IL30784A - A combination of a mortar,a launching rod and a projectile - Google Patents

Description

A oombixiatlon of a mortar, a launching rod and a projectile MBCAR 3.A, Ct-29011 The present invention relates to mortars and 3j£ in particular concerned with mortars which can he ired with a minimum amount of noise, flame and smoke.

With previously known mortars and associated projectiles interfering effects occur during firing arising from static (flaming) or dynamic (transverse vibration) effects.

It is an object of the present invention to provide a combination of a mortar and a projectile which overcomes these interfering effects.

According to the invention there is provided in combination, a mortar having a breech located at the rear of its barrel; a launching rod located in the barrel in the neighbourhood of the breech; a projectile slidable and guided in the barrel and comprising a front body portion secured to a tubular tail portion having formed at its rear end remote from the front body portion an annular restriction; a tail assembly of the calibre of said barrel located at the rear of said tubular tail portion and a piston provided with a cap located in the front part of the said tail portion and behind a propellent charge, an annular space being formed between the piston and the tail portion of the projectile, at the front and at the rear Of an annular flexible joint and an annular space being formed between said restriction and the launching rod.

Conforming to the preceding structural arrangements the projectile is only guided externally by the barrel of the mortar, the launching rod having only the sole purpose of serving for the support of the piston on which the pressure of the propellant gases are exerted, but without guiding action on the said projectile.

On the other hand, in previously proposed equipment, the launching rod served not only i r support of the projectile, but also guided the latter during the action of propulsion* According to a specific embodiment of the invention, an annular spaoe is kept between the piston and the tail of the projeotile, at the front and at the rear of an annular resilient Joint.

Due to this faot, the displacement of the projectile along the axis of the barrel is ensured, even if the axis of the launching rod is slightly excentrio or oblique with respect to that of the said barrel or again if the launching rod deflects slightly under the effect of the load of the thrust and that, due to this fact, the piston happens itself to be disaligned.

Due to the improvements according to the invention, it is now possible to launch a projectile of the type indicated in the manner of projectiles for classical mortars, thot is to say by effecting the automatic percussion of the projectile by guided fall into the gun-barrel without the tail of the projectile touching the launching rod at the time of its descent into the tube or at the time of the propulsion which follows percussion, !he same improvements also find their usefulness at the time of firing of a projectile of the aforesaid type in a mortar of which the start of the thrust is controlled by hand through a percussion mechanism.

In other words, the launching stem not being in direct mechanical contact with the tail of the projectile and the piston being able to be flexibly suspended in the cylinder which constitutes the tail, it follows that these two elements can only have a propulsive action without interfering radial effects, static (flaming) or dynamic (transverse vibrations).

In fact experience has shown that, in the absence of the aforesaid arrangements, the effects of flaming and of transverse vibrations communicated to the piston during propulsion were able to give rise to transverse stresses such that the wings of the tail assembly were deformed on contact with the surface of the bore of the barrel.

Other advantages and specific embodiments of the invention will emerge more explici¾y from the description which follows.

In order that the invention may be more clearly understood one embodiment of firing equipment according to the invention is described below purely by way of illustrative but non-limiting example, with reference to the accompanying drawing, in which : Figure 1 shows schematically a partial axial section with tear-off of one embodiment of firing equipment according to the invention, immediately before percussion; and Figure 2 shows schematically a similar section to that of Figure 1, immediately after percussion, at the beginning of propulsion.

In Figure 1, t e reference 1 designates the "barrel tube of a mortar terminated at it3 base by a breech 2 of which the ball-joint 3 is fixable on a base plate (not shown), A launching rod or propulsion rod 4e provided with a firing pin 5f is fixed by its rear end in the breech 2.

The projectile comprises a body 6, a tubular tail 7t screwed into the body 6, a tail asseably 8 of which the ends of fins 9 are of the calibre of the bore of the barrel tube 1· A cylindrical envelope 10, preferably of plastics material, comprises at the front a flange 11 of larger diameter held by clamping between the front end of the tail 12 and the bottom 13 of the body 6· The rear part of the envelope 10 is fixed by gluing, crimping or any other way on the perimeter of a piston 14· Said piston comprises an axial channel in which is located a cap 15 held in place by a cylindrical bushing 16 being closed at its upper part by a pad 18 surrounded by a washer 19 in front of which is the propellent charge 20. An annular flexible joint 21 is housed in a corresponding groove of the piston 14· An annular space 22 is arranged between the outer surface of the piston 14 and the inner surface of the tail 7· Tbe piston 14» before percussion, is centred and held as much towards the front as towards the rear by the envelope of plastics material 10· Finally an assembly of at leaat three ailerons 23, borne by a ring 24 itself fixed on the body 6, serves to guide the projectile in the barrel 1· A second annular space 25 is arranged between t e support rod 4 and a restriction 26 at the hack of the stem 7, so that, according to the invention, the tail of the projectile is never in contact with the propulsion rod 4· Figure 2 shows the projectile described in Figure 1 at the beginning of propulsion, that is to say immediately after percussion of the cap 15 and the application of fire to the charge 20.

The piston 14, shown in the view in Figure 2 separates from the envelope 10 under the effect of the deflagration of the charge 20 which pushes the projectile upwards.

Under the effect of the strong initial thrust of propulsion, the rod may yield between certain elastic limits and be disaligned momentarily with respect to the barrel 1. There then follows transverse effects of stresses and of vibrations of the rod and of the piston in the transverse direction, but without appreciable effects on the tail of the projectile, these being entirely absorbed by the deformation of the flexible joint 21, considering that, neither the piston 14 nor the rod 4 are in direot mechanical contact with the tail 7.

In other words, during the whole of the action of propulsion the piston 14 and the rod 4 possess a degree of transverse freedom whilst the projectile guided in the barrel 1 on one hand by the tips of the fins 9, and on the other hand by the ailerons 2£ follows its axial propulsion normally without transverse effects At the end of the proi-ulsion the restriction 26, through a plastic ring 27» carries away the piston 14 which takes up the speed acquired by the projectile, whilst the gases expanded into the tail 7 remain imprisoned under the sealing effect which the joint 21 constantly produces. Whatever may then be the position of the rod 4» this has no transverse effects on the projectile due to the annular space 25 maintained between the restriction 26 and the launching rod.

In a specific embodiment of the invention the barrel^of the mortar has a length greater than double that of the launching rod so that the projectile is still guided in the barrel after the end of the propulsion. It follows, that in all cases, at the moment when the projectile leaves the mortar it cannot be subjected to any secondary stress which can result from the propulsion. In a conventional mortar, on the contrary, the action of the gases exerts its effects up to the emergence of the projectile from the barrel and even when the projectile has already left the barrel of the mortar.

It will be apparent that various changes and modifications may be made in the embodiments described without departing from the inventive concept of the invention as defined in scope by the appended claims. 30784/2

Claims (5)

2. 2. In combination, a mortar having a breee* located at the rear of its barrel; a launching ro<; located in the barrel in the neighbourhood of the breech; a projectile slldable and guided in the barrel and comprising a front body portior secured to a tubular tail portion having formed at its rear end remote from the front body portion an annular restriction; a tail assembly of the calibre of said barrel located at the rear of said tubular tail portion and a piston provided with a cap located in the front pert of the said tail portio>;. and behind a propellant charge, an annular space being formed between the piston and the tail portion of the projectile, at the front and at the rear of an annular flexible joi-iw and an annular space being formed between said restriction and the launching rod. 2. A combination according to Claim 1, wherein, before percussion, the propulsive charge is located in a tube of which the rear part ie secured to the front of the piston, whilst at the front said tube comprises a flange held by clamping, between the front edge of the tall and the body of the projectile*
3. 3. · combination according to Claim 1 or 2, wherein the length of said barrel is more than double the length of the launching rod.
4. 4. * A combination according to any one of the preceding claims, wherein said piston cooperates with said annular restriction after percussion and is removed therewith*
5. 5. A combination substantially as hereinbefore described with reference to the accompanying drawings.