Subject of the invention
[0001] The invention refers to a module of a ballistic net that comprises mutually crossing
net cords as well as connectors designed to join intersecting cords of the net, whereas
such a net is meant to protect vehicles, structures or other facilities against consequences
of impacts effected by hits of armour-piercing rocket-propelled grenades (RPG) ejected
by grenade launchers.
State of the art
[0002] The patent description
WO2014/065924 discloses a module of a ballistic net provided with a frame designed to support a
net made up of mutually crossing cords. The net cords are stretched between frame
components or boundary tubular members that are designed to fix the net to the frame.
Connectors are provided at points of cords intersections and designed so that to enable
throughout passage of intersecting cords. A module of the ballistic net discloses
a connecting element which includes a multi-sided body having a hexagon base, with
an open cavity therein and with two pairs of slots made in side walls of the connecting
element. The pairs of slots are positioned in mutually opposite fashion so that to
receive cords of the net. Net cords are pushed into two pairs of slots and then secured
by means of a tightly fitted plug designed to fix positions of intersecting net cords
and lock their mutual positions.
[0003] In turn, document
US2010/0288114A1 discloses a similar module of a ballistic net provided with connectors of various
shapes. For instance, the description discloses a connector that has the shape of
a polyhedral body with an octagonal base and a flat bottom side of the body has two
mutually crosswise slots designed to receive net cords pushed therein in tightly fitted
manner. The opposite base of the connector has a shaped tip with bevelled side walls.
Therefore the net cords are fixed to connectors at the net intersections. Consequently
a portion of a grenade can pass through the net meshes but its remaining parts is
at least partly fragmented by edges of connectors.
[0004] Also
EP2662657 discloses a module of ballistic net designed to protect buildings and vehicles. Similarly,
it is also the solution where flexible and mutually intersecting cords are stretched
on a frame. The frame itself is fixed to the protected facility by means of brackets
that enable adjustment of the distance between the ballistic net and the facility.
At the locations of flexible cords intersections connectors are provided in the form
of hard points designed to penetrate outer shells of grenades that hit the ballistic
net. The hard points are shaped in a special manner so that they tumble and angle
inwardly towards the net meshes at the moment of grenade hits, which entails destruction
of outer grenade shells and penetration of their interiors. The hard points are provided
with cavities or longitudinal slots to enable fixation of net cords, nevertheless
other design of hard points is disclosed as well, where the hard points have slots
for cords provided on the both base planes so that such connectors make up a kind
of a spacer between two nets stretched on the frame. Yet another design of a connector
is disclosed as well, provided with slots for cords and a cavity for a stud that makes
up a kind of a plug designed to fix the cords. In particular, connectors of polyhedral
shape are disclosed, where corners of the polyhedral embodiment of these connectors
are designed to penetrate outer shells of grenades.
[0005] Moreover,
EP2780657 disclosed a module of ballistic net designed for protection of buildings and vehicles.
Flexible cords that make up a net are stretched on a frame that is fixed to the protected
facilities. Special connectors are provided at selected locations of cords intersections
designed to receive intersecting cords. The connector bodies have a cavity located
beyond their front surface. The cavity receives intersecting cords with interference
fit, which are secured with a plug, whereas a protrusion is provided on the front
plane of the connector body. These connectors are meant to destruct shells of grenades
hitting the ballistic net, therefore connectors and protrusions on their front planes
can be of various shapes suitable for that purpose. This solution discloses various
shapes of connectors, including ones with cylindrical or octagonal shapes as well
as ones with additional edges and provided with tapered plugs.
[0006] Furthermore, the application description
PL126568U for an utility model discloses a module of ballistic net with boundaries designed
to mount the module on a frame. A net made of cords is stretched between the boundaries,
and the intersecting cords are fixed together at the points of intersections by means
of connectors. Each single connector has a shape of a polyhedral body with an internal
cavity designed to receive a plug inserted with interference fit. Side walls of the
body are provided with slots, open at their tops and designed to receive cords, where
these slots are located in pairs, opposite one to another. The connector body has
a base plane of quadrangle shape and slots are located in centre of each side wall
of the body, whilst the end section of the cavity in the connector body has converging
surfaces, whereas the plug itself has a cylindrical form and ends up with a tapered
tip.
Aim of the invention
[0007] The invention is aimed to provide a new design of a ballistic net module to improve
efficiency of grenade destruction and to enable easy manufacturing and installation.
[0008] The invention refers specifically to a module of ballistic net for protection of
vehicles, structures or other facilities against hits of rocket propelled grenades
(RPG) ejected by grenade launchers, according to the preamble of the independent claim.
The essence of the invention consists in that the bodies of connectors have bottom
plane in the form of a rectangle, in particular a square, whilst side walls of these
connectors have the form of regular trapezium and converge towards the top plane of
the body down the full height of the connector, whereas edges in between of side walls
are inclined against the height of the connector at the angle ranging from 2,5° to
5°. Consequently, the layout of connectors combined with net cords guarantees that
hit of grenade leads to displacement of connectors outwards with simultaneous pivoting
of them and tilted side edges of connectors pierce and destruct outer shells of grenade
hitting the net.
[0009] The module of a ballistic net according to the present invention comprises connectors
that reliably fix intersecting cords of the net and enable easy assembling and installation.
But first and foremost, side walls of connectors are inclined down its full height,
which facilitates targeting of the grenade cone into the net mesh and, at the same
time, inclined side edges of connectors squeeze the grenade cone down its full length
and break the grenade shell, which improves efficiency of the outer shell destruction.
When a grenade hits the net according to the present invention, connectors are pushed
away and pivoted outwardly, which leads to incision of the outer shell of the grenade
by inclined edges of connectors. Therefore the outer shell of the grenade is penetrated
down a much longer distance, which improves efficiency of the grenade destruction
and prevents from its explosion. In addition, the top plane surface area of the connector
body is reduced at the net side exposed to shooting, i.e. where the grenades arrive
from, which enlarges the surface area of the net mesh and also increases the probability
that the grenade tip enters the net mesh. Another desirable effect is also associated
with the less surface area at the site of grenade impacts, which reduces that probability
that the grenade explodes due to impacting a net connector hard point.
Drawing and embodiment
[0010] The invention shall be explained in details by the following embodiment and accompanying
drawings, in which:
fig. 1 illustrates the net module in a schematic front view,
fig. 2 is a schematic isometric view of the connector with intersecting cords and
the locking plug,
fig. 3 presents projection view of the connector body from the bottom side,
fig. 4 is a cross-section of the connector body down the A-A plane in fig. 3,
fig. 5 presents projection view of the connector body from the top side,
fig. 6 is a side view of the locking plug,
fig. 7 is an isometric view of the locking plug,
fig. 8 is a half-section schematic longwise view of the connector body with the plug
in place,
fig. 9 is a graphic schematic explanation of the ballistic net safeguarding effect
during subsequent phases of a grenade hit as seen from the side of protected facility,
and
fig. 10 is a graphic schematic explanation of the ballistic net safeguarding effect
during subsequent phases of a grenade hit as shown in the longwise section.
[0011] A module of ballistic net 1 designed to protect vehicles, structures and other facilities
against consequences of impacts effected by hits of armour-piercing rocket-propelled
grenades (RPG) ejected by grenade launchers, comprises mutually crossing cords 2 and
3 that make up a net. The cords 2 and 3 can be made, for instance, of aramid fibres
and preferably coated with a polyester material. The net 1 is fixed to a frame that
is not shown on the drawing. The cords 2 and 3 at the points of mutual intersections
are joined together by means of connectors 4 that can be made for instance of steel
or composite materials. Each single connector 4 has a body 5 shaped in the form of
a polyhedral with a bottom plane 6 with the quadrangular shape, in particular a square,
and a top plane 7. Side walls 8 have the form of regular trapezium and converge towards
the top plane 7 of the body down the full height
h of the body 5 of the connector 4, whereas side edges 9 in between of mutually adjacent
side walls 8 are inclined against the height
h of the connectors' body 5 at the angle α selected from the range from 2.5° to 5°,
for instance 3.6°. The bottom plane 6 facing the protected facility has an internal
cavity 10. In addition, the side walls 8 have slots 11 made at the elevation of the
internal cavity 10. These slots are open at the side of the bottom plane and designed
to receive cords 2 and 3. After placing the cords 2 and 3 in slots 11, the cavity
10 is filled with a locking plug 12 tightly fitted into the cavity.
[0012] Fig. 9 and fig. 10 explain subsequent phases of the net 1 behaviour after it is hit
by a grenade. The arrangement of connectors 4 joined to cords 2 and 3 in sliding and
pivoted manner enables displacement of connectors 4 outwardly with respect to the
net mesh when a grenade hits the net, which leads to destruction of the external shell
of a grenade hitting the net 1 by means of inclined side edges 9 of connectors 4.
[0013] Detailed parameters of the net, for instance diameters and number of cords as well
as distances between adjacent cords or degree of connector density within the net
module can be determined by experiments depending on specific purpose of ballistic
net modules according to the present invention.
Reference numbers
[0014]
1 - module of ballistic net
2 - cords
3 - cords
4 - connector
5 - body of the connector
6 - bottom plane
7 - top plane
8 - side walls
9 - side edges
10 - cavity in the bottom plane
11 - slots in side walls
12 - plug
h - height of the connector
α - inclination angle between the side edge of the connector body to its height
1. A module of ballistic net (1) provided to protect vehicles, structures or other facilities
against consequences of impacts effected by hits of armour-piercing rocket-propelled
grenades ejected by grenade launchers, where the module comprises cords (2, 3) that
make up the net (1), where the mutually crossing cords (2, 3) are joined together
at the locations of intersections of cords (2) and cords (3) by means of connectors
(4) and each individual connector (4) comprises a body (5) shaped in the form of polyhedral
and having a bottom plane (6), side walls (8) and top plane (7), whereas the bottom
plane (6) facing the facility to be protected has an internal cavity (10) designed
to receive a plug (12) tightly fitted into the cavity (10) and meant to lock cords
(2, 3) of the net (1), whilst side walls (8) have slots (11) made at the elevation
of the internal cavity (10), open at the side of the bottom plane (6) and designed
to receive cords (2, 3), characterized in that single body (5) of the connector (4) has its bottom plane (6) shaped in the form
of a quadrangle, in particular a square, whilst the side walls (8) have the form of
regular trapeziums and converge towards the top plane (7) of the body down the full
height of the body (5) of the connector (4), whereas side edges (9) in between of
mutually adjacent side walls (8) are inclined against the height (h) of the body (5) of the connector (4) at the angle (α) selected from the range from
2.5° to 5° so that the arrangement of connectors (4) joined to cords (2,3) of the
net enables displacement of connectors (4) outwardly when a grenade hits the net,
which leads to destruction of the external shell of a grenade hitting the net (1)
by means of inclined side edges (9) of connectors (4).