Patent Description:
Booster rockets are sometimes used to add thrust to flight vehicles, such as missiles. Certain limitations are sometimes present regarding the characteristics for add-on booster rockets.

<CIT> discloses multiple stage rocked propelled missile systems.

<CIT> discloses missile configurations, controls and utilization techniques.

A booster rocket has an annular shape, allowing it to be placed around an object, with one or more nozzle insert defining one or more nozzles of the rocket.

A booster rocket is mechanically coupled to a nozzle of a main propulsion system, such as a jet, without interfering with operation of the jet.

A booster rocket is couplable to a part of existing flight vehicle, adding thrust without expanding the envelope of the flight vehicle.

A booster rocket is mechanically coupled to a part of main propulsion system, and remains so coupled even after the propellant (fuel) of the booster rocket is expended.

According to an aspect of the invention, a booster rocket includes: an annular casing defining an annular space therewithin, and having a central opening; a solid rocket fuel in the annular space; and one or more nozzle pieces mechanically coupled to the annular casing, defining one or more nozzles at an aft end of the annular casing, wherein the multiple casing parts include an inner casing part and an outer casing part, the inner casing part and the outer casing part are threadedly coupled together.

According to an embodiment of any paragraph(s) of this summary, the one or more nozzle pieces includes an annular nozzle piece that defines an annular nozzle.

According to an embodiment of any paragraph(s) of this summary, the annular nozzle piece is bolted to the annular casing.

According to an embodiment of any paragraph(s) of this summary, the booster rocket further includes a seal between the annular nozzle piece and the annular casing.

According to an embodiment of any paragraph(s) of this summary, the seal is a silicone seal.

According to an embodiment of any paragraph(s) of this summary, the annular nozzle piece defines the annular nozzle in combination with an inner nozzle insert that is attached to the annular casing.

According to an embodiment of any paragraph(s) of this summary, the inner nozzle insert is bonded and attached by shear bolts to the annular casing.

According to an embodiment of any paragraph(s) of this summary, the annular nozzle piece and the inner nozzle insert together constitute a throat insert set.

According to an embodiment of any paragraph(s) of this summary, the annular nozzle piece has protrusions protruding inward from an inner edge, the protrusions facilitating maintaining an annular gap of the annular nozzle.

According to an embodiment of any paragraph(s) of this summary, the annular nozzle piece is made of a metallic material.

According to an embodiment of any paragraph(s) of this summary, the annular nozzle piece is made of a non-metallic material.

According to an embodiment of any paragraph(s) of this summary, the annular nozzle piece is made of aluminum.

According to an embodiment of any paragraph(s) of this summary, the annular nozzle piece and the annular casing are made of the same material.

According to an embodiment of any paragraph(s) of this summary, the annular nozzle piece is made of a phenolic material.

According to an embodiment of any paragraph(s) of this summary, the one or more nozzle pieces includes multiple nozzle pieces.

According to an embodiment of any paragraph(s) of this summary, the multiple nozzle pieces are circumferentially spaced around aft end of the annular casing.

According to an embodiment of any paragraph(s) of this summary, the multiple nozzle pieces are located in circular openings in the aft end of the annular casing.

According to an embodiment of any paragraph(s) of this summary, the booster rocket further includes an igniter coupled to an outer surface of the annular casing, with the igniter operatively coupled to the solid rocket fuel, to facilitate initiation of combustion of the solid rocket fuel.

According to an embodiment of any paragraph(s) of this summary, the booster rocket further includes an ignition booster on an inner wall of the annular casing, with the ignition booster operatively coupled to the igniter and the solid rocket fuel, to facilitate initiation of combustion of the solid rocket fuel.

According to an embodiment of any paragraph(s) of this summary, the casing is made of metal.

According to an embodiment of any paragraph(s) of this summary, the casing is made of sheet metal.

According to an embodiment of any paragraph(s) of this summary, the inner casing part and the outer casing part are threadedly coupled together.

According to an embodiment of any paragraph(s) of this summary, the casing includes a liner along at least part of an inside surface of the casing, with the liner at least in part defining the annular space.

According to an embodiment of any paragraph(s) of this summary, the fuel is configured within the annular space for end burning.

According to an embodiment of any paragraph(s) of this summary, the fuel is configured within the annular space for core burning.

According to an embodiment of any paragraph(s) of this summary, the fuel is configured within the annular space for both end burning and core burning.

According to an embodiment of any paragraph(s) of this summary, the fuel has one or more channels therein.

According to an embodiment of any paragraph(s) of this summary, the one or more channels include at least one channel in a longitudinal direction.

According to an embodiment of any paragraph(s) of this summary, the fuel is along an outer wall of the casing, with a space between the fuel and an inner wall of the casing.

According to an embodiment of any paragraph(s) of this summary, the booster rocket further includes an igniter in the casing.

According to an embodiment of any paragraph(s) of this summary, the booster rocket is in combination with an object to which the rocket booster is mechanically coupled.

According to an embodiment of any paragraph(s) of this summary, the object is a part of a flight vehicle.

According to an embodiment of any paragraph(s) of this summary, the object is an aft part of a flight vehicle.

According to an embodiment of any paragraph(s) of this summary, the object is part of a propulsion device at an aft end of the flight vehicle.

According to an embodiment of any paragraph(s) of this summary, the object is centered on a longitudinal centerline of the flight vehicle.

According to an embodiment of any paragraph(s) of this summary, the rocket booster is centered around a longitudinal centerline of the flight vehicle.

According to an embodiment of any paragraph(s) of this summary, the object is a turbojet engine.

According to an embodiment of any paragraph(s) of this summary, the object protrudes from an aft end of a fuselage of the flight vehicle.

According to an embodiment of any paragraph(s) of this summary, the flight vehicle is a missile.

According to another aspect of the invention, a missile includes: a fuselage; a main propulsion system that includes a nozzle protruding aftward from the fuselage; and a booster rocket around the nozzle. The booster rocket includes: an annular casing defining an annular space therewithin, and having a central opening through which the nozzle protrudes; a solid rocket fuel in the annular space; and one or more nozzle pieces mechanically coupled to the annular casing, defining one or more nozzles at an aft end of the annular casing, wherein the multiple casing parts include an inner casing part and an outer casing part, the inner casing part and the outer casing part are threadedly coupled together.

According to yet another aspect of the invention, which is not part of the claims, a method for increasing thrust of a flight vehicle includes the steps of: placing an annular booster rocket around a part of a main propulsion system of the flight vehicle; and burning fuel of the booster rocket to product thrust.

To the accomplishment of the foregoing and related ends, the invention comprises the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings set forth in detail certain illustrative embodiments of the invention. These embodiments are indicative, however, of but a few of the various ways in which the principles of the invention may be employed. Other objects, advantages and novel features of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the drawings.

A rocket booster has an annular shape, with a casing defining an annular space therewithin, and a solid rocket fuel in the annular spacing. The rocket booster also includes one or more nozzle pieces, mechanically coupled to the casing, that define one or more nozzles at the aft side of the rocket booster. The rocket booster may be mechanically coupled to an object protruding from the back of a fuselage of a flight vehicle, such as a missile. For example, the rocket booster may be placed around an aft turbojet nozzle of the flight vehicle. This allows the rocket booster to be used in situations where primary propulsion must be running both before and after (and perhaps during) the firing of the rocket booster. The rocket booster also advantageously may provide thrust along the centerline of the flight vehicle, and may be used in situations where there is a requirement to maintain the booster as part of the flight vehicle throughout flight. The rocket booster may have a truncated aerospike nozzle configuration, and may provide for a low-drag additional propulsion system that does not interfere with the operation of the primary propulsion system. Further, the casing of the rocket booster may double as a rear jet engine mount.

With reference initially to <FIG>, a flight vehicle <NUM>, such as a missile, includes a fuselage <NUM>, with a main propulsion device <NUM> protruding from or as part of an aft end <NUM> of the fuselage <NUM>. The main propulsion device <NUM> may be a turbojet engine. The protruding part of the main propulsion device <NUM> may be a nozzle <NUM> of the turbojet engine.

As shown in <FIG>, a booster rocket <NUM> may be mounted on and around the nozzle <NUM>, with the nozzle <NUM> protruding through a central opening <NUM> in the booster rocket <NUM>. The booster rocket <NUM> may thereby provide additional thrust to the flight vehicle <NUM>, without interfering with the operability of the main propulsion device <NUM>. The booster rocket <NUM> may provide the additional thrust without affecting the general envelope of the flight vehicle <NUM>.

The missile (flight vehicle) <NUM> may have additional features, for example fins <NUM> or other wings or control surfaces. Other types of additional features include a guidance system, a communications system, various types of sensors or information-gathering features, and a payload such as a warhead or other destructive material.

The booster rocket <NUM> is shown mounted around the nozzle <NUM>, but it will be appreciated that the nozzle <NUM> is but one example of a broader category of objects to which the booster rocket <NUM> is mounted. The object may alternatively be other sorts of structures, whether provide a propulsive function or not, that pass into or through the central opening <NUM> of the booster rocket <NUM>. Advantageously, both the object (the nozzle <NUM> in the illustrated embodiment) and the booster rocket <NUM> are centered around a longitudinal centerline (central axis) <NUM> of the flight vehicle <NUM>.

As explained in greater detail below with regard to various embodiments, the booster rocket <NUM> has one or more one or more nozzle pieces, defining one or more nozzles for output of the pressurized gases from the booster <NUM>. In one embodiment the one or more nozzle pieces includes a ring-shaped annular piece that defines (at least in part) an annular nozzle. In another embodiment the one or more nozzle pieces include multiple nozzle pieces that define multiple nozzles, for instance circumferentially spaced about the booster <NUM>.

The flight vehicle <NUM> is just one example of the many types of flight vehicles that may receive the booster rocket <NUM>, in order to produce additional thrust. Alternatives to the missile are other types of vehicles with main propulsion devices of any of a variety of suitable types.

<FIG> show further details of one embodiment of the booster rocket <NUM>. The rocket <NUM> includes an annular casing <NUM> that defines an annular space <NUM> where a solid rocket fuel (propellant) <NUM> is located. Many configurations are possible for the fuel (propellant) <NUM>. As described further below, the fuel <NUM> may optionally have one or more channels therein, of any of various suitable configurations, to control the burn rate. Such channels, when present, may include at least one channel in a longitudinal (axial) direction, parallel to an axis of the flight vehicle <NUM> (the centerline <NUM>), which may be coincident with axes of both the booster rocket <NUM> and the object (such as the turbojet nozzle <NUM>) to and around which the booster rocket <NUM> is mounted. The fuel <NUM> is located between the inner part <NUM> and the outer part <NUM>. Combustion of the fuel <NUM> occurs in the annular space <NUM>, which acts as a combustion chamber for the booster rocket <NUM>.

The casing <NUM> is formed out of two separate pieces or parts <NUM> and <NUM>, which are threadedly joined together. The parts <NUM> and <NUM> are formed separately and screwed together along threads <NUM>, after an annular solid fuel (propellant) <NUM> is put into place. The threaded connection may be sealed, as with a silicone sealant, to prevent egress of hot gasses. Once the parts <NUM> and <NUM> are joined together the fuel <NUM> is in an annular space <NUM> defined by the parts <NUM> and <NUM>. The fuel <NUM> can be ignited by an igniter <NUM> that is secured in a hole in the outer casing part <NUM>. An ignition booster <NUM> may be placed on the inner casing part <NUM>, to work in combination with the igniter <NUM> to facilitate ignition of the fuel <NUM>. The ignition booster <NUM> may be any of a variety of easily ignitable/combustible materials.

The casing parts <NUM> and <NUM> may have a liner <NUM> on their surfaces that define the annular space <NUM> that acts as the combustion chamber. The liner <NUM> may be a heat-resistant material that provides some protection to the casing parts <NUM> and <NUM>. The liner <NUM> may be made of any of a variety of suitable materials, non-limiting examples being aluminum and cardboard.

The inner casing part <NUM> has a cylindrical forward section <NUM> and an inwardly-angled aft section <NUM>. The inner casing part sections <NUM> and <NUM> may correspond in exterior shape to an object to which the rocket booster <NUM>, for example to the shape of a turbojet nozzle. Further, the inwardly-angled aft section <NUM> may constitute a truncated aerospike shape, which may provide for efficiency in the operation of the booster rocket <NUM>. The inner casing part <NUM> includes a forward end <NUM> which constitutes the forward end of the rocket booster <NUM>. The forward end <NUM> may have mechanical connections <NUM> and <NUM> thereupon, which may be configured to connect the booster rocket <NUM> to a flight vehicle. The mechanical connections <NUM> and <NUM> may be any of a variety of suitable clips, clamps, or other suitable mechanisms for making a connection. The inner casing part <NUM> also includes an externally threaded outer portion <NUM> that is used to make the threaded connection with an internally threaded cylindrical aft section <NUM> of the outer casing part <NUM>.

The outer casing part <NUM> includes a cylindrical forward section <NUM>, and an inwardly-sloped aft section <NUM> that is bent inward toward the turbojet nozzle <NUM>. In some embodiments the slope of the aft section <NUM> may correspond to a slope of the turbojet nozzle <NUM>. The igniter <NUM> may be located in the sloped aft section <NUM>, and the ignition booster <NUM> may be located on an outer surface of the cylindrical section <NUM> of the inner casing part <NUM>.

In the illustrated embodiment the booster rocket <NUM> includes a ring-shaped annular nozzle piece <NUM>. The nozzle piece <NUM> is mechanically coupled or attached to the aft end of the annular casing <NUM>, more specifically to the aft side of the sloped aft section <NUM> of the outer casing part <NUM>. The nozzle piece <NUM> may be bolted to the aft section <NUM>. A seal <NUM>, such as a silicone seal, may be provided between the nozzle piece <NUM> and the aft section <NUM>.

The annular nozzle piece <NUM> may be part of a throat insert set <NUM> that also includes an inner nozzle insert <NUM>. The inner nozzle insert <NUM> has an annular shape, a band that fits around the inner casing part <NUM>. The inner nozzle insert <NUM> is attached to an other surface of the inner casing part <NUM>. For example, the inner nozzle insert <NUM> may be located in a slot <NUM> at or close to the intersection of the cylindrical forward section <NUM> and the inwardly-angled aft section <NUM>. The inner nozzle insert <NUM> may be bonded and attached by shear bolts to the inner casing part <NUM>.

The annular nozzle piece <NUM> and the inner nozzle insert <NUM> together define an annular nozzle <NUM> through which pressurized gases from the combustion of the fuel <NUM> exit the booster rocket <NUM> at its aft end. In the illustrated embodiment the annular nozzle <NUM> is an annular gap between the outer casing part <NUM> and an outer surface of the turbojet nozzle <NUM> that serves as the object around which the rocket booster <NUM> is installed.

The annular nozzle piece <NUM> and the inner nozzle insert <NUM> may be made of any of a variety of suitable materials. The piece <NUM> and/or the insert <NUM> may be made of a metallic or nonmetallic material. For example, they may be made of the same material as the casing parts <NUM> and <NUM>, for example being made of aluminum. Alternatively the annular nozzle piece <NUM> and/or the inner nozzle insert <NUM> may be made of a phenolic material or other suitable non-metallic material.

The use of the nozzle piece <NUM> and the nozzle insert <NUM> to define the annular nozzle <NUM> may facilitate better performance of the booster rocket <NUM>. The use of the throat insert set <NUM> may provide for better tolerances in the annular gap of the annular nozzle <NUM>, may provide for more better performance during the operation of the booster rocket <NUM>, and/or may provide the opportunity to switch out different insert sets providing better and/or different performance characteristics.

With reference now in addition to <FIG>, further details of the annular nozzle piece <NUM> are shown. The annular piece <NUM> as a series of holes <NUM> which may be used for bolts or other fasteners to couple the annular piece <NUM> to the aft section <NUM> (<FIG>). Further, as best shown in <FIG>, the annular piece <NUM> may have a series of protrusions <NUM> along its inner edge <NUM>. The protrusions <NUM> may help maintain a desired configuration of the annular gap that serves as the annular nozzle <NUM>, for example maintaining concentricity. The protrusions <NUM> protrude inward to maintain a desired spacing between the edge <NUM> and the inner nozzle insert <NUM> (<FIG>). The protrusions <NUM> may be evenly circumferentially spaced around the edge <NUM>. The protrusions may have a height of about <NUM> (<NUM> inch), as a non-limiting example.

Many variations are possible in the configuration of a booster rocket that is capable of being installed around an object. Some alternative configurations are described below, and different sorts of manufacturing techniques may be used to produce the booster rocket <NUM>, and alternative booster rocket configurations.

The booster rocket <NUM> may have additional features not shown in the figures, for example having an igniter placed in an opening in the casing <NUM> at a suitable location for igniting the fuel (propellant) <NUM>. Such additional features may be shown in one or more of the other embodiments shown below.

The booster rocket <NUM> provides a low profile, without impacting the envelope of the flight vehicle <NUM> (<FIG>). The low profile means that the rocket booster <NUM> does not significantly impact the drag of the flight vehicle <NUM>. The rocket <NUM> is retained without the flight vehicle <NUM> after use, and does not prevent use of the main propulsion device <NUM> (<FIG>), before, after, or during firing of the booster rocket <NUM>. The rocket <NUM> may be configured to operate with a truncated aerospace nozzle configuration, which is compact and altitude compensating.

<FIG> shows another embodiment, a rocket booster <NUM> that includes multiple nozzle pieces <NUM> circumferentially spaced (for example evenly circumferentially spaced) in a series of circular openings <NUM> on an aft surface of an annular casing <NUM> of the rocket booster <NUM>. The nozzle pieces <NUM> define respective nozzles through which pressurized gasses pass from the interior of the annular casing <NUM>, in which annular fuel <NUM> burns. In other circumstances, the rocket booster <NUM> may be similar to the other rocket boosters (and variations) described elsewhere herewithin.

<FIG> shows a cross-sectional shape of an annular fuel <NUM> that includes a series of longitudinal channels <NUM> to regulate the burn speed and thus the thrust production. Such channels may have any of a variety of suitable configurations (depths and/or shapes, for example), and there may be various numbers of channels, with any of various suitable spacings, to produce a desire thrust profile over time. It should be appreciated that the configuration shown in <FIG> is for illustration purposes, and the channels <NUM> shown are necessarily to scale.

Claim 1:
A booster rocket (<NUM>) comprising:
an annular casing (<NUM>, <NUM>) defining an annular space (<NUM>) therewithin, and having a central opening (<NUM>);
a solid rocket fuel (<NUM>) in the annular space (<NUM>); and
one or more nozzle pieces (<NUM>) mechanically coupled to the annular casing (<NUM>, <NUM>), defining one or more nozzles at an aft end of the annular casing (<NUM>, <NUM>), wherein the casing includes multiple casing parts (<NUM>, <NUM>), and
wherein the multiple casing parts (<NUM>, <NUM>) include an inner casing part and an outer casing part; and
wherein the inner casing part and the outer casing part are threadedly coupled together.