January-February - Air Defense Artillery

A Hole Filler
By Major K. C. Smith, Coast
Artillery Corps
EDITOR'S NOTE: This is a type disposition, just as is
the "square." Whatever type disposition is accepted as
basic, the actual disposition in the emplacement of the
guns must conform to the physical characteristics of the
terrain. The liberal allowance for clearance that we
have used during peacetime conditions seems capable of
being reduced in order to bring fire to bear earlier and
to continue longer in battle.
In the late 't~'enties we happily discarded the parallax
features of the vVind and Parallax Computor,
MI920, "v\!henthe practice of placing the (data) computor
at the gun position became standardized procedure."
Then along came the M2 and subsequent
directors with provisions for setting in parallax as \vell
as wind. Also along came a fair quantity of AA BC
Observation Instruments, Ml (BC Scopes). So we cast
aside the 'Wind and Parallax Computor, as it had degenerated
into nothing but a substitute for missing BC
S~opes. We pulled the director off the directing point
of the battery and set it somewhere out of the wav.
However: we left the guns in the classic 'rough
square, fifty yards on the side, as in Figure 1. Why?-
Well, for several reasons. As nearly as we can t;ack
them down they \vere: '
1. The dang~r space of a shell burst (Figure 3) was
considered to be of such size that lethal areas would
overlap with the guns fifty yards apart.
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2. \ Ve felt that if ,,'e "'ere closer than thirty-five
yards to another element of the battery, one bo~b hit
might destroy two elements. and fift~, yards 'spacing
was eyen better.
3. l\1uzzle blast from one gun closer than thirtv-five
yards to another element of the battery might int~rfere
with the efficiencyof this other element, and fiftv yards
was even safer. ..
4. A square, fifty yards on the side was a nice convenient
figure, and we had drawings and cuts all made
up for such a formation.
In the late 'thirties we took all the dimensions off
the danger space in all publications. We kne~' that
they were far too large from information obtained during
the Spanish Civil War, and the consensus seems to
be that they were over four times too great.'
Let's grant item t\\'O,above, as a valid reason, but stay
dow~ to thirty-five yards as ample distance, in a properly
fortified position.
The matter of muzzle blast makes no sense to one
:vho wi~h quaking knees has stood on the director platform
of a Navy 5-inch 38 caliber battery developing
over 2600 foot seconds. On a series of normal courses,
rounds were fired when this plaform was within six
yards of the muzzle of one gun, in a direction that
would make an angle of less than forty-fivedegrees with
the axis of the bore. There was no basis for the knee
quaking. Those navy people regularly fire their guns
over each others heads at elevations of thirty-five degrees,
and drop to ten degrees if one gun is' deflected
from the other by fifteen degrees. The guns of the battery
observed were only twenty-five feet from pintle to
pintle and the b-arrelswould crack together if they were
pointed at each other. Now and then a man would get
his hat knocked off, but the point is that the blasts
did not interfere \vith the firing.
Figure 1 Figure 2