# US 8,539,751 B2 · Methods of controlling thrust in a rocket motor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,539,751 B2 - Document ID: US8539751B2 - Status: Granted - Kind: B2 - Application number: 12/760,069 - Filed: 2010-04-14 - Published: 2010-08-05 - Granted: 2013-09-24 - Earliest claimed: 2006-03-02 - Assignees: Alliant Techsystems Inc. - Applicants: Cary Lee Cover; Sean Scott Stroud; Michael Joseph Piovoso; Timothy James Kelly - Inventors: Cary Lee Cover; Sean Scott Stroud; Michael Joseph Piovoso; Timothy James Kelly - Web page: https://patentgrep.com/patent/US8539751B2 ## CPC - F02K 9/80: characterised by thrust or thrust vector control (burning control of solid propellants F02K9/26; feeding control of liquid or gaseous propellants F02K9/56; re-ignitable, restartable or intermittently operated rocket-engine plants F02K9/94) - F02K 9/08: using solid propellants (F02K9/72 takes precedence; using semi-solid or pulverulent propellants F02K9/70) - F05D 2200/11: Sum - 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) - F05D: INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS ## Abstract A propulsion thrust control system and method for controlling thrust in a rocket motor includes configuring valves of an energized rocket motor to an initial total valve area according to a total thrust command. The total thrust command is converted into a commanded propellant mass flow discharge rate. A varying total valve area is computed from an error between the commanded propellant mass flow discharge rate and a calculated propellant mass flow discharge rate. The valves are reconfigured according to a distribution of the varying total valve area. The propulsion system includes a pressure vessel with valves and a controller for regulating the valve area according to a propellant mass flow discharge rate from the pressure vessel. ## Claims ### Claim 1 A method of controlling thrust in a rocket motor, comprising: configuring axial and maneuver control valves of an energized rocket motor to achieve an initial total valve area corresponding to a total thrust command; determining a commanded discharged propellant mass flow discharge rate that corresponds to the total thrust command; calculating a compensated total valve area corresponding to an error between the commanded propellant mass flow discharge rate and at least one of a calculated propellant mass flow discharge rate and a measured propellant mass flow discharge rate; and reconfiguring at least one of the axial and maneuver control valves to achieve the compensated total valve area. ### Claim 2 (depends on 1) The method of claim 1, further comprising calculating the total thrust command from at least one of a sum of all net thrust commands from each of the axial and maneuver control valves of the energized rocket motor and a maximum net thrust command. ### Claim 3 (depends on 1) The method of claim 1, further comprising: measuring a pressure within a gas generator of the energized rocket motor; and reconfiguring one or more of the axial and maneuver control valves when the pressure exceeds a pressure limit of the gas generator. ### Claim 4 (depends on 1) The method of claim 1, wherein reconfiguring at least one of the axial and maneuver control valves further comprises configuring at least one of the axial and maneuver control valves to one of a substantially maximally open position and a substantially maximally closed position in response to the error between the commanded propellant mass flow discharge rate and the at least one of the calculated propellant mass flow discharge rate and the measured propellant mass flow discharge rate. ### Claim 5 (depends on 4) The method of claim 4, further comprising reconfiguring at least one of the valves incrementally to approach the intial total valve area when a measured pressure within a gas generator of the energized rocket motor is within a threshold corresponding to the total thrust command. ### Claim 6 (depends on 1) The method of claim 1, wherein reconfiguring at least one of the axial and maneuver control valves further comprises incrementally adjusting at least one of the axial and maneuver control valves. ### Claim 7 (depends on 1) The method of claim 1, further comprising reconfiguring at least one of the axial and maneuver control values according to a priority command when the total thrust command exceeds available thrust of the energized rocket motor. ### Claim 8 (depends on 1) The method of claim 1, further comprising: calculating a burn rate from a measured pressure within a gas generator of the energized rocket motor and the compensated total valve area; and estimating the burn rate utilizing a comparison between the measured pressure and an estimated pressure. ### Claim 9 A method for controlling thrust in a rocket motor, comprising: receiving net thrust commands comprising at least one thrust command for orienting a rocket motor propelled vehicle; calculating a minimum total thrust command for a gas generator of a rocket motor to meet the net thrust commands; configuring axial and maneuver control valves of the rocket motor according to the minimum total thrust command; and reconfiguring at least one of the axial and maneuver control valves to change a valve area of the axial and maneuver control valves in response to a comparison of a commanded propellant mass flow discharge rate and a calculated propellant mass flow discharge rate. ### Claim 10 (depends on 9) The method of claim 9, wherein calculating the minimum total thrust comprises calculating at least one of a sum of the net thrust commands and a sum of worst case net thrusts. ### Claim 11 (depends on 9) The method of claim 9, wherein reconfiguring at least one of the axial and maneuver control valves comprises configuring at least one of the axial and maneuver control valves to one of a substantially maximally open and a substantially maximally closed position. ### Claim 12 (depends on 9) The method of claim 9, wherein reconfiguring at least one of the axial and maneuver control valves comprises incrementally adjusting at least one of the axial and maneuver control valves in response to the minimum total thrust command. ### Claim 13 (depends on 9) The method of claim 9, further comprising calculating the commanded propellant mass flow discharge rate from the minimum total thrust command. ### Claim 14 (depends on 9) The method of claim 9, further comprising reconfiguring at least one of the axial and maneuver control valves according to a priority command when the minimum total thrust command exceeds available thrust of the rocket motor. ### Claim 15 (depends on 9) The method of claim 9, further comprising: calculating a burn rate from a measured pressure within a gas generator of the rocket motor and a total valve area; and recalculating the burn rate utlizing a comparison between the measured pressure and an estimated pressure.