The invention is in the field of rocket motors, and missiles that include rocket motors.
Shoulder-fired missiles that include rocket motors present a danger to the operator in that combustion gases from the rocket motor are directed back at the operator. The danger from these hot gases (and other combustion byproducts, such as debris) is often addressed by delaying firing of the rocket motor until the missile has flown a significant distance away from the operator. However this can have adverse system-level implications, such as a significantly large minimum range for the missile.
A missile includes a rocket motor having a flow deflector in its exhaust region, deflecting combustion products so as to create a safe region for the operator, behind the missile.
According to an aspect of the invention, a rocket motor includes: a fuel element; a converge-diverge nozzle through which combustion products from the burning of the fuel element pass; and a flow detector along a centerline of an expansion region of the nozzle. The flow deflector deflects away from the centerline combustion products from the burning of the fuel.
According to an embodiment of any paragraph(s) of this summary, the flow deflector is generally conical.
According to an embodiment of any paragraph(s) of this summary, the flow deflector has a maximum diameter.
According to an embodiment of any paragraph(s) of this summary, the flow deflector has a wedge shape.
According to an embodiment of any paragraph(s) of this summary, the flow deflector has a maximum extent of at least 3.2 mm (0.125 inches).
According to an embodiment of any paragraph(s) of this summary, the ratio of the maximum cross-sectional area of the flow deflector 52 to that of the exit port rocket motor 24 may be 1:16 to 1:64.
According to an embodiment of any paragraph(s) of this summary, the flow deflector is attached to an inner wall of a diverge portion of the nozzle, with the diverge portion defining the expansion region.
According to an embodiment of any paragraph(s) of this summary, the rocket motor further includes struts that attach the inner wall and the flow deflector together.
According to an embodiment of any paragraph(s) of this summary, the flow deflector, the struts, and at least part of the diverge portion are a single unitary additively-manufactured part.
According to an embodiment of any paragraph(s) of this summary, the rocket motor is part of a missile.
According to an embodiment of any paragraph(s) of this summary, the missile includes: a payload; and a booster that provides initial thrust to the missile, prior to operation of the rocket motor.
According to an embodiment of any paragraph(s) of this summary, the missile is in combination with a tubular launcher that launches the missile, wherein the launcher contains and directs force from the booster to provide thrust to the missile.
According to an embodiment of any paragraph(s) of this summary, the launcher is a shoulder-fired launcher.
According to another aspect of the invention, a method of firing a rocket-propelled missile includes the steps of: launching the missile from a launcher operated by an operator; and propelling the missile using a rocket motor of the missile. The propelling includes deflecting combustion products using a flow deflector in an expansion region of a nozzle of the rocket motor, thereby creating a safe region behind the missile, with the operator of the launcher is in the safe region.
According to an embodiment of any paragraph(s) of this summary, the launching includes the operator supporting the launcher on a shoulder of the operator.
According to an embodiment of any paragraph(s) of this summary, the creating the safe region includes creating a conical safe region, with the conical safe region having an axis coincident with a central axis of the expansion region.
According to an embodiment of any paragraph(s) of this summary, the creating the safe region includes creating a wedge-shape safe region.
According to an embodiment of any paragraph(s) of this summary, the creating the safe region includes creating a region having an extent of at least 30 cm perpendicular to a flight path of the missile at a distance of 6 meters behind the missile.
According to an embodiment of any paragraph(s) of this summary, the propelling is initiated with the missile at at least a 6 meters away from the launcher.
According to an embodiment of any paragraph(s) of this summary, the deflecting includes deflecting the combustion products using a bow shock produced by the deflector.
According to an embodiment of any paragraph(s) of this summary, the creating the safe region includes creating a region having a suitable extent perpendicular to a flight path of the missile at a suitable distance behind the missile.
According to an embodiment of any paragraph(s) of this summary, the propelling is initiated at the missile at at least a suitable time after the launching.
According to an embodiment of any paragraph(s) of this summary, the propelling is initiated with the missile at at least a suitable distance away from the launcher.
According to yet another aspect of the invention, a missile includes: a payload; a rocket motor for providing thrust to the missile during flight; and a booster for providing initial thrust to move the payload and the rocket motor out of a launcher. The rocket motor includes a flow deflector along a centerline of the rocket motor. The flow deflector deflects away from the centerline combustion products from the burning of fuel in the rocket motor.
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.
The annexed drawings, which are not necessarily to scale, show various aspects of the invention.
A missile includes a rocket motor that has a flow deflector in an expansion region of the rocket motor's nozzle. The flow deflector diverts flow of combustion products away from a safe region that is aft of the missile. The safe region protects an operator of a launcher used to fire the missile, such as a shoulder-fired launcher, from harm caused by the combustion products. The flow deflector may be small enough such that it does not significantly adversely affect the performance of the rocket motor. The presence of the flow diverter may allow for the rocket motor to be started sooner in the flight of the missile, or at a distance closer to the operator, while still keeping the operator safe. The flow deflector and supporting structure, such as struts, may be additively manufactured with at least an aft part of the nozzle, as a continuous single-piece part.
The missile 16 is initially propelled from the launcher 12 by combustion or explosions within the launcher 12. This initial propulsion is produced by a boost charge (or booster), which may be a part of the missile 16. The products 18 produced by this initial boost exit out of the aft end of the launcher 12, the end of the launcher opposite from where the missile 16 is expelled. For a shoulder-fired weapon these combustion products (hot gasses, debris, and/or exhaust species) 18 do not represent a hazard to the operator 14 since they are directed behind and away from the operator 14.
The missile 16 includes a rocket motor to provide additional thrust during its flight. As described in greater detail below, the rocket motor includes a flow deflector that deflects some of the combustion products of the rocket motor (hot gasses, debris, and/or exhaust species) away from a region behind the missile, creating a safe region in which the operator 14 is located. The existence of this safe region allows ignition of the rocket motor more quickly in the flight of the missile 16, with the missile 16 closer to the launcher 12, relative to prior art approaches that require a missile to be further from the launch position before initiating a rocket motor, in order to avoid danger to the operator launching the missile.
A flow deflector 52 is located within an expansion region 53 defined by the diverging portion 44, along a centerline 54 of the expansion 44. The expansion region centerline 54 will generally correspond with (be coincident with) centerlines of the rocket motor 24 and of the missile 16 (
The flow deflector 52 is held in place by a series of struts 56 that link the flow deflector 52 to an inner wall 58 of the expansion portion 44. The struts 56 may be symmetrically spread in a circumferential direction around the centerline 54. There may be any suitable number of the struts 56, for example three or four of the struts 56. As an alternative to the struts 56, there may be a different support structure that supports the flow deflector 52.
The flow deflector 52 and the struts 56 may be made as a single part with all or a part of the nozzle 38. The single part may be made, for example, using additive manufacturing techniques, although non-additive techniques may be used instead. Any suitable material may be used for the flow deflector 52, for example a metal or ceramic capable of withstanding high temperatures.
The flow deflector 52 is generally conical, with a rounded point (nearing blunt/flat), as opposed to a sharp point, in the illustrated embodiment. The narrow portion of the cone faces forward, toward the front of the missile 16 (
With reference again to
The safe region 70 may have a radius near the flow deflector 52 that is about the radius of the wide end of the flow detector 52, or of the region inside the bow shock 62 at the Downstream of the flow detector 52 the safe region 70 may have an angle of expansion of suitable extent, for example having an angle of about 2 degrees. The flow deflector 52 may have a diameter of 3.2 mm (0.125 inches) to 6.4 mm (0.25 inches), although other sizes are possible. The ratio of the maximum cross-sectional area of the flow deflector 52 to that of the exit port rocket motor 24 may be 1:16 to 1:64, although again other ratios are possible.
The safe region 70 may be significantly wide at a reasonable distance downstream of the missile 70 to protect the operator 14. This may be the case even when the flow deflector 52 has a small diameter and thus a small effect on the performance of the rocket motor 24. To give one non-limiting example, the flow deflector 52 may have a diameter suitable to produce the safe region 70 with a suitable diameter at a suitable distance downstream from the aft end of the rocket motor 24. For example the safe region 70 may have a diameter of 30.5 cm (12 inches) at a distance of 6 meters (20 feet) from the missile 16. This may allow firing of the rocket motor 24 at such a distance away from the operator, while giving protection to exposed/vulnerable body parts of the operator firing a shoulder-fired missile. For example the head /face of the operator may be within the safe region 70. This may allow less hazard to the operator, and/or may reduce the requirement for protective plates or other structures of the launcher, which would otherwise be used to protect the operator.
More broadly, the use of the flow deflector 52 may allow firing of the rocket motor at a distance of 6 meters (20 feet) to 15 meters (50 feet) into flight of the missile 16. This contrasts with missiles without a flow deflector, which may require 30 meters (100 feet) of flight distance before firing of a rocket motor.
The placement of the flow deflector 52 on the centerline 54 means that the exhaust plume is diverted in an axisymmetric manner. This advantageously does not impart any nonaxial thrust vector into the rocket motor 24 of the missile 16. However, as noted above, other configurations are possible that put a nonaxial thrust vector onto the missile 16, which may be desirable in some situations.
The use of flow deflector 52 reduces to some extent the undesirable effects of the combustion products on the operator 14 (
The flow deflector 152 may have comparable dimensions, features, and/or variations to those described above for the flow deflector 52. For example the maximum width of the flow deflector 152 may be similar to diameter of the flow deflector 52, the extend of the safe region 170 may be similar to that of the safe region 70, the material of the two flow deflectors 52 and 152 may be the same, and/or the leading edge of the flow deflector 152 may be rounded or flat.
Although the invention has been shown and described with respect to a certain preferred embodiment or embodiments, it is obvious that 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 invention. In addition, while a particular feature of the invention 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.