Two-piece base pad igniter bag

Details Two-piece base pad igniter bag Two-piece base pad igniter bag

2000-11-07

2002-05-07

Poon, Peter M. (Department: 3641)

Ammunition and explosives

Propellent chemical charge container

Reexamination Certificate

active

06382104

ABSTRACT:

BACKGROUND OF THE INVENTION
The invention in general relates to igniter bags, and in particular to igniter bags used to ignite stick propellant.
FIG. 1
schematically shows an example of the environment wherein a base pad igniter bag is used. A barrel
10
contains a projectile
12
that rests on a metal cartridge case
14
. Case
14
is closed at its upper end by a polyurethane plug
16
. Case
14
is filled with stick propellant
18
. A case base
20
closes the lower end of the case
14
. A stub igniter
22
is disposed centrally in the case base
20
. A base pad igniter bag
24
fits in the cupped region of the case base
20
.
Base pad igniter bag
24
is typically shaped like a doughnut to fit around stub igniter
22
. Igniter bag
24
is generally sewn from clean-burning cloth and filled with a granular igniter material
26
. Igniter bag
24
transfers the ignition from stub igniter
22
to the stick propellant
18
. Initially, stub igniter
22
is ignited and it transfers its combustion products radially through openings
28
into the igniter bag
24
. The combustion products from the igniter bag
24
vent into the stick propellant
18
, igniting the ends of the sticks and flowing through the channels between the sticks to ignite their other surfaces.
FIG. 2
schematically shows a prior two-piece igniter bag
30
with a seam at the inner circumference
32
. The bag of
FIG. 2
is made by sewing two identically shaped pieces of material together along their inner and outer circumferences
32
,
34
. The design of
FIG. 2
offers no real surface area normal to the venting gases from the stub igniter. This lack of intimate contact between the stub igniter and the igniter bag leads to excessive ignition delays. Providing more intimate contact is the object of the bag shown in FIG.
3
.
FIG. 3
schematically shows a three-piece igniter bag
40
in which a separate flat piece
42
is sewn like a sleeve between the two doughnut shaped pieces of material. While better ignition is achieved, the bag of
FIG. 3
takes much longer to make because of the difficult seam between the straight sleeve
42
and the two doughnut shaped main pieces. The small radius, on the order of two centimeters, is very extreme and difficult to sew by machine. In addition, the fabric bulk of the seam allowances is still in the critical region next to the stub igniter vents, so ignition transfer difficulties may be experienced.
SUMMARY OF THE INVENTION
The igniter bag of the present invention uses only two pieces of cloth, but retains the sleeve effect to achieve reliable ignition transfer to the igniter material contained in the bag. Seams are either straight or have a considerably larger radius of about 6 centimeters and are easier to sew. Furthermore, most seam allowance bulk is on the flat surface of the pad rather than near the interface with the stub igniter. Only two short, axial seams break the surface presented to the stub igniter.


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patent: 304218 (1920-04-01), None
patent: 692609 (1930-03-01), None

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