PROPELLANT CHARGE

Abstract

The invention is in the field of propellants. In particular the invention is directed to a propellant for ammunition, such as medium and large caliber gun ammunition, having improved performance. In accordance with the present invention a propellant charge comprises one or more longitudinally extending, progressive-externally burning grains having a number of perforations passing through the grains in the length direction and having a cross-sectional shape (perpendicular to the grain's length direction) that is elongated.

Claims

1. Propellant charge comprising one or more longitudinally extending, progressive-externally burning grains having a number of perforations passing through the grains in the length direction and wherein said grains have a cross-sectional shape (perpendicular to the grain's length direction) that is elongated.

2. Propellant charge according to claim 1, wherein said grains have a cross-sectional shape that is line-symmetric in at most two different lines.

3. Propellant charge according to claim 1, wherein said grains comprise eight or more perforations.

4. Propellant charge according to claim 1, wherein said grains have a cross-sectional shape that is diamond shaped having four or five edges, or an elongated polygon having six edges, of which four have the same length.

5. Propellant charge according to claim 1, wherein said grains are cut under an angle of 45-90, relative to their longitudinal axis.

6. Propellant charge according to claim 1, wherein said grains are made by extrusion.

7. Propellant charge according to claim 1, wherein at least part of said grains are provided with an outer layer that has a chemical composition that is less energetic than the inner composition of the respective grain.

8. Ammunition comprising a propellant charge according to claim 1.

9. Propellant charge according to claim 3, wherein said grains comprise less than eighteen perforations.

10. Propellant charge according to claim 9, wherein said grains comprise fourteen perforations.

11. Propellant charge according to claim 10, wherein said grains comprise nine perforations.

12. Propellant charge according to claim 5, wherein said grains are cut under an angle of about 60, relative to their longitudinal axis.

Description

EXAMPLES

Example 1

[0032] A solvent free gun propellant composition, comprising 50 to 60 wt. % nitrocellulose and 40 to 50 wt. % of plasticizers like nitroglycerine and diethylene glycol dinitrate as the main constituents was pressed through a cylindrical die with 19 pins as depicted in FIG. 2. The propellant burning rate and the die dimensions were such that the propellant combustion properties were suited for use in ammunition for 120 mm tank weapons. The diameter of the obtained propellant grains was 11.5 mm and the propellant grains were cut at a length equal to the diameter. The bulk density of the propellant grains was determined by pouring the grains in a cylinder of 0.5 litre volume and a diameter of 81 mm and measuring the mass of the propellant. The bulk density appeared to be 0.81 kg/dm.sup.3.

Example 2

[0033] The same propellant composition as mentioned in Example 1 was pressed through dies with 9 pins with a cross sectional shape as depicted in FIG. 3. The obtained propellant strands, laying on one of the flat strand sides, were cut using a straight knife at an angle of 60 with respect to the longitudinal direction of the strands at a length of approximately 1.5 to 2 times the distance between two opposite flat strand sides. The obtained propellant grains were used to determine the bulk density using the same cylinder and procedure as mentioned in Example 1. The bulk density appeared to be 0.85 kg/dm.sup.3.

Example 3

[0034] The same propellant composition as mentioned in Example 1 was pressed through a die with 14 pins of 0.5 mm diameter with a cross sectional shape as depicted in FIG. 3. The obtained propellant strands, laying on one of the flat strand sides, were cut using a straight knife at an angle of 60 with respect to the longitudinal direction of the strands at a length of approximately 1.5 to 2 times the distance between two opposite flat strand sides. The obtained propellant grains were used to determine the bulk density using the same cylinder and procedure as mentioned in Example 1. The bulk density appeared to be 0.88 kg/dm.sup.3.

Example 4

[0035] Grains with an outer shape as depicted in FIG. 5 without perforations were made by a certain additive manufacturing (3D-printing) technique. The length and outer diameter of the grains was approximately equal to the propellant grains described in Example 3. All corners of the grains were rounded with a radius equal to two times the shortest distance between two perforations. The bulk density of the molded bodies was determined using the same cylinder and procedure as mentioned in Example 1. The obtained bulk density was converted to the bulk density of propellant grains with the same composition as those described in Example 1, with the same outer shape as the molded bodies, and having 14 perforations with a diameter of 0.5 mm. The converted bulk density appeared to be 0.96 kg/dm.sup.3.