Impact-actuated projectile fuze

BACKGROUND OF THE INVENTION

The present invention relates to fuzes, and more particularly to those which are armed upon firing and actuated upon impact.

Fuzes have been used which prevent immediately actuation of the main charge by the provision of a fixed delay period or by the provision for impact actuation or both. The systems utilizing impact actuation usually incorporate some form of mechanical latching or detaining means which is released upon impact of the projectile. Such mechanical structure suffers from several serious drawbacks. Mechanical systems are usually costly, large and may be subject to premature actuation due to rough handling.

SUMMARY OF THE INVENTION

The foregoing as well as other disadvantages of prior devices are overcome according to the principles of the present invention which provides an impact actuated fuze which is inexpensive, safe and compact.

Basically, the present invention provides a pyrotechnic delay material packed in a tube or container which is rigidly affixed to the base end of the projectile. Upon suitable ignition of the delay material, the mechanical properties of the tube are effectively destroyed, thus permitting the burning pyrotechnic to travel in a direction which makes contact with the main charge upon impact.

According to one aspect of the invention, suitable for stabilized projectiles, the burning pyrotechnic delay material travels forward toward the nose end of the projectile upon impact.

According to a second aspect of the invention, suitable for nonstabilized projectiles such as grenades, the burning pyrotechnic delay material may travel radially outward through slots in a supporting member.

BRIEF DESCRIPTION OF THE DRAWINGS

For a fuller understanding of the present invention reference should now be had to the following detailed description of the same taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a longitudinal sectional view of a projectile embodying the principles of the present invention,

FIG. 2 is a fragmentary sectional view of a second embodiment, and

FIG. 3 is a schematic plan representation of a third embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings and, more particularly, to FIG. 1, the projectile housing is generally depicted by the numeral 10 and is defined by a generally cylindral central section 12 to which is suitably affixed a cup-shaped forward end or ogive 14 and a base end plug, 16. Forward end 14 has a conventional vent opening 15 therethrough. The housing may be fabricated of any suitable material such as an aluminum alloy or steel. The base end plug 16 has an inwardly stepped ledge 18 terminating in a central opening 20. Passing through opening 20 and extending into the projectile housing is a tubular insulating and supporting sleeve 22, which may be fabricated of any suitable material such as plastic. Sleeve 22 is affixed to the plug 16 at the ledge 18 by means of an integral flange 24.

A cylindrical, tubular fuze container 26 is received in sleeve 22 and is suitably affixed thereto, as by cement or the like, adjacent flange 24. In this manner the fuze container is fixed to the base end of the projectile housing.

A body of fusing material 28 is located within container 26. This material might typically comprise a slag and/or gas producing pyrotechnic such as 3 percent boron and 97 percent barium chromate mixture. A first fire mix 30 of a suitable pressed priming material such as red lead and silicon closes the base end of container 26 and passes through an opening 32 in flange 24 to the exterior of the projectile housing for ignition in the conventional manner. A similar output mix 34 closes the opposite or forward end of container 26.

A main charge 36 substantially fills the interior of the housing 10 except for a central bore 38 in which is located the fusing material 28, its container 26 and supporting sleeve 22. The main charge might comprise any suitable type of burning pyrotechnic such as red smoke, for example.

The fuze container 26 is fabricated of a material which is sufficiently weakened by the traveling flame front in the fusing material 28 such that upon impact of the forward end of the projectile the forward portions of the container separates from the rearward portion thereof. Various materials exhibiting such a weakness, may be chosen. For example, a thin-walled aluminum tube having a thickness of about 0.012 inches becomes molten adjacent the flame front. Alternatively, a phenolic or plastic tube, would become pyrolized adjacent the flame front. In either case, the flame front causes the material of the container adjacent thereto to loose its structural integrity whereby upon impact separation occurs.

The operation of the device according to the present invention should be apparent from the foregoing description. Thus, when the projectile is fired by conventional means (not illustrated) the first fire mix 30 receives ignition (from propellant in a cartridge case, for example) and burns through the opening 32 into the fusing material 28 which is thereby ignited generating a flame front which travels towards the forward end of the projectile. The heat of the flame front is sufficient to melt, pyrolize or otherwise weaken the structural integrity of the fuse container. Upon impact with a target, the container 26 separates at the weakened spot and the unburned portion of the fusing material together with the flame front and considerable quantities of slag from the burned portion of the fusing material travel beyond the sleeve 22 into the main charge 36 and ignite the same. In the event that an insufficient impact fails to part the container or if impact does not occur in a specified time, say 6 seconds, the fusing material continues to burn until it ignites the output mix 34 which sprays flame and slag into main charge to ignite the same. The insulating sleeve 22 prevents the heat of combustion of the burning delay mix 28 from igniting the main charge 36 prior to impact or before the end of the specified time period.

Although the foregoing description related, by way of example, to the ignition of a pyrotechnic material by means of a traveling ignition source, it is obvious that a pin or stab could be placed on the forward end of the fuze which would function to initiate a primer at the forward end of the projectile. In this manner a detonation output can be obtained.

The forms of the invention shown in FIGS. 2 and 3 relate to projectiles that are not stabilized in flight such as hand-thrown grenades or the like. Here there is no guarantee that the projectile will impact in a nose-forward position.

The FIG. 2 embodiment is similar to the previously described FIG. 1 embodiment, except that the insulating and supporting sleeve, designated as 22; has a plurality of longitudinally extending slots 23’. Upon impact at any orientation, the molten or pyrolized portions of fuse container 26 together with the slag and flame from the fusing material 28 splashes through the slots 23' to trigger the ignition of the main charge.

Alternatively as shown in FIG. 3, a plurality of fuzes, each similar to the fuze elements 22, 26,28.30 and 34 of the FIG. 1 embodiment, could be joined together at hub 100, which structure would then be located in a spherical projectile housing embedded within a main charge (not illustrated). In this manner one of the fuzes of the set would be subject to set-forward forces regardless of the angle of impact of the device. The fuzes are shown in a common plane for ease in presentation only. It is preferable that various planes be occupied by separate fuzes.

Although various embodiments of the present invention have been described by way of example, other forms thereof will be obvious to those skilled in the art.