Evening star., 1946-03-08
Midway Plans 10 Test
Fire-ConfroI Device
In Arctic Conditions
By Thomos R. Henry
Stor StoH Correspondent


TO THE ARCTIC.-The Navy's new
5-inch, 54-caliber antiaircraft guns
with a much higher ceiling. longer
range and firing a heavier shell
than any antiaircraft ordnance used
on ships during the war will be
tested under adverse conditions
during the present Arctic cruise of
this carrier.
OF special interest is the effect
of extremely low temperatures on a
new fire-control system developed
at the Johns Hopkins University
Laboratory of Applied Physics at
Silver Spring, Md.
The new system makes 1t possible
for the first time to fire effectively
on enemy aircraft within a range
of less than mile.
During most of the war reliance
was placed on the 80 and so caliber
machine guns to destroy planes
which had approached closer than
mile.
Old System Failed.
The 5-inch, 38-caliber guns-with
a shorter barrel and less effective
fire power than the new guns-were
controlled from a central station
below deck. This was effective in CAL
culating trajectorieS over consid-
cradle distance but it was compli-
Gated and cumbersome when enemy
planes came closer to the ship.
Once the enemy has come closer
than about mile this system failed.
The guns had to be aimed and fired
by the gun crews on deck.
The old multigun fire-control ap-
paratus was entirely mechanical like
an adding machine on a big scale
1t performed its calculations
) through an extraordinary complex
system of intermeshing gears which
. were subject to time lags and me-
chanical errors. The new control
mechanism is an electronic opera
tion with the speed of light. The
Importance of this is clear when it
is considered that in extreme cases
a lag of half a second in the func-
stioning of the fire-control system
may mean difference of 1000 feet
in the trajectory of the shell.
The new fire-control mechanism
is small and light. One can be pro-
vided for each gun. 1t tracks the
approaching plane continuously by
radar and operates instantaneously
Tt functions, however, only in, the
straight section of the trajectory
and would be of no value for long
range firing where the target would
be beyond the peak of the shells
trajectory.
Something of the sort was essen
tial once 5-inch guns were furnished
with the new proximity fuses de-
veloped at Silver Spring, which, at
one step, increased the fire power of
guns several fold by making one
shell do the work of several time
fuzed or contact-fuzed projectiles.
Small Guns Still Used.
The main reliance for close-in
defense against aircraft continues
to be the very rapid 20-mm and
40-mm. machine guns for which
hitherto there has been no available
fire-control system. The efficiency
OF each gun depended on the alert
ness and quickness of its crew. The
40-mm. guns also can be controlled
from below decks by the new fire
control system. 1t represents long
step towards the ideal of naval bat
ties which can be operated entirely
from below heavily armored decks.
An automatic loading mechanism
will be necessary to achieve this.
The efficiency of the new fire
control system was tested in the
Pacific with the old 5-inch guns
during the last months of the war.
The extreme cold of the Arctic,
however, introduces some new vari-
able. One Is the functioning of the
so-called amplidyse, the mechan-
ism by which an extremely small
electrical impulse from the fire con-
troll mechanism is amplifled 10000
times so that it becomes powerful
enough to move the heavy guns.
Also there is little data on the func-
tioning of radar antennae under
icing conditions.
There also is the problem of the
effect of icing on the recou springs
of the guns themselves For 20-mm. |
and 40-mm. guns it probably will be
impossible altogether to prevent this
icing once the canvas coverings are
removed from the guns.
Regardless of fire-control devices
gunnery officers of the Midway ex-
plain the human factor remains of
extreme Importance and little is
known of the effect of extreme tenn
peratures on the alertness of men
under extremely exacting conditions
of modern warfare. A difference of
as much as a second in the time it
takes to put the shell into a gun
might be of vital Importance. A
variety of tests are planned of the
length of watches on the condition
of the crews.