Projectile having a tubular body

A projectile comprises a tubular body and a sabot or impact base connected to the rear portion. The tubular body is connected to the sabot by radially extending pins, and the rear face of the body is spaced from a circular shoulder of the sabot by a distance equal to, or larger than, the diameter of the pins. To ensure a transfer of the spin of the sabot to the body, the rear face of the body is provided with a corrugation, such as teeth, or a knurling, which, at the discharge and after the pins are sheared off, digs into the surface of the circular shoulder.

FIELD AND BACKGROUND OF THE INVENTION 
This invention relates in general to the construction of projectiles and in 
particular to a new and useful projectile having a tubular body which is 
connected to an impact base. 
German OS No. 27 53 633 discloses a projectile to be fired at a supersonic 
velocity, comprising a tubular body having a substantially circular cross 
section, an inlet opening in the front, an outlet opening in the rear, and 
a central bore extending therebetween. Connected to the rear portion is a 
drive member with a sabot ring. The sabot ring is detached after the 
discharge by centrifugal forces. Due to the dynamic pressure built up in 
the interior of the projectile, the drive member is then pushed away 
therefrom. Since the sabot ring must be adjusted, the tubular body must be 
fitted to the drive member, and an annular lip must be provided serving as 
a gas seal during the firing, the projectile is relatively expensive and 
requires many accurately machined parts. 
Further, the inwardly protruding rear portion of the tubular body produces 
an unfavorable effect on the flow conditions about the projectile. 
In the projectiles with a tubular body, the so called tube projectiles, the 
aerodynamic flow conditions are of primary importance. A smooth flow along 
the body in the supersonic region is obtained only if constructional 
elements are provided which do not cause turbulence. 
SUMMARY OF THE INVENTION 
The invention is directed to a tubular body which can be fired at 
velocities in the upper supersonic range, is simple in design and produces 
optimum flow conditions. 
In accordance with the invention, a projectile comprises a tubular 
projectile body having a rear portion which is connected to an impact base 
which has a forward portion connected to the rear portion and has an 
exterior surface with an annular groove with a rotating band in the 
groove. The projectile body is of a size formable to the forward portion 
of the impact base and for example engages snugly over the forward end of 
the base. The two parts are positively locked together by interrengageable 
elements such as a shearing pin, flange or the like. Preferably the rear 
face of the projectile body is spaced away from a raised circular shoulder 
of the impact base. The rear face and the circular shoulder are spaced 
from each other by an axial distance which is preferably equal to or 
larger than the diameter of the shearing pins. The shearing pins include 
one or more, for example, four equally circumferentially spaced pins which 
extend through the projectile body and into accommodating bores of the 
impact base. 
Advantageously, the rear face of the projectile body is provided with a 
corrugation or knurling or teeth formations which engage into the circular 
shoulder of the impact base after the pins are sheared so that the impact 
body imparts a spinning rotation to the projectile. Advantageously the 
material of the projectile body is harder than that of the impact base. 
The impact base may be made of a plastic material. 
To obtain the required effect, the projectile is fired by means of a sabot 
which is connected to the tubular body in the most simple way. Depending 
on the rifling, the provided axial spacing may be omitted, and the pins 
are then sheared off under the effect of rotary acceleration. The sabot 
carries the rotating band and is provided with an engagement groove for 
the charge case. 
This makes it possible to employ conventional propellant cases and to 
provide the usual method of connecting the shell to the case. 
Advantageously, the sabot may be of such shape that the tubular shell body 
remains cylindrical in its rear portion, i.e. the wall thickness thereof 
does not change. The tubular shell body is connected to the sabot through 
radially engaged pins ensuring a satisfactory handling and loading of the 
projectile. At the discharge, the pins are sheared off, so that the 
tubular body can butt against the circular shoulder of the sabot. With a 
sufficient spin, the pins are sheared off due to the unequal taking up of 
the spin by the sabot and the tubular body. Advantageously, and in a 
simple way, the spin is transferred from the sabot to the tubular body 
through a corrugation provided on the rear face of the tubular body. As 
the projectile is fired, the tubular body impinges on the sabot, with the 
corrugated rear face penetrating into the opposite softer shoulder, thus 
ensuring a transmission of the spin. 
In a preferred construction of the invention, the impact base or sabot is 
made of a plastic material and has its forward portion formed integrally 
with radial pins which extend outwardly and engage into bores provided in 
the projectile body. 
The so-called tube projectiles are relatively very stable. Conventional 
barrels, which are not specially designed for tube projectiles, would 
therefore impart to such a projectile a spin by far exceeding the rotation 
needed for stabilization. That is why it is advantageous to partly reduce 
the spin transfer, so as not to unfavorably affect the aerodynamic and 
ballistic conditions. 
To enlarge the space for the charge, and also to reduce the masses to be 
accelerated, the sabot may be provided in its rear with a blind bore. 
Further, a hood or ogive provided with rated breaking areas may be engaged 
onto the forward portion of the tubular body, to protect the projectile 
during storage and handling. At the firing, the hood is broken up at the 
rated areas. 
To avoid damages to the sabot of plastic material at certain discharge 
accelerations and certain wall thicknesses of the tubular projectile body, 
the sabot includes an end portion which carries a metallic intermediate 
ring comprising a collar which fits the sabot and is axially spaced from 
the rear face of the rear portion of the tubular projectile body. The 
intermediate ring is firmly connected to an extension of the sabot by a 
force fit. The metallic intermediate ring thus forms a buffer which is 
connected to the extension or forward portion of the sabot. 
Accordingly, it is an object of the invention to provide an improved 
projectile which has a tubular projectile body and a rear portion and 
including an impact base having a forward portion connected to the rear 
portion which has an exterior surface with an annular groove in which a 
rotating band is positioned, the rear portion of the tubular body and the 
impact base being of a size and shape conformable to each other which 
permit interengagement and with further including means for positively 
locking the base to the projectile body. 
A further object of the invention is to provide a projectile which is 
simple in design, rugged in construction and economical to manufacture. 
The various features of novelty which characterize the invention are 
pointed out with particularity in the claims annexed to and forming a part 
of this disclosure. For a better understanding of the invention, its 
operating advantages and specific objects attained by its uses, reference 
is made to the accommodating drawings and descriptive matter in which 
preferred embodiments of the invention are illustrated.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring to the drawings in particular the invention embodied therein a 
comprises a projectile which has a tubular projectile body generally 
designated 1 and has a rear portion 6 including an impact base or sabot 8 
connected to the body 2 at its rear portion 6 which has an annular groove 
14 with a rotating band 15 therein. Means 9 in the form of shearing pins 
provide a positive locking of the base to the projectile body. 
The inventive projectile 1 comprises a tubular body 2 which, except for its 
front end portion, is cylindrical over its entire length, i.e. has a 
constant wall thickness. The invention covers also other tubular bodies. 
At the front end, the inside diameter of the body diminishes from a 
frontal bite edge 3 over a slight taper 4 to a continuous inner bore 5. 
The rear portion 6 having a constant inside diameter of tubular body 2 is 
fitted over a correspondingly shaped forward portion 7 of the sabot 8. 
These two parts are connected to each other by pins 9 which are radially 
inserted in aligned bores 10 of tubular body 2 and sabot 8. Prior to a 
discharge (FIG. 1), the distance between the rear face 11 of the tubular 
body and a circular shoulder 12 of the sabot is equal to, or larger than, 
the diameter of pins 9. The rear face 11 is provided with corrugations 13 
of some shape, such as teeth, knurling, milling, etc. 
The rear portion of the sabot is provided with the annular groove 14 for 
receiving the rotating band 15. At the discharge of projectile 1, the pins 
9 which are uniformly distributed over the circumference, are sheared off. 
Due to the high acceleration within the barrel, tubular body 2 of the 
projectile impinges by its rear face 11 against circular shoulder 12 of 
the sabot and digs by its corrugation 13 into shoulder 12 which is of a 
softer material than projectile body 2 (FIG. 2). The spin imparted to 
sabot 8 is thereby transferred to tubular projectile body 2. With a small 
depth and sharpness of the corrugation, the shoulder of the sabot slips 
through and the spin is transferred only partly. This partial compensation 
for the rotation is advantageous since the spin of the projectile body is 
critical for the ballistic conditions. 
Upon leaving the barrel, sabot 8 is detached from tubular shell body 2, 
because of the produced dynamic pressure, so that the projectile body 
alone continues to follow the trajectory (FIG. 3). 
In another embodiment of the invention, which is dependent on the rifling, 
no spacing of rear face 11 of rear portion 6 of body 2 from sabot shoulder 
13 is provided. Pins 9 are then sheared off by the rotary acceleration. 
FIGS. 6 and 7 show a projectile 1' which has a tubular body 2 and is 
connected to a sabot 8.1 of plastic, having integral radially projecting 
pins 9.1. Rear face 11 of tubular body 2 applies against pins 9.1 and 
extends beyond them. The pins might also be received in bores. Here again, 
as in the embodiments of FIGS. 1 to 5, the rear face 11 of the tubular 
body 2 is spaced from the circular shoulder 13 by a distance equal to or 
exceeding the diameter of pins 9.1. 
According to FIG. 8, the rear end 8.2 of the sabot 8.2 of projectile 1" is 
provided with a blind bore 16 permitting augmentation of the charge and 
reduction of the masses to be accelerated. A hood or ogive 17 with rated 
breaking lines is fitted onto the front end of tubular body 2, which is an 
effective protection of the projectile for storage and handling. 
FIG. 9 shows a tubular projectile comprising a body 2 and sabot 8.3 with a 
metallic intermediate ring 19 having a collar 20 being engaged on a stud 
portion 18 of sabot 8.3. Intermediate ring 19 must be firmly connected to 
sabot 8.3, which may be effected by press-fitting, direct injection 
molding of a plastic thereon, or by means of an adhesive, a thread, etc. 
Intermediate ring 19 forms a buffer between body 2 and sabot 8.3 of 
plastic. Pins 9 are inserted in bores 10 provided in body 2 and in 
intermediate ring 19. The face 11 of rear portion 6 of tubular body 2 is 
also provided with a corrugation 13. After shearing off pins 9, rear face 
11 impinges on collar 20 of intermediate ring 19. 
While specific embodiments of the invention have been shown and described 
in detail to illustrate the application of the principles of the 
invention, it will be understood that the invention may be embodied 
otherwise without departing from such principles.