Evening star. [volume] (Washington, D.C.) 1854-1972, 1899-05-30
Army Officers Investigating the
SerVioeability of Various Forms.
CAUSE OF PREMATURE COMBUSTION
Recent Fatal Accident at the Sandy
Hook Proving Grounds.
FACTS NOW ASCERTAlNED

The ordnance bureau of the War Depart
Tnent is carrying on an Interesting and ex-
haustive investigation In smokeless powder.
having partiC ular reference to the form Of
grain best adapted for service use. The de-
mand for this inquiry arose in the recent
accident at the Sandy Hook proving
grounds, when a smokeless powder charge
blew out the breech block from a ten-inch
gun and killed one of the firing squad. 1t
was suggested AT the time that this acct
dent might have been due to deterioration
in the powder during storage This view
WAS advanced by some of the naval experts
and others. who claim that the nitro pow
der used by the army is not so reliable a
compound the pyro-culuiose powder
which has been perfected for use in naval
guns.
Fault Found with the Grains Form.
The army ordnance people do not admit
that there is any defect in the gun in ques-
ton, or in the keeping quality of the pow
der Their explanation is that the shape
Of the powder grain was not as good 1t
might have been. and the present series of
experiments is aimed to correct this defect.
1t has been proved by long experience with
the old black and brown powder charges
that The amount of energy produced and
the speed with which this energy Is ac
the form IF grain into which the powder is
nodded. With the brown powder, which
has been used for a number of years. IL
was found hat a large hexagonal grain.
with mole through the center, came the
nearest to producing ideal results This
grain in general appearance was almost
exactly Ike A hree-quarter-inch machine
nut. II had just the amount of surface to
produce q not too rapid combustion of the
charge, AM at the same time to put
maximum of power behind the shot as II
was leaving the gun. This Is the principle
governing powder charges for all guns. The
shot as it rests IN the bore of the gun has
a certain amount of inertia. This has to
be overcome before the projectile is started
on its flight. With a powder charge where
the combustion is very rapid, there Is
danger of bursting the gun before the pro-
tcctlle can be started On the other hand.
there must be a certain amount of energy
To secure satisfac tory velocity.
Danger of Too Rapid Combustion.
With the smokeIess powder the danger of
too rapid combustion is very serious ques-
lion. because of the immense amount of en-
eIgy developed when it ignited too rapidly.
The explanation offered for the accident to
the 1e-inch gun is technic ally known as
wave action. In cases of this sort ii is
explained that the explosion at the rear of
the charge. whore il * first ign!ted. drives
the remainder of the powder forward
against the base of the pIoJectile and into
the Choke Of the bore. This impact
brushes the remaining grains Of powder and
thus gives a much larger surface for COM
bustiOn than j. intended. This extra rapid
combustion produces an immensely greater
force than the gun is built TO stand, and
coming suddenly. rebounds from the base
of the shell toward the hreech before the
inertia 0t the prOJectile in the bore of the
gun can De overcome. The result is either
10 spring or blow out the hreech block or to
wreck the gun. The powder presSures de
v-loped in cases of this sort are infinitely
greater than any Of the pressure gauges
have ever been able to register.
Forms of the Powder Grains.
FtIe :IoWtler grains now in use by the de
partner. are of several forms, but in the
main rest mble short lengths of macaroni.
Some Of them nave e.e single large hole
through the center. like the Italian ma
tional dish while others have a number of
smaller holes like the strands in the sub
marine cable The investigation Of the ord
nance department indicates that these
grains burn at the proper speed if left to
themselves. but under se-vicc conditions
they are subjected to great pressure while
they are igniting. and the walls growing
thinner as they burn are easily crushed
down into dust producing the disastrous
explosion described
The department is now experimenting
with grains OF various shapes. which. while
burning at proper speed, will still retain
strength enough to resist the crushing
pressure in the powder cha nber. 1t is also
intended to ignite the charge from the front
instead OF from the rear. in the belief that
this will reduce tn" destructive effect OF
wave action should it ever be set up in
the powder chamber