US3911823A

US3911823A - Pyrotechnic devices

Info

Publication number: US3911823A
Application number: US383109A
Authority: US
Inventors: Dudley Charles Murray; William Rupert Brooke Elstow
Original assignee: Pains Wessex Ltd
Current assignee: Pains Wessex Ltd
Priority date: 1973-07-31
Filing date: 1973-07-27
Publication date: 1975-10-14
Anticipated expiration: 1992-10-14
Also published as: CA1011597A; JPS504226A; DE2338554A1; GB1445564A; FR2194942A1; JPS5212772B2; FR2194942B1; AU5870373A

Abstract

Primers comprising a deformable tube, lengthwise anvil therein and primer composition between tube and anvil are used for igniting pyrotechnic compositions such as propellants having a solid oxidising agent. The use of such primers which were previously only used as part of photographic flash bulbs gives considerable advantages.

Description

United States Patent Murray et al.

Oct. 14, 1975 PYROTECHNIC DEVICES lnventors: Dudley Charles Murray, Salisbury;

William Rupert Brooke Elstow, Laverstock, both of England Assignee: Pains-Wessex Limited, Salisbury,

England Filed: July 27, 1973 Appl. No.1 383,109

Foreign Application Priority Data Aug. 1, 1972 United Kingdom 35969/72 US. Cl. 102/86.5; 102/32; 102/45; 102/70 R Int. Cl. F42C 19/08; F42B 4/02 Field of Search 102/45, 86.5, 34.4, 70, 102/32 References Cited UNITED STATES PATENTS 11/1964 Root 102/45 7/1919 Asbury l02/85.6

2,519,123 8/1950 Dwyer et a1. l02/34.4 X

2,818,811 1/1958 Kempler 102/45 3,046,891 7/1962 Treat, Jr. 102/45 3,457,860 7/1969 Allen 102/32 3,611,939 10/1971 Stadler et al.. l02/86.5

3,685,451 8/1972 Bowring 102/70 OTHER PUBLICATIONS Military Pyrotechnics Series; Part Three; AMCP 706-187, Oct. 1963, pp. 243-245.

Primary Examinerl-larvey E. Behrend Assistant ExaminerC. T. Jordan Attorney, Agent, or Firm-Hall & Houghton [57] ABSTRACT 15 Claims, 10 Drawing Figures US. Patent Oct. 14,1975 Sheet1of4 3,911,823

FIGJ.

Oct. 14, 1975 Sheet 2 of4 3,911,823

US. Patent U.S.'Patent Oct. 14,1975 Sheet30f4 3,911,823

US. Patent Oct. 14, 1975 FIG. IO.

Sheet 4 of 4 Fla. 9

PYROTECHNIC DEVICES This invention relates to pyrotechnic devices, and especially to the ignition of such devices.

Primers are generally used for the ignition of pyrotechnic devices and these fall into two main categories, that is to say, electrically-operated primers and mechanically-operated primers. Mechanicallyoperated primers comprise friction-operated primers and impact-operated primers, for example, percussion primers (for example, percussion caps). For portable pyrotechnic devices, with electrically-operated primers a source of electrical power either has to be carried with the devices or built into them and, usually, with impact-operated primers a striker mechanism either has to be built into the devices or carried with them. Such a source of electrical power or such a striker mechanism in general occupies a significant proportion of the volume and weight of the respective pyrotechnic device with which it is carried or into which it is built.

The invention provides a pyrotechnic device which includes pyrotechnic composition and a percussion primer for igniting the composition, wherein the pyrotechnic composition includes a fuel and a solid oxidising agent and the percussion primer comprises a tube, the circumferentially-extending wall of which is deformable and an end of which is open, an anvil extending lengthwise in the tube, and a mass of primer composition located in the tube between the anvil and the circumferentially-extending wall of the tube.

Such primers have previously only been proposed as part of photographic flash bulbs. Their use as primers in pyrotechnic devices with a solid oxidising agent gives considerable advantages.

It is to be understood that the phase the pyrotechnic composition includes a fuel and a solid oxidising agent includes the case where a single compound, for example, T.N.T., constitutes both the fuel and the solid oxidising'agent.

To ignite the pyrotechnic device it is merely necessary for a blow so to impinge on the tube that primer composition is compressed between the circumferentially-extending wall of the tube and the anvil, or for the tube as a whole to be squashed, for example, to be compressed against an external anvil. Any tendency that the blow would have to close the tube between the composition and the said open end is overcome by the anvil extending lengthwise in the tube.

With a suitable choice of primer composition, the primer can be made very sensitive. With a suitable choice of material for the wall of the tube, the primer can be operated by a less powerful blow than that required to operate conventional percussion primers since little or no stretching of the wall occurs when the blow impinges on the tube. These two facts, together with the fact that, provided the primer composition is suitably distributed, the primer will ignite if the tube is struck at any of a number of positions along its length and around its circumference, enable a striker mechanism to be used of a much smaller and much simpler construction that that of conventional striker mechanisms for conventional percussion caps, and also be built to much wider tolerances than conventional striker mechanisms.

Various forms of primer comprising a deformable tube and anvil extending lengthwise in the tube and suitable for use in a pyrotechnic device according to the invention are described and claimed in Patent Specifications referred to hereinafter.

Advantageously, the mass of primer composition is supported on the anvil; this facilitates the assembly of the primer. Preferably, the mass of primer composition is spaced from the inside wall of the tube. With such a construction, the primer tube is sufficiently inactive during assembly and handling prior to its being struck to avoid premature ignition, but is nevertheless sensitive when struck in use. Preferably, the anvil has a portion of greater diameter than that of the primer composition, the primer composition being arranged on the anvil to the side of the said portion that is nearer to the said open end of the tube. Thisassists in preventing ignition of the composition during insertion of the anvil into the tube in assembly of the primer. Preferably, the anvil has a further portion of greater diameter than that of the primer composition spaced apart in the tube from the first-mentioned portion, the primer composition being arranged on the anvil between the said portions. Advantageously, the anvil is supported in the tube by engagement of the anvil, directly or indirectly, with the walls of the tube. Thus, the anvil may comprise a wire deformed so as to abut the inside of the tube and be thereby retained. Preferably, the anvil is provided with two or more protuberances spaced apart along the length of the anvil and in engagement with the wall of the tube. One of the protuberances may comprise a head portion at the end of the anvil that is innermost in the tube, the tube being crimped to maintain the head in position. This tends to stabilise the anvil against movement along its length. The protuberances may comprise the said portions of the anvil of diameter greater than that of the primer composition. Primers possessing the above features and suitable for use in pyrotechnic devices according to the invention are described and claimed in United Kingdom Pat. Specifications Nos. 1,215,276 and 1,204,975.

Advantageously, a refractory member, preferably supported on the anvil, is supported adjacent to the said open end of the tube and lying on the axis of the tube. Such a member deflects and spreads the stream of hot primer particles leaving the tube when it is struck, therefore facilitating the ignition of the pyrotechnic device. The refractory member also enables more primer composition to be used. Primers comprising a defonnable tube and anvil extending lengthwise in the tube which possess such a refractory member and are suitable for use in pyrotechnic devices according to the invention are described and claimed in United Kingdom Pat. Specification No. 1,216,056.

The tube of the primer may be open at both ends, which enables two combustions to be initiated at the same time. instead, the opposite end of the tube to that which is open may be closed.

In order that a flame should emanate from the ends, or from the desired end, of the tube, the tube should be made of a material which defonns but does not rupture to any substantial degree when the tube is struck. A small rupture of the tube caused by the impingement of the striker on the tube may not affect the operation of the primer since the striker may itself seal the break in the tube.

The tube is preferably of soft metal (for example, copper or so-called "No. 4 alloy," a nickel-chromium steel), and the anvil, which may be a wire, is preferably of hard metal, for example, tungsten. Primers in which the tube and anvil are constructed of these materials, and which are suitable for use in pyrotechnic devices according to the invention are described and claimed in United Kingdom Pat. Specification No. 1,204,973.

Advantageously, the primer composition comprises particles of a percussively ignitable material and an incandescible substance in powder form, which is such that, when the primer is struck, the ignitable material itself ignites and forces hot particles of the incandescible substance to issue from the primer and cause ignition of the pyrotechnic device. The incandescible substance serves to dilute the percussively ignitable material and provides glowing particles for communicating the combustion. The percussively ignitable material preferably comprises a mixture of phosphorus (preferably, red phosphorus) and potassium chlorate; the weight ratio of the phosphorus to the potassium chrate is preferably between 1:5 and 1:2. Such mixtures explode easily when the primer is struck. The primer composition may be one of the forms described and claimed in United Kingdom Pat. Specification No. 1,203,857.

The incandescible substance is preferably an incandescible metal, and may comprise zirconium, hafnium or thorium; the particle size may be within the range of from approximately 0.5 microns to approximately 5 microns. The incandescible substance may comprise silicon. It has been found that this decreases the velocity of gas leaving the primer as compared with when zirconium is used. Although this effect can also be obtained, when the incandescible metal comprises zirconium, by increasing the relative quantity of incandescible metal in the mixture, this carries with it the disadvantage of a reduction in impact sensitivity. To give a further decrease in gas velocity and increase in impact sensitivity, the incandescible substance may comprise boron. Preferably, the incandescible substance comprises a mixture of zirconium and boron, which has better impact sensitivity and burning characteristics and gives more reliable ignition than boron alone. Suitable proportions for primer compositons incorporating silicon, boron, and zirconium and boron together are described and claimed in United Kingdom Pat. Specification Nos. 1,208,532, 1,203,897 and 1,208,709, respectively.

Details of additives which may be incorporated in the primer composition and of a suitable binder are described and claimed in United Kingdom Patent Specification No. 1,203,857. United Kingdom Pat. Specifications Nos. 1,207,779, 1,203,859, 1,204,974 and 1,205,090, describe and claim ways in which the primer may be constructed.

Advantageously, there is provided an intermediate composition arranged to be directly ignited by the primer and in turn arranged to ignite the pyrotechnic composition. The pyrotechnic composition may be ignited directly or indirectly by the intermediate composition. The intermediate composition may be a powdered combustible substance, for example, gunpowder. The powdered combustible substance may extend into the said open end of the primer tube; there may be provided a tubular member, the said open end of the primer tube being in close fit with the interior of the tubular member, and the combustible substance being contained in the tubular member. Instead, the intermediate composition may be impregnated on a textile material; the intermediate composition may for example be formed by quickmatch or primed cambric. Instead,

the intermediate composition may be formed by a length of safety fuse. In such a case, the end of the fuse to be ignited may have a surface layer of powdered combustible material, for example, gunpowder.

The pyrotechnic composition may be flare-producing composition, smoke-producing composition or rocket propellant, the respective devices being flares, smoke devices, or rockets. Many other types of pyrotechnic composition can be ignited using the primer, the only restriction placed on them being that they must include a fuel and a solid oxidising agent. For example, the pyrotechnic composition may be a flash-producing composition (as in a thunder flash) or other light-producing composition. Or the pyrotechnic composition may be a gas-producing composition as used in oxygenproducing devices (so-called oxygen candles), a pyrotechnic composition for use in exothermic (or heatproducing) devices of the incendiary type (which may be used for welding), an explosive composition as used in explosives or as an ejection charge, or a delay train, for example, a Bickford fuse. Although it will generally be preferable to use an intermediate composition, the pyrotechnic composition of such pyrotechnic devices may in certain instances be ignited directly by the hot gases from the primer. Gunpowder, for example, could be ignited directly. Examples of pyrotechnic devices in which such a combination of primer and intermediate composition may be employed for igniting the pyrotechnic device, in accordance with the invention, are described and claimed in the Applicants United Kingdom Pat. Specifications Nos. 1,138,192, 1,231,181, 1,276,085, 1,277,573, 1,275,735, 1,284,499 1,312,444, 1,309,548, 1,314,811, 51563/70, 19537/71, and 15517/72, and in United Kingdom Pat. Specifications Nos. 929,309 and 996,872.

Alternatively, the pyrotechnic device may simply be an igniter, in which case the said pyrotechnic composition is an intermediate composition for igniting a further pyrotechnic device, the intermediate composition being arranged to be directly ignited by the primer. Such intermediate composition could be any of the forms of intermediate composition referred to hereinbefore. Such an igniter could be simply inserted, for example, into a suitably-designed smoke-producing, flare-producing or rocket device when it was desired to fire it.

It should be noted that either of the two basic forms of primer described hereinbefore, that is, the deformable tube and lengthwise anvil form and the cup-shaped member and flat-faced anvil form, can be used in the pyrotechnic devices described.

The pyrotechnic device may include a length of resilient wire for striking the primer, the wire being so arranged that, when retracted and released, it strikes the primer tube transversly. Such an arrangement may be used for igniting a pyrotechnic device underwater, since the frictional drag on the wire would be relatively small. Alternatively, the device may include a cocked spring-loaded striker. The striker may be retained in a cocked position by the body housing the primer tube, and permitted to enter an aperture in a body housing the primer tube on relative movement between the body and the striker.

An advantage of the form of primer comprising the deformable tube is that, with many forms of striker mechanism, it will be possible to operate the device even if the striker mechanism fails to operate simply by tapping the primer tube with a suitable implement, for example, a pencil.

Pyrotechnic devices constructed in accordance with the invention will now be described, by way of example, with reference to the accompanying drawings, in which:

FIG. 1 is a plan view of an igniter;

FIG. 2 is an axial cross-section of the igniter;

FIG. 3 is a section through the plane 33 in FIG. 2;

FIG. 4 is an enlarged view of the primer tube of the device;

FIG. 5 is an axial view, partly in section, of a linethrower incorporating the igniter of FIGS. 1 to 4;

FIG. 6 is an axial cross-section of a further igniter;

FIG. 7 is an axial cross-section of a further igniter;

FIG. 8 is an axial cross-section of a smoke grenade incorporating the igniter of FIG. 7;

FIG. 9 is an axial cross-section of a rocket incorporating the igniter of FIG. 6; and

FIG. 10 is an axial cross-section of a hand-flare incorporating an igniter similar to that of FIGS. 1 to 4.

Like parts are given like reference numerals in all the Figures.

The igniter of FIGS. 1 to 4 may be used for igniting and ejecting a rocket from a discharge tube. The igniter may, for example, be inserted in the lower end of a discharge tube of suitable dimensions.

Referring to FIGS. 1 to 4, the device comprisesa tubular primer, indicated generally by the reference numeral 1, a mass of intermediate composition 2 and an ejection charge 3. These are housed in an assembly comprising a base portion of plastics material indicated generally by the reference numeral 4 and a hollow tubular portion 5 of plastics material. The ejection charge 3 is held in position by a bursting disc 6 in turn held in position by a circlip 7.

Referring to FIG. 4, the primer comprises a tube 8 of copper and an anvil 9 which extends lengthwise in the tube and co-axially with respect to the tube 8, and which is formed of tungsten. One end of the tube 8 is closed.

The anvil 9 carries a mass of primer composition 12 which may have the following composition, the parts being by weight on a dried basis: powdered boron, 21.23%; powdered zirconium, 19.59%, red phosphorus, 28.71%; potassium chlorate, 28.71%; hydroxyethyl cellulose, 1.74%; and ortho-phenyl-phenol, 0.01%. Water is added to give a primer composition of a viscosity facilitating its application to the anvil 9.

The anvil 9 is supported in the tube 8 by means of protuberances l0 and 11. The protuberance 11 is formed as a head on the anvil and is adjacent to the closed end of the tube 8. The tube 8 is crimped around it to stabilise the anvil 9 against movement along its length. The protuberance 10 comprises four equally spaced apart circular vanes which engage the inner wall of the tube. The primer composition 12 is spaced apart from the wall of the tube. The diameter of the protuberances 10 and 11 is greater than that of the mass of composition 12 so as to assist in preventing contact with the wall of the tube 8 as the anvil 9 is being inserted into the tube and hence assist in preventing ignition of the composition 12.

A refractory bead 13 is supported on the anvil 9 adjacent to the open end of the tube for deflecting the stream of gases issuing from the tube when the primer is struck.

As an example of suitable dimensions for the primer 1, the primer tube 8 may be about 8 mm. long and about 1 /2 mm. in diameter, and the overall length of the primer about 14 mm.

The primer 1 is maintained in position in the assembly'by means of a circlip 14 which engages a groove in the inner'wall of a cup-shaped member 15 which is in turn secured in an aperture in the base portion 4. The flared wall of the open end of the primer tube 8 engages the wall of the adjacent end portion of the bore in the tubular portion 5 and also assists in maintaining the primer in position. Alternatively, the primer may be in a light push-fit in a recess in the assembly, and/or may be secured in position by adhesive.

The base portion 4 has an annular extension 16, a part of which is cut away to define a slot between the base portion and the tubular portion 5 which receives a striker plate 17. The striker plate 17 is slidable in the direction of the arrow 18. A spring indicated generally by the reference numeral 19 is secured to the tubular portion 5 at 19a and extends around a post 20 secured to the tubular portion. A turned-over portion 21 of the striker plate 17 retains an arm 22 of the spring 19. The spring 19 urges the plate 17 against the inner wall of the annular extension 16, and the relative dimensions of the parts are such that the arm 22 is clear of the primer tube.

The device is assembled by placing the circlip 14 on the primer tube and inserting it into the cup-shaped member 15. The base portion is then secured to the tubular portion (the spring and plate having been inserted), and finally the cup-shaped member 15 is inserted into the aperture in the base portion and secured in position.

The intermediate composition 2 may be FFF gunpowder (marketed by ICI Limited), the grains of which are nominally of sizes such as to pass a 24 mesh sieve and be retained on a mesh sieve (B.S.S. 410) and which has the following composition, the parts being by weight:

Potassium nitrate parts Sulphur 10 parts Charcoal 15 parts The ejection charge 3 may be a coarser gunpowder, for example, T.P. Cannon (marketed by [C1 Limited), the grains of which are nominally of sizes such as to pass an 8 mesh sieve and to be retained on a 20 mesh sieve (B.S.S. 410) and which has the same composition as given above for the igniter composition. In each case, the potassium nitrate constitutes the solid oxidising agent.

In operation, the striker plate 17 is moved in the direction of the arrow 18 until the arm 22 of the spring 19 slides out of the turned-over portion 21 of the plate 17. The arm 22 then strikes the primer tube 1, the primer tube being so positioned that it does so in the region of the primer composition 12. This deforms the circumferentially-extending wall of the tube 8 and compresses the primer composition 12 between the anvil 9 and the circumferentially-extending wall of the tube 8 thereby igniting the primer composition. The flame from the primer composition 12 ignites the intermediate composition 2 which in turn ignites the ejection charge 3. With the assembly suitably positioned in a discharge tube, the flame from the ejection charge ignites and ejects the rocket from the discharge tube.

Referring to FIG. 5, the igniter of FIGS. 1 to 4 may be used for igniting and firing a line-throwing rocket. The igniter is secured, by means of pegs 23, in a bayonet-fitting socket in the lower end of a tube 24, which is itself secured to the lower end of a discharge tube 25. The tube 24 opens into the lower end of the discharge tube 25.

The igniter is operated by means of a trigger 26, which is guided in apertures in the outer case 27 of the line-throwing rocket and in a protective casing 28 which houses the igniter unit. One end portion of the trigger 26 is bent at right angles and extendss in the opening in the striker plate 17, and the other end portion of the trigger 26 is formed in a loop.

A rocket 29 has a bridle 30 secured to its upper end, and the rocket 29 rests in the discharge tube by means of a band 31 surrounding the rocket.

The bridle is connected by means of a heat resisting connection portion 32 to a coil of line 33 housed in a tubular container 34.

In operation, the device is held by means of a handle 35 and, after removal of an upper closure 36, the device is operated by retracting the end of the trigger 26 that is formed in a loop. This causes the igniter to operate in the manner described with reference to FIGS. 1 to 4, and the rocket 29 is both ignited and ejected from the discharge tube 25 by the explosion of the gunpowder 3.

Referring to FIG. 6, the igniter shown is identical to that shown in FIGS. 1 to 4 as far as the construction, arrangement and composition of the primer 1 and the striker mechanism is concerned. The igniter of FIG. 6 differs from that shown in FIGS. 1 to 4 in that the primer ignites an intermediate composition impregnated on a textile material, rather than an intermediate composition in the form of a powdered combustible material as in FIGS. 1 to 4.

The tubular portion 5 of FIG. 2 is considerably shorter in the igniter of FIG. 6 and terminates in a neck 37 having a lip 38. A ferrule 39 is secured to the neck 37 by means of a hollow cup 40 which is crimped at the edge 41.

The ferrule holds a strand 42 of quickmatch, the end of which is exposed to the open end of the primer tube 8.

In operation, the striker plate 17 is moved in the same direction as in the striker of FIGS. 1 to 4 until the spring is released ans strikes the primer 1. The flame from the primer 1 ignites the quickmatch 2, which may then itself ignite a suitable pyrotechnic devices. The striker plate 17 is secured by means of a ring 43 to a length of cord 44, and the striker plate 17 may be withdrawn by means of the cord 44.

Referring to FIG. 7, the igniter shown is again similar to that shown in FIGS. 1 to 4 in the construction, arrangement, and composition of the primer 1, and in the construction and operation of the striker mechanism. In this igniter, however, the primer 1 ignites an intermediate composition which is formed by the central train of gunpowder of a Bickford or safety fuse 45.

The tubular member 5 is modified in the same way as in FIG. 6 to terminate in the neck 37 bearing a lip 38. A ferrule 46 is secured to the neck 37 by means of a hollow cup 40 which is crimped around the lower edge of the lip 38. The ferrule 46 is provided with two vent apertures 47.

In order to facilitate ignition of the Bickford fuse, the end of the fuse that is exposed to the primer 1 has a surface layer of combustible material in hte form of mealed gunpowder. The Bickford fuse may be dry (for example by a dusting treatment) or wet (for example by means of a slurry in gum arabic and water) primed with the gunpowder.

In operation, the striker plate 17 is withdrawn (by means of a cord 44 if desired) until the arm 22 of the spring 19 is released, an strikes the primer 1. The flame from the primer ignites the Bickford fuse, which may then be used to itself ignite a suitable pyrotechnic device.

FIG. 8 shows an example of the way in which the igniter of FIG. 7 may be used, the igniter being used in a smoke grenade.

The smoke grenade has an aluminum outer casing 48 which contains smoke producing composition 49 in its lower part, and a smoke baffle in its upper part. The casing 48 is protected from the smoke producing composition 49 by means of a tubular sleeve 50 and a thick disc 51. The smoke baffle is formed by a perforated tin plate disc 52, an intermediate perforated disc 53 and an upper perforated disc 54, the

discs

52 and 53, and 53 and 54, being spaced apart by

collars

55 and 56, respectively. The upper end of the aluminum case 48 is turned on to a retaining collar 57 to hold the contents of the smoke grenade in position.

The upper surface of the smoke producing composition 49 has a layer of igniter composition 58, and this layer of igniter composition is in turn covered by an annular primed cambric disc 59, which is held in position by the baffle disc 52. Rolls of primed

cambric

60 and 61 are also included to promote rapid ignition of the smoke producing composition 49.

The igniter extends into a central bore in the smoke producing composition 49, and the upper part of the bore is of larger diameter and lined with a perforated aluminum sleeve 62 to facilitate ignition of the grenade.

The igniter is that shown in FIG. 7. In addition, a capsule 62a containing gunpowder (or equivalent) is pushed over, and secured to, the lower end of the Bickford fuse 45. The body of the igniter is held in a central aperture in the perforated tin plate disc 52, and the igniter is operated by pulling the cord 44 which is secured to a ring 63. The cord 44 is run through the eyelets 64 secured to the

collars

55 and 56, and passes through apertures in the

discs

53 and 54. The ring 63 is secured to the disc 54 by means of a tear-off strip (not shown) which closes the apertures in the disc 54.

As an example of a suitable smoke-producing composition, the smoke-producing composition may be as follows:

Potassium chlorate Lactose or Sucrose Dyestuff 25 parts by weight 25 parts by weight 50 parts by weight In operation, the tear-off strip is removed to release the ring 63, and the ring 63 is then pulled away from the smoke grenade. The striker plate 17 is retracted in the same direction as FIG. 7, and the Bickford fuse 45 is ignited as described with reference to FIG. 7. (Immediately after pulling the cord 63, the device is thrown by the user.) This ignites the gunpowder capsule 62a which in turn ignites the primed cambric roll 61 and, because of the sleeve 62, the primed cambric disc 59. The smoke producing composition 49 is thus ignited rapidly.

If desired, the igniters of FIG. 6 and FIGS. 1 to 4 (with the possible elimination of the ejection charge 3) could be used in a smoke grenade of FIG. 8. Also, the igniters could be used to ignite smoke producing composition in other types of device, for example, in hand held smoke signals, buoyant smoke signals, smoke markers for marking positions on the ground, or pesticides.

FIG. 9 shows the igniter of FIG. 6 used to ignite a rocket indicated generally by the reference numeral 65. The rocket 65 comprises an outer casing 66 and a motor casing 67, which houses the rocket propellant 68 and a nozzle 69. The nozzle 69 has an annular recess containing igniter substance, suitable forms of which are described in British Pat. Specification No. 1,138,192, to facilitate ignition of the propellant 68. The rocket is housed in a discharge tube 70, the upper and lower ends of which are covered by push fit closures 71 and 72, respectively.

The igniter of FIG. 6 is supported in a disc 73 which closes the lower end of the discharge tube 70. The quickmatch strand 42 extends from the igniter through the nozzle aperture of the rocket to the region adjacent the propellant 68. The quickmatch is supported by a plastic or rolled paper tube 74 between the igniter and the nozzle aperture, and the upper end of the quickmatch is bent over.

The cord 44 extends through an eyelet 75 to a ring 76.

As an example of a suitable propellant, the following composition may be employed, the percentages being by weight,

Ammonium perchlorate 84.5% Polyisobutene 12.5% Surface-active agent 1% (Pentaerthritol dioleate 30% Ehtyl oleate 40% Sodium dioctyl sulphosuccinate 30% Copper chromate 2% The ammonium perchlorate constitues the solid oxidising agent.

ln operation, both the upper and lower closures 71 and 72, respectively, areremoved, and the ring 76 is pulled away from the discharge tube 70. The igniter is operated as described with reference to FIG. 6, and the rocket propellant 68 is ignited by means of the quickmatch 42, so that the rocket leaves the discharge tube 70.

If desired the igniter of FIG. 7 could be used in FIG. 9, for example, by using a length of quickmatch to lgnite the rocket that was ignited by the fuse 45.

FIG. shows a hand flare which incorporates an igniter similar to that of FIGS. 1 to 4. The flare comprises an outer casing 77, a mass of flare composition 78 contained therein and protected from the wall of the casing 77 by an inhibiting layer 79. The lower end of the casing 77 is used as a handle for the device.

A layer of clay 80 covers the lower surface of the flare composition, and the upper surface is gunpowderprimed.

The igniter is identical to that shown in FIGS. 1 to 4 except that the ejection charge 3, the bursting disc and the circlip 7 are omitted, and the intermediate composition 2 is held in by means of a paper disc located at the inner end of the portion of the bore in the tubular member 5 that is of greatest diameter. The body of the igniter is held in the casing 79 by means of a spider 81. The cord 44 is secured via an eyelet 82 to a ring 83. The upper end of the casing 77 is a removable closure 84.

As an example of a suitable flare composition, the following may be employed, the parts being by weight Magnesium 35 Boiled Linseed Oil 4 Potassium Perchlorate 30 Strontium Carbonate l l Chlorinated Rubber 20 This will produce a red flare. The potassium perchlorate constitutes the solid oxidising agent.

In operation, the closure 78 is removed and the ring 83 is pulled to operate the igniter. The flame from the intermediate composition 2 ignites the flare composition 78.

If desired, the igniters of FIGS. 6 or 7 could be used in place of that shown in FIG. 10. Also, the igniters could be used to ignite flare composition other than in a hand flare. For example, the flare composition could be in a device designed to be released from underwater or in a buoyant device to be thrown into water, or a parachute flare used for reconnaissance.

We claim:

1. A pyrotechnic device which includes pyrotechnic composition and a percussion primer located therein for igniting said composition, wherein said pyrotechnic composition includes a fuel and a solid oxidising agent and said percussion primer is a photoflash-lamp-type primer comprising a tube having a wall deformable by striking the same, a rod-like anvil extending lengthwise in said tube, and a mass of sensitive primer composition supported on said anvil and spaced apart from the inside surface of said wall, said primer composition ineluding phosphorus anda chlorate salt.

2. A pyrotechnic device which includes pyrotechnic composition and a percussion primer located therein for igniting said composition, wherein said pyrotechnic composition includes a fuel and a solid oxidising agent and said percussion primer is a photoflash-lamp-type primer comprising a tube having a wall deformable by striking the same, a rod-like anvil extending lengthwise in said tube, and a mass of sensitive primer composition supported on said anvil and spaced apart from the inside surface of said wall, said primer composition comprising particles of a percussively ignitable material and an incandescible substance in powder form, whereby, when said primer is struck, said ignitable material itself ignites and forces hot particles of said incandescible substance to issue from said primer to ignite said pyrotechnic device.

3. A pyrotechnic device according to claim 2, wherein said percussively ignitable material includes phosphorus and a chlorate salt.

4. A device according to claim 3, wherein said device further includes a tubular member, an open end of said primer tube being in close fit with the interior of said tubular member, powdered combustible substance contained in said tubular member, and a retainer to retain said combustible substance within said tubular member.

5. A device according to claim 3, including a quickmatch strand, and means to retain said quickmatch strand in the region of an open end of said primer tube.

6. A device according to claim 3, including a length of safety fuse, means to retain an end of said length of safety fuse in the region of an open end of said primer tube, said end of said safety fuse having a surface layer of powdered combustible material.

7. A device according to claim 3, including a length of resilient wire, said wire being positioned for transverse striking of said primer tube, whereby, when said wire is retracted and released, it strikes said primer tube transversly.

8. A device according to claim 3, wherein said primer tube has one closed end.

9. A device according to claim 8, wherein said primer tube is of soft metal and said anvil is of hard metal.

10. A device according to claim 9, including a refractory member, said refractory member being supported on said anvil adjacent said open end of said tube and lying on the axis of said tube, and having a greater diameter than the anvil in a plane perpendicular to the axis of the anvil.

11. A device according to claim 10, wherein said percussively ignitable material includes red phosphorus and potassium chlorate in a weight ratio of said phosphorus to said potassium chlorate of between 1:5 and 1:2.

12. A flare-producing device which includes flareproducing composition and a percussion primer located therein for igniting said composition, wherein said flare-producing composition includes a fuel and a solid oxidising agent and said percussion primer is a photoflash-lamp-type primer comprising a tube having a wall deformable by striking the same, a rod-like anvil extending lengthwise in said tube, and a mass of sensitive primer composition supported on said anvil and spaced apart from the inside surface of said wall, said primer composition comprising particles of a percussively ignitable material and an incandescible substance in powder form, said percussively ignitable material including phosphorus and a chlorate salt, whereby, when said primer is struck, said ignitable material itself ignites and forces hot particles of said incandescible substance to issue form said primer to ignite said flare-producing device.

13. A smoke-producing device which includes smoke-producing composition and a percussion primer located therein for igniting said composition, wherein said smoke-producing composition includes a fuel and a solid oxidising agent and said percussion primer is a photoflash-lamp-type primer comprising a tube having a wall deformable by striking the same, a rod-like anvil extending lengthwise in said tube, and a mass of sensitive primer composition supported on said anvil and spaced apart from the inside surface of said wall, said primer composition comprising particles of a percussively ignitable material and an incandescible substance in powder form, said percussively ignitable material including phosphorus and a chlorate salt, whereby, when said primer is struck, said ignitable material itself ignites and forces hot particles of said incandescible substance to issue from said primer to ignite said smoke-producing device.

14. A rocket which includes rocket propellant and a percussion primer located therein for igniting said propellant, wherein said propellant includes a fuel and a solid oxidising agent and said percussion primer is a photoflash-lamp-type primer comprising a tube having a wall deformable by striking the same, a rod-like anvil extending lengthwise in said tube, and a mass of sensitive primer composition supported on said anvil and spaced apart from the inside surface of said wall, said primer composition comprising particles of a percussively ignitable material and an incandescible substance in powder form, said percussively ignitable material including phosphorus and a chlorate salt, whereby, when said primer is struck, said ignitable material itself ignites and forces hot particles of said incandescible substance to issue from said primer to ignite said rocket.

15. An igniter unit comprising a body portion adapted to be received in the ignition chamber of a device, intermediate composition contained in said body portion and a percussion primer secured to said body portion for igniting said composition, wherein said interniediate composition includes a fuel and a solid oxidising agent and said percussion primer is a photoflashlamp-type primer comprising a tube having a wall deformable by striking the same, a rod-like anvil extending lengthwise in said tube, and a mass of sensitive primer composition supported on said anvil and spaced apart from the inside surface of said wall, said primer composition comprising particles of a percussively ignitable material and an incandescible substance in powder form, said percussively ignitable material including phosphorus and a chlorate salt, whereby, when said primer is struck, said ignitable material itself ignites and forces hot particles of said incandescible substance to issue from said primer to ignite said intermediate composition.

Claims

1. A pyrotechnic device which includes pyrotechnic composition and a percussion primer located therein for igniting said composition, wherein said pyrotechnic composition includes a fuel and a solid oxidising agent and said percussion primer is a photoflash-lamp-type primer comprising a tube having a wall deformable by striking the same, a rod-like anvil extending lengthwise in said tube, and a mass of sensitive primer composition supported on said anvil and spaced apart from the inside surface of said wall, said primer composition including phosphorus and a chlorate salt.

8. A device according to claim 3, wherein said primer tube has one closed end.

12. A flare-producing device which includes flare-producing composition and a percussion primer located therein for igniting said composition, wherein said flare-producing composition includes a fuel and a solid oxidising agent and said percussion primer is a photoflash-lamp-type primer comprising a tube having a wall deformable by striking the same, a rod-like anvil extending lengthwise in said tube, and a mass of sensitive primer composition supported on said anvil and spaced apart from the inside surface of said wall, said primer composition comprising particles of a percussively ignitable material and an incandescible substance in powder form, said percussively ignitable material including phosphorus and a chlorate salt, whereby, when said primer is struck, said ignitable material itself ignites and forces hot particles of said incandescible substance to issue form said primer to ignite said flare-producing device.

15. An igniter unit comprising a body portion adapted to be received in the ignition chamber of a device, intermediate composition contained in said body portion and a percussion primer secured to said body portion for igniting said composition, wherein said intermediate composition includes a fuel and a solid oxidising agent and said percussion primer is a photoflash-lamp-type primer comprising a tube having a wall deformable by striking the same, a rod-like anvil extending lengthwise in said tube, and a mass of sensitive primer composition supported on said anvil and spaced apart from the inside surface of said wall, said primer composition comprising particles of a percussively ignitable material and an incandescible substance in powder form, said percussively ignitable material including phosphorus and a chlorate salt, whereby, when sAid primer is struck, said ignitable material itself ignites and forces hot particles of said incandescible substance to issue from said primer to ignite said intermediate composition.