The Princeton union. [volume] (Princeton, Minn.) 1876-1976, 1915-11-11
TESTING A SHELL.
0rdeaIs Through Which a Big Gun
Missile Must Pass.
THE SOFT NOSE PR0JECTltE.

Its Ability to Bore Its Way Through
Heavy Armor Plate Without ExpIod-
ing Until After Its Impact Was Dis
covered by Accident. t.. .
Everybody knows that the modern
shell is one of the most diabolical of
mans inventions, but how many of us
realize that it is also one of the most
delicate and complicated?
Recently some firms holding con-
tracts for making high explosive shells
took upon themselves to correct a
detail in the specification, and, as re-
suit, a, certain thread was Improved"
They will never do anything of the
kind again, because all their work was
rejected. The apparent absurdity-it
is, in fact, an absolute absurdity, from
an engineering point of view-is de-
signed of set purpose
There is a somewhat similar anon
ally in the big shell for penetrating
armor plating, which was introduced
in consequence Of an accident. One
day test shell was fired at piece of
armor plating from the soft side, and
the projectile went clean through it
and exploded after impact, whereas a
similar shell fired against the 'front.'
the hardened and tempered side-shat-
tered and left an indentation of only a
few inches.
This singular incident set somebody
thinking, and in consequence the high
explosive armor piercing shell is now
given soft nose. To the hard point is
attached cap of soft metal, with
which addition it will go through the
toughest piece of armor plate. What
happens on impact seems to be this:
The cap spreads, holding the point and
SO enabling remember that the shell
is revolving rapidly-to force it's way
| unbroken through the hard face Of the
plate by sort Of boring action.
No less curious is another fact con-
corning the points Of such projectiles.
After the heads have been worked the
shells are left for weeks before they
undergo the next stage, because, strong
as they look, they are liable to snap.
Why? Think Of the razor Constant
stropping twists the grain, with the re-
suit that the steel gets "tired' and will
not yield keen edge. But if you put
the thing away for a few weeks the
grain will return to it's normal state,
and you can get a satisfactory shave.
In similar way the grain of the steel
is affected by working, though of course
to much greater extent, and until it is
''set'' the makers must go cautiously.
Steel shows like eccentricity in the
| making Of test gauges. Some of the
measurements Of shells are very fine,
and the instruments employed are so
delicate that they have to be used
quickly lest the heat of the hand causes
the metal totexpand.
Now. when a groove is cut in piece
of steel which is to be used as a test
gauge the work is laid aside for weeks.
perhaps months. Why not finish it at
| once? Because the groove, though dead
| true when cut out, may be otherwise in
short time, even though it has been
absolutely untouched.
AS concrete proof of the elaborate
| nature Of projectile making take the
case of the shrapnel shell. The steel
portion undergoes about score of op-
erations, and the brass cartridge case
attached to the base requires about six
teen, counting from the disk of sheet
brass to the finished article Then
there is the fuse. the delicacy of which
resembles matchmaking
Altogether the shell is subjected to
about forty inspections and may be re-
jected at any stage ..'
After shell has survived this ordeal
it ought to be, one would think, per-
feet, but test shell is taken from
every 120 and actually fired from gun
into bank of sand. 1t is then again
examined. and if the contour about the
powder pocket is expanded away goes
the whole batch. because if they were
fired the growing might be torn out Of
the gun.
of the, minute care exercised in projec-
tile making is, that every shell is weigh
ed over and over again. If you produce
an eighteen FOUNDER high explosive
shell it must be only a few drains over
or under its normal weight; otherwise
it is rejected. &
In this connection it may be of inter
est to note that an explosive shell that
weighs only about seventy pounds will
break into a shower Of some 1900
pieces. A single one of the monster
projectiles fired from fifteen inch ma
val gun will weigh 1850 pounds. It.
takes twelve seconds for the projectilc
of twelve inch naval gun to reach its
point of impact when firing at range
Of five miles. To fire battleship
broadside costs about $4,000. - Ex-
change. - H.