Ammunition and explosives – Having reaction motor
Reexamination Certificate
1999-01-05
2002-03-19
Carone, Michael J. (Department: 3641)
Ammunition and explosives
Having reaction motor
C102S380000, C102S430000, C060S253000, C060S256000
Reexamination Certificate
active
06357357
ABSTRACT:
BACKGROUND OF THE INVENTION
I. Field of the Invention
The present invention relates generally to gas generating propulsion systems and principally those suitable for use in rocket motors or for firing artillery pieces. More particularly, the invention is directed to an improved system for creating high surface area for burning in an uncatalyzed or partially catalyzed bulk propellant mass at high pressure and velocity using a highly efficient separating device.
II. Related Art
The successful firing of rocket motors and large caliber munition cartridges rests in no small measure with the performance of the associated propellants including the repeatable predictability of that performance. Important aspects include loading density and burning rate. However, the two commonly seem to work against each other because dense loads inherently create difficulties in achieving a sufficiently rapid and high, increasing ignition surface area necessary for successful high performance burning.
With respect to ammunition, efforts have been directed toward increasing the amount of propellant available per unit cartridge volume (propellant charge density) without sacrificing burn rate by employing a variety of perforated grain shapes. Bulk liquid propellants have also been used, but have generally exhibited unpredictable burn characteristics.
FIG. 1
depicts a typical large caliber round which may be fired from the main turret cannon of a tank or other large caliber device and having propellant loaded in accordance with one prior art method. The round is shown generally at
10
at FIG.
1
and includes a base plate section
12
connected with the wall of a cartridge casing and having a generally cylindrical portion
14
and a necked down or tapered upper portion
16
. The cartridge shell itself is normally made of metal or a combustible material such as molded nitrocellulose or other such material which is consumed during the firing of the shell. The projectile itself is shown at
18
with discarding sabot members
20
and
22
which peel away and drop off just after the projectile is discharged from the muzzle of the cannon. A plurality of stabilizing guidance fins as at
24
are also provided. The nose cone section
26
may contain an electronics package and the warhead section
28
may contain arming and detonating circuitry.
With respect to the firing of the shell, a primer housing shown generally at
30
contains a conductive ignition electrode or primer button (not shown). The primer housing is connected with a generally hollow brass or other type metal primer tube
32
which has a plurality of openings as at
34
which access and address the general propellant charge volume
36
. The available propellant charge volume is filled with closely packed, generally uniformly shaped granular solid propellant grains
38
which may be 2 to 3 cm long by about 0.5 cm in diameter.
The shell is normally fired electrically using direct current to ignite the primer in the primer housing and through the primer tube
32
, thereby igniting the main propellant
38
via the openings
34
. In accordance with improving one aspect of performance, i.e., achieving the highest, repeatable muzzle velocity for the projectile, it is desirable that the propellant burn as rapidly and uniformly (with respect to the load) as possible.
Other propellant configurations have included extruded stick shapes. The propellant manufacture begins with carpet rolled propellant, which is dried, aged, pre-cut for extrusion, extruded with perforations and cut to length. Each length is blended to minimize lot to lot performance variation, and each length must be notched or kerf cut in several places on the side to prevent over pressurization during the burn before the propellant may be used. The loading process for a cartridge using stick propellant is labor intensive and the stick shapes have presented difficulties in achieving high loading densities. Performance is not optimum because of mating surfaces of the sticks, as in the case of random placement with granular propellant.
In addition, repeatability of acceptable or good performance of stick propellant also requires uniformity of the notch or kerf size and web between the kerfs for proper burning. Current extrusion and kerf cutting processes are rarely able to achieve this so that the sticks must be blended or mixed prior to loading to achieve some uniformity. As a result of mixing the stick propellant, performance is not optimized.
Another method utilizing ribbed sheet propellant rolled into cylindrical sections has been tested on smaller caliber ammunition. This method used longitudinal ribs replacing perforations to assist ignition. The rolled method experienced difficulty in conformance to the projectile geometry, poor progressitivity, poor flame spread and poor ignition characteristics.
Additional load arrangements for solid propellants are shown and described in Kassuelke et al (U.S. Pat. No. 5,712,445) assigned to the same assignee as the present application. Those loadings are generally in the form of arrangements of closely packed perforated slab or disk-shaped.
There remains a need for a propulsion system that improves pressure control while delivering a high burn rate from a relatively dense load. The present invention represents a different approach to allowing increased loading density in a dynamic system that enables a high, controlled burn rate. Embodiments of the system of the present invention are adaptable to both rocket motor and projectile-firing uses.
In accordance with desirable artillery performance, it is desirable that the pressure history in a launch tube be held nearly constant. This is especially important with respect to higher burning efficiency configurations. An additional goal of manufacture, particularly relevant to cartridge, is to reduce production costs related to shaping grains and labor costs related to loading the shaped grains into the casings. A propellant system which allows increased and more reproducible burning together with lower production and loading costs is very desirable.
Accordingly, it is a primary object of the present invention to provide a system that creates a high surface area propellant at high pressure and velocity from a bulk propellant mass which achieves a controlled burn.
Another object of the invention is to provide an improved propellant system at a lower production cost.
A further object of the present invention is to provide a propellant system wherein a bulk mass of uncatalyzed or partially catalyzed propellant is pressed through a shredder plate with many holes or orifices to create a large number of long, high surface area strings, which simultaneously burn to produce a very high burn rate propellant.
A still further object of the present invention is to create such a system wherein the pressure to force the propellant through the perforated plate can be programmed to suit various design conditions.
A yet further object of the present invention is to provide a system wherein the uncatalyzed or partially catalyzed propellant can itself be used as the pressurization source by suitably adjusting the area of the pressure face on the chamber side versus the bulk propellant side.
A yet still further object of the present invention is to provide a system that provides auto ignition of the propellant strings by a combination of pump work heating and friction between the extended propellant strings and the rims of the holes.
Yet another object of the present invention is to provide a system that can be operated in a stable mode wherein variations and pressure and burn rate are self-correcting to a design rate.
A yet still further object of the present invention is to provide such a system that can be operated in a gun application wherein the system is in an inherently unstable mode in which the pressure tries to increase arbitrarily, but is controlled by an initial shaped volume of inert material that limits the pressure rise until the rate of cavity enlargement is appropriate to the inherent instability of the burn r
Alliant Techsystems Inc.
Baker Aileen J.
Carone Michael J.
Nikolai & Mersereau , P.A.
LandOfFree
Propulsion system does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Propulsion system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Propulsion system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2837377