# US 8,539,753 B2 · Hybrid rocket motor with annular, concentric solid fuel elements

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 8,539,753 B2
- Document ID: US8539753B2
- Status: Granted
- Kind: B2
- Application number: 11/764,677
- Filed: 2007-06-18
- Published: 2009-08-27
- Granted: 2013-09-24
- Earliest claimed: 2006-06-29
- Assignees: SpaceDev, Inc.
- Applicants: Frank Macklin
- Inventors: Frank Macklin
- Web page: https://patentgrep.com/patent/US8539753B2

## CPC

- F02K 9/28: having two or more propellant charges with the propulsion gases exhausting through a common nozzle
- F02K 9/72: using liquid and solid propellants, i.e. hybrid rocket-engine plants
- F02K: JET-PROPULSION PLANTS (features of jet-propulsion plants common to gas-turbine plants, air intakes or fuel supply control of air-breathing jet-propulsion plants F02C7/00, F02C9/00)

## Abstract

A hybrid rocket motor includes a supply of oxidizer, a first solid fuel element positioned around the supply of oxidizer, a second solid fuel element positioned concentrically around the first solid fuel element, and a combustion port positioned between the first and second solid fuel elements. The oxidizer interacts with the first and second solid fuel elements within the combustion port to produce a combustion product. A nozzle is in communication with the combustion port for combustion discharge of the combustion product.

## Claims

### Claim 1

A hybrid rocket motor, comprising:
an oxidizer tank containing a supply of oxidizer;
a first, annular solid fuel element positioned around the supply of oxidizer;
a second solid fuel element positioned concentrically around the first solid fuel element;
a combustion port positioned between the first and second solid fuel elements, wherein the oxidizer interacts with the first and second solid fuel elements within the combustion port to produce a combustion product; and
a nozzle in communication with the combustion port for combustion discharge of the combustion product;
wherein a generally enclosed space is positioned below the oxidizer tank and below the first solid fuel element, such that the widest diameter of the generally enclosed space is substantially equal to the outer diameter of the first, annular solid fuel element, wherein the space communicates with a throat of the nozzle via at least one passageway therebetween and wherein the at least one passageway can be used to facilitate liquid injection vector thrust control of the nozzle.

### Claim 2 (depends on 1)

A hybrid rocket motor as in claim 1, wherein the second solid fuel element is annular.

### Claim 3 (depends on 1)

A hybrid rocket motor as in claim 1, wherein the oxidizer comprises Nitrous Oxide.

### Claim 4 (depends on 1)

A hybrid rocket motor as in claim 1, wherein the first and second solid fuel elements comprise polymethyl methacrylate, high density polyethylene, or hydroxyl terminated polybutadiene.

### Claim 5 (depends on 1)

A hybrid rocket motor as in claim 1, wherein the first and second solid fuel elements are contained within a solid fuel tank that surrounds the supply of oxidizer.

### Claim 6 (depends on 5)

A hybrid rocket motor as in claim 5, further comprising at least one injector adapted to inject oxidizer from the supply of oxidizer into the solid fuel tank.

### Claim 7 (depends on 5)

A hybrid rocket motor as in claim 5, further comprising a plurality of injectors spaced around a circumference of the solid fuel tank.

### Claim 8 (depends on 1)

A hybrid rocket motor as in claim 1, wherein the hybrid rocket motor comprises an aerospike.

### Claim 9

A hybrid rocket motor, comprising: an oxidizer tank containing an oxidizer; a main casing surrounding the oxidizer tank; at least one injector adapted to inject oxidizer from the oxidizer tank into the main casing; wherein the main casing includes:
a first, annular solid fuel element;
a second, annular solid fuel element positioned concentrically around the first, annular solid fuel element;
a combustion port positioned between the first and second annular solid fuel elements wherein the oxidizer interacts with the first and second solid fuel elements within the combustion port to produce a combustion product; and
a nozzle in communication with the combustion port for combustion discharge of the combustion product;
wherein a generally enclosed space is positioned below the oxidizer tank and below the first, annular solid fuel element, such that the widest diameter of the generally enclosed space is substantially equal to the outer diameter of the first, annular solid fuel element, wherein the space communicates with a throat of the nozzle via at least one passageway therebetween and wherein the at least one passageway can be used to facilitate liquid injection vector thrust control of the nozzle.

### Claim 10 (depends on 9)

A hybrid rocket motor as in claim 9, wherein the hybrid rocket motor comprises an aerospike.

### Claim 11 (depends on 9)

A hybrid rocket motor as in claim 9, wherein the at least one injector comprises a plurality of injectors spaced around a circumference of the main casing.

### Claim 12 (depends on 9)

A hybrid rocket motor as in claim 9, wherein the oxidizer comprises Nitrous Oxide.

### Claim 13 (depends on 9)

A hybrid rocket motor as in claim 9, wherein the first and second solid fuel elements comprise polymethyl methacrylate, high density polyethylene, or hydroxyl terminated polybutadiene.

### Claim 14 (depends on 9)

A hybrid rocket motor as in claim 9, further comprising a third solid fuel element concentrically surrounding the second solid fuel element.