<s>
The	O
Mark	B-Device
XIV	I-Device
Bomb	I-Device
Sight	I-Device
was	O
a	O
bombsight	B-Application
developed	O
by	O
Royal	O
Air	O
Force	O
(	O
RAF	O
)	O
Bomber	O
Command	O
during	O
the	O
Second	O
World	O
War	O
.	O
</s>
<s>
It	O
was	O
the	O
RAF	O
's	O
standard	O
bombsight	B-Application
for	O
the	O
second	O
half	O
of	O
the	O
war	O
.	O
</s>
<s>
XIV	O
began	O
replacing	O
the	O
First	O
World	O
War	O
–	O
era	O
Course	B-Device
Setting	I-Device
Bomb	I-Device
Sight	I-Device
in	O
1942	O
.	O
</s>
<s>
XIV	O
was	O
essentially	O
an	O
automated	O
version	O
of	O
the	O
Course	O
Setting	O
sight	O
,	O
using	O
a	O
mechanical	B-Device
computer	I-Device
to	O
update	O
the	O
sights	O
in	O
real-time	O
as	O
conditions	O
changed	O
.	O
</s>
<s>
XIV	O
was	O
theoretically	O
less	O
accurate	O
than	O
the	O
contemporary	O
Norden	B-Device
bombsight	I-Device
.	O
</s>
<s>
It	O
equipped	O
the	O
majority	O
of	O
the	O
RAF	O
bomber	O
fleet	O
during	O
the	O
second	O
half	O
of	O
the	O
war	O
;	O
small	O
numbers	O
of	O
the	O
Stabilized	B-Device
Automatic	I-Device
Bomb	I-Device
Sight	I-Device
and	O
Low	B-Device
Level	I-Device
Bombsight	I-Device
,	I-Device
Mark	I-Device
III	I-Device
were	O
used	O
in	O
specialist	O
roles	O
.	O
</s>
<s>
The	O
Low	O
Level	O
Bombsight	B-Application
was	O
built	O
using	O
parts	O
of	O
the	O
Mark	O
XIV	O
,	O
stabilized	O
in	O
pitch	O
rather	O
than	O
roll	O
.	O
</s>
<s>
A	O
post-war	O
upgrade	O
,	O
the	O
T-4	O
,	O
also	O
known	O
by	O
its	O
rainbow	O
code	O
Blue	B-Device
Devil	I-Device
,	O
connected	O
directly	O
to	O
the	O
Navigation	B-Device
and	I-Device
Bombing	I-Device
System	I-Device
computers	O
to	O
automate	O
the	O
setting	O
of	O
wind	O
speed	O
and	O
direction	O
.	O
</s>
<s>
A	O
problem	O
with	O
early	O
bombsights	B-Application
was	O
that	O
they	O
could	O
only	O
correct	O
for	O
the	O
effects	O
of	O
the	O
wind	O
in	O
a	O
simple	O
way	O
and	O
required	O
the	O
bomber	O
to	O
fly	O
directly	O
up	O
-	O
or	O
down-wind	O
from	O
the	O
target	O
,	O
to	O
minimise	O
the	O
complexity	O
of	O
the	O
required	O
calculations	O
.	O
</s>
<s>
In	O
1917	O
Harry	O
Wimperis	O
introduced	O
the	O
Course	B-Device
Setting	I-Device
Bomb	I-Device
Sight	I-Device
(	O
CSBS	B-Device
)	O
,	O
which	O
replaced	O
the	O
tables	O
and	O
timings	O
used	O
in	O
earlier	O
sights	O
with	O
a	O
simple	O
mechanical	O
calculator	O
capable	O
of	O
solving	O
the	O
sideways	O
drift	O
due	O
to	O
the	O
wind	O
.	O
</s>
<s>
The	O
CSBS	B-Device
was	O
the	O
first	O
bombsight	B-Application
that	O
allowed	O
the	O
bomber	O
to	O
approach	O
the	O
target	O
from	O
any	O
direction	O
,	O
which	O
offered	O
greatly	O
increased	O
tactical	O
freedom	O
.	O
</s>
<s>
The	O
downside	O
to	O
the	O
CSBS	B-Device
was	O
that	O
the	O
settings	O
,	O
made	O
through	O
four	O
main	O
input	O
dials	O
,	O
were	O
useful	O
for	O
one	O
operational	O
setup	O
,	O
a	O
given	O
altitude	O
and	O
heading	O
.	O
</s>
<s>
The	O
CSBS	B-Device
generally	O
required	O
the	O
bomber	O
to	O
fly	O
straight	O
and	O
level	O
for	O
a	O
lengthy	O
time	O
.	O
</s>
<s>
Although	O
the	O
need	O
for	O
an	O
improved	O
CSBS	B-Device
was	O
known	O
in	O
the	O
1930s	O
,	O
little	O
work	O
on	O
developing	O
such	O
a	O
sight	O
was	O
carried	O
out	O
.	O
</s>
<s>
That	O
was	O
because	O
an	O
entirely	O
new	O
class	O
of	O
tachometric	B-Device
bombsights	I-Device
were	O
being	O
developed	O
,	O
which	O
offered	O
dramatically	O
improved	O
accuracy	O
and	O
automated	O
much	O
of	O
the	O
setup	O
.	O
</s>
<s>
The	O
RAF	O
was	O
working	O
on	O
such	O
a	O
design	O
,	O
the	O
Automatic	O
Bomb	B-Application
Sight	I-Application
,	O
but	O
development	O
was	O
slow	O
and	O
it	O
had	O
not	O
been	O
accepted	O
for	O
use	O
when	O
the	O
war	O
started	O
.	O
</s>
<s>
Learning	O
of	O
a	O
similar	O
design	O
developed	O
by	O
the	O
US	O
Navy	O
,	O
the	O
Air	O
Ministry	O
began	O
extensive	O
negotiations	O
in	O
an	O
effort	O
to	O
gain	O
a	O
production	O
licence	O
for	O
this	O
Norden	B-Device
bombsight	I-Device
.	O
</s>
<s>
Ironically	O
,	O
the	O
plans	O
of	O
the	O
Norden	B-Device
bombsight	I-Device
had	O
been	O
passed	O
to	O
the	O
German	O
military	O
by	O
a	O
US-based	O
spy	O
in	O
1938	O
.	O
</s>
<s>
As	O
the	O
war	O
started	O
,	O
revised	O
versions	O
of	O
the	O
CSBS	B-Device
,	O
the	O
Mk	O
.	O
</s>
<s>
Among	O
the	O
many	O
problems	O
with	O
operational	O
readiness	O
,	O
he	O
noted	O
that	O
RAF	O
bombs	O
were	O
much	O
too	O
small	O
and	O
that	O
bombsight	B-Application
technology	O
was	O
obsolete	O
.	O
</s>
<s>
Given	O
the	O
problems	O
of	O
obtaining	O
a	O
modern	O
bombsight	B-Application
,	O
he	O
pressed	O
for	O
the	O
creation	O
of	O
a	O
high-speed	O
bomber	O
design	O
that	O
could	O
safely	O
attack	O
at	O
low	O
levels	O
.	O
</s>
<s>
Detected	O
on	O
radar	B-Application
and	O
engaged	O
en	O
route	O
to	O
their	O
targets	O
,	O
over	O
half	O
the	O
attacking	O
force	O
was	O
destroyed	O
or	O
damaged	O
beyond	O
repair	O
.	O
</s>
<s>
Ludlow-Hewitt	O
presented	O
a	O
report	O
on	O
the	O
attack	O
on	O
22	O
December	O
1939	O
,	O
noting	O
that	O
flying	O
straight	O
and	O
level	O
for	O
the	O
CSBS	B-Device
made	O
the	O
bombers	O
easy	O
targets	O
for	O
fighters	O
and	O
anti-aircraft	O
gunners	O
.	O
</s>
<s>
He	O
again	O
pressed	O
for	O
a	O
new	O
bombsight	B-Application
that	O
featured	O
stabilization	O
to	O
allow	O
the	O
aircraft	O
to	O
manoeuvre	O
while	O
it	O
approached	O
the	O
target	O
.	O
</s>
<s>
The	O
CSBS	B-Device
and	O
the	O
improved	O
version	O
,	O
the	O
Mk	O
.	O
</s>
<s>
Because	O
of	O
the	O
way	O
it	O
was	O
built	O
,	O
the	O
Automatic	O
Bomb	B-Application
Sight	I-Application
could	O
be	O
equipped	O
with	O
a	O
stabilizer	O
but	O
it	O
was	O
estimated	O
that	O
it	O
would	O
be	O
some	O
time	O
before	O
it	O
could	O
be	O
modified	O
and	O
brought	O
into	O
production	O
.	O
</s>
<s>
What	O
was	O
needed	O
was	O
a	O
new	O
bombsight	B-Application
,	O
one	O
that	O
could	O
be	O
very	O
quickly	O
set	O
up	O
,	O
had	O
useful	O
illumination	O
of	O
the	O
crosshairs	O
for	O
night	O
use	O
,	O
and	O
was	O
stabilized	O
so	O
the	O
bomb	O
aimer	O
could	O
watch	O
the	O
approach	O
as	O
the	O
bomber	O
was	O
manoeuvring	O
.	O
</s>
<s>
XI	O
,	O
which	O
mounted	O
a	O
cut-down	O
CSBS	B-Device
on	O
the	O
front	O
of	O
a	O
gyro	O
unit	O
taken	O
from	O
a	O
Sperry	O
Gyroscope	O
artificial	O
horizon	O
,	O
to	O
provide	O
stabilization	O
in	O
the	O
horizontal	O
plane	O
,	O
useful	O
for	O
aiding	O
drift	O
measurements	O
and	O
corrections	O
.	O
</s>
<s>
The	O
request	O
for	O
a	O
new	O
bombsight	B-Application
was	O
quickly	O
passed	O
on	O
to	O
the	O
Royal	O
Aircraft	O
Establishment	O
,	O
where	O
Patrick	O
Blackett	O
of	O
the	O
Aeronautical	O
Research	O
Committee	O
volunteered	O
to	O
lead	O
the	O
effort	O
.	O
</s>
<s>
His	O
solution	O
to	O
the	O
problem	O
was	O
a	O
thorough	O
revision	O
of	O
the	O
CSBS	B-Device
concept	O
.	O
</s>
<s>
Instead	O
of	O
dialling	O
the	O
parameters	O
into	O
the	O
sight	O
directly	O
as	O
in	O
the	O
CSBS	B-Device
,	O
these	O
inputs	O
were	O
dialled	O
into	O
a	O
separate	O
console	O
.	O
</s>
<s>
With	O
the	O
CSBS	B-Device
,	O
the	O
sighting	O
system	O
and	O
calculator	O
were	O
the	O
same	O
device	O
,	O
which	O
required	O
the	O
bombsight	B-Application
to	O
be	O
fairly	O
large	O
.	O
</s>
<s>
XII	O
bombsight	B-Application
was	O
first	O
tested	O
in	O
September	O
and	O
October	O
1940	O
and	O
by	O
the	O
end	O
of	O
October	O
,	O
20	O
examples	O
had	O
been	O
built	O
.	O
</s>
<s>
Two	O
of	O
these	O
could	O
be	O
set	O
before	O
the	O
mission	O
:	O
the	O
altitude	O
of	O
the	O
target	O
above	O
sea	O
level	O
and	O
the	O
terminal	B-Application
velocity	I-Application
of	O
the	O
bomb	O
,	O
a	O
function	O
of	O
the	O
particular	O
bomb	O
being	O
used	O
on	O
that	O
mission	O
.	O
</s>
<s>
It	O
was	O
the	O
first	O
modern	O
bombsight	B-Application
that	O
allowed	O
for	O
accurate	O
bombing	O
immediately	O
after	O
radical	O
manoeuvring	O
,	O
with	O
a	O
settling	O
time	O
as	O
little	O
as	O
10	O
seconds	O
.	O
</s>
<s>
Even	O
slow	O
turns	O
made	O
it	O
difficult	O
for	O
night	O
fighters	O
to	O
track	O
the	O
bombers	O
within	O
the	O
limited	O
view	O
of	O
their	O
radar	B-Application
systems	I-Application
and	O
continually	O
changing	O
altitude	O
was	O
an	O
effective	O
way	O
to	O
avoid	O
anti-aircraft	O
fire	O
.	O
</s>
<s>
When	O
the	O
need	O
for	O
more	O
accuracy	O
for	O
use	O
with	O
the	O
Tallboy	O
bombs	O
arose	O
in	O
1943	O
,	O
the	O
Stabilized	B-Device
Automatic	I-Device
Bomb	I-Device
Sight	I-Device
(	O
SABS	O
)	O
,	O
a	O
development	O
of	O
the	O
earlier	O
Automatic	O
Bomb	B-Application
Sight	I-Application
,	O
was	O
introduced	O
in	O
limited	O
numbers	O
.	O
</s>
<s>
To	O
fill	O
the	O
demand	O
for	O
other	O
aircraft	O
,	O
especially	O
smaller	O
ones	O
like	O
the	O
de	O
Havilland	O
Mosquito	O
,	O
the	O
Air	O
Ministry	O
began	O
looking	O
at	O
US	O
manufacturers	O
to	O
supply	O
the	O
bombsight	B-Application
.	O
</s>
<s>
The	O
A	O
model	O
also	O
introduced	O
the	O
ability	O
for	O
the	O
minor	O
differences	O
in	O
instrument	O
readings	O
for	O
indicated	O
and	O
true	O
air	O
speed	O
between	O
aircraft	O
to	O
be	O
corrected	O
simply	O
by	O
replacing	O
a	O
cam	B-Data_Structure
.	O
</s>
<s>
XV	O
allowed	O
the	O
altitude	O
input	O
to	O
be	O
taken	O
directly	O
from	O
a	O
radar	B-Application
altimeter	O
,	O
eliminating	O
these	O
inaccuracies	O
and	O
any	O
instrument	O
lag	O
.	O
</s>
<s>
These	O
T-2	O
and	O
T-4	O
(	O
Blue	B-Device
Devil	I-Device
)	O
designs	O
had	O
much	O
higher	O
altitude	O
,	O
airspeed	O
and	O
wind-speed	O
settings	O
,	O
suitable	O
for	O
high-altitude	O
bombing	O
in	O
the	O
jet	O
stream	O
.	O
</s>
<s>
These	O
were	O
normally	O
part	O
of	O
the	O
Navigation	B-Device
and	I-Device
Bombing	I-Device
System	I-Device
,	O
which	O
combined	O
inputs	O
from	O
aircraft	O
instruments	O
,	O
H2S	O
and	O
Green	O
Satin	O
radars	B-Application
,	O
star	O
fixes	O
and	O
radio	O
navigation	O
systems	O
.	O
</s>
<s>
These	O
measurements	O
were	O
fed	O
into	O
a	O
mechanical	B-Device
computer	I-Device
that	O
directly	O
output	O
the	O
latitude	O
and	O
longitude	O
of	O
the	O
aircraft	O
,	O
based	O
on	O
automatic	O
dead	O
reckoning	O
.	O
</s>
<s>
Optical	O
bombing	O
gave	O
way	O
to	O
radar	B-Application
bombing	O
,	O
and	O
the	O
Mk	O
.	O
</s>
<s>
On	O
the	O
left	O
side	O
of	O
the	O
chassis	O
,	O
from	O
top	O
to	O
bottom	O
,	O
were	O
dials	O
that	O
set	O
the	O
wind	O
direction	O
,	O
wind	O
speed	O
,	O
target	O
altitude	O
and	O
terminal	B-Application
velocity	I-Application
of	O
the	O
bomb	O
.	O
</s>
<s>
A	O
separate	O
electrical	O
connection	O
input	O
the	O
direction	O
measured	O
on	O
the	O
distant	O
reading	O
compass	O
,	O
using	O
a	O
selsyn	B-Algorithm
.	O
</s>
<s>
The	O
CSBS	B-Device
had	O
introduced	O
a	O
mounting	O
system	O
on	O
the	O
left	O
side	O
of	O
the	O
bombsight	B-Application
that	O
allowed	O
it	O
to	O
be	O
easily	O
removed	O
and	O
then	O
replaced	O
without	O
affecting	O
its	O
levelling	O
.	O
</s>
<s>
The	O
vertical	O
line	O
on	O
the	O
sight	O
was	O
relatively	O
short	O
,	O
and	O
could	O
not	O
be	O
used	O
directly	O
to	O
measure	O
drift	O
–	O
unlike	O
the	O
long	O
drift	O
wires	O
of	O
the	O
CSBS	B-Device
it	O
replaced	O
.	O
</s>
<s>
In	O
particular	O
,	O
the	O
terminal	B-Application
velocity	I-Application
was	O
based	O
on	O
the	O
type	O
of	O
bomb	O
being	O
dropped	O
and	O
did	O
not	O
change	O
during	O
the	O
mission	O
.	O
</s>
<s>
This	O
was	O
used	O
to	O
calculate	O
how	O
steep	O
the	O
path	O
of	O
the	O
bomb	O
would	O
be	O
when	O
dropped	O
from	O
high	O
altitudes	O
;	O
at	O
lower	O
altitudes	O
and	O
airspeeds	O
,	O
the	O
bomb	O
did	O
not	O
reach	O
terminal	B-Application
velocity	I-Application
and	O
followed	O
a	O
more	O
parabolic	O
path	O
.	O
</s>
<s>
Taking	O
this	O
measurement	O
while	O
nearing	O
the	O
target	O
was	O
an	O
important	O
procedure	O
on	O
the	O
CSBS	B-Device
;	O
its	O
manual	O
included	O
several	O
methods	O
of	O
determining	O
the	O
wind	O
speed	O
.	O
</s>
<s>
XIV	O
described	O
only	O
one	O
method	O
of	O
determining	O
the	O
wind	O
speed	O
,	O
equivalent	O
to	O
the	O
most	O
complex	O
of	O
the	O
procedures	O
from	O
the	O
CSBS	B-Device
model	O
.	O
</s>
<s>
III	O
Navigation	O
Computor	O
,	O
the	O
RAF	O
's	O
version	O
of	O
the	O
modern	O
E6B	B-Device
,	O
the	O
three	O
sets	O
of	O
angles	O
were	O
entered	O
on	O
the	O
wind	O
calculator	O
face	O
.	O
</s>
<s>
The	O
bomb	B-Application
sight	I-Application
was	O
also	O
supplied	O
with	O
the	O
Emergency	O
Computor	O
,	O
a	O
simple	O
circular	O
slide	O
rule	O
for	O
use	O
when	O
the	O
main	O
computor	O
stopped	O
working	O
.	O
</s>
<s>
In	O
comparison	O
,	O
units	O
using	O
the	O
much	O
more	O
complex	O
Stabilized	B-Device
Automatic	I-Device
Bomb	I-Device
Sight	I-Device
(	O
SABS	O
)	O
improved	O
the	O
systematic	O
error	O
to	O
under	O
the	O
same	O
operational	O
conditions	O
and	O
altitude	O
.	O
</s>
<s>
A	O
series	O
of	O
reports	O
in	O
the	O
summer	O
of	O
1944	O
produced	O
by	O
Bomber	O
Command	O
's	O
operational	O
research	O
division	O
attempted	O
to	O
explain	O
these	O
differences	O
,	O
starting	O
with	O
problems	O
in	O
the	O
bombsight	B-Application
itself	O
.	O
</s>
