Five Mile Beach weekly journal., 1917-03-30
BENDS IN BIC Guns
Their Weight Gives Some of Them
a Curvature of the Spine.
DROOP AT THEIR MUZZLES.
In Some Cases the Flexure ls Great
Enough, II Not Allowed For, to Affect
the Accuracy OF tho Weapon-How
the Defect ls Corrected.

the Defect ls Corrected.
The newest American dreadnaughts
are to be armed with sixteen inch RI.
hes, and the layman takes 1t as a mat
ter of course hat these monster weap-
ons are merely bigger brothers of the
fourteen inch gun. But this offhand
conclusion Is decidedly at fault. The
sixteen Inch gun is q more exacting
engineering problem than the fourteen
inch weapon, and just because Of It's
greater length and girth and weight 1t
is a more difficult piece to make pre-
else In It's action. The bigger the gun
the more It is prone to develop trou-
blesome characteristics, and the ord
lance engineer has his cunning heavi-
~ taxed In order to neutralize or to
minimize these inherent tendencies.
To begin with, the sixteen inch
gun, without its mount, represents an
outlay of $175,000, that being the price
paid for the materials used and the
skilled workmanship. U11ess fabricat-
ed with exquisite regard to accuracy
the weapon is neither safe to fire nor
SdPoOl0 " Sioiiolh6 UP W 10 vi
during a relatively short active career,
measured by something like a couple
of hundred rounds.
1t must be remembered that q six
teen inch shell weighs about a ton
to be exact, 2,100 pounds-and the
powder impulse exerts sufficient en-
ergy back of the p~rojectile to start 1t
from a standstill and to send 1t hur-
ting from the weapons muzzle at a
velocity of $500 feet a second. 1t would
not do to have that speeding shell Jam
in the bore of the rife, because If sud
denly arrested it would probably frac-
ture the weapon IL it did not cause a
graver disaster. Therefore the ord
nance engineer must see that the path
represented by the bore is as nearly
a straight line as it is mechanically
and physically possible to make 1t.
A twelve inch gun of do caliber is
forty-fiye feet long, and except at the
single supporting point the heavy mass
of tie extended weapon is without any
sustaining help. These monster pieces
of ordnance are virtually single pivot
ed girders, and their power to resist
bending or reformation depends es-
sentially upon the strength of the ma
terials employed and the distribution
of the mass. Clearly, then, the big
ger the rifle the greater becomes the
disposition to droop toward the muz-
zle, II not only does this impair the
shooting accuracy, but in time the
weapon becomes a source of danger to
its W people.
The weight of some of the big guns
now in use in the navy causes them to
droop at their muzzles as much as half
or three-quafters of an inch, and this,
If mo- realized and allowed for in sight
ing, will make the shooting inaccurate,
the inaccuracy increasing with the
length of range. In fact, the projec-
tile on leaving the gun Is directed by
the last six feet of the muzzle. That
is to say that if the rifle has a droop
the shell follows the curvature instead
of taking the line assumed by the gun
pointer at the telescope sight.
The bureau of ordnance in Washing
ton has been working at this problem
as guns have grown in length and di-
ameter of bore. At the present time
the great fourteen inch weapons have
an appreciable droop of only .3S of an
inch. This droop is not enough to en-
danger the life of the gun or to impair
its range, provided the sights are adj
justed to it. But there is another in
fuence at work which tends to affect
this droop and to cause it to vary some
hundredths of an inch from time to
time. This is the weather. For In
stance, a gun will droop when the sun
shines fercely upon its upper side,
while the under side is shaded. But
so long as this total DETECTION does
not exceed half an inch there is no dan
ger of the shell jamming in passing
along the slightly curved bore.
In the latest of our big naval weapons
this droop has been still further re-
duced by extending the jacket or hoop
ing further out over the forward part
of the gun This serves to stiffen the
gun so that the sun has not as much
reforming effect as heretofore. 1t may
be asked, what about the other guns
now in service that have not been so
REINFORCED to check drooping?" The
bureau of ordnance has resorted to a
very simple expedient In correcting this
curative.
The deformed weapon is simply ro-
tated in the recoil sleeve of the mount
until the underside of the rifle is up
permost. The muzzle then, instead of
dipping actually, is curved skyward.
In time the natural elasticity of the
metal asserts itself, and the over
hanging weight of the outstretched
muzzle gradually presses the chase
downward and straightens out the
piece.-New York Sun.
Well Balanced Tires.
Balance In a tire means that the
tire must 10 So hnilt as to Wpar even