The Richmond palladium and sun-telegram. [volume] (Richmond, Ind.) 1907-1939, 1918-04-08
EXPERTS STRIP
MYSTERY FROM
miracle" GUN
Explain by Figures How Ger
mans Long Range Cannon
Works.
BY JAMES O'DONNELL BENNETT
In the Chictqo Tribune.

STOCKHOLM, April S.-The opin
ion Is increasing among Swedish artil
lerists who stand high in European
military circles that the Germans
new long range cannon presents nc
problems that cannot be solved by
known ballistic principles.
All agree it is no occasion for any
Jules Verne flights OF Imagination in
accounting for the new guns success
and that its moral effect on a great
capital is by no means negligible. The
consensus is that it is a real cannon
employing a projectile and not self
driving air torpedo. Summing up the
deductions of the safest and best in.
formed men, their conclusions run
, thus:
II the projectile is fred at an angle
of from 50 to IS degrees 1t soon at
tains height where the air is SO thin
that the air friction can be practically
disregarded and calculations made al
most as il dealing with vacuum.
She'll Rises to Vacuum.
At height of twelve and one-half
miles atmospheric pressure is as low
as forty-two millimeters, and even
though the temperature here is low
SIS degrees Co. the air resistance
has sunk to about 6 per cent. of the
original resistance.
When under these conditions the
projectile of about twenty-five miles,
then throughout the longest period of
Its journey the air resistance will be
at minimum.
1t is now known that twenty-four
centimeter shell-about eight and a
half inches--is used. hence it appears
that the Germans have chosen as a
point of departure for this shell a
fifteen and one-half inch cannon, the
length OF which is fifty times that of
the caliber-in other words, nearly
sixty-six feet.
Cannon Within a Cannon.
In the gun they have placed an In
ner tube with a caliber OF eight and
one-half inches, thus the gun would
have the strength to withstand enor-
nous pressure during firing and have
the same amount of space for the
charge as fifteen and one-half inch
cannon has.
This leaves room for a charge of
$50 pounds Of specially suitable pow
der and the cannon can be made about
eighty time as long as the caliber.
Thus the projectile receives a pro-
puplsive power of about 100000 metric
tons, and It's eight and one-half inch
projectile. weighing 44O pounds. OBJ
tains an initial velocity of about $500
feet per second In order to obtain a
range Of seventy-fve miles in a vac
uum the projectile requires an initial
speed of $3.50 feet per second, with a
reparture angle OF forty-flve degrees.
Pierces Strata of Air.
1t may therefore be imagined that
the projectile will be released at a
somewhat larger elevation so that the
dense strata OF air 1t has to pass
through will be as short as possible
If we then conceive that the projec-
tiles course, on reaching at height
of twelve and one-half miles, has an
inclination toward the horizontal
plane of forty-five degrees, 1t requires
a remaining velocity of about 3.0SS
feet a second to give it the total range
of seventy-fve miles from the point
of departure to the target.
Although guided by the preceding
!. ballistic tables. we can calculate the
loss of velocity up to a height of
twelve and one-half miles, we know
this loss chiefly depends on air re-
sistance.
Must Overcome Gravity.
Gravity deprives the projectile of
velocity of about 1900 feet a second
The gun Upon which we have based
our calculations gives its projectile