US2103155A

US2103155A - Projectile

Info

Publication number: US2103155A
Application number: US10974A
Authority: US
Inventors: Willing B Foulke
Original assignee: Hercules Powder Co
Current assignee: Hercules Powder Co
Priority date: 1935-03-14
Filing date: 1935-03-14
Publication date: 1937-12-21
Anticipated expiration: 1954-12-21

Description

Dec. 2 1, 1937. W, B, FOULKE; ZBSS PROJECTILE Filed March 14, 1955 Patented Dee. 2i, l i

' STA enr a claims. (ci, roamed This invention relates to an lmprovement'in projectiles and more particularly to projectiles or bullets `ior small arms, and more particularly for rifles, machine guns, anti-tank guns, and

5 the like.

' For many years rifle bullets were formed from lead or lead alloy. However, the lead or leadv reference to the eiiect of pressures, developed on i burning of the powder charge, upon the'bullet within the barrel of the gun and the effect of the atmosphere upon the bullet after it leaves the barrel, all with a view to obtaining a maximum of eiliciericy from the standpoint or range, penetration and accuracy. It is recognized that the most modern military riflebullet, which may be' exemplied by the 173 grain cal. Springfleld rie bullet of the so g5 called 9 degree boat tail type and comprising a lead alloy core jacketed with a copper alloy, will not stand muzzle velocities above about 3000 feet per second. Y

As is well known', a rie barrel, extending from 3o a chamber adapted to receive a cartridge, is grooved or rifled in order that the bullet forced through the barrel by the gas 'pressure developed r by the burning of gun powder will be given a rotary motion so that on' leaving the barrel it will not gyrate. In usual practice a progressive or slow burning gun powder is used to the end that pressure is built up behind the bullet as it travels through thebarrel to the end that it will lproceed with increasing velocity through the 40 barrel.

In passing through a rifle barrel the bullet, which is of a diameter equal to the maximum diameter, vgroove diameter, of the barrel from the bottoms of the rifling grooves, is initially en- 4.5' graved or threaded by the riding to conform vtherewith'throughout its cylindrical body portion, as compared with its point and tail portions, :zand is, as it were, squeezed through the ,barrel and discharged therefrom with a rotative motion,

-- 0 as `well as a forward velocity.

In ,the barrel the bullet is subjected to friction and, due to the great pressure behind it, has a i tendency vto ll out into the barrel, or upset,

l wherethe barrel has increased in diameter due 56 to the increasingr pressure. Again,- tlire if; a

tendency for a bullet to elongate on entering the rifling from the action of gas escaping around it, which subjects its cylindrical portion as well as its base to tremendous pressure, which causes the point, not in the high pressure area, to pro 5 gress faster than the base, or, in other words, for the bullet to be, as it were, extruded in the bar rel and miss the riing, with the result that the gas leakage increases with loss of velocity to the bullet and accuracy decreases due to lack of spin. l)

Due to the friction, upsetting or elongation of the bullet and also due to various gas leaks around the shell or cartridge, to "neat losses lay-radiation, convection and absorption from and'by the rifle and to a degree by the bullet, to the alr'resistance i5 in the barrel and to the rotative inertia of the bullet, large loss of energy made available by the burning of the 'powder charge occurs, with the result that bullet velocity is limited and accuracy is below a maximum ad The maximum muzzle velocity of the present modern bullet is further limited by its lack of capacity to resist the i'oroes acting upon it at velocities such that the forces, tending, more particularly, to upset the bullet, are in excess of 25 the elastic limit of the copper alloy jacket; and by the necessity for entering the bullet into the rifling with reference to its rotative inertia with== out stripping.

In the atmosphere the bullet in its flight is 3o hindered, or its energy absorbed, by the necessity for displacing air as it progresses, by the vacuum formed at its base due to its rapid flight, by the skin friction between the bullet and the air, by a boundary Vlayer of air which the bullet carries, a5 and by its gyration in the air, which results from its deformation under the forces acting upon it in the barrel or arising i'rom a rotative and/or forward muzzle velocity resulting in forces exceeding ythe elastic limit of the material from fio which it is formed.

Now in accordance with this invention there is provided a bullet,A more especially for small arms, as ries, machine guns, anti-tank guns, and the like, which is of a novel design such that losses of energy within and without the barrel suilered in connection with use of the most modern bullets heretofore known will be minimized and, at the same time. such as to permit of greatly-increased velocities irom the energy developed by 5@ the powder charges used heretofore and with use of heavier powder charges than were practical for' use with prior bullets.

The bullet in accordance with this invention will, generally speaking, be formed from a ma a5 terial having an elastic limit in excess of the forties acting to upset or elongate it and to deform it in its passage through the barrel and will have a form such as to largely eliminate the negative forces tending to retard its iiight.

More particularly, the bullet in accordance with this invention will comprise a body portion, a tail vor'base portion of suitable shape and a point of suitable shape, and will be provided with a forward and a rear riiling band.

Essentially, the riiiing bands will be positioned so that the rear edge of the forward riing band and the forward edge of the rear band will be equidistant from the center of mass of the bullet, and the diameter of the bullet throughout will be less than the bore diameter by anamount greater than the diilerence between the bore and groove diameters.

Having now indicated in a general way they nature and purpose of this invention, I will now proceed to a detailed description thereof With reference to the accompanying drawing, in which:

Figure 1 is a side view of a bullet embodying this invention. I

Figure 2 is a side view of the bullet, showin in Figure l, in flight.

Figure 3 is a cross-sectional view of a rie barrel with the relative diameter of the barrel and bullet exemplied.

'Ihebullet illustrated comprises a body A, a point B, and a base or tail C and 'is equipped with a forward riiing band D and rea-r band D', which is grooved as at e.

The point B of thebullet may be of any deaired shape. Thus, for example, the point may be ogival, as shown in full lines, Figure 1, or it may have the form shown in dotted lines Figure l.

The base or tall C may be of any desired shape. Thus, for example, it may have the so-called boat tail shape as shown. f"

'I'he bullet may be constructed of any suitable material having an elastic limit such asto with' stand the forces acting upon it at high velocities. For example, the bullet may be formed from a cupro-nickel alloy having various proportions of copper and nickel, depending upon the type of arm or upon the' caliber or shape of .the bullet.

The rif-ling bands D and D' may be made of any suitable material adapted to take the riiiing of a gun barrel and the bands may be formed separately or integral with the body of the bullet, depending upon the material from which the bullet is formed and the anticipated velocities..

Thus, for example, the bands may be formed of guilding metal, Monel metal, cupro-nickel alloy. etc.

Where, for example, the ,bullet body is formed from steel, the rling bands will be formed separately and applied to the body, shoulders f, g being formed to prevent slipping of the bands respectively. The shoulder f will be lower than the shoulder-a and the hand D" will be4 bored to'pass overthe shoulder f for application. Again, where the bullet is formed from a metal, such as Monel metal, the riing bands may be formed integral with the body, without the necessity for forming the shoulders f and a by, for example, turning the bnllet'and bands to form from a blank. y

As has been indicated, the bands, whether they are formed separately and applied to the body of the bullet, or formed integrally therewith, win be so positioned that the rear edge d of the forward band and the front edge d'of the rear band will be spaced equidistant from the center of mass of the bulletindicated at X,

Figure l.

The body of the bullet will, as has been. in-

in diameter than the difference in the diameters of the barrel, i. @between the lands and between the grooves; and even more preferably the di ameter of the bullet will be not -more than twothirds ofthe bore diameter of the barrel, i. e.

between the lands. l l

As illustrative, for example, a practical comparison between the diameter of a .30 cal.

p Springfield riiie bullet andthe diameter of the riiie barrel is shown in Figure 3, in which H indicates a rifle barrel, the lands and grooves of the rifling being indicated by i and i, respectively. A indicates the body of a bullet within the barrel, the rifling bands on the bullet being omitted, it being thought unnecessary to illustratetheir well Iknown relationship with the riiilng. In the showing of Figure 3, the rifle will, for example,4 have a maximum diameter, between the grooves, of about .309 inch and a minimum di ameter, between the lands, of about .301.inch. It follows that the groove depth is .004 inch and that the difference in diameters is'.008 inch.

Now, the diameter of the bullet in accordance' with this invention will be, for example, .290 inch, i. e. .D11-inch less than .301 inch, the minimum diameter oi' the barrel, i. e. between the lands. As has been indicated,4 the body of the bullet will desirably be. considerably less in diameter than the minimum diameter of the barrel, as, for example, of a diameter two-thirds or less of the minimum or bore diameter of the barrel. For example.' in the illustration given with reference to Figure 3, the diameterI of theA body of the bullet may be .200 inch or less.

In consequence of the material, form and relative proportions with respect to the rifle barrel of the bullet in accordance with this invention. the bullet may be subjected to greatly increased pressures in the riile barrel and will withstan greatly increased velocities.

On the firing of the bullet in accordance with this invention, the forward' riding band D,lwill enter and be engaged by the rifling while the bullet is traveling at its slowest speed'and has as a consequence a low turning moment. As a con-4 sequence, the forward band may Vbe 'relatively short longitudinally and due to its'shortness will be readily engraved and enter the trifling without gaged with the riing and before the engagement of the rear band D', gas will have escaped past the base of the bullet and will enter the barrel where, since the pressure will be relatively'low..

for-

it will be stopped by and readily held by the ward band which has taken the riiiing.

The rear band will engage therifling shortly after engagement by the -forwardA band, 'and it will be noted that the rear band will engage on a spiral generated by the forward band.v Con-j Lil arcaica sequently, stripping edect on the rear band due to jp will be avoided.

The rear band, since it must piel; up the main load of the turning moment of the bullet as the maximum. gas pressure is exerted and the bullet increases in velocity, is made of greater extent longitudinally than the forward band. The rear band is desirably also provided with the groove e in order that the band may be wiped toward the rear by the riding in two steps without deforming the band throughout its entire longitudinal extension. 'Ille groove e also acts as a secondary gas seal.

The gas entering the barrel ahead of the rear band D will be trapped between the bands and gas will also be trapped in the groove e. The pressure of the trapped gas will be lower than the ultimate pressure behind the rear band. However, it will oiset the ultimate pressure and reduce the tendency of maximum ultimate pressures to upset the rear band. Again, the pressure of gas trapped between the front and rear bands will offset the tendency oi pressure developed in the barrel ahead of the bullet (from the column of air inthe barrel)` to upset the forward band. l

Since the diameter of the body of the bullet in accordance with this invention is substantially reference to the length of the body of the bullet and as a consequence since the body is entirely free of the barrel the frictional resistance to the bullets passage through the barrel is at a. minimum.

The bullet in accordance with this invention will not upset or elongate in thek barrel and as a consequence leaves the barrel without deformation from its true shape.

'I'he bullet on leaving the barrel will travel through the air with a rotary motion and, since with any type of bullet it has been found impossible to have the center of gravity of the bullet exactlyon the axis of the bore, the bullet will travel on a spiral. However, in the case of the bullet according to this invention, the angle of the spiral will be at a minimum, due to the lack of deformation in the barrel (upset and elongation) taken with .accuracy in formation of the bullet.

The action of the bullet in its travel after leaving the muzzle is indicated in Figure 2, from which it will be noted that the point B entering the air l ahead of it at high velocity drives the air aside and forms a partial vacuum about the point of the bullet, which offsets the eect of the partial vacuum area o behind the base. A boundary layer of air, indicated at m, however, tends to travel with the bullet about its point, behind the point n at which the air flows oil. the body, and to retard its velocity and interfere with yits accuracy. This boundary layer of air is removed in the initial night of the bullet by the action of the engraving by the riding on the forward band D, since the engraved band acts in effect as a high speed centrifugal pump and discharges the boundary layer, as indicated by the lines p.

It will be appreciated that the projectile or bullet of this invention is contemplated as capable of withstanding velocities very substantially higher than are obtained with bullets heretofore known and that the bullet, aside from its formation and the formation of its rifling bands from material having an elastic limit greater than the forces acting on the bullet and bands, respectively, derives its capacity essentially from the relative diameter of its body with respect to the minimum diameter of the barrel through which it is to be fired, and from the arrange-v ment and location of the riing bands.

Et will be appreciated that the particular material of which the bullet and -bands are constructed will be selected in view of the velocity and hence the forces to which it is to be subjected.

Generally, it will be appreciated that the bullet in accordance with this invention is contemplated ior use in any calibre and type of gun for which it may be adaptable.

What l claim and desire to protect by Letters Patent is: f

l. A projectile adapted for high velocities cornprising a body portion and riiiing bands having a high tensile strength, the'body portion being throughout of a diameter less than the bore diameter of the barrel of the gun for which it is intended by an amount in excess of the difference between the groove and bore diameters ofthe barrel, and shoulders on the body portion in engagement with the bands to prevent rearward movement thereof.

2. A projectile adapted forhigh velocities coma high tensile strength, the body portion beingV throughout of a diameter less than two thirds of the bore diameter of the barrel of the gun for which it iseintended, and shoulders on the body portion in engagement with the bands to prevent rearward movement thereof.

4. A projectile adapted for high velocities comprising a body portion and rifling bands having a high tensile strength, the body portion being formed from a metal from the group consisting of steel Monel metal and copper-nickel alloy and being throughout of a diameter less than the bore diameter of the barrel of the gun for which ameter of the barrel of the gun for which it is intended by an amount in excess of'the dierence between the groove and bore diameters of the barrel and the rifling bands having a high tensile strength and comprising a front band and a rear band, the front edge of the rear band -andv the rear edge front band being spaced equidistant from the center of mass of the projectile, and shoulders on the body portion in engagement with the bands to prevent rearward movement thereof.

6. A projectile adapted for high velocities comprising a body portion formed from materials having elastic limits in excess of the forces acting thereon on firing, the body portion being throughout of a diameter less than the bore diameter of the barrel of the gun for which it is intended by an amount in excess of the difference between the groove and bore diameters of the barrel and the riiiing bands having a high tensile strength and comprising a front band and a rear band, the front band being of substantially less extent longitudinally than the rear band, and shoulders on the body portion in engagement with the bands to prevent rearward movement thereof.

7. A projectile adapted for high velocities comprising a body portion formed from materials having elastic limits in excess of the forces acting thereon on firing, the body portion being throughout of a diameter less than the bore diameter of the barrel of the gun for which it is intended by an amount in excess of the dierence between the groove and bore diameters of the barrel and the rifiing bands having a high tensile strength and comprising a front band and a rear band, the rear band being of substantially greater extent longitudinally than the front band and having a circumferential groove dividing its surface into two sections, and shoulders on the body portion in engagement with the bands to prevent rearward movement thereof.

8. A projectile adapted for high velosities comprising a body portion and riiiing bands having a high tensile strength, the body portion being formed of steel and being throughout of a diameter less than the minimum bore of the barrel of the gun vfor which it is intended by an amount in excess of ythe dierence between the groove and bore diameters of the barrel and the rifling bands being formed from a cupro-nickel alloy.A

9. A projectile adapted for high velocities comprising a body portion and riing bands having a high tensile strengthdntegral with the body, the body portion and the riiling bands being formed of Monel metal and the body portion being throughout of a diameterl less than the bore diameter of the barrel of the gun for which it is intended by an amount in excess of the difference between the groove and bore diameters of the barrel.

WILLING B. FOULKE.