GB2108641A - Rocket motors - Google Patents

Abstract

A rocket motor has an electrical cable (15) extending through a conduit (7) which is embedded in a liner (6) on the inner surface of the motor case (1). The cable passes out of the motor case at the rear end through a union (13) and at the forward end through a union (9) in the forward wall (3) of the motor case. By running the cable on the inside of the motor case external drag-producing conduits can be avoided. <IMAGE>

Description

SPECIFICATION Rocket motors This invention relates to rocket motors.

In rocket propelled vehicles there is frequently a requirement for electrical connections between the regions adjacent the nozzle end and adjacent the forward end of the rocket motor case. For example such electrical connections may be required for connections between an antenna and the electronic equipment using the signals from the antenna. Hitherto such electrical connections have been provided by means of an electrical cable passing through a conduit secured to the outside of the motor case. It has been found that because of the adverse environment in which the conduit is located it is necessary to provide a thick walled conduit and to secure this conduit to the motor casing by heavy welding.Furthermore, because a single conduit and its contained cable provide an imbalance it has been necessary to provide at least one complementary protrusion spaced around the circumference to produce dynamic and aerodynamic balance. These external formations increase drag and may produce undesirable lift during certain manoeuvres.

According to the present invention, a rocket motor has an electrical cable passing through a conduit which is embedded in a liner on the inner surface of the motor case. The cable is thus inside the motor case and accordingly it offers no aerodynamic resistance and since it is not exposed to the air or to the risk of damage by being knocked the conduit can be relatively thin.

The invention may be carried into practice in various ways but one rocket motor embodying the invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 is a partial longitudinal section of the motor; and Figure 2 is a partial cross section on the line Il-Il in Figure 1.

The rocket motor shown in the drawings forms part of a rocket, the majority of parts of which are not shown. The rocket motor comprises a rocket motor case 1 having a main cylindrical wall 2, a domed forward end 3 and a rear nozzle portion 4.

Except for the nozzle portion, the motor case is filled with a solid propellant which burns in cigarette fashion, that is to say it burns at a rear face 5, this surface moving towards the forward end as the propellant is consumed. Beetween the motor case and the propellant there is a rubber liner 6 which, over most of the circumference, is of cylindrical shape but which on one portion is thickened to contain a thin walled electrical conduit 7. At the forward end the conduit 7 has a cranked portion 8 and passes out of the motor case through a union 9 containing a gland 10 comprising an olive or O-seal 11 to provide an airtight seal between the motor case and the outside of the conduit. At the rear end the conduit passes through a similar union 13. Within the conduit there is a multi-core hard sheathed cable 1 5.

The rocket motor described is case-bonded but this is not essential. The invention may also be applied to radial burning rockets.

1. A rocket motor having an electrical cable passing through a conduit which is embedded in a liner on the inner surface of the motor case.

2. A rocket motor as claimed in Claim 1 which is of the cigarette burning type.

3. A rocket motor as claimed in Claim 1 or Claim 2 in which the conduit passes through the wall of the motor case at at least one end.

4. A rocket motor substantially as described herein with reference to the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (4)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Rocket motors This invention relates to rocket motors. In rocket propelled vehicles there is frequently a requirement for electrical connections between the regions adjacent the nozzle end and adjacent the forward end of the rocket motor case. For example such electrical connections may be required for connections between an antenna and the electronic equipment using the signals from the antenna. Hitherto such electrical connections have been provided by means of an electrical cable passing through a conduit secured to the outside of the motor case. It has been found that because of the adverse environment in which the conduit is located it is necessary to provide a thick walled conduit and to secure this conduit to the motor casing by heavy welding.Furthermore, because a single conduit and its contained cable provide an imbalance it has been necessary to provide at least one complementary protrusion spaced around the circumference to produce dynamic and aerodynamic balance. These external formations increase drag and may produce undesirable lift during certain manoeuvres. According to the present invention, a rocket motor has an electrical cable passing through a conduit which is embedded in a liner on the inner surface of the motor case. The cable is thus inside the motor case and accordingly it offers no aerodynamic resistance and since it is not exposed to the air or to the risk of damage by being knocked the conduit can be relatively thin. The invention may be carried into practice in various ways but one rocket motor embodying the invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 is a partial longitudinal section of the motor; and Figure 2 is a partial cross section on the line Il-Il in Figure 1. The rocket motor shown in the drawings forms part of a rocket, the majority of parts of which are not shown. The rocket motor comprises a rocket motor case 1 having a main cylindrical wall 2, a domed forward end 3 and a rear nozzle portion 4. Except for the nozzle portion, the motor case is filled with a solid propellant which burns in cigarette fashion, that is to say it burns at a rear face 5, this surface moving towards the forward end as the propellant is consumed. Beetween the motor case and the propellant there is a rubber liner 6 which, over most of the circumference, is of cylindrical shape but which on one portion is thickened to contain a thin walled electrical conduit 7. At the forward end the conduit 7 has a cranked portion 8 and passes out of the motor case through a union 9 containing a gland 10 comprising an olive or O-seal 11 to provide an airtight seal between the motor case and the outside of the conduit. At the rear end the conduit passes through a similar union 13. Within the conduit there is a multi-core hard sheathed cable 1 5. The rocket motor described is case-bonded but this is not essential. The invention may also be applied to radial burning rockets. CLAIMS

1. A rocket motor having an electrical cable passing through a conduit which is embedded in a liner on the inner surface of the motor case.

2. A rocket motor as claimed in Claim 1 which is of the cigarette burning type.

3. A rocket motor as claimed in Claim 1 or Claim 2 in which the conduit passes through the wall of the motor case at at least one end.

4. A rocket motor substantially as described herein with reference to the accompanying drawings.