US2276110A - Explosive missile - Google Patents

Description

rch 10, 1942. w. o. sNELLlNG 2,276,110

EXPLOS IVE MISS ILE Filed March 18, 1939 INVENTOR.

BY "i". n v v ATTORN EY Patented Mar. 10., 1942 ExrLosIvE MissiLE walter o. sneuing, Allentown, ra., asignor to Troian Powder Company, Allentown, Pa.

Application March 18, 1939, Serial No. 262,608 7 Claims. (Cl. 102-29) This invention relates to explosive missiles. It relates more particularly to projectiles for use against troops and especially to means for caus- Ing proper fragmentation of brittle metal shell. A The missiles to which the invention refers include those adapted to be fired from guns, hurled or dropped, especially high explosive shell or projectiles.

Shell for use against infantry are now usually made of forged steel. The operation of forging the shells is relatively slow and expensive; the equipment required in the manufacture is costly and may prove to be dimcult to obtain in adequate amount in times of major warsLwhen the need is greatest.

On the other hand, it is easy to provide the relatively simple equipment necessary to form castlron into shell. Also, the operation of casting is relatively quick and inexpensive.

A reason for the use of steel forgings as shell in the past has been the impossibility of making cast-iron shell which meet the severe requirements. It is necessary that shell for stopping troops should give, on explosion of the charge therewithin, the largest possible number of fragments of effective size, moving at a suiiiciently high velocity. Thus, shell for use against infantry should fragment predominantly into pieces of such size as to pass a screen having one mesh to the linear' inch and be retained on a 3-inch screen. Furthermore, the individual particles should each have preferably not less than 60 it. lbs. of energy and should be able to penetrate a 'V8 inch pine board and, preferably, penetrate twice this thickness of board.

When cast iron shell are used with the conventional high explosive charge therewithin, the shell are blown into small fragments of size predominantly below that preferred. If, on the other hand, there is used a charge of slow explosive, then the resulting pieces of the cast iron .shell are suiiiciently large, and are usually too large, but have insufficient velocity.

It is an object. of the present invention to pro- -vide a cast metal shell of desired fragmentation when used with a detonating explosive bursting charge. `Another object of the invention is to provide a shell containing a protection for an inherently weak but not necessarily brittle portion thereof. of a method of making loaded shell of the kind described. Other objects and advantages of the invention will appear from the detailed description that follows.

Briefly state, the preferred embodiment of the A further object-is the provision y invention comprises a shell of fragmenting relatively brittle metal, a detonating lexplosive charge therewithin, and a liner disposed between the shell and the said charge, the liner being firm so as to avoid set-back of the explosive charge, but crushable on explosion of the said charge.

The invention is illustrated in the attached drawing and will be exemplified by description in connection therewith.

Fig. 1 is a. view largely in section of a trench mortar shell provided with the liner inside the shell.

Fig. 2 is a similar view of a shell for use in a mm. or other calibre of cannon, the lining being omitted over the back portion of the shell.

Fig. 3 is a similar view of a shell 'having the lining over only a portion of the shell that is structurally relatively weak.

The figures are in part diagrammatic, features not illustrated in detail being conventional.

In the several figures there are shown the fragmenting metal shell 1 and the bursting charge of high explosive 8.

In the trench mortar shell of Fig. 1 there are shown a liner 9 fitting snugly within the shell and around the explosive charge, in tight relationship to each, means for exploding the said charge,

including the fuse I0 and the booster charge II.

the tail I2 including suitably a number of radial fins I3, a propellant I4 such asa series of cylinders filled with smokeless powder and held in the space between adjacent ones of the fins, and a shot gun shell I5, or the like, adapted to ignite the propelling explosive I4 when the shell is dropped into the usual trench mortar.

In Fig. 2 the liner I6 extends over the side and Y front portions only of the shell; the rear portion of the shell is directly in contact with the explosive charge 8. Furthermore, in the said rear portion, the width of the explosive charge at all points is at least as great as that at the mid-point or widest portion of the charge, this feature avoiding set-back of the explosive under the most severe conditions of projection of the shell.

In connection with the danger of set-back, it will be understood that shells are frequently given a velocity of 1,800 to 2,200 feet a second or higher as the shell traverses only the length of the free portion of the barrel of the cannon. As a result of this tremendous acceleration, there is a tendency for the explosive charge to move backward and to iill any space presented to it at the rear of the shell, this movement or shift of the explosive being known as set-back and being likely to be lplosive charge as illustrated in Figs. 1 and 3, for

most types of shell.

In Fig. 3 there is shown a modified form of shell that may be made, for example, from forged steel pipe shaped suitably at the front end and closed at the base or rear by means of the end portion I1 screwed into the main portion. In case the use of a liner inside all parts of the metal shell is not desired-and it is not necessaryfor all purposes when the materialk of construction of the shell is steel-then the liner is omitted except over the relatively weak end portion. In this case, the liner I8 should extend completely over the end portion, so `as to protect the end portion momentarily from the fullforce of the explosive charge and thus avoid disrupting the screw engagement until. there has been built up in theshell pressure adequate .to give desired velocity to the resulting fragments of the shell.

In the shells shown in Figs. 2 and 3, the means for exploding the bursting charge are conventional and include suitably the fuse I9 which is inserted at any suitable timey and the adapter and booster charge 2Q, theadapter not being shown.

The charge of high explosive 8 within the shell is of the brisant type and may be one ordinarily used by the United States Government as the bursting'charge for such shells. Trinltrotoluene is Vthe preferred explosive although there may be` used to advantage a mixture of trinitrotoluene with ammonium nitrate (amatol). A suitable amatol -is made by mixing molten triuse of material of at least the firmness of set plaster, that is, hydrated gypsum plaster or plaster of Paris` i l Suitably, the liner is adhered to the inside of the shell as, for example, by being poured into the shell in owable condition and hardened in situ or by means of an adhesive (not shown) forming a.' lllm that is preferably continuous between the shell and the liner. Adhesives thatmay be used are thin layers of tar, asphalt. pitch or the like.

'I'he liner should be thick. For most purposes theliner should be at least half as thick and preferably should be as thick as the shell wall, say, t inch to 1%; inches thick, in order to give proper protection to a cast iron shell against .fragmenting to a large extent into undesirably small pieces. Among the materialsl that'are suitable for use as the liner' are compositions containing plaster. Portland cement, or magnesium oxychloride.

These various compositions may include reinforcing materials such as asbestos fibers or various fillers or admixtures. l

Hydrated liner compositions such as described serve also as energy ballast, as will be discussed later. The liner is preferably formed by introducing into the shell a ilowable 'composition adapted to harden -in situ. Thus, plaster or Portland cement compositions may be introduced in `in timate mixture with water in amount required forhydratidn or setting, the shell being supported vertically and rotated during the period nitrotoluene and an equal weight of crystals of ammonium nitrate.` Picric acid is another explosive that may bel plosive substantially fills the yspace within the liner, that' is, the space not occupied by the booster charge or casing.

The booster charge, also, may be of conventional kind or tetryl. The lshell wall should be thick, say one-half composition, as for example used. The detonating ex- Y to one inch or so, and composed of a'fragmentmg metal. Asstated, cast iron is satisfactory under the conditions of use. Being low in cost,

it is preferred for the present-purpose, but cast steel may be used for some purposes. Cast iron and cast steel are referred to herein as cast ferrous metal. The liners 9, IG and I8 -are of a composition that must be selected care# fully if there is to be on the one hand absence of set-back sufficient to expl'ode the projectile on its projection from the gun, and on the other hand proper fragmentation on the explosion of the bursting charge.

The material of .the liner should be inert to the extent of having. no appreciable injurious eji'rect upon the shell on the one side or the explosive on the other. The liner must absorb or mechanically transform a portion of the initial energy of the explosive charge 8. It must be so rm as to allow no appreciable set-backof the explosive` at the time the shell is projected'but must be crusiiable charge 8.

set-back, I und advantageous the of illling and setting, so as to spin a liner of desired interior contour. If Portland cement is used, the retarder of setting conventionally present in Portland cement may be omitted, in order to avoid long delay in hydration of the Portland cement. Preferably, no appreciable excess of water is used over that which chemically combines in the hardening. Should any excess water be used or the setliner be not dry, drying is effected at a temperature below that of dehydration of the set material.

' Additional thickness of liner may be provided at any point within the shells, as over thin spots of the liner centrifuged into position. Such additional lining material may be introduced in any convenient way and the shell inclined, in such manner as to cause the said material to ow over the spot to be further protected. Hardening is then effected as described.

'I'he liner may be made to have any desired shape of interior surface by being cast toiill the entire shell space and then bored out, to remove'undesiredmaterial.'

A serious problem arises in the use of the liner u 'complete assembly. -In this manner there is upon the explosion of the produced a nal loaded shell having, for a given calibre, the same weight as would be produced with the lining omitted, and with the explosive charge occupying the entire shell cavity.

To increase the density of the lining composition there may be used particles of heavy materials such as finely divided barytes, celestite, magnetite, ilmenite, lcieite or the like. To lowei the density of a liner composition that. by itself.

is more dense than the explosive charge 8, I may incorporate suchlight weight fillers asv diatomaceous earth, pumice or the like, pores in or between particles of the fillers being left largely in unfilled condition, in order to give the 5 desired lightness.

In place of the centrifugal method of llingL described above, the liner composition may be introduced so as to fill approximately the entire space within the shell; drilling is then employed, to form the central cavity for receiving the explosive charge.

In introducing the lining over the screwed-in end portion only rof the shell shown in Fig. 3,

the shell is placed upright with the said end portion downward and the liner composition in flowable condition introduced, so'as to give Ythe desired `depth of layer, 'this introduction obviously being made before the shell is loaded.

The composition is' thenl hardened as .described 20 previously.

The rear end of the shell .of Fig. 1 may be lined in the same manner in lining the forward end of this shelL'the proper quantity of composition is introduced, the shell closed by a tem- V25 porary cap or plug, the shell placed vertically,d with the forward end down, and the composition hardened. The cap or plug is then removed and the liner drilled to receive the booster casing'. The sides of this shell may be 30 lined as previously described, either before or after the ends are lined. v

Shell lined as described and filled with a detonating explosive such as trinitrotoluene fragment on detonation of the explosive into pieces predominantly of size such as are retained on a B-mesh screen. Without the lining, the fragments formed are mostly of size iiner than 3-mesh.

The superior fragmentation produced in shells '4.0

brisant explosive in direct Contact with the relatively brittle metal of the shell wall. Efforts to correct this pulverizing action by employing slower explosives has resulted in improved fragmentation, but in such cases the fragments have not been projected with sufficient velocity to be effective. By the present invention the brisant explosive reaches full detonation by the time the shell wall is fragmented, and accordingly the shell fragments are projected at the desired high velocity, although the momentary effect of the o0 lining is to control and moderate the pulverizing action of the brisant explosive upon the brittle metal.

The explosive missiles 'herein described, are

vadapted for use particularly in connection with shells of about three to six inches internal diameter. Shells of larger lsize are ordinarily used primarily for demolition and in such demolition shell, the fragmentation of the shell into pieces of preferred size for stopping infantry is not a feature of special importance.

However, the invention is applicable to other shapes of shells or explosive missiles than those shown in the drawing.

One of the purposes of my improved shell lin 75 In previous 45 ing is to act momentarily as an absorbent of energy or energy ballast, during the period of time required for the brisant explosive to reach full detonation. I flnd highly desirable the presence in the shell lining of an energy absorbing material, suitably a stable hydrated sub- `stance, as, for example ulexite, colemanite.

gypsum or vermiculite. In the presence of such a compound having combined water of crystallization or Water of constitution, a portion of the energy of the explosive is 'absorbed momentarily in performing chemical or physical` effects upon the lining material, part or all of this absorbed energy being then available torincrease the propellant action, the action being best explained as a transformation of the brisant or shattering eect of the explosive into a propulsive or Ypropellant action, thuns modifying the manner in which the energy is utilized rather than a change inthe total quantity of energy involved` When such energy ballasting material is used` it may be incorporated in granular or powdered form in the liner composition, as by being mixed with abinder, such as -sulfur, rosin, or the like, the binder being in molten condition before the composition is introduced into the shell and allowed to solidify. A suitable proportion is 5 to 40 parts by Weight of the said material to 100 of dry Weight of the liner composition.

It will be understood thai'l the admixed absorbent of energy is `not necessary when the liner is composed largely of a hydrated composition, such as plaster or Portland cement, that is itself an energy absorbent. It is to be understood that the terms liner and lining composition as used herein refer to materials that do not constitute a portion of the explosive charge of the shell or missile and that are wholly or predominantly non-explosive in nature.

It will be understood also that the details given are for the purpose of illustration, not restriction, and that variations Within the spirit of the invention are intended to be included in the scope of the appended claims.

I claim:

1. An explosive projectile for use against troops comprising a cast iron shell, a charge of detonating explosive within the shell, means for exploding the said charge, and a crushable energy-modifying liner disposed between the shell and detonating explosive, in direct contact with each, the liner being at least as firm as set plaster, so as to prevent set-back of the explosive charge on projection of the projectile, but crushable by the force of explosion of the said charge and having a thickness of at least half the thickness of the wall of the shell.

2. An explosive missile for use against troops comprising a cast iron shell, a charge of detonating explosive Within the shell, means for exploding the said charge, and a crushable liner disposed between the shell and detonating explosive, in direct contact with each, the liner being at least as rm as set plaster, but crushable by the force of explosion of the said charge and being one-half inch to one and one-half inches thick and the shell fragmenting on explosion of the charge predominantly into pieces of size of the order of those retained on a 3- mesh screen.

3. An explosive missile comprising a cast iron shell, a hollow liner, therewithin of a hydraulic cementitous composition in set condition, a charge of detonating explosive filling the space within the liner, `and means for exploding the said charge, the liner being in direct `contact on one side with the shell and on the other side with the said explosive.

4. An explosive missile comprising a fragmenting metal shell, a hollow liner therewithin of a. solidiied monolithic sulphur composition, a hydrated material distributed throughout the said composition, a charge of detonating explosive lling the space within the liner, and means for exploding the saidcharge.

5. An explosive missile for use against troops comprising a thick fragmenting vmetal shell, a charge ofdetonating explosive within the shell, means for exploding the Said charge, and a crushable liner within the side and front portions only of the shell and around the explosive charge, the rear end of the shell being indirect contact with the explosive.

6. An explosive projectile for use against troops comprising a thick fragmenting cast ferrous metal shell, a charge of detonating explosive Within the shell, means for exploding the Pat-ent No.' 2,27 6,110.

said charge, and a crushable liner within the side and front portions only of the shell and around the explosive charge, the width of` the explosive charge at all positions back ofthe-midpoint of the shell being at least as great as at anyot po n in the shell, so as to minimize the danger of p emature yielding of the liner and set-back of t e charge.

' 7. An' explosive missile comprising a fragxnenting metal shell, an end portion thereof screwed into the main portion of; the shell', a

detonating explosive charge within the shell,

CERTIFICATE CORRECTION WALTER o. SNELLING.

means for exploding the said charge, and a rm liner disposed within and `completely over the said end portion, the said. liner being of thickness at least half'that of the end portion, being at least asy rm as set plaster, filling the space between-` the said end portion -of the shell and thev explosive charge, and protecting the said portion momentarily from the full force of the explosion of theexplosive charge. e

. WALTER O. SNELLING.

mmh 19. 191e# It 1s vhereby certified that err-or appears in the printed specification of the above numbered patent requiring correction as follows; Page 1 frst reed v vth this correction therein that the same may conformto therecoi'd .of the case in. the Patent Office.

` signeqfa'na sealed this mth day .of July, A. Di 19ll2.

h( Sea-1 vhenry' Van Arsdale; Acting Commissioner oit` Pat'errts.v

page', second co-lumn, line and that tlie said fettI-s Fatent should'be CERTIFICATE #0E CORRECTION. y Patent NQ; 2,276,11o.- i Manch 1 0,- 1942-.

WALTER o. SNELLING 'It isl 'hereby eertified that error appears' in tlie printed specification of the abbve numbered patent requiring co'rrectien as follows; Page l, first column', line 50, for'"5inch read --mesh-q pge, second 4ao'lumn, line 1 18, f or thune read 'thus and that'the said Lettrs Patent should'be- .read vwith this rrection therein that the same may confonn to therecord '.of the case in the Patent Office. I

'Sisfnifang seal-ed this 1mm day of July, A, D 191m.

.l .Eenry van Arrsdale;

(Seal) "i Aeting Gemmissioner of Patents.

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