Page 2 - us2869463

United States Patent Office 2,869,463
Patented Jan. 20, 1959

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It is a further object to provide a cartridge construction
which can withstand long periods of vibration and much
2,869,463 rough handling without alteration in time delay or
reliability of firing.
DELAYED FIRING CARTRIDGE 5 The time delay of the cartridge is provided by the
James T. McKnight, Los Angeles, Calif., assignor to burning of a train of slow burning mixtures containing,
Bermite Powder Company, Saugus, Calif., a corpora- primarily, powdered metals and metaliic oxides, similar
tion of California to the well known Thermite mixture of powdered
aluminum and powdered iron oxide. An inert material
Application March 26, 1956, Serial No. 573,684 10 may also be included in the mixture to slow down the
4 Claims. (Cl. 102-39) speed of reaction, if desired. The preferred powder for
the time delay is that developed by the Naval Ordnance
Laboratory at White Oaks, Maryland, and designated by
the formula number D-16. Preferably, the burning of
This invention relates generally to explosive cartridges, 15 the delay train is initiated and completed by first fire and
and more particularly to a cartridge which is manu- after fire charges, respectively, which are comprised of the
factured to explode a predetermined number of seconds metal, metal oxide, and inert ingredient mixture different
or fraction of a second after firing. In its preferred form, from that of the delay powder. The preferred material
the invention includes a train of pressure-consolidated for first fire and after fire is the powder developed
ignitable charges containing metal and metallic oxide 20 and designated by the United States Naval Ordnance
which serves as a fuse leading from a primer and an Laboratory at White Oaks, Maryland, as F33b. However,
initial shock chan1ber to an explosive propellant adapted any powdered mixture, stable under ordinary conditions,
to deliver a work output on some device such as a and slow burning with the production of substantially no
parachute assembly. gas may be used. The mixture may include one or more
The cartridge of the present invention provides a 25 active metals, such as aluminum or magnesium and one
reliable means for opening a parachute a precise interval or more o,xides ,or oxidizing compounds of weaker metals,
of time after an object has been dropped from an airplane. such as iron. Some traces of organic matter may be
Heretobe£ore, the most widely used means for opening a present, but all gas producing combustibles must be ex-
parachute en a dropped object has been by means of a tremely minute in qnantity, since the delay train must
rop cord line extending from the plane, and of a length 30 burn while completely contained within the ,cartridge,
believed to be great enough to avoid entanglement of the and without any provision for the escape of gas. Exces-
parachute by the plane or the air currents produced by it. sive pressure rise within the cartridge causes erratic
The rip cord line itself has been a cause of erratic per- burning of the. time delay train.
forinance and accident, however. Sometimes it became Some gas production by firing of the primer and the
entangled with the plane or dropped object, or with other 35 burning of organic impurities unavoidably present in the
planes or parachutes engaged in the same dropping opera- powder of the delay train is inevitable. It is one of the
tion. The time lapse before opening of the parachute novel features of this invention that the construction
could not be controlled with accuracy. The lines and provides an empty pressure chamber of maximum volume
mechanical connections added useless weight and were consistent with ruggedness and small c1rtridge size to
subject to deterioration and damage even prior to-use. 40 minimize both firing shock and pressure rise from gas
The delayed firing cartridge eliminates the need for forming combustibles.
any connection between the plane and the dropped object. Other objects and advantages of the invention will be
It and the operating mechanism by which it opens the apparent from the following description of specific em-
parachute are very reliable in operation, s:nall in size, bodiments illustrated in the drawings in which:
and light in weight. Moreover, the cartridge can be 45 Figure 1 is a longitudinal sectional view of a preferred
fabricated to discharge at precisely the desired interval form of the delayed firing cartridge;
after firin° without being subject as rip cord lines are, Figure 2 is an exploded perspective view of the cartridge
to variati;~s in time arising out of different flying and assembly of Figure 1; .
dropping conditions. . . Figure 3 is a longitudinal sectional view, with the center
The present cartridge may be used m other apphca- 50 portion removed, of another embodiment of the invention;
tions in which a time fuse is required, particularly for and
delivering a few foot pounds of work after the lapse of a Figure 4 is a perspective view of a longitudinally_ sec-
few seconds. It can be used in aircraft ejector seats, tioned cartridge constructed. with cylindrical laminattons.
missile mechanism, submarine emergency devices; fire In Figure 1, a cylindrical sheil casing rn, having a
alarm systems, etc. In. larger sizes the time delay an~ 5 5 relatively thick base 11 at its firing end 12, is closed at
energy output can be greatly increased. In su~h size~, it its discharge end 13 by a thin clos,Ee disc 1A held in
can. be used for small blasting purposes, and 111 devices position by the inwardly rolled flange 15 formed in the
for lifting heavy objects into position; . end of the case 10.
In order that the cartridge may effectually serve these A primer capsule 16 is tightly. fitted int? .a pr~mer
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purposes, it must discharge pr cisely_ at_~ predetermined· HO recess 17 in the base 11. Both the case ]O ana tne pnmer
time after firing. Moreover, its rel!ab1hty must not ?e capsule 16 may be standard ammunition materials, For
impaired by long periods of stor~ge, ~r exposure to air- example, a standard brass .38 caliber s~ell c:i~e may be
plane engine vibration. Its firmg- time mus~ not ?e used; and a standard vVinchester perc'.lss10n pnmer, such
appreciably affected by the shock of the explosion of its as the M-42 low- power primer used in hand grenad~s,
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own primer. . . . is suitable. It wili be understood, however, that the 111-
It is therefore a major object of the present mvent1on vention is not restricted to M-42 primers or even to
to provide a delayed firing cartridge which. will absorb . - b
·
1 pnmers can . e
fl ·
the brissance o f . its own rmg wi "thout adverse effect percussion p.rimers. Various swtab e
-
on its accuracy of time- delay. prepared. by those skilled in the art, for example usmg
It is-another importantobject of.the invention to provide 70 various mixtures of potassium chlorate· and lead sulfo-
a cartridge construction which can:be-readily, manufac.; cyanate, ,or lead styphnate.-alonc; and electrical ignition
tured to a predetermined time delay, may be used instead of percussion.