The morning news. [volume] (Savannah, Ga.) 1887-1900, 1899-07-02
Importance of shape in Powder
Grains.
From the Washington Star.

From the Washington Star.
The ordnance bureau of the war depart
ment Is carrying on an interesting and ex-
haustive investigation in smokeiess pow
der. having particular reference TO the
form of grain best adapted for service use.
The demand for this inquiry arose in the
recent accident at the Sandy Hook prov
ing-g grounds, when a smOkeless powder
charge blew out the breeck- block from
10-inch gun and killed one of the firing
squad. it was suggested at the time that
this accident might have been due to de-
terioration in the powder during storage.
This view was advanced by some of the
naval experts and others, who claim that
the nitro-powder used by the army is not
so reliable a compound as the pyro-celulose
powder which has been perfected for use
in naval guns.
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 as 1t
might have been, and the present series Of
experiments is aimed to correct this de-
feet 1t has been proved by long expert
ence with the old black and brown pow
der charges that the amount of energy
produced and the speed with which this
energy is accumulated can be controlled 10
a nicely by the form of grain into which
the powder is nodded. With the brown
powder, which has been used for num-
Der Of years, it was found that a large hex
agonal grain with hole through the CEN
ter came the nearest to producing ideal re-
suits. This grain in general appearance
was almost exactly like a three-quarter-
inch machine nut. 1t had just the amount
of surface to produce a not too rapid COM
busuon of the charge, and at the same
times to put maximum of power behind
the shot as it was leaving the gun. This
is the principle governing powder charges
for all guns. The shot as Ii 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 projectile can be started.
On the other hand, there must be GER
tain amount of energy to secure salts
factory velocity
With the smokeless powder the danger
of too rapid combustion is very serious
question, because Of The immense amount
of energy developed when it ignltes TOO
rapidly. The explanation offered for the
accident to the 10-inch gun is technically
known as wave action" In cases OF this
sort it is explained that the explosion at
the rear of the charge, where 4 is frst
ignited drives the remainder OF the pow
Ger forward against the base of the pro
This impact brushes the remaining grains
of powder and thus gives q much larger
surface for combustion than 1t intended.
This extra rapid combustion produces an
Immensely greater force than the gun is
built to stand, and. coming suddenly re-
bounds from The base of the shell towards
the breech before the inertia Of the pro-
jectile in the bore of the gun can be over
come The result is either TO spring or
blow out the breech block or to wreck the
gun The powder pressure developed in
cases of this sort are infinitely greater
than any of the pressure gauges have ever
been able to register.
The powder grains now in use by the
department are OF several forms, but In
the main resemble short lengths Of maca-
roni Some Of them have the single large
hole through the center. like the Italian
national dish while others have a num-
her of smaller holes, like the strands in
the submarine cable. The investigation
Of the ordnance department indicates that
these grains burn at the proper speed II
left to themselves, but under service con-
dtions they are subjected to great pres
sure while they are ignitng, 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, win etill
reIa.n strength enough TO resist the crush
ing pressure in the powder chamber. IT
Is also intended 70 ignite the charge from
The front instead Of from the rear, in the
belief that this viii reduce the destruc-
tive effect Of wave action should II ever
be set up IN the powder chamber