EP1563247B1

EP1563247B1 - Increased-range mortar projectile

Info

Publication number: EP1563247B1
Application number: EP02765127A
Authority: EP
Inventors: Kresimir Lovro Marcelic
Original assignee: Individual
Current assignee: Individual
Priority date: 2002-08-06
Filing date: 2002-08-06
Publication date: 2008-04-02
Anticipated expiration: 2022-08-06
Also published as: WO2003029747A8; EP1563247A1; WO2003029747A1; ATE391280T1; DE60225949D1

Abstract

The invention relates to increased-range mortar projectile, to be fired from smooth bore barrels, furnished with stabiliser (C) with aerodynamically designed fins (9), of fixed maximum outer diameter, equal to the barrel bore (calibre fins).The fins (9) are in their front part straight, and in the rear part bent in positive direction by the angle /3, which is greater than zero. On the stabiliser body (6), fins (9) are fitted slanted relative to the stabiliser and projectile axes by the angle a, which is greater than zero, which enables the projectile to rotate during the flight, this resulting in enhanced projectile stability and range, larger precision and lesser scattering of hits. All fins are similar by their shape, area and dimensions, and designed to produce minimum resistance during the projectile flight. The fin bases and tops are designed so that their shape approaches the shape of a water drop.

Description

1. FIELD OF APPLICATION

The invention is mortar projectile furnished with slanted and bent stabiliser wings that enable the projectile to rotate around its longitudinal axis, this enhancing its stability and precision as well as range and efficiency at the target.
In the International Patent Classification, it is classified as F 42 B 10/00: Weapons - Ammunition and Blasting - Means for influencing, e.g. improving, the aerodynamic properties of projectiles or missiles; Arrangements on projectiles or missiles for stabilising, steering, range-reducing, range-increasing or fall-retarding.

2. TECHNICAL PROBLEM

Achieving of better stability, larger range and lesser scattering of hits with projectiles fired from mortars, where the bore is smooth and stabilising fins have the largest outer diameter fixed and equal to the mortar barrel bore (calibre fins). This problem is particularly present at various projectile initial speeds (minimum and maximum).
The technical problem that is solved by this invention relates to mortar projectiles with stabilisers, where fins' diameter is fixed and equal to the mortar barrel bore (calibre fins), but where fins are designed and fitted on the stabiliser, related to the projectile axis, to enable rotation of the axis during flight, this enhancing the projectile stability, precision and range.

3. STATE OF THE ART

At existing projectiles, with regard to fin number (6 to 8), shape and position, stabilisers are based on classic solutions of flat fins. Such solutions are satisfactory with projectiles of low range and precision demands. Such projectiles are affected by weather.
When larger ranges are demanded, such projectiles are unstable, this resulting in non-precision (large scattering of hits).
There are two basic stabiliser solutions: stabilisers with calibre fins, and stabilisers with over-calibre fins. Stabilisers with calibre fins has its outer diameter fixed and equal to the mortar barrel bore. Stabilisers with have fins that unfold when the projectile leaves the barrel, after which the projectile has outer diameter larger than the mortar barrel bore.
The patent document GB 508 201 A shows a projectile where both fin sides are by their entire lengths parallel to each other and straight, and placed at an angle to the stabiliser body.
The patent document US 3 650 213 A shows a projectile where both fin sides are by their entire lengths of regular aerodynamic shape and positioned parallel to the projectile axis.
The patent document US 2 494 026 A shows a projectile with several fin designs, straight and parallel and leaned against the projectile body. One of the designs shows over-calibre fins.
US 2 694 364 shows a mortar projectile according to the preamble of claim 1.

4. DISCLOSURE OF THE INVENTION

The essence of the invention is mortar projectile, to be fired from smooth bore mortars, furnished with fins of fixed outer diameter that is equal to the barrel bore (calibre fins). In their front part, the fins are flat, whereas in the rare part they are bent. All fins are fitted to the stabiliser slanted relative to the projectile axis by an angle larger than zero. This enables the projectile to rotate in the flight, which results in the projectile enhanced stability, precision and range.
All fins are of similar shape, area and dimensions. Related to the projectile calibre, they are made to produce minimum resistance in the flight. The fin bases and peaks are designed to approach the shape of a water drop.
The increased-range mortar projectile comprises point-detonating fuse with safety pin; shell with the basic charge and ring for lessening the powder gas losses; stabiliser with slanted and bent fins; additional charge with additional charge carrier; and propelling charge with detonating cap.

5. ILLUSTRATION DESCRIPTIONS

Figure 1.: shows the complete increased-range mortar projectile, with a partial cross-section, side view.
Figure 2.: shows the mortar projectile from Fig. 1, with no additional charge (partial cross-section) - side view.
Figure 3.: shows stabiliser of the increased-range mortar projectile - side view.
Figure 4.: shows stabiliser of the increased-range mortar projectile - front view.
Figure 5.: shows the stabiliser fin position relative to the stabiliser and projectile axes, base cross-section - top view.
Figure 6.: shows stabiliser fin, base cross-section - top view.
Figure 7.: shows stabiliser fin, top cross-section - top view.
Figure 8.: shows stabiliser fin - top view.

6. DETAILED DESCRIPTION OF INVENTION EMBODIMENT

Figures 1, 2 and 3 show that the increased-range mortar projectile, to be fired from smooth bore barrel, consists of the following assemblies:

Assembly A: projectile head, including the fuse 1 with safety pin 2, which, upon hitting the target causes explosion of the basic charge;
Assembly B: projectile body, including the shell 3 which houses the basic charge 4 and the ring 5 which seals between the projectile and the barrel to lessen powder gas losses from the lower part of the barrel at the moment of firing the projectile;
Assembly C: stabiliser, including the stabiliser body 6, on the outer side of which there are fins 9, and through the body there are openings 7 to let the basic-charge powder gas out, and thread 8 to connect the stabiliser and the projectile body 3;
Assembly D: propelling charge, including the propelling charge 17 and the detonating cap 18; and
Assembly E: additional charge, including the vessels 19 with powder charge 20 and carrier 21 which keeps the vessels 19 in a given position.

The increased-range mortar projectile, to be fired from smooth bore barrels, and rotating around its longitudinal axis during the flight, may have stabilisers of various numbers of slanted and bent fins. Figs. 1 and 2 show the increased-range mortar projectile furnished with the stabiliser C with eight regularly distributed fins. At projectiles with eight fins 9, fins are fitted on the stabiliser body 6 symmetrically relevant to the projectile axis, turned by 45° one from another, Fig. 4.
All fins are identical by shape, area and dimensions and, as related to the projectile calibre, they are designed to produce minimum resistance during the projectile flight.
Figs. 5 and 6 show cross-section of the base of a fin 9, Fig. 7 show the top of a fin, and Fig. 8 top view of a fin. As shown in Figs. 6 and 7, the side 10 of the fin 9 is straight, whereas the side 11 is designed as a curve of two lines: line 12 and line 13, crossing each other in the centre of gravity of the cross-section 14, so that the line 13 is slanted relative to the line 12 by the angle β, which is larger then zero, in the positive direction. Crossing of the lines 12 and 13 in the fin centre of gravity 14 is rounded from the fin base to the top in order to reduce resistance during the projectile flight. The line 12 is parallel to the edge 10. The front part of the edge 11 follows the line 12. The rear crossing of the side 10 and the bent part of the side 11 is constructed of the minimum, technologically required, thickness - ideal would be the shape of a dull knife 15. The front part of the fin 16, from base to top, is designed like a half of ellipse.
Fin base cross-section, Fig. 6, and top cross-sections, Fig. 7, are designed so that their aerodynamic shape approaches the shape of a water drop, Fig. 8.
The projectile viewed from the front side, Fig. 4, fins 9 change their thickness from the centre towards the ends, by technological angles designed to make its extracting from the tool easier.
Fins 9, viewed from a side, Fig. 3, are designed to enable extraction from the tool and to achieve the most favourable aerodynamic shape.
Position of fins 9 on the stabiliser body 6 is shown on Figs. 3 and 5. Each fin 9 is fitted on the stabiliser body 6 slanted by its front edge by the angle α, which is larger than zero, relative to the projectile axis. Therefore, air flow over the fins during the flight creates on the slanted fin surface a force that makes the projectile to rotate around its longitudinal axis.
The described fin geometric shape and projectile rotation during the flight increase the projectile stability which, again, results in the projectile increased range with lesser scattering of hits and larger shooting precision.
Centre of gravity of the projectile is determined by distribution of masses within the projectile.

7. INVENTION APPLICATION

The increased-range mortar projectile, to be fired from smooth bore barrels, with stabiliser that enables rotation of the projectile during the flight, embodied in the above described way, results in enhanced projectile stability and range, larger precision and lesser scattering of hits, which has a positive effect to the projectile technology and cost.

Claims

Mortar projectile of increased range, launched from a mortar barrel, the inner surface of which is smooth, and which consists of the following assemblies: assembly (A): projectile head, including a fuse (1) with a safety pin; assembly (B): projectile body, including a shell (3) with a basic charge (4) and a sealing ring (5); assembly (C): a stabiliser, including a stabiliser body (6) on the outer side of which are symmetrically placed fins (9) that enable rotation of the projectile in flight; assembly (D): a propelling charge, including a charge (17) and a detonating cap (18); assembly (E): additional charge, including vessels (19) with powder charge (20) and carrier (21), characterised in that the fins (9) have a straight side (10) and a slanted side (11); the slanted side (11) being in its front part relative to the fin gravity point (14), parallel to the straight side (10); the slanted side (11), from the fin gravity point (14) to the fin end (15), being designed as the curve defined by a line (12) that is parallel to the straight side (10) and a line (13) that crosses the line (12) in the gravity point (14) of the cross-section of the base of a fin (9), so that the line (13) is, as relative to the line (12), slanted by the angle β which is greater than zero in the positive direction; the connection of the lines (12 and 13), in the gravity point (14) of the cross-section of the base of a fin (9), being mildly bent from the root to the tip of the fin; and in that the fins (9) are positioned to the stabiliser body (6), slanted as related to the projectile axis by the angle α which is greater than zero.
Mortar projectile of increased range as claimed in the Claim 1, whereby said fins (9) have the front side of the fin root and tip designed as one half of ellipse; the connection of the straight side (10) and the bent part of the slanted side (11) at the end (15) of the fin is shaped as a blunt knife.
Mortar projectile of increased range as claimed in the Claims 1 and 2, whereby said fins (9) have a shape and surface, with regard to cross sections of the fin root and tip, designed so that their aerodynamic shape produces the minimum resistance in flight.