Monopropellant thruster

A monopropellant thruster comprising:

• a thruster body having a thrust chamber therein for containing catalyst for exothermically decomposing monopropellant into hot gas to produce thrust;
• means for injecting monopropellant into the catalyst, said injection means comprising a plurality of divergently oriented injector tubes extending into said thrust chamber so that catalyst in said thrust chamber extends around said injector tubes, each of said injector tubes having a flow passage therethrough having an inlet and an outlet and being imperforate between said inlet and said outlet and said injector tubes being positioned so that the inlets of said flow passages are adjacent each other and the outlets are separated from each other said flow passage being of such diameter and the tube walls being of such thickness and the flow rate being such that liquid monopropellant more than 0.005 inches away from the injector tube walls is at a temperature lower than the monopropellant vaporization temperature at that point so that thermally caused autodecomposition is inhibited in said injector tubes.

A monopropellant thruster comprising a thruster body having a thrust chamber therein for containing a catalyst for exothermic decomposition of a liquid monopropellant into hot gas for producing thrust;

• means for injecting liquid monopropellant into said thrust chamber, said injection means comprising an injector tube extending partway through said thrust chamber and having an outlet for liquid monopropellant into said thrust chamber, said injector tube having a bore of such diameter and the tube walls being of such thickness and the flow rate being such that liquid monopropellant more than 0.005 inches away from the injector tube walls is at a temperature lower than the monopropellant vaporization temperature at that point;
• a screen positioned across said thrust chamber to divide said thrust chamber in catalyst position therein into first and second zones, said screen being positioned so that liquid monopropellant from said injection means passes therethrough, said screen being positioned so that the void produced by thermal cycling of a catalyst is positioned downstream of said screen so that the void cannot reach the injector tube outlet by catalyst shifting, thereby enhancing thrust reproducibility and useful life.

A monopropellant thruster comprising:

• a thruster body having walls defining a thrust chamber therein for containing a particulate monopropellant dissociation catalyst for exothermic monopropellant dissocation;
• a laterally imperforate injector tube extending into said thrust chamber, said injector tube having a bore therein, the tube bore being of such diameter and the tube walls being of such thickness and the flow rate being such that liquid monopropellant more than 0.005 inches away from the injector tube walls is at a temperature lower than the monopropellant vaporization temperature at that point, said injector tube terminating with an injector orifice, said injector tube extending into said thrust chamber a distance substantially equal to half the distance between said thrust chamber walls, a cap on said injector and a screen under said cap, said injector orifice being in said cap, said screen and said orifice being dimensioned so that a full stream of liquid monopropellant is discharged from said orifice into the monopropellant dissociation catalyst.

A monopropellant thruster comprising:

• a thruster body having a thrust chamber therein for containing catalyst for exothermically decomposing monopropellant into hot gas to produce thrust;
• means for injecting monopropellant into the catalyst, said injection means comprising a plurality of divergently oriented injector tubes extending into said thrust chamber so that the catalyst in said thrust chamber extends around said injector tubes, each of said injector tubes having a flow passage therethrough having an inlet and an outlet and being imperforate between said inlet and said outlet and said injector tubes being positioned so that the inlets of said flow passages are adjacent each other and the outlets are separated from each other, each of said injector tubes terminating at an injector orifice, screens positioned over the orifice outlets of said flow passages in each of said injector tubes, said screens having openings therein of such size to break up flow out of the flow passages in the streams having a size at least as large as the size of the catalyst in said thrust chamber, said streams being directed and the stream flow being such that each stream is broken up in the catalyst in the thrust chamber before the liquid monopropellant impinges on a thrust chamber wall or on another monopropellant stream.