application
Control	I-Application
systems	I-Application
are	O
able	O
to	O
track	O
and	O
fire	O
at	O
targets	O
at	O
a	O
greater	O
range	O
and	O
with	O
increased	O
accuracy	O
during	O
the	O
day	O
,	O
night	O
,	O
or	O
inclement	O
weather	O
.	O
</s>
<s>
This	O
was	O
demonstrated	O
in	O
November	O
1942	O
when	O
the	O
battleship	B-Application
engaged	O
the	O
Imperial	O
Japanese	O
Navy	O
battlecruiser	B-Application
at	O
a	O
range	O
of	O
at	O
night	O
.	O
</s>
<s>
This	O
gave	O
the	O
United	O
States	O
Navy	O
a	O
major	O
advantage	O
in	O
World	O
War	O
II	O
,	O
as	O
the	O
Japanese	O
did	O
not	O
develop	O
radar	B-Application
or	O
automated	O
fire	O
control	O
to	O
the	O
level	O
of	O
the	O
US	O
Navy	O
and	O
were	O
at	O
a	O
significant	O
disadvantage	O
.	O
</s>
<s>
The	O
parallax	B-Device
correctors	O
are	O
needed	O
because	O
the	O
turrets	O
are	O
located	O
hundreds	O
of	O
feet	O
from	O
the	O
director	O
.	O
</s>
<s>
The	O
assistant	O
Gunnery	O
Officers	O
and	O
Fire	O
Control	O
Technicians	O
operated	O
the	O
equipment	O
,	O
talked	O
to	O
the	O
turrets	O
and	O
ship	O
's	O
command	O
by	O
sound-powered	O
telephone	O
,	O
and	O
watched	O
the	O
Rangekeeper	B-Device
's	O
dials	O
and	O
system	O
status	O
indicators	O
for	O
problems	O
.	O
</s>
<s>
This	O
GFCS	B-Application
was	O
an	O
intermediate-range	O
,	O
anti-aircraft	O
gun	O
fire-control	B-Application
system	I-Application
.	O
</s>
<s>
Its	O
Mark	O
35	O
Radar	B-Application
was	O
capable	O
of	O
automatic	O
tracking	O
in	O
bearing	O
,	O
elevation	O
,	O
and	O
range	O
that	O
was	O
as	O
accurate	O
as	O
any	O
optical	O
tracking	O
.	O
</s>
<s>
This	O
allowed	O
for	O
rapid	O
target	O
acquisition	O
when	O
a	O
target	O
was	O
first	O
detected	O
and	O
designated	O
by	O
the	O
ship	O
's	O
air-search	O
radar	B-Application
,	O
and	O
not	O
yet	O
visible	O
from	O
on	O
deck	O
.	O
</s>
<s>
Its	O
target	O
solution	O
time	O
was	O
less	O
than	O
2	O
seconds	O
after	O
Mark	O
35	O
radar	B-Application
"	O
Lock	O
on	O
"	O
.	O
</s>
<s>
Below	O
decks	O
in	O
Plot	O
,	O
was	O
the	O
Mark	O
4	O
Radar	B-Application
Console	O
where	O
the	O
Radar	B-Application
Operator	O
and	O
Radar	B-Application
Tracker	O
sat	O
.	O
</s>
<s>
In	O
the	O
1968	O
upgrade	O
to	O
for	O
service	O
off	O
Vietnam	O
,	O
three	O
Mark	O
56	O
Gun	B-Application
Fire	I-Application
Control	I-Application
Systems	I-Application
were	O
installed	O
.	O
</s>
<s>
The	O
GFCS	B-Application
consists	O
of	O
an	O
AN/SPG	O
-34	O
radar	B-Application
tracker	O
and	O
a	O
Mark	O
29	O
gun	O
sight	O
.	O
</s>
<s>
It	O
combined	O
a	O
manned	O
topside	O
director	O
,	O
a	O
conical	O
scan	O
acquisition	O
and	O
tracking	O
radar	B-Application
,	O
an	O
analog	O
computer	O
to	O
compute	O
ballistics	O
solutions	O
,	O
and	O
a	O
gyro	O
stabilization	O
unit	O
.	O
</s>
<s>
The	O
AN/SPG	O
-53	O
'''	O
was	O
a	O
United	O
States	O
Navy	O
gun	O
fire-control	B-Application
radar	B-Application
used	O
in	O
conjunction	O
with	O
the	O
Mark	O
68	O
gun	O
fire-control	B-Application
system	I-Application
.	O
</s>
<s>
The	O
US	O
Navy	O
desired	O
a	O
digital	O
computerized	O
gun	O
fire-control	B-Application
system	I-Application
in	O
1961	O
for	O
more	O
accurate	O
shore	O
bombardment	O
.	O
</s>
<s>
Lockheed	O
Electronics	O
produced	O
a	O
prototype	O
with	O
AN/SPQ	B-Algorithm
-9	I-Algorithm
radar	B-Application
fire	O
control	O
in	O
1965	O
.	O
</s>
<s>
It	O
also	O
uses	O
a	O
Remote	O
Optical	O
Sighting	O
system	O
which	O
uses	O
a	O
TV	O
camera	O
with	O
a	O
telephoto	O
zoom	O
lens	O
mounted	O
on	O
the	O
mast	O
and	O
each	O
of	O
the	O
illuminating	O
radars	B-Application
.	O
</s>
<s>
The	O
Mark	O
92	O
fire	B-Application
control	I-Application
system	I-Application
,	O
an	O
Americanized	O
version	O
of	O
the	O
WM-25	B-Application
system	O
designed	O
in	O
The	O
Netherlands	O
,	O
was	O
approved	O
for	O
service	O
use	O
in	O
1975	O
.	O
</s>
<s>
Oliver	O
Hazard	O
Perry''-class	O
frigates	O
with	O
the	O
Mod	O
2	O
system	O
can	O
track	O
an	O
additional	O
air	O
or	O
surface	O
target	O
using	O
the	O
Separate	O
Track	O
Illuminating	O
Radar	B-Application
(	O
STIR	O
)	O
.	O
</s>
<s>
Used	O
in	O
the	O
Mark	O
34	O
Gun	O
Weapon	O
System	O
,	O
the	O
Mark	O
160	O
Gun	O
Computing	O
System	O
(	O
GCS	O
)	O
contains	O
a	O
gun	B-Device
console	I-Device
computer	I-Device
(	O
GCC	O
)	O
,	O
a	O
computer	B-Device
display	I-Device
console	O
(	O
CDC	O
)	O
,	O
a	O
magnetic	B-Architecture
tape	I-Architecture
recorder-reproducer	O
,	O
a	O
watertight	O
cabinet	O
housing	O
the	O
signal	O
data	B-General_Concept
converter	I-General_Concept
and	O
gun	O
mount	O
microprocessor	B-Architecture
,	O
a	O
gun	O
mount	O
control	O
panel	O
(	O
GMCP	O
)	O
,	O
and	O
a	O
velocimeter	O
.	O
</s>
