US2697400A - Projectile with shaped charge and point initiating fuze - Google Patents

Description

Dec. 21, 1954 K. LILJEGREN PROJECTILE WITH SHAPED CHARGE AND POINT INITIATING FUZE I Filed Feb. 14, 1944 3 Sheets-Sheet l gwumn/bo'n LY LE K L ILJEEIREN,

MWWM L. K. LILJEGREN 2,697,400

3 Sheets-Sheet 2 PROJECTILE WITH SHAPED CHARGE AND POINT INITIATING FUZE.

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A W A c WWI Ilium United States Patent i thee 2,697,400 Patented Dec. 21, 1954 PROJECTILE WITH SHAPED CHARGE AND PDINT INITIATING FUZE Lyle K. Liljegren, Pasadena, Calif., assignor to the United States of America as represented by the Secretary of War Application February 14, 1944, Serial No. 522,290

16 Claims. (Cl. 192-56) (Granted under Title 35, U. S. Code (1952), see. 266) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment to me of any royalty thereon.

This invention relates to fuses for pro ectiles, and has for an object to effect an improvement in the construction and arrangement of parts whereby the device w1ll be simplified and its action made more simple and effective while at the same time retaining the advantages .of safety.

It is an important object to reduce the number of parts required in the fuse, and to also avoid the use of extremely small centrifugally moved parts to the end that the possibility of relatively high variables of friction in proportions to mass of such elements, and the possibility that the friction :factor may exceed the moment of inertia in such parts will be largely if not entirely obviated.

It is an aim to offer a point detonated base fuse construction of novel form, in which will be overcome objections to prior base fuses, such as irregularities or uncertainties due to varying sensitivity of the fuse as a Whole, varying velocities, and varying retardation of the Wind shield, and particularly variation of deceleration after impact, during collapse of the wind shield.

A further aim of the invention is to enable its use in conventional shell body construction, wind shield, hollow cone and main explosive charge.

A still further object is to provide a novel form of centrifugally operated arming device of novel construction including the usual safety from accidental arming by lateral shocks accidentally suffered by the projectiles, or accidental operation of the point detonator.

A further important aim is to present a novel construction for effecting the detonation of a base booster charge by a point-mounted primer fuse which includes a shaped charge detonatable upon impact and upon collapse of the projectile wind shield to detonate the booster charge by means of a kinetic element, viz. a

blast effect or pellet, released by the detonated primer and projected rearwardly in timed relation to the forward speed of the projectile to initiate action of a base booster detonator.

A further aim is to give a novel connection between base and point structure in such a fuse to the end that automatic compensation is effected for variation from standard dimensions of the various parts longitudinally of the shell and for variation in spacing of the base and point elements of the device, both as to assembly of the round in manufacture and in the operative and safety functioning of the parts.

Additional objects, advantages and features of invention reside in the construction, arrangement and combination of parts involved in the embodiment of the invention as will appear and be understood from the following description and accompanying drawings, wherein:

Fig. l is a longitudinal section of an armor penetrating or demolition projectile, in which my invention is incorporated;

Fig. 2 is a transverse section taken on line 2-2 of Figure 4;

'Fig. 3 is a fragmentary longitudinal section taken on line 3-3 of Figure l.

'4 is a section on the line 4?4 of Fig. 1. Fig. 5 is a section on the line 5-5 of Figure 4,

Figure 6 is a view corresponding to Figure 4 with slide moved to right and with booster detonator on longitudinal axis of projectile.

Figure 7 is a fragmentary longitudinal section taken on line 7--7 of Figure 4.

Fig. 8 is a fragmentary longitudinal section of a modification of the tube for transmitting the kinetic element from the point located fuse to the base detonator.

Fig. 9 is a detail of a modified tube.

Fig. 10 is a detail of a further modification.

Fig. 11 is a sectional view of a modification of the base fuse.

Referring to the drawings, there is illustrated a projectile built to utilize the Munroe efiect in penetrating armor or concrete structures, or for other purposes, and comprising a shell body 15 of conventional form, the ogival portion of which is a frusto conical wind shield 16 of conventional structure mounted on the end of the shell, conical elements of the shield being tangent to the short ogival curve .17. The shell has a bore or cavity 18 of cylindrical form throughout, the face of which is relieved at each end of the projectile to afford circumferential shoulders 19 and 20 at the front and rear respectively, the shoulder 20 being somewhat further from the rear end of the body than the shoulder i9 is from the forward end. The relieved portions are interiorly threaded. A hollow cone 21 is provided, formed of thin material, with a base flange 22 set against the shoulder 19 and held thereto by an exteriorly threaded nipple 23 screwed into the interiorly threaded forward end of the shell body and extending forwardly therefrom a distance. An interior .base ring 24 of the wind shield is screwed onto this forward part of the nipple so that the shield abuts snugly the forward end of the shell body.

A point detonator or fuse 25 :is mounted at the .apex of the wind shield, consisting of a heavy walled metal body 26 set and secured in a suitable concentric opening in the shield, with a broad point 26' and a reduced tubular stem 27 extending axially into the space within the windshield.

A circular coaxial recess 28 is formed in the point 26, open forwardly through the end of the point and of such size that a relatively thin wall 29 is left around the recess, collapsible by target impact. A small axial bore 30 is formed from the bottom of the recess inwardly, communicating with a larger primer bore 31 rearwardly thereof, in which a cased detonating primer 32 formed as a rearwardly opening shaped charge having a thin metal liner 32a is secured by means of a bushing 33 screwed into an enlargement of the bore behind the primer. A tube 35 is set in the apex of the cone, extending therefrom to a base fuse to be described. In practice the tube has been formed with an external diameter of three eighths of an inch and an internal diameter of five sixteenths of an inch or more. The tube extends through the vertex of the cone 21, which is suitably necked therearound, and forms communication axially between the interior of the cone and the base fuse as will appear.

The shaped charge with, or produces from its cup materialor liner 32a on detonation, a pellet or slug, which is pro elled rearwardly through space to and through the tube to detonate the base fuse. It is contemplated also that the detonator will produce a Munroe efiect which will act through the tube 35 to detonate the base fuse. In the small bore 30 there is slidab'le a firing pin 36 having a mushroom head 37 in the recess 28 normally close to the extremity of the wall 29, and in the wall there is set a thin frangible or otherwise impact-yielding wind and dust guard plate 38, which may be of lead or gildingmetal.

The pin 36 is of such length that its extremity is within the :bore 30 initially and retained in this position by a tubular support 39 frangible or collapsible under a predetermined force acting on the head 37 of the pin. This support 39 is set loosely, Or slightly frjctiorially engaged around the pin and resting on the bottom of the recess 28 and against the head 37 of the pin.

The base fuse 4% consists in this instance of a substanprimer 32 in one form is provided tially cylindrical body 41 of steel, and for a six inch shell has been made approximately two inches in diameter, its length being somewhat greater. In addition it is formed with a threaded tenon 42 at the rear and an axially bored gland neck 43 forwardly. The tenon is screwed into a circular base plate 44, which is set against the shoulder with an interposed gasket 44. and so held by the base plug 45 screwed into the threaded enlarged rear end portion of the bore or cavity of the body 15. In this way the body 41 is supported concentrically in the projectile with the gland neck 43 receiving therein slidably a small portion of the end of the tube 35. The rear extremity of the tube may be closed with a thin weak septum 47 in the form of lead foil across the opening through the tube. The rear end edge of the tube is rounded at the outer side, as at 48. A relatively large booster chamber 49 is formed at the rear part of the body 41. This consists of a simple cylindrical diametrical bore opening flush through opposite sides of the body 41. Its rear side is spaced slightly from the base plate 44 and it has a diameter of somewhat more than one inch in the size of fuse mentioned.

The bore 50 in the neck 43 extends into the body 41 a distance but stops short of the chamber 49. A cylindrical recess 51 is bored in the side of the body 41 thereof and stopping short of the bore 50 so that an intervening partial wall portion 52 is left at the bottom of the recess. A smaller bore 53 forms a transverse continuation of recess 51 stopping at its inner end a distance from the periphery of the body and bore 53 are aligned facing the chamber 49, and a flash port 54 coaxial with the body 41 and bore 50 is formed through the material intervening between the booster chamber and bore 53. Diametrical detent guide passages 55 are bored through the body 41 on an axis normal to a plane including the axes of the body and bore 53, of slightly less diameter than the bore 50 and intersecting the bore 53. Around the body 41 a circumferential narrow groove 56 is formed in a plane including the axis of the passages 55 and intersecting each end of the latter and the recess 51.

In the bore 53 there is engaged an arming slider 57, including a cylindrical bar or stem 58 fitted slidably in the bore 53 and having an eccentric circular weight head 59 fitting slidably in the recess 51 normally at the bottom of the latter, and of such thickness radially of the fuse body as to permit necessary sliding movement of the slider in the bore 53 and recess 51. In the forward side of the slider stem 58, there is formed a transverse cam recess 60 having flat sides sloping divergently in opposite directions longitudinally of the stem and at an acute angle to the axis of the stem, from a central line of maximum depth of the recess to the periphery of the stem 58. The depth of this recess and the disposition of 41. The lower faces of the recess its sides is such that the recess will include a geometrical projection of the passages 55 across the bore 53. The recess 6% will be termed the cam face 61. Slidable in the passages 55 there are respective detent centrifugals 62 having at their inner ends reduced normally meeting flatend pins 63. Slidable in the inner or rearward part of the bore 50 there is a slider lock 64, consisting of a cylindrical block having opposite bevelled rear end faces conforming and normally fitting to the sides of the recess 60. The lock 64 has formed in opposite sides small apertures 65 inwhich the pins 63 engage initially.

The plns initially close the passage 66 through the lock 64. The centrifugals 62 are initially held in detent positlon as in Fig. 5 by means of a U-shaped spring 67 set in the groove 56, the ends of 'the spring bearing on the outer ends of the centrifugals, which extend initially into the groove 56 slightly and are movable outwardly to the per phery of the fuse body, clearing the lock 64. The spring has a reentrant bight portion 68 bowed inwardly so as to rest against the bottom of the groove 56, While its arms 69 lie in the groove and across the ends of the passages 55 and centrifugals 62. The shoulders 68' of the blght are at the periphery of the body 41 and retained there by a fuse case 70 to be subsequently described.

I in the extreme inner end portion of the slider 57 there 1s a detonator receiving opening or cup 69 extending from the forward side nearly through the stem 58 but having a reduced opening through the rear side of the stem. A shoulder 71 is thus provided at the rear end of the opening against which there is seated a detonator 72 of conventional kind for the purposes intended. When the slider is at the outer limit of its movement the detenator 72 is in line with the flash port 54 at the rear and with the bore 50 at its forward side. The bore 50 is slightly relieved at its outer part near the end of the tube 35, forming a shoulder there, and a cup 73 of gilding metal is set against the shoulder spacing the end of the tube 35. The material of the cup is quite thin, material such as gilding metal having a thickness of .OOZ-inch having been employed in one embodiment of the inventron.

The body of the fuse is snugly enclosed by a cylindrical case 70 of soft steel in the form of a cup having a flanged opening through its inner part to receive the neck 43 therethrough, the flange 74 lying flat against the inner end of the body 41. The lip 75 of the case is crimped into a base groove 71 of the body 41 immediately adjacent the base plate 44. In this way the fuse is securely enclosed and may be made waterproof with application of shellac or other suitable material under or at the edges of the casing.

In the base fuse, for operation with the point detonator described, the detonator 72 may have in the forward part a material 76 such as lead azide or fulminate of mercury suitable for detonation by blast propagation, penetration or concussion, as by a blast, a firing pin or the pellet before mentioned, and at the rear part may have an explosive 77 such as tetryl. Usual retaining and sealing discs may be used, one at each end of the detonator as customary.

In the chamber 49 a booster 79 such as tetryl is packed, retained by the case 70, and in the large cavity of the shell around the base fuse and rearwardly of the cone 21 a charge 80 of a suitable high explosive is provided.

In the manufacture of my fuse, it is an advantage that the cavities in the body may be produced by simple and very few drill operations as the transverse bores have but two directions and the whole may be drilled in two gang operations. The bore 50 and flash port 54 may be produced in one operation. Also the slide and centrifugals are correspondingly simple and free from complications in securing good working fits and functioning. The surfaces of the various parts may be coated with protective noncorrosive material, if desired, and in practice a cadmium coating has been employed, which has the further advantage of minimizing friction.

My invention also enables the centrifugals to be made of good bulk in order to attain adequate mass for good working qualities, and ready calculation of the forces developed, to readily determine the necessary strength in the spring, as well as reducing the factor of fllCllOIl in proportion to the force of the spring and centrifugal force in the centrifugals 62 as well as in the slider 57, and lock 64.

Assembly and loading of the projectile My invention also simplifies and facilitates assembly of the parts of the projectile and loading thereof with its main charge.

The shell, cone, be assembled before loading,

windshield and point detonator may or, for safety, the point detonator omitted until after loading and then introduced.

The base fuse may be assembled on its base plate and positioned after loading of the shell with its main or bursting charge. The latter has been produced in a plastic state and its lower part moulded to afford a recess conforming to the shape and location of the base fuse when finally positioned. In the placing of the charge with such form, the rear end of the tube 35 projects axially into the smaller inner part of the recess of the charge, and the neck 43 of the fuse body engages slidingly around this tube end as the base fuze is inserted in the base of the shell and charge, and the base plate 44 brought to rest against the gasket 44 and shoulder 20. The shell is then closed with the base plug '45, which holds the parts rigidly secured in their proper positions.

Fuse action Qn firing, during lmtlal propulsion movement of the projectile in the gun, the parts remain in the same positions, and they remain so until axial acceleration of the projectile in engagement with the rifling of the gun produces the rate of rotation of the projectile at which it has been predetermined as desirable for the centrifugals 62 to overcome the force of the spring 67. This rate may be in the neighborhood of 2000 revolutions per minute, and may be'more or less depending upon the total twist of the rifling in the gun, and/or the maximum rate of propulsion produced as the projectile leaves the muzzle of the gun. While the safety of the fuze is greater before action of the centrifugals, the purpose of this limitation of their action is not entirely to delay arming of the fuse, during movement in the gun, as will appear, but will be effective in preventing arming if a mistake in the selection or amount of the propelling charge is made which results in too little speed in the projectile and so an explosion too near the gun will not occur. Also safety in case of accidental lateral shock is attained.

After the centrifugals have moved out of engagement with the lock, the latter still remains firmly pressed against the cam face 61 by set back or inertia of the lock acting rearwardly under forward acceleration of the projectile still occurring in the gun. This acceleration continues until the projectile leaves the muzzle. As soon as the projectile leaves the gun nuzzle the forces of setback cease, and the projectile continues to accelerate until the designed speed to attain the predetermined centrifugal force is achieved, whereupon slider 57 will move outwardly displacing the lock 64 forwardly from the cam recess 60 by camming action of the face 61 against the rear end of the lock. The slider thus reaches its armed position, at the outermost limit of movement, with the detonator 72 in line with the passage through the lock 64 and with the flash port 54 behind which the booster charge 79 is exposed.

On impact of the projectile with the target, the head 37 of the firing pin of the point fuse is operated, driving the pin 36 into the primer and detonating the same. The wall portion 29 may collapse at the same time, but detonation at 25 will occur before any material impedance or obstruction occurs in the path of the pin or in the passage to or through the tube 35. Explosion of the primer 32 results in projection of a pellet or blast, or

both, from the point detonator rearwardly through the tube 35, through the foil 47 and cup 73 in the bore 50 and against the sensitive material 76, which immediately fires the high explosive primer powder 77. This produces a flash through the port 54, exploding the booster 79 and setting off the main charge 80 in the projectile.

During the described occurrences, incident to impact on the target, elements or factors of time and movement will have been manifest, including the time and movement occurring after impact during which the windshield is collapsing, and the mouth of the shell and cone are moving into position for best utilization of the Munroe effect. The nature and amount of the explosive in the primer 32 and the weight of the pellet are selected relative to the force of impact of the projectile, its forward speed, and the rate of collapse of the windshield, so that the main explosive charge is detonated at the proper stand-off distance of the shaped charge from the target, to give maximum penetration and optimum explosive effect.

These elements are so coordinated that the explosion of the main charge will occur as, or about when the mouth of the shell body reaches the material engaged by the point and by which initial detonation at the point is caused. The time of movement of the pellet or blast to the detonator 72 will compensate for the time of movement of the shell body the length of the windshield, including retardation involved in effecting the collapse or telescoping of the latter.

In consequence, the blast of the main charge will be delivered against the target with the maximum practical utilization of the energy released in its application by the Munroe efiFect method.

It should be appreciated that while there may be some variation in the time required for complete collapse of the windshield due to various causes including longer or shorter deceleration incident to longer or shorter range, or variations in wind resistance, etc. the time will nevertheless vary within a small degree. Consequently, by selecting a primer for the point detonator which will project its detonating effect to the detonator 72 in a period of time which is a mean of those which experience show may be required under extremes of variance in the retardance to be expected, there will be an automatic compensation in the practical functioning of the organization by departures in either direction from such mean requirement. That is to say, where the communicated detonation is ideal for a given speed of the shell in collapse of the windshield the transmission from the point to the base will involve a time x. If the shell engages the target at a greater speed, the convergent movement of the base and the projected detonating wave or pellet will be correspondingly more rapid, shortening the time of travel of the communicated effect, to accord with the earlier arrival of the shell cavity in good operative relation to the target body. correspondingly, if the speed of the projectile is slower than the chosen mean projectile speed, the convergence of the base fuse and the propagated element from the point fuse will be correspondingly slower and delayed.

In the form of the invention, shown in Fig. 8, the bore in the stem 27 of the point body is extended further and enlarged rearwardly of the primer retaining bushing of the point structure, as at 28 and a tube 35 engaged and secured therein which is extended rearwardly and into the neck 43 where it may be secured. The base and point structure may otherwise be the same as before de scribed. In this form, the forward part or the whole length of the tube between the cone and stem 27' of the point is of a light weight meltable or quickly combustible material. Onernaterial suitable for the purpose is known as Pentalite. In another form the tube 84 may be metalsheathed tetryl as in Fig. 9. The sheath may be on the interior, as at 85, as well as the exterior of the tube, as at 86. A lead sheath has been used. With the modification indicated, on detonation of the primer at the point, the blast with the Munroe effect, or a projected part from the primer, will travel through the tube with great certainty effecting the detonation of the detonator 72.

Explosion of the main charge will destroy the tube 35' instantly. The blast from the point primer will tend to ignite the tube 35', but such ignition will not occur until after communication of the necessary concussion to the rear detonator, or at least until after passage of the dense area of the Munroe wave or pellet or both, past the point of ignition and ahead of any propogation of ignition along or in the material of the tube. This applies particularly to the metal-sheathed tetryl the metal serving to delay the ignition and combustion of the tube.

On account of the great stresses set up in the body of the tube 35, 35 and 84 when the projectile engages the target, due to inertia of momentum in the tube material, and to guard against possible breakage of the tube before completion of communication of the detonating effect to the base detonator, I have shown in Fig. 8 an anchoring means on the base fuse by which the tube is automatically connected to the base when the base fuse is put in place. In this instance the tube is thickened at its rear end portion and formed with a circumscribing groove 87 near its rear extremity and its rear end is bevelled as at 88. The neck 43' and bore 50' are suitably enlarged to receive the enlarged end of the tube, and an interior groove 89 formed in the enlarged bore 50 arranged and proportioned to aline with the groove 87 when the tube end is inserted. A C-spring 90 of circular form, set initially in the groove 89, is of a radial cross sectional dlmension sufiicient to lie with portions in the grooves when the latter are alined. The spring 90 has flat sides in parallel planes normal to the axis of the tube and neck, but is bevelled on its inner side so as to permit the end of the tube to be readily pushed through it when the base fuse is being put in place. After assembly the tube cannot be pulled from the neck 43, except destructively, due to the engagement of the spring 90 therewith.

The construction of the safety and arming features in the base fuse of my invention are of such character as to be applicable to various forms of fuses, and in Figure 11 I have shown an adaptation of that part of the invention in the base fuse structure to use as an inertia base fuse of general application. Here, the booster chamber and charge, and the slider except 'centrifugals 62 as before described, are embodied in the identical form and relation already described, and the rear portion of the body 41 of the fuse may be of similar form. The forward part, however, instead of having the reduced neck is extended the full size of the rear part. and a large bore 100 formed concentrically, opening. on the forward end, from which a smaller bore openson the bore 53. A look and, primer carrier 101 having an axial passage 102 therethrough is slidable in the large bore, having also a reduced hollow stem 103 (through which the passage 102 continues) extending through the bore 55 into the recess of the slider, this recess being of the same form as before, and having the inner cam face 61 acting against the end of the stem 103 in the same manner as it acts against the lock 64 in the first construction.

The forward end of the bore is interiorly threaded and has screwed thereinto a closing plug 104, on the inner side. of which. there is a firing pin alined with the. passage 102 and adapted to enter the same on relative forward movement of the lock 101. The inner rear end of the passage 102, is formed with a stop shoulder or lip and against this is set a conventional primer 106 having a percussion material at its end toward the pin 105. In the initial or safety position of the parts. as shown in Figure 11, the stem 103 being fully engaged in the recess 60, the primer is spaced from the pin slightly more than the depth of the recess 60 in the stemof the slider. As a safety for the detonator 106 diametrically opposite centrifugals 107 may be mounted in suitable recesses in the body 41' adjacent the forward end, of. the lock 101, held by a C-spring 108 in a groove 109 so as to operate in the same manner as the centrifugals 62 or 62 which may be omitted. The centrifugals 107 have small pin portions extending through reduced openings through the wall of the bore 100 and projecting only a short distance before the lock, so that the necessary radial movement for arming may be provided for in the material of the fuse body beside the bore.

The action of this fuse in the gun on firing is similar to that first described. The centrifugals 107 are thrown out after the projectile reaches a rotation rate sufiicient to overcome the force of the spring 108, but the stem 103 of the lock 101 remains in the recess 60, opposing arming movement of the slide 57 under set back effect.

After the projectile leaves the gun, the slider operates centrifugally, as before moving the cup 69 into line with the port 54. The element 72 in this particular cup may 75 be omitted if. desired for certain uses, or may be so composed as to constitute a delay button of relatively slow burningpowder, or may he a second percussion detonator. This cup 69 is at the same time alined with the passage 102 and detonator 106. The movement of the slider moves the lock forwardly until the primer 106 is near the pin 105, and on impact of the projectile with the target, inertia of the lock 101 carries it forward driving the primer. against the pin. The resulting flash through the rear end of the stem 55 will pass through the cup 69, if empty, and also the flash port 54, exploding the booster charge 79.

If a delay button is incorporated in the cup 659 there will be a correspondingly delayed ignition of the booster charge and if a second detonator is set in the cup there will be a consequent quicker detonation of the booster.

As shown in Figure 10 l have embodied the Munroe effect more definitely to act by propulsion of a detonating wave' or blast, by forming the base of the cup 110 for the point detonator or primer with an extended and deepened reentrant cone 111, and in such case the wall .material of the cone 111 may be much thinner than the usual cup base. It may also be made of zinc, aluminum, or magnesium, or alloys, or a combustible plastic, so as to'beconsumed ondetonation of the primer.

It is a further advantage of my invention that the arrangement of the centrifugals 62, enables them to be located a greater distance from the axis of the projectile than is usual; This has important advantages from several aspects. Thus, it obviates liability of failure to operate due to variations from manufacturing specifications as to mass and dimensions. And, perhaps most important. reduces or eliminates liability of failure of the centrifugals to clear the detonating train by reason of yaw or rotation of the centrifugals eccentrically for any other reason. Oftenthe axis of rotation is not/the axis of the projectile and if the center of gravity of the centrifugal is close to the projectile axis, the moments of the centrifugals may have either reduced values or even negative effects.

While I- have disclosed my invention with particularity in the best embodiment developed at this time, it will be understood that: this is exemplary only and that modifications of construction, arrangement and combination, substitution of materials and equivalents, mechanical or otherwise may be made without departing from the spirit of the invention.

I claim:

1. in a projectile, an impact responsive primer located in the point thereof for initiating action of. said projectile upon impact with a target, said primer including a first rearwardly directed, shaped charge, a second forwardly opening shaped charge in said projectile axially separated from said first shaped charge, said first and second shaped charges defining a, space which is free of intervening structure, detonating means at the base of said projectile for initiating action of said second shaped charge, there being an axial passage formed in said second; shaped charge and communicating with said detonating means, and a kinetic element responsive to the detonation of said first shaped charge rearwardly projectible through said space and to and through said axial passage to initiate action of said detonating means.

2. In a projectile, an impact responsive primer located in the point thereof for initiating action of said projectile upon impact with a, target, said primer including a first rearwardly directed. shaped charge, a second forwardly opening shaped explosive charge in said projectile axially separated from said first shaped charge, said first and second shaped, charges defining a space free of intervening structure, detonating means at the base of said projectile for initiating action of said. second shaped charge, and means, including an axial elongated passage in said second shaped charge and intermediate said primer and said detonating. means, responsive to detonation of said first shaped charge for initiating action of said. detonating means.

3. In a projectile, an impact responsive primer located in the point thereof for initiating action of said projectile upon impact with a target, said primer including a rearwardly directed first shaped charge and a liner for said first charge forming a kinetic element, projectible rear wardly by the blast propagated by said first shaped charge, a second forwardly opening shaped explosive charge in said projectile axially separated from said. primer, said primer and said second shaped charge defining a space free of intervening structure, detonating means at the base of said projectile responsive to impact of said kinetic element for setting off said second. shaped charge, said second shaped charge having an axial passage formed therein providing an open path for said kinetic element between said first shaped charge and said detonatmg means.

4. In a projectile having a cylindrical body portion and a frusto-conical forwardly extending impact collapsible windshield secured to said body portion, an im pact detonatable primer in the nose of said windshield, said primer comprising an explosive having a small rearwardly opening conical cavity forming a first shaped 1 charge, an explosive charge in said body portion, said explosive charge having a forwardly opening large conical cavity forming a second shaped. charge, said windshield, said primer and said second shaped charge defining a space free of intervening structure, a detonator in said body portion adjacent the base thereof for setting oif said explosive charge, said explosive charge in said. body portion having an elongated axial passage intermediate said base detonator and said primer, whereby said detonator is responsive to the blast produced by said impact detonatable primer traversing through said space and to and through saidv axial passage to set off said explosive charge.

5. In a projectile having a cylindrical body portion. and a forwardly extending frusto-conical impact collapsible windshield secured tosaid body portion, an impact detonatable primer in the nose of said Windshield comprising an explosive forming a first shaped charge, a liner for said first shaped charge forming a pellet when said primer is exploded, an explosive charge in said body portion, said explosive charge having a forwardly opening large conical cavity forming a second shaped charge, said windshield, said primer and said second shaped charge defining'a space free of intervening structure, a detonator in said body portion adjacent the base thereof for setting off of said explosive charge, said explosive charge having an elongated axial passage intermediate said base detonator and said first shaped charge, whereby the blast from said first shaped charge on impact drives said pellet reainvardly through said space and to and through said axial passage to set-off said detonator.

6. A projectile comprising in combination a shell having a hollow front end, a load of explosive located in said shell with its front face rearward of said hollow front end, said load of explosive being formed with a cavity extending rearwardly from its front face, said cavity increasing in diameter from rear to front, a sheet metal hood applied against the wall of said cavity, said hood having an aperture at the rear end thereof, a main detonator located in the explosive load rearward of the sheet metal hood, a tubular member located in said load of explosive and extending through the aperture and having its front end centered in the hood with a front orifice opening into the space in said hood, said tubular member cooperating with the hood for preventing gases of the exploded charge from penetrating inside the hood, a sensitive head fuse located at the front end of the projectile and including a priming detonator having a part extending into the hollow front end positioned for delivering the flame of detonation into said hollow front end of said hood, said detonators being held spaced one from the other, said part, front end, hood and tubular member providing means for fire transmission in a direct path from the priming detonator to the main detonator whereby the space within said hollow front end and said hood is free of any intervening structure between said part and said tubular member.

7. In a fuzed projectile, a casing, a main explosive charge within said casing and having a forwardly-facing shaped cavity, a detonator in detonating relation with said charge at the rearward end thereof, there being an axial passage in said charge extending only from the apex of said cavity to said detonator, an impact fuze, means mounting said fuze in fixed relation with said casing and on the forwardly-extended axis of said charge in spaced relation with said charge, there being a free uninterrupted space between said impact fuze and said cavity, and means directing the combustion flame of said fuze through said space and through said passage to said detonator out of contact with said main explosive charge.

8. The projectile in claim 7 wherein said impact fuze includes a rearwardly directed shaped cavity.

9. The projectile in claim 7 including a liner for said shaped cavity.

10. The projectile in claim 8 and including a first liner for the shaped cavity of said main charge and a second liner for the shaped cavity of said impact fuze.

11. in a spin stabilized projectile having a cylindrical body and an impact collapsible frusto-conical windshield secured to said body, an impact responsive primer located in the point of said windshield for initiating action of said projectile upon impact with a target, said primer including a first rearwardly directed shaped charge, a second forwardly opening shaped charge within and coextensive with said body, there being an axial separation between the apices of said shaped charges, said wind shield, said first and said second shaped charges defining a space free of intervening structure, detonating means at the base of said projectile for detonating said second charge, there being an elongated axial passage in said second charge and communicating with said detonating means, and a kinetic element responsive to the detonation of said first charge rearwardly projectible through said space and to and through said axial passage to initiate action of said detonating means.

12. The projectile of claim 11 and including a centrifugally responsive slide member transversely slidable in a bore formed in said detonating means, a detonator in said slide member integrally movable therewith from first safe position to second armed position in axial alinement with said flash passage, and centrifugally responsive detent means in said detonating means releasably engaging said slide member, said detent means releasable at a predetermined forward speed of said projectile to permit said slide and detonator to move to arming position.

13. The projectile of claim 11 and including a liner for said first shaped charge, said liner forming said kinetic element when said first shaped charge is detonated.

14. The projectile of claim 13 and including a centrifugally responsive slide member transversely slidable in a bore formed in said detonating means, a detonator in said slide member integrally movable therewith from first safe position to second armed position in axial alinement with said flash passage, and centrifugally responsive detent means in said detonating means releasably engaging said slide member, said detent means releasable at a predetermined forward speed of said projectile to permit said slide and detonator to move to arming position.

15. The projectile of claim 11 wherein said kinetic element is the blast propogated by detonation of said first shaped charge.

16. The projectile of claim 15 and including a centrifugally responsive slide member transversely slidable in a bore formed in said detonating means, a detonator in said slide member integrally movable therewith from first safe position to second armed position in axial alinement with said flash passage, and centrifugally responsive detent means in said detonating means releasably engaging said slide member, said detent means releasable at a predetermined forward speed of said projectile to permit said slide and detonator to move to arming position.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 633,458 Jared Sept. 19, 1899 1,322,683 Barlow Nov. 18, 1919 1,534,012 Watson Apr. 14, 1925 1,563,418 Adelman Dec. 1, 1925 1,955,779 Teitscheid Apr. 24, 1934 FOREIGN PATENTS N umb er Country Date 28,030 Great Britain Dec. 13, 1911 217,955 Great Britain June 24, 1924 467,392 Great Britain June 16, 1937 113,685 Australia Aug. 14, 1941

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