Patent Publication Number: US-11643997-B2

Title: Propulsion system with single initiator for multiple rocket motors

Description:
FIELD 
     The present disclosure is in the field of devices and methods for propulsion using rocket motors. 
     BACKGROUND 
     Rocket motors are a known way to provide thrust. Multi-motor thrust systems are not typically utilized when the thrust system cannot be put on the centerline of the body. In addition, multi-motor ignition systems typically require multiple initiators with complex factors including ignition timing and thrust balancing for successful launch. 
     SUMMARY 
     According to an aspect of the disclosure, a propulsion system has multiple rocket motors activated by a single initiator. 
     According to an aspect of the disclosure, multiple rocket motors are operatively coupled together through a single plenum. 
     According to an aspect of the disclosure, a propulsion system includes: a manifold; and an initiator operatively coupled to the manifold; wherein the manifold has a plenum therein to which multiple rocket motors may be coupled, to provide ignition to the multiple rocket motors; and wherein the plenum is a non-annular plenum. 
     According to an embodiment of any paragraph(s) of this summary, the manifold is a cylindrical manifold. 
     According to an embodiment of any paragraph(s) of this summary, at least some of the rocket motors are circumferentially spaced around the manifold. 
     According to an embodiment of any paragraph(s) of this summary, one of the rocket motors is located along a longitudinal axis of the propulsion system. 
     According to an embodiment of any paragraph(s) of this summary, the at least some of the rocket motors are pairs of rocket motors diametrically opposed to one another. 
     According to another aspect of the disclosure, a flight vehicle includes: a fuselage; and a propulsion system coupled to the fuselage, the propulsion system including: a manifold; and an initiator operatively coupled to the manifold; wherein the manifold has a non-annular plenum therein to which multiple rocket motors may be coupled, to provide ignition to the multiple rocket motors. 
     According to still another aspect of the disclosure, a method of operating a propulsion system includes the steps of: igniting an ignition charge in a non-annular plenum in a manifold; and using pressurized gasses from the plenum to ignite multiple rockets that are operatively coupled to the non-annular plenum and mechanically coupled to the manifold. 
     According to an aspect of the disclosure, a propulsion system includes: a manifold; and an initiator operatively coupled to the manifold; wherein the manifold has a plenum therein to which multiple rocket motors may be coupled, to provide ignition to the multiple rocket motors. 
     According to an embodiment of any paragraph(s) of this summary, the plenum is an annular plenum. 
     According to an embodiment of any paragraph(s) of this summary, the plenum is in an annular manifold. 
     According to an embodiment of any paragraph(s) of this summary, the initiator is coupled to an outer surface of the manifold. 
     According to an embodiment of any paragraph(s) of this summary, the system further includes an ignition material in the plenum, configured to be ignited by the initiator. 
     According to an embodiment of any paragraph(s) of this summary, the system further includes a cover on the manifold. 
     According to an embodiment of any paragraph(s) of this summary, the cover has mounts for receiving the rocket motors. 
     According to an embodiment of any paragraph(s) of this summary, the mounts have chambers therein, with ignition boosters in the chambers. 
     According to an embodiment of any paragraph(s) of this summary, the plenum is a non-annular plenum. 
     According to an embodiment of any paragraph(s) of this summary, the non-annular plenum includes radial channels. 
     According to an embodiment of any paragraph(s) of this summary, the non-annular plenum includes circumferential connections between the radial channels. 
     According to an embodiment of any paragraph(s) of this summary, the initiator is coupled to the non-annular plenum at a center of the non-annular plenum. 
     According to an embodiment of any paragraph(s) of this summary, the system further includes an insulator on an inner surface of the plenum. 
     According to an embodiment of any paragraph(s) of this summary, the insulator is a silicone material. 
     According to an embodiment of any paragraph(s) of this summary, the system further includes the rocket motors, operatively coupled to the plenum. 
     According to an embodiment of any paragraph(s) of this summary, the rocket motors are circumferentially spaced around the manifold. 
     According to an embodiment of any paragraph(s) of this summary, the rocket motors are threadedly coupled to mounts on a cover on the manifold. 
     According to another aspect of the disclosure, a flight vehicle includes: a fuselage; and a propulsion system coupled to the fuselage, the propulsion system including: a manifold; and an initiator operatively coupled to the manifold; wherein the manifold has a plenum therein to which multiple rocket motors may be coupled, to provide ignition to the multiple rocket motors. 
     According to an embodiment of any paragraph(s) of this summary, the manifold is an annular manifold with a central opening; and the flight further includes a jet engine making use of the central opening. 
     According to yet another aspect of the disclosure, a method of operating a propulsion system includes the steps of: igniting an ignition charge in a plenum in a manifold; and using pressurized gasses from the plenum to ignite multiple rockets that are operatively coupled to the plenum and mechanically coupled to the manifold. 
     According to an embodiment of any paragraph(s) of this summary, the manifold is made of metal. 
     According to an embodiment of any paragraph(s) of this summary, wherein the manifold is made of steel. 
     While a number of features are described herein with respect to embodiments of the disclosure; features described with respect to a given embodiment also may be employed in connection with other embodiments. The following description and the annexed drawings set forth certain illustrative embodiments of the disclosure. These embodiments are indicative, however, of but a few of the various ways in which the principles of the disclosure may be employed. Other objects, advantages, and novel features according to aspects of the disclosure will become apparent from the following detailed description when considered in conjunction with the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The annexed drawings, which are not necessarily to scale, show various aspects of the disclosure. 
         FIG.  1    is an oblique view of a propulsion system in accordance with an embodiment of the disclosure. 
         FIG.  2    is an oblique view of part of the propulsion system of  FIG.  1   . 
         FIG.  3    is a side sectional view of the propulsion system of  FIG.  1   . 
         FIG.  4    is a high-level flowchart of a method of using a propulsion system, such as the system of  FIG.  1   , according to an embodiment of the disclosure. 
         FIG.  5    is an oblique view of the propulsion system of  FIG.  1   , at a first step of the method of  FIG.  4   . 
         FIG.  6    is a side sectional view of the propulsion system of  FIG.  1   , at the first step of the method of  FIG.  4   . 
         FIG.  7    is an oblique view of the propulsion system of  FIG.  1   , at a second step of the method of  FIG.  4   . 
         FIG.  8    is a side sectional view of the propulsion system of  FIG.  1   , at the second step of the method of  FIG.  4   . 
         FIG.  9    is an oblique view of the propulsion system of  FIG.  1   , at a third step of the method of  FIG.  4   . 
         FIG.  10    is a side sectional view of the propulsion system of  FIG.  1   , at the third step of the method of  FIG.  4   . 
         FIG.  11    is an oblique view of a portion of a flight vehicle that includes the propulsion system of  FIG.  1   . 
         FIG.  12    is an oblique view of a propulsion system in accordance with another embodiment of the disclosure. 
         FIG.  13    is a plan view of one configuration of the manifold of the propulsion system of  FIG.  12   . 
         FIG.  14    is a plan view of another configuration of the manifold of the propulsion system of  FIG.  12   . 
         FIG.  15    is an oblique view of a propulsion system in accordance with yet another embodiment of the disclosure. 
         FIG.  16    is another oblique view of the propulsion system of  FIG.  15   . 
         FIG.  17    is a side sectional view of the propulsion system of  FIG.  15   . 
         FIG.  18    is an oblique view of a manifold cover of the propulsion system of  FIG.  15   , illustrating the configuration of the non-annular plenum. 
         FIG.  19    is a bottom view showing mounts of the cover of  FIG.  18   . 
     
    
    
     DETAILED DESCRIPTION 
     A propulsion system includes multiple solid rocket motors that are activated by a single initiator. The rocket motors act in parallel, providing thrust in a single direction. The initiator activates an ignition charge that is in or operatively coupled to a non-annular plenum that transports hot gasses from the ignition charge to the rockets to be ignited. The plenum may be an unchoked plenum, allowing flow of hot gasses without choking. The plenum may be lined with an insulator material. A cover may be used to cover the plenum, and also to receive the rocket motors. The rocket motors may be solid-fuel rocket motors, with propellant grains and nozzles. The individual rocket motors may have separate ignition booster charges coupled to the plenum, which are ignited by the ignition charge and which in turn ignite the propellant grains. 
       FIG.  1    shows a propulsion system  10  that includes multiple solid rocket motors  12 ,  14 ,  16 , and  18 , which are activated (ignited) by a single initiator  20 . The rocket motors  12 - 18  and the initiator  20  are both attached to a manifold  22 . As described further below the manifold  22  includes a passage therein, a plenum, linking the initiator  20  to the rocket motors  12 - 18 . 
     A cover  24  on the manifold  22  encloses and partially defines the plenum, and provides mounts  32 ,  34 ,  36 , and  38  to which the rocket motors  12 - 18  are secured. The cover  24  and the manifold  22  may be made of suitable metal, such as steel, aluminum, titanium, or other suitable metals (or non-metals). 
     In the illustrated embodiment the manifold  22  has an annular shape, with material of the manifold  22  around a central opening  26 . In other embodiments, some of which are described below, the manifold  22  may have other shapes. 
     Referring in addition to  FIGS.  2  and  3   , further details are shown of inner parts of the propulsion system  10 .  FIG.  2    shows an annular plenum  42  that is in the manifold  22 , that provides a fluid communication to (and between) the rocket motors  12 - 18 . The plenum  42  may be lined with a thermal insulator material  44 , which aids in protecting the manifold  22  and the cover  24  from erosion from hot gasses, or from other effects of exposure to hot gas (such as from heating). An example of a suitable thermal insulating material is silicone RTV, although a variety of other suitable materials may be used as alternatives. The insulator material  44  may only need to be operative for during the transient time when operation of the rocket motors  12 - 18  is initiated. Other instances of motor operation may require insulation through the entire operation of the motor. 
     An ignition charge  48  is located within the plenum  42 . The initiator  20  ignites the ignition charge  48 . Hot pressurized gasses from the ignited ignition charge  48  go through plenum  42  to ignite the rockets  12 - 18 . The initiator  20  may ignite the ignition charge  48  using any suitable mechanism, including chemical ignition using an energetic chemically-reacting starter material, or electrical ignition, such as with use of a bridge wire. The ignition charge  48  may be a length of igniter material or rapid deflagration cord. 
     The hot gasses from the ignition charge  48  ignite ignition booster charges, such as the charges  52  and  56  ( FIG.  3   ), corresponding to respective of the rocket motors  12 - 18 . The ignition booster charges  52  and  56  may be located in chambers, such as chambers  62  and  66 , that are in the mounts  32 - 38  that receive the rocket motors  12 - 18 . 
     With reference to the rocket motor  12 , the ignition booster charge  52  produces hot ignition products that enter a combustion chamber  72  in a solid fuel grain  74 , and ignite the grain  74 . The burning solid fuel  74  produces pressurized gasses that pass through a nozzle  76  on a distal end of the rocket motor  12 , producing thrust. Similar processes occur in the other rocket motors  14 - 18 . 
     The mounts  32 - 38  may have threaded connections, such as externally threaded connectors  82  and  86 , that allow the rocket motors  12 - 18  to be threaded onto the mounts  32 - 38 . The mounts  32 - 38  may receive any of a variety of different types of rocket motors  12 - 18 , for example having different propellants, different combustion chamber configurations, and/or other differences, for example providing different amounts of thrust and/or different thrust profiles. 
     The illustrated embodiment has four rocket motors  12 - 18 , evenly distributed around the manifold  22 . Alternatively the propulsion system  10  may have a different number of rocket motors (greater or lesser), although it is desirable that the rocket motors be symmetric with regard to a center of the system. 
     The propulsion system  10  has many advantages, for example flexibility in configuration, reduction in number of parts, and ensuring simultaneity in ignition of the rockets  12 - 18 . In addition the coupling of the rocket motors  12 - 18  through the plenum  42  may aid in equilibrating operation of the rocket motors  12 - 18  with each other, for example in avoiding pressure differences between the rocket motors  12 - 18 . Any combination of or all of these benefits may be achieved in a particular system. 
       FIG.  4    shows high-level steps of a method  100  of operating the system  10  ( FIG.  1   ), with  FIGS.  5 - 10    illustrating the steps of the method  100 . In step  102 , illustrated in  FIGS.  5  and  6   , the initiator  20  sets off the ignition charge  48 , filling the plenum  42  with hot gasses  112 . 
       FIGS.  7  and  8    illustrate step  104 , where hot gasses  112  have fully filled the plenum  42 . The hot gasses  112  enter the chambers  62  and  66 , where the hot gasses  112  ignite the booster charges  52  and  56 . 
       FIGS.  9  and  10    illustrate step  106 , with the booster charges  52  and  56  igniting the propellent grains of the rocket motors  12  and  16 . Similar booster charges simultaneously ignite the other rocket motors as well. The rocket motors  12 - 18  produce thrust and, as mentioned earlier, the fluid communication of the rocket motors  12 - 18  through the plenum  42  may tend to equalize the operation of the different rocket motors  12 - 18 . 
       FIG.  11    shows one possible use for the propulsion system  10 , as part of a missile or other flight vehicle  200 . The missile  200  may have the propulsion system  10  used to provide propulsive thrust in conjunction with another propulsion device  212  that is located in or makes use (such as by expelling pressurized gasses through) the central opening  26  in the manifold  22 . For example the additional propulsion device  212  may be a jet engine. The propulsion system  10  may be coupled to an aft end of a fuselage  220  of the flight vehicle  200 . 
       FIG.  12    shows an alternative embodiment, a propulsion system  410  with a disk-shaped manifold  422 , having rocket motors  412 ,  414 ,  416 , and  418  attached thereto. An initiator  420  is attached to the manifold  422  at the center of a major surface of the manifold  422 . The initiator  420  is able to activate the rocket motors  412 - 418  through a plenum in the manifold. In one configuration, illustrated in  FIG.  13   , a plenum  442  has a star shape, with radial passages  452 ,  454 ,  456 , and  458  extending from a center of the plenum  442  to locations where the rockets  412 - 418  are connected to the manifold  422 . 
     In another embodiment, illustrated in  FIG.  14   , a plenum  442 ′ has a circumferential passage  460  in addition to radial passages  452 ′,  454 ′,  456 ′ and  458 ′, forming a spokes-and-wheel arrangement. The plenum  442 ′ may provide for better pressure equalization between different of the rockets  412 - 418  ( FIG.  12   ). 
       FIGS.  15 - 19    show another embodiment, a propulsion system  610  that includes seven rocket motors  612 ,  613 ,  614 ,  615 ,  616 ,  617 , and  618 , all of which are ignited by a single initiator  620 . The rocket motors  612 - 618  include a central longitudinal rocket motor  612 , along a longitudinal axis  621  of the propulsion system  610 , surrounded by six rocket motors  613 - 618  circumferentially spaced at a radial distance away from the longitudinal axis  621 . 
     The initiator  620  is attached at a center of a cylindrical or disc-shaped manifold  622 , with a cover  624  providing mounts  632 ,  633 ,  634 ,  635 ,  636 ,  637 , and  638  for securing respective of the rocket motors  612 - 618 . The mounts  632 - 628  have threaded connectors for making threaded connections to the rocket motors  612 - 618 , and have respective chambers containing respective ignition booster charges, both of which are described above with regard to other embodiments. The cover  624  on the manifold  622  encloses and partially defines a star-shaped plenum  642 , which may be lined with a thermal insulation material. The plenum  642  has a central ignition charge  648 , located at the center of the plenum  642 , where the initiator  620  is located. 
     The ignition charge  648  is ignited, igniting the central rocket motor  612  at the center of the plenum  642 . Pressurized gasses spread out from the center of the plenum  642  through radial channels or arms  653 ,  654 ,  655 ,  656 ,  657 , and  658  of the plenum  642 , which are in fluid communication with respective rocket motors  613 - 618 , to ignite the rocket motors  613 - 618 . Operation of the rocket motors  612 - 618 , once ignited, may be similar to (or the same as) that described above in other embodiments. 
     Although the disclosure has been shown and described with respect to a certain embodiment or embodiments, equivalent alterations and modifications will occur to others skilled in the art upon the reading and understanding of this specification and the annexed drawings. In particular regard to the various functions performed by the above described elements (components, assemblies, devices, compositions, etc.), the terms (including a reference to a “means”) used to describe such elements are intended to correspond, unless otherwise indicated, to any element which performs the specified function of the described element (i.e., that is functionally equivalent), even though not structurally equivalent to the disclosed structure which performs the function in the herein illustrated exemplary embodiment or embodiments of the disclosure. In addition, while a particular feature of the disclosure may have been described above with respect to only one or more of several illustrated embodiments, such feature may be combined with one or more other features of the other embodiments, as may be desired and advantageous for any given or particular application.