Multi-pulse solid rocket motor ignition method

Patent metadata

Field	Value
Publication number	US-11512668-B2
Application number	US-202017106089-A
Country	US
Kind code	B2
Filing date	Nov 28, 2020
Priority date	Nov 28, 2020
Publication date	Nov 29, 2022
Grant date	Nov 29, 2022

Abstract

A rocket motor has an electrically operated propellant initiator for a propellant grain that includes an electrode arrangement configured to concentrate an electric field at an ignition electrode for igniting an electrically operated propellant. The rocket motor includes a combustion chamber containing at least one propellant grain and an electrically operated propellant initiator operatively coupled to the propellant grain to initiate combustion of the propellant grain. The electrically operated propellant initiator includes the electrically operated propellant and at least one pair of electrodes configured to ignite the electrically operated propellant. The pair of electrodes includes a ground plane electrode and an ignition electrode. When an electrical input is applied to the electrically operated propellant initiator, the electric field is concentrated at the ignition electrode to ignite the electrically operated propellant at the location where the ignition electrode is arranged.

First claim

What is claimed is:

1. A rocket motor comprising:
a combustion chamber containing at least one propellant grain; and
an electrically operated propellant initiator operatively coupled to the at least one propellant grain to initiate combustion of the at least one propellant grain, the electrically operated propellant initiator including an electrically operated propellant and at least one pair of electrodes arranged to ignite the electrically operated propellant, the at least one pair of electrodes including a ground plane electrode and an ignition electrode at which an electric field is concentrated to ignite the electrically operated propellant,
wherein the ground plane electrode extends along a first surface area of the at least one propellant grain that is larger than a second surface area of the at least one propellant grain along which the ignition electrode extends, wherein a ratio of the first surface area to the second surface area is at least 2:1; and
wherein the first surface area and the second surface area are along an interface between the electrically operated propellant and a propellant grain of the at least one propellant grain.

2. The rocket motor according to claim 1 , wherein the ignition electrode has a greater current density than the ground plane electrode.

3. The rocket motor according to claim 1 , wherein the ground plane electrode is formed of wires having a first diameter that is larger than a second diameter of wires forming the ignition electrode.

4. The rocket motor according to claim 1 , wherein the at least one pair of electrodes are formed of a plurality of wires having a zig-zag, diagonal, crisscross, rectangular, parallel, non-parallel, or serpentine arrangement.

5. The rocket motor according to claim 1 , wherein the at least one pair of electrodes are separately arranged without crossing each other.

6. The rocket motor according to claim 1 , wherein the at least one propellant grain has at least one cavity in which at least one of the ignition electrode and the ground plane electrode is arranged.

7. The rocket motor according to claim 1 , wherein the ignition electrode and the ground plane electrode are oriented along and within a plane that is parallel with an outer surface of the at least one propellant grain.

8. The rocket motor according to claim 1 , wherein the ignition electrode and the ground plane electrode are arranged in different planes.

9. The rocket motor according to claim 1 , wherein the ignition electrode is formed of a refractory metal or refractory alloy.

10. The rocket motor according to claim 1 , wherein the rocket motor is a multi-pulse rocket motor and the at least one propellant grain includes a first propellant grain and a second propellant grain that is burned during a second pulse of the multi-pulse rocket motor, the second propellant grain being operatively isolated from the first propellant grain via the electrically operated propellant initiator whereby the first propellant grain and the second propellant grain are individually initiated.

11. The rocket motor according to claim 10 , wherein the at least one propellant grain includes a third propellant grain that is burned during a third pulse of the multi-pulse rocket motor, the third propellant grain being operatively isolated from the second propellant grain via another electrically operated propellant initiator.

12. The rocket motor according to claim 1 , wherein the electrically operated propellant is configured to transition from an unignited state to an ignited state when electrical input is applied across the electrically operated propellant initiator, and is configured to maintain the unignited state when the electrical input is not applied.

13. The rocket motor according to claim 1 further including a power source and a pair of leads extending from the power source to the electrically operated propellant initiator.

14. A multi-pulse rocket motor comprising:
a first pulse containing a first propellant grain;
a second pulse containing a second propellant grain operatively isolated from the first propellant grain; and
at least one electrically operated propellant initiator configured to isolate the first propellant grain and the second propellant grain, the at least one electrically operated propellant initiator being configured to initiate combustion of the first propellant grain or the second propellant grain;
the at least one electrically operated propellant initiator including an electrically operated propellant and at least one pair of electrodes that are configured to ignite the electrically operated propellant, the at least one pair of electrodes including a ground plane electrode and an ignition electrode, the ground plane electrode extending along a first surface area of the second propellant grain that is larger than a second surface area of the second propellant grain along which the ignition electrode extends, the ignition electrode having a greater current density than the ground plane electrode whereby an electric field is concentrated at the ignition electrode, wherein a ratio of the first surface area to the second surface area is at least 2:1; and
wherein the first surface area and the second surface area are along an interface between the electrically operated propellant and a propellant grain of the at least one propellant grain.

15. The multi-pulse rocket motor according to claim 14 further comprising a third pulse containing a third propellant grain operatively isolated from the first propellant grain and the second propellant grain, wherein the at least one electrically operated propellant initiator includes a first electrically operated propellant initiator configured to isolate the first propellant grain and the second propellant grain and a second electrically operated propellant initiator configured to isolate the second propellant grain and the third propellant grain.

16. A rocket motor comprising:
a combustion chamber containing at least one propellant grain; and
an electrically operated propellant initiator operatively coupled to the at least one propellant grain to initiate combustion of the at least one propellant grain, the electrically operated propellant initiator including an electrically operated propellant and at least one pair of corresponding electrodes arranged to cooperate together to ignite the electrically operated propellant, the at least one pair of corresponding electrodes including a ground plane electrode and an ignition electrode at which an electric field is concentrated to ignite the electrically operated propellant,
wherein the at least one propellant grain has at least one groove that is formed in the at least one propellant grain and in which the ignition electrode is arranged, the ground plane electrode being arranged outside the groove, wherein the electric field is directed into the groove for ignition in the groove.

Assignees

• Raytheon Co

Inventors

• Koehler Frederick B
• Pinello-Benavides Jacob A
• Copeland Curtis S
• Mcneil Isaiah M
• Kadlec Paul
• Brunacini Lauren E
• Langhenry Mark T

Classifications

• F02K9/28

  having two or more propellant charges with the propulsion gases exhausting through a common nozzle · CPC title

• F02K9/38

  Safety devices, e.g. to prevent accidental ignition · CPC title

• F02K9/95 Primary

  characterised by starting or ignition means or arrangements (safety devices F02K9/38) · CPC title

• F02K9/94

  Re-ignitable or restartable rocket- engine plants; Intermittently operated rocket-engine plants · CPC title