Abstract
A flare including: a casing; and a grain assembly, at least a portion of the grain assembly being slidably disposed in the casing, the grain assembly including: a shell structure; and a grain component at least partially disposed in the shell structure, the grain component including at least one combustible material and at least one reactive material positioned relative to the combustible material and configured to ignite combustion of the at least one combustible material; wherein the shell structure includes one or more fins at an aft end of the shell structure, the one or more fins being restrained into a first shape in the casing and configured to have a second shape, different from the first shape, when the restraint is removed.
Claims
1. A flare comprising: a casing; and a grain assembly, at least a portion of which is slidably disposed in the casing, the grain assembly comprising: a shell structure; and a grain component at least partially disposed in the shell structure, the grain component including at least one combustible material and at least one reactive material positioned relative to the combustible material and configured to ignite combustion of the at least one combustible material; wherein the shell structure includes one or more fins at an aft end of the shell structure, the one or more fins being restrained into a first shape in the casing and configured to have a second shape, different from the first shape, when the restraint is removed; and the one or more fins are rotatably disposed on the shell structure.
2. The flare of claim 1, wherein the one or more fins are biased into the second shape.
3. The flare of claim 1, wherein the one or more fins are configured to impart a spin to the grain assembly when the grain assembly is ejected from the casing.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) These and other features, aspects, and advantages of the apparatus of the present invention will become better understood with regard to the following description, appended claims, and accompanying drawings where:
(2) FIG. 1A illustrates the schematic of a perspective view of a flare of the prior art.
(3) FIG. 1B illustrates a cross-sectional view of the prior art flare of FIG. 1A.
(4) FIG. 2 illustrates the cross-sectional view 4-4 of the prior art flare of FIGS. 1A and 1B.
(5) FIG. 3 is the schematic of the first embodiment of the countermeasure flare of the present invention.
(6) FIG. 4 is the schematic of one alternative nozzle section design for the first embodiment of the countermeasure flare of FIG. 3.
(7) FIG. 5 is the schematic of another alternative nozzle section design for the first embodiment of the countermeasure flare of FIG. 3.
(8) FIGS. 6A and 6B illustrate another alternative nozzle section design for the first embodiment of the countermeasure flare of FIG. 3.
(9) FIG. 7 illustrates another alternative nozzle section design for the first embodiment of the countermeasure flare of FIG. 3.
(10) FIGS. 8A and 8B illustrates another alternative nozzle section design for the first embodiment of the countermeasure flare of FIG. 3.
(11) FIGS. 9A and 9B illustrates another alternative nozzle section design for the first embodiment of the countermeasure flare of FIG. 3.
(12) FIGS. 10A and 10B illustrates another alternative nozzle section design for the first embodiment of the countermeasure flare of FIG. 3.
(13) FIGS. 11A and 11B illustrates another alternative nozzle section design for the first embodiment of the countermeasure flare of FIG. 3.
(14) FIGS. 12A and 12B illustrates another alternative nozzle section design for the first embodiment of the countermeasure flare of FIG. 3.
(15) FIG. 13 is the schematic of an embodiment of the grain assembly of the countermeasure flare of the present invention that is provided with deployable fins for enhanced stability during the flight.
(16) FIG. 14 is the schematic of another embodiment of the grain assembly of the countermeasure flare of the present invention that is provided with deployable fins for enhanced stability during the flight.
(17) FIGS. 15A and 15B illustrate the schematic of another embodiment of the grain assembly of the countermeasure flare of the present invention that is provided with multi-sectional and axially expanding grain component to significantly increase the surface area of the grain upon ejection.
(18) FIGS. 16A and 16B illustrate the schematic of an alternative assembly of the grain assembly of the countermeasure flare of the with multi-sectional and axially expanding grain component of FIGS. 15A and 15B.
(19) FIGS. 17A and 17B illustrate the schematic of another embodiment of the grain assembly of the countermeasure flare of flare of FIG. 3.
(20) FIGS. 18A, 18B and 18C illustrate the schematic of another embodiment of the grain assembly of the countermeasure flare of flare of FIG. 3 and its various components.
(21) FIGS. 19A and 19B illustrate the schematic of another embodiment of the grain assembly of the countermeasure flare of flare of FIG. 3.
(22) FIGS. 20A and 20B illustrate the schematic of another embodiment of the grain assembly of the countermeasure flare of flare of FIG. 3.
(23) FIGS. 21A and 21B illustrate the schematic of another embodiment of the grain assembly of the countermeasure flare of FIG. 3.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
(24) FIG. 3 illustrates the schematic of the longitudinal cross-sectional view of a first embodiment 100 of a flare 100. The flare 100 includes a grain assembly 101 which is disposed within a casing 102. The casing 102 may have a first, aft end 104 and a second, opposite forward end 105. The grain assembly 101 includes the grain component 103, which consists of at least one combustible material and at least one reactive material which is positioned relative to the combustible material and configured to ignite combustion of the at least one combustible material. The grain assembly 101 is provided with a shell structure 106, which encases at least a portion of the grain component 103 of the grain assembly 101. The grain component 103 may also include at least one non-combustible material that is added to achieve certain effects such as generation and/or intensification of electromagnetic radiation at the desired wavelengths.
(25) The flare 100 may be configured as a decoy flare, and the combustible material(s) of the grain component 103 may be configured to emit electromagnetic radiation with peak emission wavelength within the infrared region of the electromagnetic radiation spectrum and/or other spectrum(s) upon combustion of the combustible material(s) of the grain component 103 and interaction of the other said added noncombustible material(s), if present. The flare 100 may be configured for signaling, illumination, or both, and may be configured to emit at least a peak emission wavelength within the visible region of the electromagnetic radiation spectrum. The flare 100 may be configured to emit at least a peak emission wavelength within the ultraviolet region of the electromagnetic radiation spectrum.
(26) As shown in the cross-sectional view of FIG. 3, both the grain component 103 and the grain assembly 101 and the casing 102 may have an elongated shape with essentially constant cross-sectional area, which may be almost of any shape, such as rectangular (as shown for the prior art flare shown in FIGS. 1A, 1B and 2) or circular. In general, the cross-sectional area can be selected to be square and not circular when it is desired to pack as many such flares as possible in as small a volume as possible.
(27) On its aft end 104, the shell structure 106 of the grain assembly 101 is formed into a nozzle section 107. The interior volume of the nozzle section 107 is preferably filled with at least one material composition 108, which may be composed of the same grain component 103; or may at least partly include certain appropriate propellant material; or may be composed of at least certain pyrotechnic material that is used to initiate ignition of the grain component 103 of the flare and at the same time generate a thrust in the direction of launching the grain assembly 101 from inside the flare casing 102.
(28) The nozzle section 107 may be designed with the usual converging section that is connected via a throat section to the diverging section (aft section of the nozzle 107 as seen in FIG. 3), where the accelerated gasses exit at relatively high speeds. The length of each section and the throat diameter ratio are selected to achieve the desired effects as described below.
(29) An impulse charge device 109 may be provided at or within the first end 104 of the flare casing 102 or may be coupled to the flare 100 when the flare 100 is ready to be deployed or mounted on the intended platform. The impulse charge device 109 may be configured to force the grain assembly 101 out from the second end 105 of the casing 102 upon ignition of the impulse charge device 109. The flare 100 may be provided with a piston member 110 which is disposed within the casing 102 between the impulse charge device 109 and the grain assembly 101. The piston member 110 is used to provide a sealing action to allow the pressurized gasses generated by the initiation of the impulse charge device 109 to effectively act on the grain assembly 101 and eject it from the second end 105 of the casing 102. The flare 100 may be provided with an end cap 111, preferably to seal the grain assembly inside the casing 102.
(30) As can be seen in the embodiment 100 of FIG. 3, a separate piston member 110 is used as a seal to allow the pressurized gasses generated by the initiation of the impulse charge device 109 to propel the grain assembly 101 and eject it from the second end 105 of the casing 102. It is, however, appreciated by those skilled in the art that the piston may be formed around at least a portion of the length of the nozzle 107 as shown in FIG. 3 by dashed lines and indicated by the numeral 112, thereby allowing more space for the grain component 103. It is also appreciated by those skilled in the art that at least a portion of the aft expanding portion of the nozzle could be used to form the impulse charge device 109, in which case the aft end 104 of the flare casing needs to be securely closed with a closing member (not shown), preferably as an integral part of the casing 102, to allow the pressurized gasses generated by the initiation of the impulse charges to effectively accelerate and eject the grain assembly 101.
(31) In the flair embodiment 100 shown in FIG. 3, the shell structure 106 is used to encase the entire length of the grain component 103 of the grain assembly 101. In this design, upon ejection, the flare component 103 would burn primarily from its aft end since it is otherwise encased in the shell structure 106 and the generated gasses are discharged through the nozzle 107, thereby generating certain level of thrust that could be used to propel the grain assembly along its path of travel (trajectory). This embodiment has the advantage of providing a relatively long flare burn time (and the forward thrust), but due to its limited burn surface of the grain component, the amount of gasses and illumination that it can produce is relatively limited. To achieve the same level of nozzle 107 generated thrust while significantly increasing the burning rate (burning surface area), the following modifications can be made to the embodiment 100 shown in FIG. 3.
(32) A first modification consists of providing openings on the surface of the shell structure 106 of the grain component 103, starting certain distance from the side of the nozzle 107, for example from the dashed line 113 to the forward end 105, to provide larger exposed burn areas for the grain component 103 (the method of igniting the exposed surfaces to be described below).
(33) A second modification consists of totally eliminating the shell structure 106 from the dashed line 113 to the forward end 105, thereby exposing the entire surface of this section (from the dashed line 113 to the forward end 105) of the grain component 103 to combustion. It is appreciated by those skilled in the art that the exposed section of the grain component 103 could cover a very large portion of the length of the grain component 103, and thereby allow a significant increase in the rate of burning of the grain component 103, particularly if measures are taken to increase the outer surface area of the grain component 103 as, for example, shown in FIG. 2.
(34) It is noted that in the embodiment 100 of FIG. 3, the gasses generated by the burning of the grain component 103 are accelerated through the nozzle 107 to generate forward thrust. It is, however, appreciated by those skilled in the art that if desired, the volume of the grain component 103 at and near the nozzle 107 may be filled with any type of propellant material and used to generate significantly larger nozzle 107 thrust.
(35) It is also appreciated by those skilled in the art that layers of different pyrotechnic compositions and/or materials and/or combinations/mixtures may be used to fill the interior volume of the nozzle section 107 and/or make the grain component 103 itself with such layered materials so that different exhaust gasses are dispersed in a sequential manner and with different patterns (while also making it possible to vary the thrust generated by the nozzle 107) to achieve the desired flare countermeasure effects, including the generation of intermittent forward thrust.
(36) In the flare embodiment 100 shown in FIG. 3, the nozzle 107 is considered to have a fixed geometry. As a result, the geometry of the nozzle, and particularly the size of the expanding (exhaust) section is limited by the shape and area of the cross-sectional area of the casing 102. In an alternative embodiment of the flare 100, the nozzle 107 is designed to be collapsible (deformable, expandable, deployable or capable of morphing), such that it is initially collapsed to a first geometry to fit inside the casing 102, but that would expand or morph to a second geometry following ejection from the casing 102. As an example and without implying any limitation, the expanding section of the nozzle 107 could be designed to assume the first geometry 114 shown in the partial cross-sectional view of FIG. 4 and subsequent to ejection from the casing 102 to assume the second geometry 115 shown in dashed lines, thereby significantly increasing the diverging section of the nozzle 107. The different methods and means of achieving the collapsible (deformable, expandable, deployable or capable of morphing) nozzles will be described below.
(37) In the flare embodiment 100 shown in FIG. 3, a single the nozzle 107 with fixed geometry is considered to be used. In an alternative embodiment of the flare 100, more than one individual nozzle (collectively indicated as the nozzle section 116 in the schematic of FIG. 5) are instead used. In the cross-sectional view of FIG. 5, the nozzle section 116 is shown to consist of two separate nozzles 117 and 118 which are symmetrical in the plane of the cross-section. However, it is appreciated by those skilled in the art that more than two separate nozzles of different shapes and cross-sections and non-symmetric may also be employed, which could also provide different advantageous and operational functionality to the resulting countermeasure flares as will be described below.
(38) In addition, one or more of the nozzles provided in the nozzle section 116, FIG. 5, may be provided with the aforementioned feature of being collapsible (deformable, expandable, deployable or capable of morphing), such that they are initially collapsed to a first geometrical configuration (shown in solid lines in FIG. 5 for the nozzles 117 and 118) to fit inside the casing 102, but that would expand or morph to a second geometrical configuration (shown with dashed lines for the nozzles 117 and 118 and enumerated as 119 and 120, respectively) following ejection from the casing 102.
(39) It is appreciated by those skilled in the art that in the flare embodiment 100 and its various aforementioned variations as well as those to be described below, the geometry of the nozzles (i.e., the shape and size of their cross-sectional area along the length of the converging, diverging and throat sections of the nozzle) may be symmetrical or non-symmetrical and of arbitrary shape to achieve the desired gas dispersion pattern and/or thrust and/or spinning torque. For example, to achieve a spinning torque about the long axis of the flare, at least two identical nozzles 121 and 122 may be positioned as shown in the schematic of FIG. 6 of the aft section of the ejected flare. It is noted that the nozzles 121 and 122 shown in FIGS. 6A and 6B are considered to be collapsible (deformable, expandable, deployable or capable of morphing), such that they are initially collapsed to a first geometrical configuration to fit inside the casing 102, FIG. 3, but that would expand or morph to a second geometrical configuration 121 and 122 shown in FIGS. 6A and 6B as was described for the embodiments of FIGS. 4 and 5. The nozzles 121 and 122 are positioned symmetrically about the long axis of the flare shell structure 106 as indicated by the (intersection of the) centerlines 123 and 124. The nozzles 121 and 122 are also are positioned at an identical angles relative to the plane of the centerlines 123 and 124, so that the net thrust generated accelerated gasses exiting the said nozzles and indicated by the arrows 125 and 126, respectively, in FIG. 6B, are also directed at the same angles relative to the plane of the centerlines 123 and 124. As a result, the two nozzles 121 and 122 would essentially generate a total of thrust in the direction of the long axis of the flare 100 as well as a net torque (couple) about the said long axis of the flare.
(40) It is appreciated by those skilled in the art that by providing the aforementioned at least two nozzles 121 and 122, FIGS. 6A and 6B, the ejected flare is provided with a net thrust in the direction of its long axis, while being provided with a net toque (couple) that would tend to spin the flare about its long axis, thereby providing the ejected flare with the capability of achieving flight stability.
(41) It is also appreciated by those skilled in the art that by using one or more nozzles with symmetrical or arbitrary cross-sectional areas, which are positioned and oriented symmetrically or non-symmetrically about the long axis of the fare, and by providing propellants that consist of grain component 103 and/or pyrotechnics and/or other materials, the flare nozzle system can be used to perform many different functions, including one or more of the following:
(42) 1. To generate thrust, and/or
(43) 2. Cause the flare to spin by providing a spinning couple to it, and/or
(44) 3. Cause the exhaust gasses to disperse with certain pattern along the flare trajectory, or
(45) 4. Achieve any combination of the above effects.
(46) As it can be observed in the schematic of the embodiment 100 of FIG. 3, within the section of the casing 102 where the nozzle 107 is located, there is a gap between the outer surfaces of the nozzle 107 and the inner surface of the casing 102. It is appreciated by those skilled in the art that it is highly desirable to utilize all the available space within a flare (casing 102) volume. The following nozzle section embodiments are developed to allow the flare designer to provide a flare with at least one nozzle as previously described, while at the same time convert essentially the entire aforementioned gap between the outer surface(s) of the nozzle(s) 107 and casing 102 into a usable space.
(47) The first such nozzle section embodiment is shown in the schematic of FIG. 7. In this embodiment, the nozzle section in its pre-ejection configuration 127 has essentially the same cross-sectional area and shape, hereinafter referred to as the first configuration 127, as the shell structure 106 of the grain assembly 101 to which it is attached. As a result, the entire volume inside the flare 100 in the nozzle section can be filled with grain component 103 and/or pyrotechnics and/or other materials prior to ejection. Then upon flare ejection, as the nozzle fill (grain component 103 and/or pyrotechnics and/or other materials) is burned, the nozzle section walls deform from its initial shape (aforementioned first configuration 127) to its nozzle shape (second configuration) shown by dashed lines in FIG. 7 and indicated by the numeral 130. In general, the transformation of the nozzle section walls from the first configuration 127 to the second configuration 130 is accomplished by initially forming the nozzle walls in shape of their second configuration 130, and then elastically deforming the walls to their aforementioned first configuration 127, and keeping them in their said first configuration by the nozzle fill (grain component 103 and/or pyrotechnics and/or other materials). Then as the nozzle fill is burned, the nozzle walls would deform in the direction of the arrows 128 and 129 shown in FIG. 7, and transform the nozzle to its second configuration 130. Such configuration transforming nozzle sections may be designed in a number of ways, a few examples of which and without intending to restrict the present disclosure are provided below.
(48) In one embodiment, shown schematically in FIGS. 8A and 8B, the aft end of the shell structure 106 of the grain assembly 101 (FIG. 3) is initially in the configuration shown in FIG. 8A. In this configuration, one or both of the facing side panels 131 and 132 of the nozzle section 133 are held in the configuration shown in FIG. 8A by the grain component 103 and/or other pyrotechnics and/or propellants that is used to fill the space 134 inside the nozzle section 133. The facing side panels 131 and 132 include cut outs 132a to allow for deformation of the facing side panels 131, 132. The one or both of the facing side panels 131 and 132 are elastically deformed to stay in the configurations of FIG. 8A. Then as the grain component 103 and/or other pyrotechnics and/or propellants that is used to fill the space 134 is burned, the one or both of the facing side panels 131 and 132 return to their unstrained configurations to close the cut outs 132a, as shown in FIG. 8B and enumerated by numerals 135 and 136, respectively. The nozzle section 133 would thereby form the configuration shown in FIG. 8B, thereby provide a thrust generating nozzle as the grain component 103 and/or other pyrotechnics and/or propellants filling the remaining space of the nozzle section 133 and the adjacent shell structure 106 is burned.
(49) It is appreciated by those skilled in the art that a number of alternative methods may be used to provide the required means to force the side panels 131 and 132 from their configurations of FIG. 8A to those of 135 and 136 configurations shown in FIG. 8B with or without the aforementioned initial elastic deformation. For example, the panels 131 and 132 may be constructed with a shape memory alloy material such that once heated due to the burning of the filling grain component 103 and/or other pyrotechnics and/or propellants, the panels deform to their 135 and 136 state.
(50) It is also appreciated by those skilled in the art that the flare 100 of FIG. 3 may have a circular or near circular (for example oval) cross-sectional area. When, for example, the cross-sectional area of the flare 100 (and its casing 102 and shell structure 106 and grain component 103) is circular, the aforementioned nozzle section geometry transformation (similar to the transformation from the configuration of FIG. 8A to that of FIG. 8B) can be achieved using a number of methods, examples of which without intending to indicate limitations, are hereby provided.
(51) One embodiment of such configuration transforming nozzles with circular or near circular cross-sectional areas is shown schematically in FIGS. 9A and 9B. In this embodiment, the nozzle section 137, which is attached to the aft end of the shell structure 106 of the grain assembly 101 (FIG. 3), is constructed with a number of flaps 138 that in their first configuration shown FIG. 9A form essentially the same cylindrical shape as the shell structure 106 of the flare 100. In this configuration, the flaps 138 are held in their (essentially straight) state by the filling grain component 103 and/or other pyrotechnics and/or propellants that are used to fill the space 139 inside the nozzle section 137. In an embodiment, flaps 138 are elastically deformed to stay in the (essentially straight) state of FIG. 9A. Then as the grain component 103 and/or other pyrotechnics and/or propellants that are used to fill the space 139 is burned, the flaps 138 return to their unstrained configurations shown in FIG. 9B and enumerated by numerals 140. The flaps 138 can be partially fluted (not shown) to provide them with strength and are overlapping to minimize leakage of the generated gasses. The nozzle section 137 would thereby form the configuration shown in FIG. 9B, to provide a thrust generating nozzle as the grain component 103 and/or other pyrotechnics and/or propellants filling the remaining space of the nozzle section 137 and the adjacent shell structure 106 is burned.
(52) It is appreciated by those skilled in the art that at least one elastically preloaded elastic ring or spring 141 may be provided to force the flaps 138 from their essentially straight configuration shown in FIG. 9A to their configuration 140 shown in FIG. 9B. The preloaded elastic ring/spring 141 may also be used to keep the flaps in their configuration 140 as the filling grain component 103 and/or other pyrotechnics and/or propellants are burned and gas pressure builds up inside the nozzle section 137. The use of at least one elastically preloaded elastic ring/spring 141 minimizes the aforementioned required elastic deformation of the flaps 138 to their first (essentially straight) configuration, and even eliminate the need for such elastic deformation of the flaps 138 if the at least one elastic ring/spring 141 is provided with an appropriate level of preload.
(53) In addition, the flaps 138 and/or ring 141 may be fabricated from a shape memory alloy such that once heated due to the burning of the filling grain component 103 and/or other pyrotechnics and/or propellants, the flaps 138 and/or ring 141 deform to the configuration shown in FIG. 9B.
(54) Although the flaps 138 are shown as being cut to the ends thereof, that may also to configured as a single cylinder with longitudinal slits that define the individual flaps 138 except such slits do not need to extend all the way to the end of the cylinder.
(55) Another embodiment of such configuration transforming nozzles with circular cross-sectional area is shown schematically in FIGS. 10A and 10B. In this embodiment, the nozzle section 142, which is attached to the aft end of the shell structure 106 of the grain assembly 101 (FIG. 3), is constructed by a spring wire 143 (which can also have a rectangular cross-section) that is in its rest (second configuration) state 146 is shown in the configuration of FIG. 10B, i.e., form a nozzle with a throat area and expanding (flow accelerating) aft section. The rectangular or other similar cross-sectional area, which can also have overlapping lips, can minimize the amount of gasses that are passing through the nozzle section 142 from escaping out. In its first configuration shown in FIG. 10A, the nozzle (indicated by the numeral 144) forms essentially the same cylindrical shape as the shell structure 106 of the flare 100. The nozzle 144 is held in this first configuration by the filling grain component 103 and/or other pyrotechnics and/or propellants that are used to fill the space 145 inside the nozzle 144. In the preferred embodiment, the spring wire 143 is deformed from its rest state 146 (FIG. 10B) to its state 144 (FIG. 10A). Thereby, as the grain component 103 and/or other pyrotechnics and/or propellants that are used to fill the space 139 is burned, the spring wire 143 returns to its unstrained second configurations 146. The nozzle section 142 would thereby form the configuration shown in FIG. 10B and provide a thrust generating nozzle as the grain component 103 and/or other pyrotechnics and/or propellants filling the remaining space of the nozzle section and the adjacent shell structure 106 is burned.
(56) It is appreciated by those skilled in the art that one may use more than one layer of overlapping (such as rectangular cross section) wires to form the nozzle section 142 shown in the embodiment of FIGS. 10A and 10B. The advantage of using more than one overlapping layers is that the internal layer could be used to minimize the amount of gasses that could escape from the sides of the nozzle, thereby increasing the amount of thrust that the nozzle can provide.
(57) It is also appreciated by those skilled in the art that similar to the embodiment of FIGS. 9A and 9B, at least one elastically preloaded elastic ring or spring (141 in FIGS. 9A and 9B) may be provided to force the spring wire formed nozzle section from its first (essentially cylindrical) configuration 144 shown in FIG. 109A to its second configuration 146 shown in FIG. 10B. The preloaded elastic ring/spring (not shown) may also be used to keep the spring wire formed section in its configuration 146 as the filling grain component 103 and/or other pyrotechnics and/or propellants are burned and gas pressure builds up inside the nozzle section 145. The use of at least one elastically preloaded elastic ring/spring also minimizes the aforementioned required elastic deformation of the spring wire 143 to its first configuration shown in FIG. 10A, and even eliminate the need for such elastic deformation of the nozzle section spring wire 143 if the at least one elastic ring/spring (similar to the element 141 in FIGS. 9A and 9B) is provided with an appropriate level of preload.
(58) In the nozzles shown in FIGS. 3-10, the nozzle consists of a converging section, a throat section and a diverging (aft) section where the exiting gasses are accelerated. The diverging end section is provided to accelerate the gasses exiting the nozzle throat to generate higher levels of thrust. In many flare applications, the amount of thrust that is desired to be generated is, however, relatively low and can be generated with nozzles that do not have the aforementioned diverging section. Any one of the nozzles of the embodiments of FIGS. 7-10 may be constructed without a converging section. Alternatively, such nozzles may be constructed as shown in FIGS. 11A and 11B. In this embodiment, the nozzle is constructed with at least two nested rings 147 (the rings being circular or square or any other closed-loop shape) that are preferably slightly tapered along the length of the rings. The rings are initially in the packed configuration 152 as shown in FIG. 11A. The aft end of the shell structure 106 of the grain assembly 101 (FIG. 3) is provided with an inward lip 148 that would engage with the outward lip 149 of the first ring 147 as the nested rings 147 deploy outward upon the flare ejection. The first ring 147 is also provided with an inward lip 150 on its other end. Similar engaging lips are provided on all nested rings 147 so that as following flare ejection, as the nested rings 147 deploy outward, they would form the converging section of a nozzle section 151 as the inward and outward lips of the nested rings 147 are engaged as shown in FIG. 11B, and form a throat section 153. In their initial state shown in FIG. 11A, the nested rings 147 can be held in their position by strings or the like (not shown) that burn as the filling grain component 103 and/or other pyrotechnics and/or propellants in the space 153 inside the inner ring and/or the space 154 inside the shell structure above the nested rings 147 are ignited. The gas pressure generated by the ignited material in the space 154 will force the deployment of the nested rings 147 to their configuration shown in FIG. 11B and their maintenance in the deployed configuration. It is however appreciated by those skilled in the art that appropriate preloaded spring elements (not shown) may also be provided between each pair of rings 147 to assist in the deployment of the rings to their configuration of FIG. 11B.
(59) In the embodiment of FIGS. 11A and 11B, the rings 147 are individual rings that are nested as shown in these figures and deploy upon ejection and ignition of the grain component 103 and/or other pyrotechnics and/or propellants filling the spaces 153 and 154, FIGS. 11A and 11B. In an alternative embodiment, the rings 147 may be a continuously wound band of spring material with the indicated lips 149 and 150, which are wound as a helical spring commonly used in so-called power springs, which are well known in the art. The helical spring can be biased to stay in the configuration of FIG. 11B, and is held similarly in its pre-ejection configuration of FIG. 11A by strings or the like (not shown) that burn as the filling grain component 103 and/or other pyrotechnics and/or propellants in the space 153 inside the inner turn of the helical spring and/or the space 154 inside the shell structure above the helical spring are ignited. The gas pressure generated by the ignited material in the space 154 will force the deployment of the helical spring to configuration shown in FIG. 11B and their maintenance in the said deployed configuration.
(60) In the nozzles shown in FIGS. 3-10, the nozzle consists of a converging section, a throat section and a diverging (aft) section where the exiting gasses are accelerated. The diverging end section is provided to accelerate the gasses exiting the nozzle throat to generate higher levels of thrust. In flares, the diverging section may also have been provided to increase (radial) dispersion of the flare gasses, as for example, was shown in the embodiments of FIGS. 4 and 5. In certain flare applications, only a small level of thrust or even no thrust is required to be generated, thereby the nozzle section does not require minimal or no converging section to form the throat area and the diverging section is used mostly to provide for the aforementioned radial dispersion of the flare gasses passing through the nozzle. As an example and without intending to provide any limitation, an embodiment of such configuration transforming nozzles with circular cross-sectional area is shown schematically in FIGS. 12A and 12B. In this embodiment, the nozzle section 155 is constructed with at least two overlapping outer flaps 156 and inner flaps 157 as shown in FIG. 12B. In their first configuration, the flaps 156 and 157 are essentially straight and form an outer cylindrical surface that is the same as the outside surface of the shell structure 106 as shown in FIG. 12A. The flaps 156 and 157 are preferably brought from their second (not preloaded or rest) configuration shown in FIG. 12B to their first configuration shown in FIG. 12A by deforming them elastically, and holding them in the latter state by strings or the like (not shown) that burn as the filling grain component 103 and/or other pyrotechnics and/or propellants in the space 158 inside nozzle section 155 are ignited upon ejection of the flare 100. Then as the flaps 156 and 157 are released, they would return to their aforementioned rest (not elastically preloaded) configuration of FIG. 12B, thereby transforming the section 152 into a diverging nozzle section.
(61) In the embodiment of FIGS. 12A and 12B, the flaps 156 and 157 were described to assume a first configuration shown in FIG. 12A and upon ejection and the burning of the aforementioned strings or the like that are burned upon ejection, thereby allowing the flaps to assume their second configuration shown in FIG. 12B. It is, however, appreciated by those skilled in the art that almost all such deployable nozzles (such as those of the previous embodiments of the present invention) may be provided with the capability of assuming more than one deployed configuration. Such a capability can, for example, be readily achieved by providing more than one aforementioned strings or the like that hold the flaps 156 and 157 in their first configuration, but a first string or the like 172 (FIG. 12A) that once burned (released) would allow the deployment of the flaps 156 and 157 to a second configuration, and once a second string or the like 173 is burned (released), then the flaps 156 and 157 are deployed to a third (expanded nozzle) configuration, and so on if more than two such strings or the like are provided. The strings or the like can be burned sequentially by the burning of the flare filing grain component 103 and/or other pyrotechnics and/or propellants. Other means such as delay pyrotechnic burns.
(62) FIG. 13 illustrates the schematic of another embodiment 160 of the grain assembly (indicated 101 in the flare embodiment 100 of FIG. 3). The grain assembly 160 is to be similarly disposed within the casing 102 of the flare 100 shown in the schematic of FIG. 3. Similar to the flare embodiment 100, the casing 102 may have a first, aft end 104 and a second, opposite forward end 105 as shown in FIG. 3. The grain assembly 160 is similarly constructed with the shell structure 161, which is provided with a step 162 in its aft section 163, which is shaped and sized to accommodate at least one pair of deployable fins 164 described below (which can be symmetrically positioned along the long axis of the grain assembly 160). The shell structure 161, including the aft section 163, is similarly filled with grain component (similar to 103 in FIG. 3not shown in FIG. 13), which consists of at least one combustible material and at least one reactive material which is positioned relative to the combustible material and configured to ignite combustion of the at least one combustible material. The grain component may also include at least one non-combustible material that is added to achieve certain effects such as generation and/or intensification of electromagnetic radiation at the desired wavelengths.
(63) As indicated for the embodiment of FIG. 3, both the grain component 103 and the grain assembly 160 can have a (rectangular) or circular or near circular (oval) cross-sectional area, but may be almost of any shape. In the schematic of FIG. 13, the grain assembly 160 is considered to have a square cross-sectional area along the length of the grain assembly, including its aft section 163. It is, however, noted that the grain assembly may be provided with only one pair of fins 164, in which case the aft section 163 is only required to accommodate the pair of fins 164 and can therefore be constructed with steps only to accommodate the pair of fins 164.
(64) The fins 164 are attached to the shell structure 161 with rotary joints 165. Before ejection, the fins 164 can each be held in the configuration 166 shown with dashed lines in FIG. 13 and assembled inside the casing 102 of the flare 100 shown in the schematic of FIG. 3. The fins 164 can each be held in their configuration 166 by strings or the like (not shown) that burn as the filling grain component 103 and/or other pyrotechnics and/or propellants in and around the aft section 163 of the flare are ignited. The fins 164 can also be provided with preloaded (preferably torsion springs acting at the rotary joints 165) that upon release, would rotate the fins from their stowed position 166 to their deployed configuration 164 as indicated by the arrow 167.
(65) The main purpose for providing the flare 100 with the fins 164 in its aft section 163 is to generate a stabilizing drag as the flare travels along its flight trajectory following launch. It is appreciated by those skilled in the art that by varying the surface area and geometry of the fin and its angular orientation relative to the direction of the flight, the amount of generated drag can be varied. In general, the grain assembly 160 can have small fins to minimize the space that they are going to occupy within the casing 102 of the flare, FIGS. 3 and 13. In addition, the fins may also be used to cause the grain assembly 160 to start to spin along its long axis during the flight by tilting pairs of opposing fins 164 in the opposite directions similar to a propeller, thereby providing more stability to the grain assembly during the flight and thereby also reducing the size of the required fins.
(66) It is appreciated by those skilled in the art that other methods can also be used to provide deployable fins similar to the fins 164 of the grain assembly embodiment 160 of FIG. 13. For example, two or more fins may be designed to be deformed elastically and held in their first (un-deployed) configuration such that the resulting grain assembly could still fit within the casing 102 of the flare 100 shown in the schematic of FIG. 3, and then be deployed upon the grain assembly ejection. As an example and without intending to indicate any limitation, when the grain assembly has a circular cross-section as shown in FIG. 14, the fins may be leaf spring strip sections 170 that can be positioned symmetrically to the shell structure 169 and that in their first configuration are wound around the shell structure 169 of the aft section of the grain assembly 168. The wound fins 170 can be held in their configurations by strings or the like (not shown) that burn as the filling grain component 103 and/or other pyrotechnics and/or propellants in and around the aft section of the flare are ignited upon flare ejection. Then as the wound fins 170 are released following flare ejection, the fins unwind, and return to their free state 171 shown with dashed lines in FIG. 14. The fins can be rigidly attached to the shell structure 160, such as by welding or other similar methods. In their second configuration 171, the fins may be formed, oriented and positioned around the aft section of the shell structure 169 such that they would provide a pure drag force along the long axis of the flare for stability during the flight; or provide drag and a spinning torque along the long axis of the flare for increased stability during the flight and reduction of the required size of the fins; or for the stability during the flight and possibly to achieve certain other flight trajectories such as for example to achieve a helical flight path by providing the drag and torque along the long axis of the flare as well as a resultant lateral force.
(67) In the embodiments of FIGS. 13 and 14, the shell structure 160 is provided with flight stabilizing fins that are deployed following flare ejection. It is appreciated by those skilled in the art that such fin stabilized flares can also be equipped with any one of the nozzles shown in the embodiments of FIGS. 3-12 for the purpose of generating thrust and/or means of generated gas dispersion or providing the means of achieving certain gas dispersion pattern.
(68) In the flare embodiment 100 shown schematically in FIG. 3, the shell structure 106 is used to encase the entire length of the grain component 103 of the grain assembly 101, thereby limiting the exposed (burn) surface area of the grain component 103. As it was indicated previously, to increase the exposed surface area of the grain component 103, i.e., to increase the burn surface area of the grain component 103 and thereby increase its burn rate, the shell structure 106 may be eliminated forward certain distance from the aft section of the grain component, thereby exposing larger areas of the grain component 103 to combustion. The exposed (burn) surface area of the grain components may further be increased using the following embodiment 180 of the grain assembly 101.
(69) As can be seen in FIG. 3, the grain component 103 of the grain assembly is shown to be a solid component that even when only its aft section is encased in a shell structure 106, it would essentially stay as a solid element during the flare flight and burning. In the embodiment 180 shown schematically in FIG. 15, the grain component 103 is made out of at least two and preferably more sections 174 and 176 (in FIG. 15 into 6 sections), which are attached together by expanding elements 175 (in FIG. 15 shown as spring elements). In an embodiment, the aft section 176 is secured at least partially in the shortened aforementioned shell structure 177 (106 in FIG. 3), to which the deployable fins 178 such as those of the embodiments of FIG. 13 or 14 or the like are attached (in FIG. 15A, the fins 178 are shown in their deployed configuration). It is also appreciated by those skilled in the art that the shell assembly may also be provided with one of the previously disclosed nozzles to achieve one of the previously described effects; or alternatively be provided with a combination of deployable fins and nozzles; or alternatively with neither fins nor nozzles. Then following ejection, the elements 175 would expand and thereby separate the grain component sections 174 and 176 as shown in FIG. 15B, thereby significantly increasing the exposed surface area of the overall grain component, thereby allowing the burn rate of the grain component to be significantly increased.
(70) In the schematic of the embodiment 180 shown in FIGS. 15A and 15B, the expanding elements 175 are shown to be helical spring type elements, which can be preloaded in compression and held in said preloaded configuration by strings or the like (not shown) that burn as the grain component 103 is ignited following ejection, thereby releasing the spring type expanding elements 175, thereby separating the grain component sections 174 and 176 as shown in FIG. 15B. Alternatively, the expanding elements may in effect be sliding joints that allow relative axial translation between the adjacent grain component sections 174 and 176. For example and without intending any limitation, each pair of adjacent grain component sections 174 and 176, FIG. 15A, may be provided with a pair of pins 182, which are rigidly fixed to one of the grain component section as shown in FIGS. 16A and 16B, such as with anchoring protrusions 183 (in FIGS. 16 A and 16B to the left grain component section 174). The head 184 of the pair of pins are free to translate in the recesses 185 provided in the other (right hand) grain component section 174. This embodiment has the advantage of allowing the adjacent grain component sections 174 and 176 to come into contact, thereby maximizing the volume of the grain component in a flare. Then as the flare is ejected, the pairs of adjacent grain component sections 174 and 176 can be separated by allowing one (the right grain component section 174 in FIG. 16A) to separate from the other as shown in FIG. 16B. In an embodiment, the force required for pulling the adjacent grain component sections 174 and 176 apart is provided by the drag force generated by the fins 178 shown in FIGS. 15A and 15B. Otherwise, the pins 182 may be provided with springs (not shown) that are preloaded in compression in the pre-ejection configuration of FIG. 16A, and are positioned between the adjacent grain component sections 174 and 176 so that once the flare is ejected, the springs would force the right grain component section (FIGS. 16A and 16B) to translate over the pair of pins 182 and thereby separate the adjacent grain component sections as shown in FIG. 16B.
(71) Another embodiment 200 of the grain assembly (indicated 101 in the flare embodiment 100 of FIG. 3) is shown in the schematics of FIGS. 17A and 17B. The grain assembly 200 is designed to provide flight stability following ejection by spinning of a section of the grain assembly as it is ejected from the casing 187 (102 in FIG. 3), shown sectioned so as to allow viewing of the interior components. The grain assembly 200 is to be similarly disposed within the casing 187 as shown in the schematics of FIGS. 17A and 17B of the flare 100 shown in the schematic of FIG. 3. Similar to the flare embodiment 100, the casing 187 may have a first, aft end 104 and a second, opposite forward end 105 as shown in FIG. 3. The grain assembly 200 is constructed with at least two sections 186 and 188. The at least two sections 186 and 188 are connected together by a rotary joint with the shaft of the joint 201 shown in the cutaway section 189 of FIG. 17A, thereby allowing free relative rotation between the at least two sections 186 and 188 about the long axis of the grain assembly 200. The rotary joint is provided with a torsion spring 202 (such as a power type spring) which is attached to the section 186 (188) on one side (such as at the inner spring turn) and its other (such as outside) end pushing against the (such as the inner) provided recess in the other section 188 (186). Then before assembling the grain assembly 200 inside the flare casing 187, the section 186 is rotated relative to the section 188 in the direction of preloading the torsion spring 202. Then as the grain assembly 200 is ejected out of the flare casing 187 (in the direction of the arrow 203, FIG. 17A), as the grain assembly section 188 exits the flare casing 187, the preloaded torsion spring 202 will cause the exited section 188 to begin to spin in the direction of the arrow 204 relative to the (rotation constrained) section 186. Thus, as the entire grain assembly 200 is ejected, the frontal section 188 of the grain assembly 200 is provided with a flight stabilizing spin.
(72) Another embodiment 220 of the grain assembly (indicated 101 in the flare embodiment 100 of FIG. 3) is shown in the schematics of FIGS. 18A and 18B. The grain assembly 220 is to be similarly disposed within the casing 205 (102 in the schematic of FIG. 3) (shown sectioned so as to allow viewing of the interior components) as shown in the schematic of FIG. 18A of the flare 100 (shown in the schematic of FIG. 3). The grain assembly 220 is designed to provide flight stability following ejection by the spinning of the grain assembly as it is ejected from the casing 205 as shown in FIG. 18B. Similar to the flare embodiment 100, the casing 205 may have a first, aft end 104 and a second, opposite forward end 105 as shown in FIG. 3. On its aft end, the grain component 206 is provided with an embedded nut element 207 (which may also form the throat and expanding portion of a nozzle as shown in FIG. 18B). In its assembled configuration shown in FIG. 18B, the nut element 207 is engaged with the bolt portion 208 (FIG. 18C) of the spin element 209 (FIGS. 18B and 18C). In FIG. 18A, the element 210 is considered to represent the combination of the flare impulse charge device and the piston member (elements 109 and 110 in the schematic of FIG. 3, respectively). It is, however, appreciated by those skilled in the art that the spin element 209 may also be used to serve as the piston member of the flare (i.e., the piston member 110 in FIG. 3). Then as the grain assembly 220 is being ejected from the casing 205 following the initiation of the aforementioned impulse charge device, i.e., as the spin element 209 is translated in the direction of the arrow 211 as shown in FIG. 18B. The spin element 209 is provided with guiding steps or pins or the like 212 that ride in the provided matching recess guide (not shown) inside the casing 205, which ends close to the forward end 213 of the casing 205. As a result, when the spin element 209 (together with the grain component 206) reaches the forward end 213 of the casing 205 and the aforementioned guide in which the guiding steps 212 are riding ends, the spin element 209 would come to a sudden stop. At this point, the grain component 206 has already gained the prescribed speed and thereby momentum, which would force the nut element 207 to begin to turn and translate in the direction of grain component 206 travel, i.e., in the direction of releasing the nut element 207. As a result, the grain component 206 is forced to spin about its long axis, thereby providing it with a flight stabilizing spin. The described mechanism of spin generation is similar to that of gun rifling, with the difference that in the present case the barrel (the nut element 207) is translating instead of the bullet (the bolt portion 208) in the gun.
(73) It is appreciated by those skilled in the art that the spin rate that is achieved by the grain component 206 is dependent on the exit velocity of the grain component and the pitch of the mating bolt portion 208 and the nut element 207. In addition, in an alternative design, the guiding steps or pins or the like 212 may be eliminated and instead the forward end 213 be provided with a very slight inward lips (not shown) that are provided to prevent the spin element 209 to exit the casing 205.
(74) Another embodiment 240 of the grain assembly (indicated 101 in the flare embodiment 100 of FIG. 3) is shown in the schematics of FIGS. 19A and 19B. In FIGS. 19A and 19B, the longitudinal cross-sectional view of the grain assembly 240 is illustrated. In the embodiment 240, at least a portion of the grain component 214 is encased in the shell structure 215. On portions, such as the facing sides of the shell structure 215, portions of the shell structure 215 are cut out and provided with panels 216 that can be attached to the shell structure 215 via living rotary joints 217, which can be preloaded in torsion to rotate the panels 216 to their free configuration shown in FIG. 19B. The panels 216 can be held in their preloaded configuration shown in FIG. 19A by strings or the like (not shown) that burn as the filling grain component 214 inside the shell structure is ignited. Thus, as the grain assembly 240 is ejected in the direction of the arrow 218 from the casing 102 (FIG. 3), the strings or the like burn and the panels 216 open into the configuration shown in FIG. 19B. In general, the panels 216 are desired to be as large as possible to maximize the exposed surface area (burn area) of the grain component 214. The gasses generated by the burning grain component 214 under the panels 216 openings will then be forced to exit at an angle as shown by the arrow 219, thereby generating an axial thrust in the direction of the grain assembly travel shown by the arrow 218.
(75) Another embodiment 260 of the grain assembly (indicated 101 in the flare embodiment 100 of FIG. 3) is shown in the schematics of FIGS. 20A and 20B. In FIG. 20B, the longitudinal cross-section of a section (in this case the aft section) of the grain assembly 260 is shown, illustrating a section of the grain component 221, with at least a portion of the grain component 221 being encased in the shell structure 222. FIG. 20A is the aft view of the grain assembly 260. The grain assembly 260 is provided with at least two impulse generating elements 223 (thrusters with or without nozzles with converging and throat and possibly a diverging section or impulse generators that generate impulse by ejection of solid mass(es) or the like). The impulse generating elements can generate nearly identical impulse levels and are positioned symmetrical relative to the long axis of the grain assembly 260 with the direction of the generated impulse (shown by the arrows 224 in FIG. 20A) being all directed in the direction of spinning the grain assembly 260 clockwise as shown in FIG. 20A or counterclockwise to provide the grain assembly 260 with flight stability. The impulse generating elements 223 can be activated as soon as the grain assembly is ejected.
(76) In the schematic of FIG. 20B and for the sake of simplicity, the impulse generating elements 223 are shown to be positioned near the aft section of the grain assembly 260. It is, however, appreciated by those skilled in the art that that said impulse generating elements 223 can be positioned close to the center of mass of the grain assembly 260 to minimize the chances of the grain assembly to be also rotated (tumbled) upon activation of the impulse generating elements 223.
(77) In the embodiments 200, 220, 240 and 260 shown in FIGS. 17, 18, 19 and 20, respectively, such embodiments are shown without any of the aforementioned nozzles (such as those shown schematically in FIGS. 3-12 or deployable fins (such as those shown schematically in FIG. 13 or 14) or the like nozzles and/or fins. It is, however, appreciated by those skilled in the art that any one of the disclosed grain assembly embodiments of FIGS. 15 and 17-19 may be provided with one of the aforementioned nozzles and/or fins or the like nozzles and/or fins.
(78) In the embodiments of FIGS. 3-13 and 17-19, the shell structures (for example shell structure 106 in FIG. 3-12 or 161 in FIG. 13, etc.) are shown to be constructed solid sheets of relatively rigid material such as aluminum, plastic or cardboard or the like. However, it is appreciated by those skilled in the art that the shell structure may also be provided with holes of various shapes and sizes to increase the exposed surface area of the grain components to increase the grain component burn rate. Alternatively, at least portions of the shell structure may be made out of nettings woven with relatively thin metal fibers to maximize the exposed surface area of the grain components to significantly increase the grain component burn rate.
(79) In the aforementioned embodiments, the deployable nozzles (such as those of the embodiments of FIGS. 4-12) or the deployable fins (such as those of the embodiments of FIGS. 13-4), or the deployable panels 216 of the embodiment of FIG. 19 are indicated to be deployed at or shortly after flare ejection. Alternatively, the ejected grain assemblies may be provided with (such as pyrotechnic type) delay fuzes such that one or more nozzle/fin/panel deployment could be made a predetermined amount of time following flare ejection.
(80) Another embodiment 280 of the grain assembly (indicated 101 in the flare embodiment 100 of FIG. 3) is shown in the schematics of FIGS. 21A and 21B. In FIG. 21A the longitudinal cross-sectional view of the grain assembly 280 is illustrated. In the embodiment 280, at least a portion of the aft section 231 of the grain component 230 consists of at least two sections 232 and 233. The two sections 232 and 233 of the grain component 230 are attached together by a pin joint 234 such that following flare ejection, they could rotate relative to each other as shown in the side view of FIG. 21B. The two sections 232 and 233 can be provided with reinforcing casing 235 and 236, respectively, that allow the rotation of the two sections 232 and 233 about the pin joint 234. Before ejection, the grain assembly 280 is inside the shell structure (106 in the schematic of FIG. 3) and the two sections 232 and 233 are lined up along the length of the front portion of the grain component 230 (the grain component 230 is intended to include the at least two sections 232 and 233). Then as the grain assembly is ejected, torsion springs (not shown) provided on each of the at least two sections 232 and 233 would force the said to rotate outwards as shown by the arrows 237, to bring them to the configurations shown in FIG. 21B. The at least two sections 232 and 233 are provided with stops 238 to limit their rotation in the direction of the arrows 237 to a prescribed angle. Reinforcing intermediate plate(s) or the like may be inserted in the front portion of the grain component 230 to the extension of which the pin 234 is preferably attached.
(81) It is appreciated by those skilled in the art that the aforementioned at least two sections 232 and 233 of the grain component 230 may assume any desired (lengthwise) portion of the grain component 230. In fact the entire grain component 230 may be divided into at least two such sections and made to rotate as shown in FIG. 21B upon flare ejection.
(82) It is also appreciated by those skilled in the art that upon ejection of the flare, since the two sections 232 and 233 are positioned on opposite sides of the longitudinal axis of symmetry of the grain component 230, their generated aerodynamic drag would tend to generate a spinning torque on the grain component 230 during the flight. As a result, the outward rotation of the at least two sections 232 and 233 and the generated spinning of the grain component 230 (which includes the at least two sections 232 and 233) would result on the gasses generated by the burning grain component 230 to be dispersed further out. In addition, the generated spinning of the grain component will provide a stabilizing effect on the flare during its flight.
(83) It is also appreciated by those skilled in the art that by adding additional deployable aerodynamic drag/lift generating surfaces from the at least two sections 232 and 233, the amount of spinning torque acting about the longitudinal axis of symmetry of the grain component 230 can be increased, thereby increasing the spin rate of the flare during the flight. As an example and without intending to provide any limitation, the deployable aerodynamic drag/lift generating surfaces (elements) may be those indicated by the numeral 240 in the schematic of FIG. 21A. The elements can be provided with biasing springs (not shown) or the like such that after flare ejection, they would deploy to the position 241 shown with dashed lines in the schematic of FIG. 21A.
(84) While there has been shown and described what is considered to be preferred embodiments of the invention, it will, of course, be understood that various modifications and changes in form or detail could readily be made without departing from the spirit of the invention. It is therefore intended that the invention be not limited to the exact forms described and illustrated, but should be constructed to cover all modifications that may fall within the scope of the appended claims.
