Clustered, fixed cant, throttleable rocket assembly

#Thruster or rocket engines intended to be used in vacuum or near vacuum environments (e.g., the Earth's upper atmosphere and space) or terrestrial environments utilize combustion and/or decomposition of stored fuel and oxidizer to produce thrust. The fuel and oxidizer may be stored separately and combined prior to combustion (i.e., a bipropellant) or premixed and stored prior to combustion (i.e., a monopropellant). While most rocket engines are internal combustion engines, other (e.g., decomposing-only) rocket engines also exist.

#Many vehicles that utilize a rocket engine for thrust may require that overall thrust vector change over time. For example, as a vehicle consumes fuel and/or oxidizer, the center of mass of the vehicle changes. A change in the center of mass of the vehicle may change the required thrust vector to obtain a desired orientation of the vehicle. Further, unexpected conditions (e.g., environmental conditions) may affect the orientation of the vehicle and an adjustment of the thrust vector is required to correct the vehicle's orientation. Several systems and methods are currently used to vary a rocket engine's thrust vector.

#For example, the entire rocket engine may be mounted on a hinge or gimbal, which selectively aims the thrust vector of the engine. Disadvantages to this system include the potential weight and complexity of the gimbal and associated actuators(s). Further, the propellant feed may need to be routed using low pressure flexible pipes and/or rotary couplings, which may not be as robust as rigid pipes and/or other connectors. These disadvantages are compounded for ascent vehicles that must efficiently and reliably overcome the force of gravity to be effective.

#FIG. 1 is a perspective view of a vessel having an example clustered, fixed cant, throttleable rocket assembly.

#FIG. 2 is an elevation side view of a vessel having an example clustered, fixed cant, throttleable rocket assembly.

#FIG. 3 is a bottom view of a vessel having an example clustered, fixed cant, throttleable rocket assembly.

#FIG. 1 is a perspective view of a vessel 100 having an example clustered, fixed cant, throttleable rocket assembly 102. The rocket assembly 102 converts combustion and/or decomposition of propellant, which may include fuel and oxidizer components into useable energy. More specifically, the rocket assembly 102 produces thrust by the expulsion of a high-speed fluid exhaust. This fluid is typically a gas, which is created by high pressure combustion and/or decomposition of the propellant within a combustion/decomposition chamber. The fluid exhaust is then passed through a cluster of supersonic propelling nozzles 104, 106, 108, which use heat energy of the gas to accelerate the exhaust to a supersonic or hypersonic speeds (as illustrated by arrow 110) and discharge the gas out of the nozzles 104, 106, 108. A resulting pressuring distribution produced by expansion of the combusting and/or decomposing propellant pressing on inside surfaces within each of the propelling nozzles 104, 106, 108 generates a net thrust, which causes the vessel 100 to be propelled in a direction generally opposite of the discharged propellant (as illustrated by arrow 112). In one implementation, the cluster of nozzles 104, 106, 108 is faster reacting than a singular nozzle that provides a similar magnitude of thrust.

#The vessel 100 is configured to operate within one or more fluid and vacuum environments (e.g., planetary atmospheres, oceans, and space) Further, the vessel 100 may be part of a larger vessel (e.g., vessel 100 is a thruster on a space station). The propellant may be a monopropellant or bipropellant and individual components of the propellant (e.g., fuel and oxidizer) are stored in one or more tanks (not shown) within the vessel 100. Further, the supersonic propelling nozzles 104, 106, 108 may be of various types (e.g., de Laval, expansion-deflection, plug, aerospike, expanding, bell with a removable insert, stepped, dual-bell, dual-expander, dual-throat, and single expansion ramp).

#The nozzles 104, 106, 108 are oriented such that the individual thrust vectors of each of the nozzles 104, 106, 108 provide a small moment arm relative to the vessel center of mass. As a result, each nozzle can generate a torque on the vessel 100 in order to provide pitch and yaw control for the vehicle 100. In one implementation, a 15 degree outward cant of each of the nozzles 104, 106, 108 is sufficient to provide pitch and yaw control for the vehicle 100. At a 15 degree outward cant, the vehicle's effective axial thrust and associated Isp is 96.4% of nominal, which is a favorable trade to gain attitude control using throttling of the nozzle outputs. In other implementations, more or less outward cant may be used. In various implementations, the nozzles 104, 106, 108 may be inwardly canted, outwardly canted, or not canted at all. For example, the nozzles 104, 106, 108 may have a small radial offset from the vehicle 100 center of gravity, which is sufficient to provide pitch and yaw control for the vehicle 100.