GB1118365A - Variable thrust rocket motor - Google Patents

Abstract

1,118,365. Rocket motors. THIOKOL CHEMICAL CORP. 29 July, 1966, No. 34282/66. Heading F3A. [Also in Division F1] A rocket motor comprises a casing having a discharge nozzle at the rear end thereof, a body of solid propellant being located in the rearward portion of the easing adjacent the nozzle, and a container of liquid propellant being located in the casing. A conduit is provided through which liquid propellant may flow into contact with the solid propellant, the conduit being an injector tube which is embedded in the solid propellant and has holes in the walls thereof so that as the solid propellant burns, the holes are progressively uncovered so as to increase the flow of liquid propellant through the conduit. The rocket motor shown comprises a casing 32 which may be of wound glass fibre, the forward part of the casing constituting a liquid propellant container 12 which may be pressurized by means of inert gas under pressure from container 10. The rearward part of the casing 32 is lined with an ablative liner 36, for example of glass fibre reinforced phenol formaldehyde resin, the liner being shaped so as to form a convergent-divergent nozzle, having a throat 48. A liquid propellant supply tube 46 extends axially within the casing 32 from the propellant container 12, the tube being comprised of a first portion 64, a second portion 62 and a third portion 60, the tube portions being formed with discharge orifices 47 and being releasably interconnected. A body of solid propellant material 44 is formed within the liner 36 so as to embed the supply tube 46, the solid propellant body being shaped so as to provide a combustion space 52, into which the portion 60 of the tube assembly 46 projects, also a discharge nozzle 50, the throat of which is provided by an insert 54 of ablative material moulded into the solid propellant 44. In operation, the liquid propellant such as liquid oxidizer hydrogen peroxide or nitrogen tetroxide is pressurized by inert gas such as helium from the tank 10 and discharges through the openings 47 in the tube portion 60 into the combustion chamber 52 where it reacts with the solid propellant 44 which may be solid fuel such as hydrocarbon polymer cured in situ. As combustion proceeds, the solid fuel is consumed and the ablative member 54 is ejected through the nozzle 50. Also further openings 47 are uncovered so that the supply of liquid oxidizer automatically increases. When the connection between the tube portions 62, 60 is exposed to the heat of combustion, the connection releases and the tube portion 60 is ejected through the nozzle. At a later stage the connection between the tube portions 64, 62 releases and the tube portion 62 is then ejected. The discharge orifices 47 in the tube portions 64, 62, 60 are initially closed by a low melting point metal which melts when subjected to the heat of combustion. Alternatively, the solid propellant may be oxidizer such as an inorganic oxidizer and the liquid propellant may be fuel such as hydrazine.