US2498080A - Projectile equipped with fins - Google Patents

Description

Feb. 2l, i950 J. R. .JAssE PROJECTILE EQUIPPED WITH FINS Filed May 24, 1947 ns, thev body of Patented Feb. 21, 1950 Joseph Raymond Etablissements French company J asse, Paris, France, assigner to Edgar Brandt, Paris, France, a

Application Mayu, 1947, serial No. 750,253

` In France June 5, 1946 4 Claims. (c1. 1oz-49) The body of a projectile maybe manufactured in"various ways, and in particular from a forged fbar, or by moulding (semisteel), which is the `most common method or again by shrinking a steel tube.

. In the rst case, it is possible to obtain a blank which is closed at the rear, which has the advantage of being absolutely fluid-tight, wherevas in the second case, as the blank is open at both ends, it is necessary tov t ends thereto by any 'method. On the other hand, the main advantage'obtained by the Ause of a tube is a considerable saving of material, which may be as much 4as 20 to 25%, as a result of the reduction of waste vin machining; furthermore, the rate of manufacture may be much faster.

Although the useV of tubes is suitable in particular for the manufacture of hand-grenades and aerial bombs, it is quite the contrary when it is required to manufacture projectiles which are intended to be fired from a gun. As such projectiles are subjected, when firing, to the action' of the propelling gases, it is necessary for their case to be absolutely fluid-tight at the rear; the slightest leak due to a hidden fault of manufacture might, -in fact, be suicient to cause serious accidents when they are being red. This is the reason why, in the manufacture of artillery projectiles, it is preferred in general to renounce the advantages that may be obtained bythe use of tubes and to adhere to the old method consisting in using a body manufactured from a bar and completely closed at the rear. v i

` As the casing of projectiles equipped with fins, vwhich are intended to be fired by mortars, only have to support a moderate force when the shot is fired, it should be Amade as light as possible, and it would be a great advantage in this case to be able to manufacture it from a tubular blank,

the only problem to be solved, which has not yet been solved in a satisfactory. manner, beingthat of the duid-tightness at the rear.

The present' invention is intended to fill this need.v -It'relates to' a projectile equippedl with which is'provided with a' screwthreaded rear orifice,` into lwhich is screwed .a nipple which is secured, at any rate after mounting.y to a tail supportingfthe iins, said projectile being remarkable in particular in that the con- `nection between saidk tail and the body of the projectile isv provided .with a metalloplasticfdeformable fluid-tight joint mounted in an annular housing provided inlthe bodygof zthezprojectile, `said Vjoint-'being deformedsby compression; imits housing by a circular shoulder of the nipple when arrangement' enables the sheath to become des "Thereis therefore Y. of its housing a sufficient pressure same is screwed into the body of the projectile.

The fact that this fluid-tight joint is deformable by the action of screwing the nipple has the eiect that, after said nipple is'mounted, the joint completely fills its housing andthus makes the rear of the projectile duid-tight. According to another characteristic of the invention, the duid-tight joint is provided withv ai malleable metal sheath, which is open circularly on one side and contains a plastic material.

formed'without crumpling and without its edges overlapping one another when the plastic mate- Yrial is compressed.

zjSince the time'takenby the projectile to trayel through the barrel of a mortar'is very short,=the

joint is only slightly heated and may very well be made, internally, of cardboard.

When the' jointis'compressed, itl first undergoesa considerable deformation whichis permanent and irreversible, `owing to the crushing'of the plastic material which has no natural rigid'- ity,` the metal sheath only offering a slight regsistance to this deformation owing to its annular shape which enables it to undergo larger deformations by the action of small forces. i

' At the end of this period of compression, the

joint has assumed substantially the shape of its housing, save in the corners of same, where there remains a small space of approximately triangular cross-section. f' -If the compression of the joint is continued, the pressure caused by the resistance to crushing offered by said'joint quickly increases and offers more and morev resistance to further deformations. As the plastic material is'thus solely in compression, it acquires a certain resilience.

during the rst period of the compression, plastic and permanent deformation of theljoint by a slight pressure which slowly increases, whereas during the second period which is shorter, the joint isresiliently deformed, il. e. ,in a reversible manner, by a larger -force-Which quickly increases with thecompressionpath:A In order that the joint shall provide fluid-tightness it.is,necessary for it to exert` onA the walls to counterbalance. that of the gases, which is lonly possiblek if saidV joint is in the'region of resilient deformations, i. e. the second part of the compression path.

Fluid-tightness will be kmore eicient. as the 3 fect so long as the screwing travel of the nipple is only limited by the compression of the joint.

The metal sheath is preferably given a rectangular cross-section with rounded corners, whereas its housing in the projectile is of purely rectangular cross-section.

The joint is thus prevented, as it is deformed by the pressure of the screw when the nipple is being tightened from being pinched and producing a jamming which would make it impossible to screw the nipple right home; on the contrary, it only more completely lls the space provided for its uid-tight functions. Furthermore, the presence of the rounded corners of the sheath has the effect of providing small expansion spaces for the gases.

In a particular embodiment of the invention,v

the portion which forms a nipple and which is adapted to engage in the rear orifice of the projectile body is provided with two ground cylinldrical bearing surfaces of diiferent diameters, which are axially stepped and respectively engage in corresponding circular recesses provided at the rear of said projectile body, the housing for the fluid-tight joint being formed by the recess of large diameter.

This makes it possible to obtain a perfectly guided sliding device Which, at the end of its travel, locks the fluid-tight joint absolutely accurately in its housing. The length of the small diameter bearing surface is such that the same begins to engage in its recess before the Huidtight joint begins to be compressed in its housing, whereby said joint is prevented from being driven back and jammed when the nipple is being screwed tight.

The use of these two ground bearing surfaces furthermore has the advantage of eecting a suitable centring of the ns on the axis of the projectile, which is very important for the accuracy of ring. The same result cannot be obtained when, as is generally the case, the tail is only provided with a simple screw-threaded nipple adapted to screw in a blind hole bored in the end of the projectile.

For the purpose of breaking the jet of gases. by expansion, and of preventing it from propagating inside the joint, according to a further characteristic of the invention, a circular expansion groove is provided on the periphery of the large diameter ground bearing surface.

The tail of the projectile may advantageously be manufactured of preferably untreated drawn steel tube, instead of using a tail' which is machined from a bar; a saving of material and an economy of manufacture is obtained thereby. In this case, the coupling between the tail and the body of the projectile comprises a separate part forming a connection which is screwed right home in the projectile, ay second screw-thread provided on said connection serves for screwing on to the tail. This connecting member being of small size can be mass produced with the greatest accuracy, which is an advantage when it comprises ground cylindrical portions, the accuracy of which is an important matter.

Additional fluid-tightness is given to the device .'by varnishing the whole of the above described connection when mounting it. Finally, a layer of pitch cement may provide a final means for preventing the gases from passing.

Other peculiarities of the projectile according to the invention will become apparent from the ensuing description.

In the accompanying drawing:

yafter compression and deformation of the fluidtight joint and the tail being screwed right home. Fig. is a general View, in axial section, of a projectile equipped with ns according to the invention, provided with a tail which has been machined from a bar with its nipple.

Fig. 6 shows,` in partial axial section, the detail of the fluid-tight coupling, after screwing the tail (Fig. 5) on the projectile.

The projectile shown in Fig. 1 comprises a tapered body I and a cartridge-holder tail 2 provided with fins 3; said tail is adapted to screw on the rear of the projectile body I; in the example described, it is a perforated tail of known type, made from a drawn steel tube; an intermediate member or nipple 4, which is adapted to screw, on the one hand in the front part of said tail 2, and on the other hand in the rear part of the projectile body I, acts as a connection between the tail and the projectile body. It is obvious that as shown in Figs. 5 and 6, the tail could also be of any type, machined from a bar and having at the end thereof a screw-threaded nipple.

The body I of the projectile is made from a tube section. Consequently it has, after shrinking and machining the front and rear ogival portions, a front orifice 5 and a rear orifice 6; said orice 6 is tapped at 'I so that the connection li, which forms a nipple, can be screwed therein.

The tubular tail 2, for its part, is tapped at 8 'at its front part in order to enable the connection 4 to be screwed.

A deformable joint 9 forms a seal for the propelling gases between the connection 4 and the body I.

The projectile body I has, at -the rear part thereof, two stepped concentric circular recesses: the large diameter recess I0 is comparatively deep and serves as a housing for the sealing joint 9 (Fig. 2); the inner recess II is shorter.

The connection 4 is screw-threaded at both Yends at 8' and 'I' so that it can screw, on the one hand into the tail 2, and on the other hand into the rear orifice 6 of the body I which it completely closes; said connection is such that it can ber screwed right home in the body of the projectile with a screwing torque which is calculated proportionally to the capacity of deformation of the joint 9 and to the axial travel of the connection 4 when it is being screwed into the body I, and also to the strength of the thread 'I' and the pressure of use and of reception.

The connection 4 is provided with two accurately machined cylindrical bearing surfaces I2 and I3, the respective diameters of which correspond, with a very slight play, to the diameters of the two recesses I 0 and II. Said bearing surfaces serve in the rst place for guiding and centring the connection 4, and consequently the tail 2 when it is being mounted, which is very important in order that the fins shall be accurately in the axis.

The large diameter bearing surface l2 moves like a piston inside the recess II) which acts as a cylinder.

The small diameter bearing surface I3 penetrates inside the recess I I and separates the fluidtight joint 9 from the screw-thread i and makes it possible to prevent said joint from jamming in the screw while it is being tightened, which might cause it to lock; it is long enough to penetrate into its housing I I before the joint 9 begins to be compressed (Fig. 2).

The housing of the fiuid-tight joint 9 is bounded, in the radial direction,A by the inner face I4 (Fig. 3) of the recess I0 and by the periphery I5 of the bearing surface I3, and in the axial direction, by the end I0 of the recess I0 and by the annular face I1 between the bearing surfaces I2 and I3.

When the connection 4 is screwed into the rear orice 9 of the projectile body I, the uidtight joint 9 is compressed more and more between the face I I and the end I6 of the recess I0 which serves as a housing therefor, until the fluid-tight joint 9, which is deformed by the pressure, completely lls its housing, without leaving the slightest possible leak (Fig. 4) The joint 9 being completely compressed, there remains a certain empty space between the front part I3 of the bearing surface I3 and the bottom I'I of the recess II.

The fluid-tight joint 9 shown in Fig. 3 comprises a deformable metal sheath which is circularly slit along one of its sides, at 2|; said sheath contains a plastic material 22 such as cardboard. The existence of the rounded corners of the sheath 20 eliminates any risk of said sheath becoming pinched and jammed between the partitions of its housing while the tail is being screwed on, and little by little it assumes the final shape shown in Fig. 4 in which it completely fills its housing. It then only remains to screw the tail 2 on to the connection 4 until the face I8 comes into contact with the face I9 of the projectile; the tail thus acts as a lock-nut, and if the faces I8 and I9 have been carefully trued, the tail is perfectly centred on the projectile.

A circular expansion groove 23 (Fig. 2) provided on the periphery of the ground bearing surface I2 has the effect of breaking the jet of gases when the shot is fired and breaks its propagation in the direction of the uid-tight joint 9. Said groove also has the advantage of decreasing the bearing surface I2 which is thus easier to construct.

The connecting member 4 is covered with a coat of varnish not shown in the drawing, and a mass of pitch cement 24 lodged in the end of the body I makes the rear part of the projectile still more fluid-tight.

In the embodiment shown in Figs. 5 and 6, the tail 2 and its nipple 25 are in one piece, being assumed to have been machined from a bar.

The details of the fluid-tight joint, the bearing surfaces of the nipple and their housings in the body of the projectile are the same as in the example of Figs. 1 to 4.

The only dierence consists in the fact that, instead of rst screwing home the connection in the projectile, in order to press the fluid-tight joint in its housing, the joint is compressed by means of the tail itself. The construction is simpler, but the mounting and the centring of the tail are not so accurate, since said tail can only be screwed until the joint 9 is completely compressed in its housing; a slight play must therefore remain between the faces I8 and I9, and the tail cannot act as a lock-nut in the manner described in the example of Figs. 1 to 4.

It is obvious thatl the invention has only been illustrated and described by way of example and that, without exceeding its scope, many other embodiments could be constructed.

Having now described my invention, what I claim as new and desire to secure by Letters Patent is:

1. In a projectile equipped with ns, a hollow body provided at the rear with a tapped orifice followed in the outward direction and axially by a. rst cylindrical recess, then by a second rear one of larger diameter and connected at right angles to the former by a flat surface perpendicular to the longitudinal axis of said body, a nipple screwed in said tapped orifice and provided with two ground cylindrical bearing surfaces of different diameters, corresponding to the diameters of said recesses, said surfaces being axially stepped, connected by a iiat surface perpendicular to the longitudinal axis of said nipple and respectively engaged in said recesses and the bearing surface engaged in the first cylindrical recess having an axial length greater than that of said recess so that an annular space of rectangular longitudinal radial section is left in said second rear recess by said nipple, a deformable metallo-plastic fluid-tight annular seal located in said annular space and compressed by said nipple between said flat surfaces, and a tail provided with ns and connected to said hollow body by means of said nipple.

2. A projectile equipped with ns according to claim 1, wherein the length of the small diameter bearing surface of said nipple is such that said bearing surface is already engaged in the corresponding recess of said hollow body before said fluid-tight joint begins to be compressed by said nipple.

3. A projectile equipped with fins according to claim 1, wherein a circular expansion groove is provided on the periphery of the large diameter ground bearing surface of said nipple.

4. A projectile equipped with ns according to claim 1, wherein said metallo-plastic annular seal comprises a malleable metal sheath, provided with a circular slit and having a longitudinal radial cross-section in the form of a horseshoe, the longitudinal axis of which is parallel to the longitudinal axis of said body, and a plastic material in contact with the flat surface of the rear recess of said body through said circular slit.

JOSEPH RAYMOND JASSE.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 737,964 Roach Sept. 1, 1903 1,313,926 Stokes Aug. 26, 1919 1,872,107 Bond Aug. 16, 1932 2,083,658 Napier June 15, 1937 2,315,145 Wauters Mar. 30, 1943 2,362,534 Brandt Nov. 14, 1944 FOREIGN PATENTS Number Country Date 711,463 France June 30, 1931

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