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(11) | EP 1 193 463 A2 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Body for inert aerial bombs |
| (57) A body for inert aerial bombs is a single piece of cast iron, without the need for
additional heat treatment. The single piece of cast iron has an internal cavity which
does not require filling with any material. Internally, the body has protuberances
(15) for a balance of the masses along the axis of rotation of the bomb and for receiving
the functional components. |
[0001] The present invention pertains to bodies for inert aerial bombs, and in particular, but not exclusively, bombs of the series MK80, such as MK81, MK82, MK83 and MK84 having weights of 125, 250, 500 and 1,000 kg, respectively.
[0002] The MK80 series inert bombs are currently manufactured exactly like the active bombs that are loaded with traditional explosives. These also have a forged body made of steel, and the only difference consists of loading these inert bombs with an inert compound, generally a mixture of cement and scagliola, instead of the explosive.
[0003] Therefore, the inert bombs arc exactly interchangeable with the active bombs, and their cost is not very far from the latter as the only difference in the manufacturing cycle is the loading phase.
[0004] The object of the present invention is to provide bodies for inert aerial bombs that are manufactured entirely from high-resistance iron casting and subsequent partial finish machining.
[0005] Advantageously, without prejudice to the interchangeability with active bomb bodies and all the related accessories, such as fuses, warheads, fins, suspension rings, terminal guidance systems (GBU kits, JDAM, etc.), an iron-cast body has a mass distribution that requires neither treatments nor filling of the internal cavity with any material for guaranteeing weight, position of the center of gravity, moments of inertia equal to those of the active bomb bodies loaded either with a traditional explosive (Tritonal) or with an insensitive explosive (PBX N 109).
[0007] Even though the use of iron-cast bodies for aerial bombs was already proposed in the past, the present invention is innovative as it is based on the use of materials, whose characteristics of mechanical resistance are analogous or superior to those of the cast-steel bodies and their peculiar configurations of the body and methods of applying the required accessories.
[0008] According to the invention, a body for inert aerial bombs is provided made of cast iron, in a single piece, and without the need for additional heat treatment. The body has an internal cavity that does not require filling with any material.
[0009] The body preferably has, without any filling material, a profile, a weight, a position of the center of gravity and polar and transverse moments of inertia similar to those of active bombs. The body may have protuberances, provided internally, for a balance of the masses along the axis of rotation of the bomb and for receiving the functional components. Suspension eyebolts may be screwed directly to the body corresponding to two of the internal protuberances. The suspension eyebolts may be screwed to the body, corresponding to two of the internal protuberances, with the interposition of ring bolts or threaded adapters made of steel. Two of the protuberances may have notches or seats for the passage of internal pipes.
[0010] The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated.
[0011] In the drawings:
Figure 1 is a longitudinal sectional view of the bomb body alone;
Figure 2 is a cross sectional view according to the arrows II-II of Figure I ;
Figure 3 is a sectional view of a bomb body complete with accessories; and
Figure 4 is a view of a variant in the application of the eyebolts.
[0012] Referring to the drawings in particular, the inert bomb body shown has a single, whole piece 11 manufactured by casting in sand, in high-resistance iron, such as spheroidal cast iron 800-2.
[0013] The table below shows the mechanical characteristics of a spheroidal cast iron a) compared to those of an equivalent steel pipe, b) without welding after casting and hardening and tempering.
| Tensile breaking load N/mm2 |
Tensile deformation load N/mm2 |
Min. elongation % |
|
| a) | 800 | 480 | 2 |
| b) | 724 | 482 | 16 |
[0014] From the comparison of the values, it is evident that iron has mechanical resistance values that are equivalent to those of steel used for the manufacture of bomb bodies; on the other hand, its elongation value is decidedly lower. The latter characteristic, which affects the fragmentation of the body in the case of detonation or the mode of breaking in the case of an impact against a hard target, does not, however, constitute any limitation for an inert bomb body.
[0015] Moreover, there is a difference in use between inert bombs and active bombs which induces different stresses on the bomb body: the active bombs arc generally brought into flight and are then released, while inert bombs can be brought into flight many times. This leads to higher load values at least in the landing and a prolonged stress time, particularly on the eyebolt attack zones 12.
[0016] To take this different use profile into account, ring nuts 13 made of high-resistance steel are provided, which are connected to the bomb body by means of a threading 14 having a diameter and length greater than the standard housing of the eyebolts 12. The latter eyebolts 12 are then connected to the internal threading of the ring nuts 13 (Figure 3). As an alternative, the eyebolts 12' may be made with a shank of greater length and be screwed directly to the body 11 as shown in Figure 4. In each case, the bomb body 11 is provided with two pairs of internal protuberances 15 with the following functions: one to provide the housing of the wells for the application of the wells and the second to balance the masses along the axis of rotation of the bomb and to guide the internal passage pipes 16.
1. A body for inert aerial bombs, the body comprising:
a cast iron single piece provided without the need for additional heat treatment and with an internal cavity that does not require filling with any material.
2. A body for inert aerial bombs in accordance with claim 1, wherein said cast iron single
piece has, without any filling material, a profile, a weight, a position of the center
of gravity, a polar moment of inertia and a transverse moment of inertia similar to
a profile, a weight, a position of the center of gravity, a polar moment of inertia
and a transverse moment of inertia of an active bomb.
3. A body for inert aerial bombs in accordance with the claim 1, further comprising protuberances
extending in said internal cavity for a balance of masses along the axis of rotation
of the bomb and for receiving the functional components.
4. A body for inert aerial bombs in accordance with the claim 2, further comprising protuberances
extending in said internal cavity for a balance of masses along the axis of rotation
of the bomb and for receiving the functional components.
5. A body for inert aerial bombs in accordance with claim 1, further comprising suspension
eyebolts, each of said eyebolts being screwed directly to the body at locations corresponding
to one of sais two internal protuberances, respectively.
6. A body for inert aerial bombs in accordance with the claim 1, further comprising ring
bolts or threaded adapters made of steel and suspension cyebolts, each of said cyebolts
being screwed to the ring bolts or threaded adapters made of steel, respectively at
locations corresponding to one of said two internal protuberances with the interposition
ofsaid ring bolts or threaded adapters.
7. A body for inert aerial bombs in accordance with the claim I, wherein two of said
protuberances have a notch or a seat for the passage of internal pipes.
8. A body for inert aerial bombs in accordance with claim 1, wherein said cast iron single
piece has, without any filling material, a profile, a weight, a position of the center
of gravity, a polar moment of inertia and a transverse moment of inertia substantially
identical to a profile, a weight, a position of the center of gravity, a polar moment
of inertia and a transverse moment of inertia of an active bomb.