US3064577A - Practice projectile - Google Patents

Description

Nov. 20, 1962 E. W. BRAN DT PRACTICE PROJECTILE Filed March 4, 1957 2 Sheets-Sheet l INVENTOR. By MM- M4 mm Nov. 20, 1962 E. w. BRANDT 3,064,577

PRACTICE PROJECTILE Filed March 4, 1957 2 Sheets-Sheet 2 .EigzS IN V EN TOR.

@MZ M: mm M W 3,064,577 PRACTICE FROJECTILE Edgar William Brandt, Geneva, Switzerland, assignor to Anstalt fiir die Entwickluug von Erfindnngen und Gewerblichen Anwendungen Energa, Vaduz, Liechtenstein, a corporation of Liechtenstein Filed Mar. 4, 1957, Ser. No. 643,815 Claims priority, application Switzerland Mar. 8, 1956 1 Claim. (Cl. 10250) Projectiles are known which, although fired from a gun, are stabilized by a fin assembly and are given a slow rotation (resulting from a low angle of rifling of the weapon) intended to prevent the systematic deviation to which they would be subject if they did not rotate. These projectiles, which are generally fired at supersonic speeds, are often stabilized by a fin assembly of greater diameter than the caliber thereof, i.e. by one which is adapted to unfold on leaving the gun.

A practice projectile of this type has the disadvantage of being expensive, since it is not recoverable, whilst it must nevertheless be made with the same care and with the same margins of tolerance as the corresponding live projectile, in order to comply with the same ballistic conditions as the latter.

The present invention aims at producing a practice projectile which is not only inexpensive but also of simple construction, and strong and accurate in firing, even at supersonic speeds.

A projectile having a fin assembly is stable only if its center of gravity is located forward of, and at a sufficient distance from, the point of application of the air resistance (center of thrust), with a view to increasing the torque tending to keep the projectile continuously in the direction of the trajectory determined by the initial conditions of firing. As a result, it is necessary to make a number of new structural changes and to make a judicious choice of the materials used, in order thus to bring the center of gravity of the projectile as far forward as possible.

The object of the invention is a practice projectile to be fired from a gun, said practice projectile comprising a body, a tubular tail fixed to said body, a fin assembly at the extremity of said tail, a percussion fuze in front of said body, and a marking charge inside said body towards the front end of the tail, said tail constituting an expansion chamber for the gases of said charge, said gases being ejected at the rear end of said tail on impact of the projectile on the target.

By virtue of this construction, in the case of practice at a target having little resistance, for example wooden panels, marking on impact remains visible even if the projectile has already partly passed through the target on the iginition of the charge.

Preferably, the body of the projectile, interrupted near the section of maxi-mum diameter has at this point a rear annular portion normal to the axis of the projectile, through the center of which portion the tail penetrates into the body, the diameter of said tail being substantially less than that of the body.

The rear face of the body may contain a recess to the bottom of which the tail is fastened, the said recess being of a diameter greater than that of .the tail of the projectile so as to provide a peripheral space between the tail and the wall bounding said recess.

A projectile is thus produced, the body of which is reduced to a conical part which is given a high form factor and the rear caliber-size part of which is as light as possible so that, for a given weight of the assembly and a strength compatible with the accelerations and pressures inside the bore, the construction enables the center of 3,064,577 Patented Nov. 20, 1962 gravity to be brought to the vicinity of the section of maximum diameter and hence the projectile to be given the required optimum stability and precision.

According to one embodiment of the invention, the rear part of the body is provided with at least one tracer, eccentric in relation to the axis of the projectile. The projectile on being given a slow rotation on leaving the gun imparts to the tracer a helicoidal movement the result of which is to increase the visibility of the trajectory after the passing of the projectile.

Such a projectile may be provided with a plurality of tracers distributed symmetrically over the rear part of the said body.

In order to enable the invention to be more readily understood, reference is made to the accompanying drawings which illustrate diagrammatically and by way of example, two embodiments thereof, and in which:

FIGURE 1 is an axial semi-section of one embodiment,

FIGURE 2 is an axial section illustrating the operation of the projectile of FIG. 1 on impact on the target and FIGURE 3 is an axial section of a second embodiment.

In FIGURE 1, a conical body 1 contains, at the front, a fuze with a projecting head 2, in the vicinity of the maximum diameter of which is a driving band 3 and said body contains an internal recess 4 widening out from the front to the rear. A tubular and cylindrical tail 5 of substantially less diameter than that of the body, is screwed into the body 1 at the bottom of the recess 4 and said tail is provided, at its rear end with a stabilizing fin assembly 6, terminated by a tracer carrier 7 containing a pyrotechnic compound or tracer 8.

A marking charge 9, housed in a case -10 is held in the front part of the tail 5 by pinching the rim 11 of the case 10 between the front portion of the said tail and a washer 12 bearing against a bearing surface 13 at the bottom of the cavity 4. The case 10 acts also as an obturating means which is able to yield on ignition of the marking charge 9. The body 1 shown in FIGURE 1 may advantageously be made of steel, while the tail 5 and the fin assembly 6 are of light alloy.

The projectile shown in FIGURE 1 is made up into a shell inside a case (not shown on the drawing).

When the projectile illustrated in FIGURE 1 strikes the target (FIGURE 2), the fuze 2 ignites the marking charge 9. The gases of the charge and the smoke pro duced thereby expand in the tail 5 and eject the tracer carrier 7. The result is an opaque cloud, which locates the position of the impact.

In the embodiment shown in FIGURE 3 the marking charge 9a is disposed, not in the tail, but inside an axial recess provided in the body 1a. Thesaid charge 9a is held in position by an obturator or obturating means 14, which is in turn locked by screwing the tail 5 into the body 1a. Two diametrically opposite tracers 15, 16 are arranged in corresponding orifices at the rear of the body 1a. On firing, the propulsion gases impart the ignition to the tracers 15, 16. It will further be noted that the pressure of the gases is exerted simultaneously on the two faces of the tail 5, since it is open to the rear, this latter arrangement enabling the tail to be lightened in weight.

What I claim is:

A practice projectile to be fired from a gun, said projectile comprising a conical body, a percussion fuse on the front end of the body, said body having its maximum diameter at the rear end, said rear end having a recess of substantial depth flaring toward the rear, a driving band mounted on said body opposite the point of maximurn diameter of the recess, a cylindrical hollow tail fixed in said body in advance of said recess and of lesser 3 7 diameter than that of the smaller end of the recess, and 1,316,296 a fin assembly mounted on the rear end of the tail. 1, 27,372 2,338,137 References Cited in the file of this patent 2,801,586

UNITED STATES PATENTS 5 1,005,578 Schneider Oct. 10, 1911 443,451 1,011,863 Semple Dec. 12, 1911 1,077,082

1,159,653 Cushing Nov. 9, 1915 4 Gathmann Sept. 16, 1919 Bessiere Ian. 6, 1920 Shea Jan. 4, 1944 Mongello Aug. 6, 1957 FOREIGN PATENTS Great Britain Feb. 28, 1936 France Apr. 28, 1954 France Sept. 10. 1956

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