GB2071825A

GB2071825A - A fin-stabilised projectile

Info

Publication number: GB2071825A
Application number: GB8106541A
Authority: GB
Original assignee: Mauser Werke Oberndorf GmbH
Current assignee: Mauser Werke Oberndorf GmbH
Priority date: 1980-03-14
Filing date: 1981-03-02
Publication date: 1981-09-23
Also published as: NL8100586A; DE3009775A1

Abstract

A fin-stabilised projectile has a tail unit comprising a rotatable sleeve, hub or the like 1e carrying peripherally-distributed stabilising fins 1d, the projectile body having at the tail end, over approximately the length of said tail unit, a portion 1c of reduced diameter which forms an axle for the reception of said rotatable sleeve, hub or the like. This projectile is suitable for mass production and it can readily be ensured, upon launching from a rifled weapon tube, that only a minimal part of the twist of the projectile is transmitted to the tail unit. <IMAGE>

Description

SPECIFICATION A fin-stabilised projectile The invention relates to a fin-stabilised projectile. There is described herein a fin-stabilised projectile which can optionally be launched from a smooth weapon tube or one provided with grooves and lands and which is connectable, depending upon the instance of use, to a driving ring or to a propelling base or sabot and which has means for compensating for the twist imparted to it upon launching from a rifled weapon tube.

A finned projectile launched conventionally from a smooth weapon tube has, upon launching from a rifled weapon tube, a twist imparted to it. This tube-imparted twist needs, in consideration of the stability of the projectile, compensation, all the more so since, as a result of rotation imparted to a tail arrangement upon launching, the aerodynamic flight behaviour of the projectile is not inconsiderably impaired.

Withing the sphere of this problem the particular difficulty lies in the extremely low axial mass moment of inertia of the projectile in relation to that of comparable projectiles of a larger calibre. The following example should make this clear: Since the moment of inertia increases, with an increase in size, to the 5th power, a projectile of, for example 28 mm diameter would have approximately 525 times as great axial momemt of inertia as a projectile reduced in size to 8 mm. From this it can be derived that the torque acting on the projectile in the weapon tube must only be very small, in order to prevent, at least most extensively to restrict, a twist pick-up.

Taking these physical factors into account, it is already known to compensate for the twist, in the case of a projectile which is provided for example with a driving ring, either by means of a rotating disc or else by means of a rotating sealing band.

In the former case, arranged axially behind the driving ring is a ring-shaped disc. The end face of the disc slides, in this respect, on the driving ring, whilst its cylindrical surface effects sealing.

In the second case, arranged peripherally on the driving ring is a slipping sealing ring.

This sealing ring, rotating freely on the driving ring, engages itself in the manner of a projectile guide band known per se into the grooves of the weapon tube.

Although these two proposals for solution already have mutually differently-large efficiencies, nevertheless both are still in no way adequate in their effect. Already certain limits are set on both known solutions in conceptional respects.

In view of the imperfections and limits inherent in these solutions, the present invention has as an object the providing, in a simple way which takes account of the mass production of finned projectiles, a twist compensation for such finned projectiles. In this respect there should be achieved the goal of launching them ballistically optimally also from rifled weapon tubes. At the same time there should be achieved the result that upon launching, conditioned by the air forces and the inertia of the finned-projectile tail arrangement, in the most extreme case only part of the rotation of the projectile is transmitted to the tail arrangement.

According to the invention, the projectile is at the tail end, over approximately the length of a tail unit, reduced in diameter as compared with the rest of the body of the projectile, and the reduced-diameter part forms an axle for the reception of a rotatable sleeve, hub or the like which carries peripherallydistributed stabilising fins.

The sleeve, hub of the like may be protected against axial displacement by means of a member, for instance a nut, cotter or the like, which forms the end of the projectile.

Solely as a result of the extremely simple construction a finned projectile which is also suitable for the purposes of quantity production can be produced. As a result of the rotation-capability however, also of the inertia of the tail unit, it can readily be ensured, upon the launching of a finned projectile from a rifled weapon tube, that only a minimal part of the twist of the projectile is transmitted to the tail unit. In addition to this, the residual rotary speed of the tail unit, upon the exterior ballistic flight, tends as a result of the aerodynamic forces acting on this latter, virtually towards zero.

Also, according to the invention, there is provided a fin-stabilised projectile comprising a projectile body and a finned tail unit, said tail unit comprising a rotatable sleeve or hub car.rying peripherally-distributed stabilising fins, and said projectile body comprising a front portion which is of reduced diameter relatively to said front portion and which forms an axle for the rotatable fin-carrying sleeve or hub.

In the accompanying drawings, which show an exemplary embodiment of the invention: Figure 1 shows in side view a finned projectile having a rotation-capable tail unit; and Figure 2 shows the finned projectile in accordance with Fig. 1 in the direction of the arrow "A", Fig. 1.

Referring to the drawings, a finned projectile designated in is entirety by the reference 1 consists substantially of an ogival portion 1 a, a cylindrical centre portion 1 b, a tail portion 1 C which is reduced in diameter as compared with the centre portion 1 b, and a tail unit 1 d, 1 e.

The tail portion 1 C carries a rotatable sleeve, hub or the like 1 e, on which tail unit fins 1 d are arranged. The number of these fins is, in this respect, dependent on the degree of stabilisation which is necessary.

In order to prevent an axial shifting or even falling off of the sleeve, hub or the like 1 e, together with the stabilising fins 1 d, on or from the tail portion 1 c, a securing member 2, for instance a nut, cotter or the like, is provided. This member forms at the same time a tail-end closure of the projectile.

The reduced-diameter tail portion 1 C has a length "L" which corresponds approximately to the length of the tail unit formed by the sleeve 1 e and fins 1 d. This diameter is so dimensioned that a favourable aerodynamic flow-around results.

The tail portion 1 C forms, as shown, an axle, for the rotatable part 1 e.

Said rotatable part 1 e is of an externål diameter equal to or smaller than the calibre of the projectile.

Claims

1. A fin-stabiiised projectile which can be launched, selectively, from a smooth weapon tube or from one which is provided with grooves and lands, and which is connectable, depending upon the instance of use, to a driving ring or to a propelling base or sabot, and which has means for compensating for the twist impressed on it upon launching from a rifled weapon tube, characterised in that the projectile is, at the tail end, over approximately the length of a tail unit, reduced in diameter as compared with the rest of the body of the projectile; in that the reduceddiameter part forms an axle for the reception of a rotatable sleeve, hub or the like which carries peripherally-distributed stabilising fins; and in that the rotatable sleeve is, in its diameter, equal to or smaller than the calibre of the projectile.

2. A fin-stabilising projectile comprising a projectile body and a finned tail unit, said tail unit comprising a rotatable sleeve or hub carrying peripherally-distributed stabilising fins, and said projectile body comprising a front portion, and a rear portion which is of reduced diameter relatively to said front portion and which forms an axle for the rotatable fin-carrying sleeve or hub.

3. A fin-stabilised projectile as claimed in Claim 2, wherein said rotatable sleeve or hub is of an external diameter equal to or smaller than the calibre of the projectile.

4. A fin-stabilised projectile as claimed in Claim 1, wherein the sleeve, hub or the like is protected against axial shifting by means of a member, for instance a nut, cotter or the like, which forms the end of the projectile.

5. A fin-stabilised projectile substantially as herein described with reference to the accompanying drawings.