US2661691A - Projectile - Google Patents

Description

E. w. B'RAN DT Dec. 8, 1953 PROJECTILE 2 Sheets-Sheet 1 Filed Jan. 4, 1950 Fig.1

' INVENTOR.

BY M QZ $4416 ATTORNEYS.

E. W. BRANDT Dec. 8, 1953 PROJECTILE 2 Sheets-Sheet 2 Filed Jan. 4, 1950 INVENTOR.

ATTORNEYS.

Patented es. 8, 1953 PROJECTILE Edgar William Brandt, Geneva, Switzerland, as-

signor to Anstalt fiir die Entwicklung von Erfindungen und gewerblichen Anwendungen Energa, Vaduz, Liechtenstein, a corporation of Liechtenstein Application January 4, 1950, Serial No. 136,824

Claims priority, application Switzerland January 17, 1949 '7 (Claims.

This invention relates to a self-propelled pro- .iectile which is stabilized during its trajectory by the provision of a tail.

It has the advantage that it can be fired from a portable weapon with no recoil and has such a performance that its use considerably increases its defence value.

These advantages are the result of a judicious combination of efiects of the external and internal ballistics of the projectile, as will hereinafter be explained.

The projectile according to the present invention includes a self-propelling device consisting of a tubular combustion chamber containing the propellant and including at its end a nozzle assembly, its external terminal part acting as a tail carrier for stabilizing blades of the same calibre as the projectile.

Preferably, the blades are arrange in pairs, each pair of blades being arranged obliquely and symmetrically with respect to the longitudinal axis of the projectile. Experience has shown that for the same calibre of projectile and tail this arrangement of the blades, by alternate inclination, imparts to the projectile a far greater stabilizing power than that which would result from an ordinary straight tail. This phenomenon is accounted for by the carrying effect arising from the contraction of the air streams between two converging blades and by the vacuum created between the diverging ones.

In accordance with a further feature of the invention, at least one nozzle of the self-pro-' pelling device includes on its internal face an eccentric conical recess so directed as to impart to the projectile a slow rotation in relation to its linear speed. This rotation prevents any deviation of the projectile, such as might be caused by manufacturing irregularities, machining tolerances, as well as by a variation of the discharge of the nozzles as between themselves, because the ei'iect of these asymmetries on a tailed projectile tends systematically to cause it to deviate from the trajectory imparted to it so that a rotation or gyraticn, even a slow one, corrects these errors by causing the projectile to follow a helicoidal movement around its theoretical trajectory.

In addition, this gyration still further increases the action and the stabilizing power of the tail.

In accordance with the invention, experience shows that the best stabilizing effect on the one hand and the smallest dispersion on the other hand, result from an inclination of 2 to of the blades as between themselves for an initial speed of the projectile ranging from to 300 metres per second.

Accuracy of the projectile in use depends to a reat extent on careful manufacture and on the regularity with which the blades are distributed around the periphery of the combustion chamber containing the propellant. Thus, in accordance with one feature of the invention, the tail is made as a single unit and secured on the projectile by the nozzle carrier.

Finally, in accordance with another feature of the invention and in order to endow the construction of the projectile with still greater accuracy, it is advantageous that the tail and the nozzle carrier should constitute a single unit; the direction of the nozzles always remaining the same in relation to the stabilizing blades.

The gyration of the projectile is started at the beginning of the self-propulsion, i. e. in the weapon which fires said projectile, and in accordance with still a further feature of the invention, the blades which are inclined in the direction of rotation of the projectile are formed of a height greater than that of the other blades so that only the former have the calibre of the firing weapon.

This precaution is justified by the fact that the blades of greater height are initially disposed to conform with the helicoidal trajectory which they will follow on firing. On the other hand, the other blades, the inclination of which is symmetrical with respect to the blades of greater height, are prevented from grazing the inside of the weapon and thus setting up parasitic irregular frictions which are harmful to accuracy.

In accordance with another feature of the invention, the nozzles are arranged in known manner, obliquely in relation to the longitudinal axis of the projectile. The result is that the gases diverge on ejection and it is thus possible, without danger to the firer, to propel the projectile after its exit from the weapon.

Regularity of firing however is only possible if the self propulsion imparts to the projectile a well defined initial speed. This result is achieved,

in accordance with another feature of the invention, by closing each of the nozzles by a membrane which collapses only when the pressure of the ases inside the tubular combustion chamber reaches a predetermined value, which is itself a function of the thickness of the said membranes which, for equal resistances, collapse simultaneously. It is, however, advantageous to provide two or more additional safety nozzles arranged symmetrically on the periphery of the nozzle carrier and closed by a membrane having a resistance greater than that of those which close the other nozzles. The safety nozzles are intended for opening only in case of abnormal rise of pressure.

This important feature has the advantage that the Projectile may work regularly at any latitude, irrespective of the prevalent temperature. Indeed, in hot countries, where the projectiles will often be transported, and sometimes even stacked in the sun, the auto-propulsion powder will burn more briskly. It will be understood that in such circumstances the pressure of the gases in the combustion chamber might reach, at the time of firing, an unusually high value. However, by virtue of the safety nozzles which, in this case, would operate a fraction of a second after firing, the inside combustion chamber pressure will not reach dangerous proportions capable of causing the tail of the projectile to burst.

The upper pressure limit being thus determined, this precaution will enable the wall of the combustion chamber to be of a thickness smaller than that of ordinary projectiles of the same type required to work in similar conditions.

The result will be a decrease in weight of the rear of the projectile and, consequently, an increase of the stabilizing power. This decrease in weight will also cause an increase in speed of the projectile.

In addition, the membranes closing the safety nozzles may be covered, on their inside face, by insulating washers, for example, of cork, which are intended to keep constant the resistance of the said membranes, which are insulated from the high rise in temperature taking place inside the combustion chamber as soon as the propulsion agent is ignited.

In accordance with an alternative embodiment, each membrane is kept on its seat, provided in the corresponding nozzle, by means of a part made of a heat-resistant material which constitutes the collar of the nozzle. For this purpose, it is possible to use, for instance, a steel collar and to make the remainder of the nozzle of a light material such as an aluminum alloy, which proportionately decreases the weight of the self-propulsion nozzle carrier.

The self-propelling device preferably includes, between the propellant (sticks of powder, for instance) and the nozzles, a grid adapted to act as a filter to damp the jet of fire. This grid constitutes an annulus, the section of which is in the shape of a double-vault, the convex portion of which is preferably turned towards the front of the projectile.

Other advantages and features of the invention will clearly appear from the following description, when read in conjunction with the accompanying drawings, given merely by way of example and in which Fig. 1 shows a general view of one embodiment of projectile in accordance with the invention;

Fig. 2 is a rear view representing the arrangement of the nozzles and of the tail;

Fig. 3 is a cross section on the line 3-3 of Fig. 2;

Fig. 4 is a longitudinal section of the self-propelling device on the line 4-4 of Fig. 2;

Fig. 5 is a transverse section taken along the line 5-5 of Fig. 1;

Fig. 6 is a longitudinal section showing the front part of the propellent combustion chamber;

Figs. 7 and 8 illustrate, in cross section, the

23 alternative embodiments of the device shown in Fig.4; and

Figs. 9 and 10 show the closing of the safety nozzles.

As shown in Fig. 1, the projectile includes a nose fuze I, a casing 2 which contains the explosive charge and the usual devices and a tail 3 designed as a tubular combustion chamber carrying the tail blades 4, 5. The tail blades are grouped in pairs and arranged in such a way that each of the blades 4 is at a constant angle with respect to the adjoining blade 5, this angle be ing a function of the speed of the projectile along its trajectory.

It should be noted that the diameter of the tubular combustion chamber 3 is greater than half the calibre of the projectile, so that the height of the blades is necessarily limited.

The alternate inclination of the blades is clearly visible in Fig. 2, which is an end view of the projectile seen from the rear. The part 6 carries peripheral nozzles I closed internally by membranes 8. Each of the nozzles 1 includes, in addition, a conical milled recess 9 (Fig. 3), imparting to the projectile a slow rotation in the direction of the arrow. This feature of the construction facilitates machining and leads to an appreciable saving in weight.

The membranes 8 are held between a seat formed on the inside periphery of the nozzle 1' and a collar I0 constructed of a material of high heat resistance, such, for example, as steel, whilst the nozzle carrier is machined or cast in aluminum or any other light alloy. A sensitive primer cap II, fixed in the primer carrier I2, serves to ignite the powder l3 and a relay charge I3a contained in a socket I4, laterally drilled to give access to the propellant I5, shown in Figs. 4 and 5 in the form of hollow cylindrical sticks. These sticks I5, arranged annularly around the central tube I l, rest on a circular grid iii, of which the section is in the shape of a vault, the convex portion of which faces towards the front.

The openings H of this grid are distributed laterally and prevent the ejection into the nozzles of unburnt particles of propulsive powder.

As shown in Fig. 6, the front end of the combustion chamber 3 is screwed to the coupling I8 which, in turn, is screwed to the body I9 of the projectile, a part of which is shown at 29. It should be noted that the propellant I5 does not fill the combustion chamber completely but that an extension of the latter forms a complementary chamber H. The volume of this is so determined as to prevent an excessive increase of the internal pressure, for instance under the influence of a high outside temperature which, but for the safety nozzles, might go as far as to cause the tail of the projectile to explode. The securing ring 22 holds the sticks It in place at their front ends.

As shown in Fig. 7, the tail blades :i, 5 are made as a single unit, for instance, of plastic material, the low density of which advantageously reduces the weight of the rear of the projectile. The tail is forced onto the tubular combustion chamber 3 or is secured by gluing by means of a suitable coating, and is held at the rear by the nozzle carrier 6.

Another feature of the invention consists in the use of an auxiliary striker 23 operating after the fashion of a valve and protected at the rear by a membrane 24. This improved arrangement prevents the rearward ejection of the jet of fire created by the powder I 3, the effect of which is then solely devoted to the ignition of the propellant 55.

The embodiment shown in Fig. 8 differs from that of Fig. 7 in that the nozzle carrier 5 is formed as a single unit with the tail blades t, 5, which advantageously simplifies the construction.

Figs. 9 and 16 show the safety nozzles symmetrically arranged either in pairs or in groups of three in accordance with the total number of peripheral nozzles provided on the projectile; the membranes 8a are more resistant than those which adjoin them and only give way when the internal pressure in the combustion chamber exceeds the permitted limit.

In order to complete the steps tending to ensure a steady state of self-propulsion and perfect safety, it is advantageous to provide the tubular combustion chamber 3 with an internal insulating lining 25 (a cardboard sheet, for instance) and with an external coating decreasing the absorption of heat by radiation (for instance, a coat of white paint).

The hereinbefore described projectile operates as follows:

On firing, the striker of the fire-arm (not represented) hits the primer H (eventually the membrane 21; and the striker 23, Figs. 7 and 8) which fires the ignition powder 13, 13a which, in turn, uniformly fires the sticks 15.

The self-propulsion of the projectile then starts in the gun barrel under the reaction effect of the gases ejected by the nozzles E, and the projectile at the same time acquires a gyratory movement, obtained either by the asymmetrical action of the gases acting inside the nozzles and provided for this purpose, or by the suitable inclination of said nozzles.

The propellent charge, the rate of combustion of the powder and the discharge of the nozzles are so combined that the linear speed and the gyratory speed of the projectile, at the gun muzzle, are at least equal to half of the corresponding speeds achieved at the end of the combustion of the said charge.

I claim:

1. In a rocket projectile, a combustion chamber for a propelling charge, stabilizing fins on said chamber, each two successive fins being arranged obliquely and symmetrically with respect to an intermediate plane containing the longitudinal axis of said projectile.

2. In a rocket projectile, a combustion chamber for a propelling charge, stabilizing fins on said chamber, each two successive fins being arranged obliquely and symmetrically with respect to an intermediate plane containing the longitudinal axis of said projectile, any pair of two successive fins presenting between themselves a constant angle, greater than two and smaller than ten degrees, for an initial speed of the projectile ranging from 100 to 300 meters per second.

3. In a rocket projectile, a combustion chamber for a propelling charge, stabilizing fins on said chamber, each two successive fins being arranged obliquely and symmetrically with respect to an intermediate plane containing the longitudinal axis of said projectile, one fin of each pair of two successive fins having a greater radial height than the other fin of said pair.

4. In a rocket projectile, a combustion chamber for a propelling charge, stabilizing fins on said chamber, each two successive fins being arrange obliquely and symmetrically with respect to an intermediate plane containing the longitudinal axis of said projectile, one fin of each pair of two successive fins having a greater radial height than the immediately adjacent one, said greater fin being inclined in the direction of rotation of the projectile.

5. In a rocket projectile, a combustion chamber for a propelling charge, stabilizing fins on said chamber, a plug at the rear of said chamber, and a series of nozzles in said plug, each of said nozzles including on its internal face a rearwardly directed conical recess, said recess being located on the part of said internal face opposite to that which is directed in the sense of rotation of the projectile, said recess imparting a rotation to the projectile.

6. In a rocket projectile, a combustion chamber for a propelling charge, stabilizing fins on said chamber, a plug at the rear of said chamber, and

a series of nozzles in said plug, each of said nozzles including on its internal face a rearwardly directed conical recess, said recess being located on the part of said internal face opposite to that which is directed in the sense of rotation of the projectile, the axis of said recess being parallel to the axis of the projectile in order to impart a rotation to the projectile.

7. In a rocket projectile, a combustion chamher, a propelling charge in said chamber, said charge being constituted by cylindrical powder grains, an annular grid inside said chamber at the rear of the propelling charge, said grid having in the axial section the form of a double vault, the convex portion of said double-vault being directed toward the front of the projectile, said convex portion acting externally as a support for each of said powder grains.

EDGAR WILLIAM BRANDT.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 53,933 Hale Apr. 10, 1866 579,035 Bell Mar. 16, 1897 2,145,508 Denoix Jan. 31, 1939 2,412,173 Pope Dec. 3, 1946 2,479,718 Bjork et al Aug. 23, 1949 2,494,026 Anderson Jan. 10, 1950 FOREIGN PATENTS Number Country Date 2,554 Great Britain of 1877 114,144 Australia Oct. 28, 1941 594,513 Great Britain Nov. 13, 1947

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