Evening times-Republican. [volume] (Marshalltown, Iowa) 1890-1923, 1918-04-09
Experts Strip Ne,o
miracle" Gun of
All Its Myster,

Stockholm. April S.--The opinion
is increasing among Swedish artil-
lerists who stand high in European
military circles that the Germans
new long range cannon presents 70
problems that cannot be solved by
known ballistic principles.
All agree it is 10 occasion for any
Jules Verne flights of imagination
in accounting for the new guns sue
cess, and that its moral eject on a
great capital is by no means negligi-
BILE The concensus is that it is real
cannon employing a projectile and
not a self-driving air torpedo. Sum
ming up the deductions of the safest
and best informed men, their con-
illusions run thus:
II the projectile is fired at an an
gle of from 80 to % degrees it soon
attains height where the air is so
thin that the air friction can be prac-
ticaIly disregarded and calculations
made almost as if dealing with a
vacuum.
Shell Rises to Vacuum.
At a 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 c.. the air re-
sistance has sunk TO about per cent
of the original resistance.
When under these conditions the
projectile is conceived as being fired
| to a height of about twenty-five
miles, then throughout the longest
period of it's journey the air resist
ance will be at a 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 point of departure for
this shell a fifteen ard one-half inch
cannon, the length of which is fifty
times that of the caliber-in other
words. nearly sixty-six feet
Cannon Within Cannon.
In the gun they have placed an in
ner tube with a caliber of eight and
one-half inches. tEds the gun would
have the strength to withstand
enormous 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
836 pounds of specially suitable
powder and the cannon can be made
about eighty times as long as the
caliber
Thus the projectile receives a pro-
pulsive power Of about 10000 me-
trio tons, and its eight and one-half
inch projectile, weighing 440 pounds
obtains an initial velocity of about
$500 feet per sec ord. IN order to OBJ
tain range of seventv-five miles in
a vacuum the projectile requires an
initial speed of $50 feet per sec
ond, with a departure angle of forty
five degrees.
Pierccs Strata Of Air.
It may therefore be imagined that
the projectile will be released at a
somewhat larger elevation so that
the dense strata of air il has to pass
through will be as short as possible
If we then conceive that the pro-
| iectile's course, on reacting at a
| height of twelve and one-half miles,
| has an inclination toward the hori-
zontal plane of forty-five degrees. it
requires remaining velocity of
I about 3,OSS feet second to give it
the total range of seventy-five 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 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
a velocity of about ] 800 feet a sec.
cnd. The gun upon which we have
based our calculations gives its pro-
iectiie an initial velocity of $500
| feet
When the proiectile shall have
reached an altitude of twelve ant
! ore half miles, 1t must travel at &
! velocity of 3.0SS feet a second. Thi!