Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F41—WEAPONS
  • F41A—FUNCTIONAL FEATURES OR DETAILS COMMON TO BOTH SMALLARMS AND ORDNANCE, e.g. CANNONS; MOUNTINGS FOR SMALLARMS OR ORDNANCE
  • F41A1/00—Missile propulsion characterised by the use of explosive or combustible propellant charges
  • F41A1/08—Recoilless guns, i.e. guns having propulsion means producing no recoil
  • F41A1/10—Recoilless guns, i.e. guns having propulsion means producing no recoil a counter projectile being used to balance recoil

Definitions

• the invention relates to a countermass for so-called recoilless wea ⁇ pons of the kind which include a barrel which is open at both ends and which, when fired, produce a rearwardly directed impulse or thrust which counteracts the recoil forces engendered by the fired projec ⁇ tile.
• the countermass is positioned behind the propulsive charge and exits together with the rearwardly exiting propellant gases as the projectile is propelled forwards.
• the countermass is intended to move rapid ⁇ ly rearwards in the barrel, and is normally constructed so that it is vapourized or pulverized behind the weapon.
• the countermass is nor ⁇ mally accelerated as a rigid body in the barrel and then pulverized subsequent to its exit from the barrel.
• One object of the present invention is to provide a countermass which will enable the capacity of the weapon to be improved while avoiding the aforesaid drawbacks.
• the countermass includes a countermass body which will deform at the pressure and temperature that prevails in the barrel during propelling of the projectile, and has at least one throughflow passage through which propellant gases pass and which widens rearwardly in nozzle form.
• the throughflow passage is preferably an axially extending passage located centrally in the body.
• the pressure which accelerates the countermass body is built-up in front of the narrowest section of the throughflow passage. Because the throughflow passage has the form of a rearwardly widening nozzle, the accelerating force will attack or engage the leading edge of the coun ⁇ termass body (the part facing towards the combustion chamber). This ensures that the total mass of the body will be accelerated in an an- ticipatable manner and that pressure control resulting from deforma- tion of the body is achieved, as described herebelow. If the through ⁇ flow passage is given another shape, for instance the shape of a cylindrical bore, minor variations in the shape of the passage, the passage surface, etc., can cause the acceleration force to engage other parts of the body and cause the body to rupture. The behaviour of the countermass can thus be calculated and the pressure-time se ⁇ quence can be controlled with a high degree of precision when the throughflow passage has the form of a rearwardly widening nozzle.
• the body is composed of a material having a plastic behaviour, or a viscous, viscoplastic behaviour, or preferably the ideal-plastic behaviour of a free-flowing powder at the pressure and temperature concerned.
• Part of the rearwardly directed impulse can be obtained by continuous ⁇ ly dispersing countermass material and accelerating the dispersed material to a very high velocity in the propellant gases which exit through the throughflow passage during a firing sequence.
• the through ⁇ flow passage will therefore tend to widen, which is counteracted by deformation of the countermass body at the pressure and temperature prevailing in the barrel during firing of the projectile.
• the counter ⁇ mass body is therefore compressed by the forces of inertia during its acceleration in the barrel and the material of said body is redistri ⁇ ubbed towards the throughflow passage. This also enables throttling of the gas throughflow to be increased when the countermass body is powerfully accelerated.
• a reduced maximum pressure in the combustion chamber and, at the same time, a longer duration of a relatively high pressure in the barrel are obtained when using the inventive countermass.
• This enables the capacity of the weapon to be increased in comparison with earlier known recoilless weapons, without increasing the weight of the weapon.
• the weight of the weapon can be reduce, while retaining the capacity of the weapon.
• the gas outflow from the rear end of the weapon is extended in time with the novel countermass, the ⁇ reby reducing the effect of pressure on the surroundings and on the operating personnel.
• Figure 1 is a longitudinal section view of one embodiment of an inven ⁇ tive countermass positioned in a schematically illustrated barrel of a recoilless weapon.
• Figures 2-3 are sectional views of alternative embodiments of the in ⁇ ventive countermass.
• Figures 4a-c illustrate a method for producing a countermass in accor ⁇ dance with the invention.
• Figures 5a-c illustrate the manner of operation of the countermass at different points of time during a projectile firing sequence.
• numeral 1 idendifies the barrel of a recoilless weapon.
• Other weapon components such as firing mechanism, handle, sights, etc. have been omitted.
• the reference numeral 2 identifies the weapon projectile, 3 identifies a propellant charge, 4 identifies an igniting charge and 5 identifies an inventive countermass.
• the countermass comprises a countermass body 5 having a centrally located and axially extending throughflow passage 6, which widens rearwardly in nozzle form.
• a correspon ⁇ ding sealing plate may also be provided behind the countermass.
• the passage 6 may be blocked initially by a mass or the like which is blown from the passageway subsequent to having been subjected to pressure over a given period of time or when a predetermined pres ⁇ sure prevails in the barrel during the initial stage of a firing sequence.
• Figure 2 is a sectional view of a countermass which consists of a pl ⁇ rality of mutually sequential and mutually separate countermass bodies 8-11, each of which has a centrally located, nozzle-forming through ⁇ flow passage.
• Figure 3 illustrates a similar embodiment of a countermass comprising a plurality of countermass bodies 12-15.
• This embodiment differs from the preceding embodiment shown in Figure 2, in that the inlet areas of the throughflow passage have different sizes for different countermass bodies and become narrower the further rearwardly the body is located in the countermass.
• the countermass bodies are constructed from a material which will deform as the body accelerates in the barrel during firing of the projectile. This materiel will then be redistributed towards the throughflow passage, for instance by plastic flow when the materiel concerned is given plastic properties or as a result of propagation collapse due to shear forces acting thereon, when the materiel is given the free-flowing properties of a weakly bonded powder mass.
• the countermass body can be caused to reduce the cross-sectional area of the throughflow passage in this way when the body is powerfully acce ⁇ lerated.
• the counter ⁇ mass bodies are composed of a relatively weakly bonded powdered mass.
• Such bodies have been found to provide advantageous properties, both with regard to the pressure-regulating function of the body during its residence time in the barrel and also with regard to rapid and comple ⁇ te disintegration of the body upon its exit from the barrel.
• the material comprises a powdered ballast material of given grain-size distribution and particle form, and a binder.
• the counter- mass body may comprise a mixture of different types of powder.
• the grain-size distribution, the grain form and the binder content are chosen so that the ultimate countermass body will have a porosity of 30-70%. A porosity of 45-55% is particularly preferred when a small risk zone behind the weapon is desired.
• the porous structure has been found to cause those countermass parts which leave the barrel without having been earlier dispersed in the propellant gases to fragmentize very quickly and completely upon exiting from the barrel, and are therewith to slow down quickly in the ambient air.
• One contributory reason is that the porous structure of the bodies is pressurized by the gas pressure prevailing in the bar ⁇ rel.
• the fine-grain powder/gas cloud formed by these bodies behind the barrel also has an effective damping effect on the Shockwave travel ⁇ ling from the rear end of the barrel.
• the ballast material may, for instance, be silicate mineral, metal powder, gypsum, barium sulphate and heavy materials containing tung ⁇ sten, copper, iron, etc.
• the grain size should be smaller than 2 mm in diameter, so that the powder will be retarded rapidly in the ambient air when exiting from the barrel, and greater than 0.05 mm, in order for the material to disintegrate.
• the proportion of binder used is preferably from 1-10% be weight, cal ⁇ culated on the ballast material, and may consist of sugar, thermoset- ting resin, glue, Portland cement or gypsum, for instance. Particular ⁇ ly good results have been obtained with a phenol resin binder, in which case the binder content was about 5% of the weight of the bal ⁇ last material.
• the countermass bodies can be produced by first mixing the powder with the binder and then compressing or moulding the powder/binder mixture in a mould.
• FIG 4 illustrates an embodiment of one such mould 16 intended for producing a countermass body.
• the mould 16 has an inner diameter which corresponds to the diameter of the barrel of the weapon concerned and a central, conical element 17 which provi ⁇ des a nozzle-like throughflow passage in the bodies.
• Powder having a given grain-size distribution is mixed with, for instance, powdered phenol resin, and compacted in the mould 16 by shaking the mould, and then heat hardened or cured.
• the thus produced countermass element can then be divided into a number of countermass bodies 18-21, as shown in Figure 4b.
• each of these countermass bodies is then turned, so as to obtain the configuration shown in Figure 4c.
• each coun ⁇ termass body will obtain an expanding nozzle-like throughflow passage whose inlet orifice decreases in area from body to body rearwardly in the countermass.
• the igni ⁇ ting charge 4 ignites the propellant charge 3 and the gas pressure increases to a value at which the sealing plate 7 located in front of the countermass disintegrates, and thereafter also the sealing plate or the like located behind the countermass.
• the countermass consists of weakly bonded powder mass, the combustion gases will fill the cavities or pores in the countermass and therewith assume the pressure prevailing in the barrel.
• Figure 5 a illustrates the conditions that prevail when the propellant charge is fully ignited.
• the pressure in the barrel has begun to accelerate the projectile 2 and the countermass body 5.
• generated propellant gases exit through the throughflow passage 6, resulting in a reduction in the pressure maximum in the combustion chamber.
• Small parts of the countermass material are constantly dis ⁇ persed in the exiting gas and are accelerated to high velocities.
• Figure 5c illustrates how the undispersed part of the countermass body leaves the barrel and the manner in which the gas pressure prevailing in the throughflow passage 6 and in the cavities of said body contri ⁇ bute to rapid disintegration of the body.
• the defor ability of the countermass body, in combination with the configuration of the gas throughflow passage, enables a relatively high gas pressure to be maintained in the barrel over a longer time period than when using a conventional countermass.
• the countermass can be said to function as an overpressure valve which functions to reduce the bried maximum pressure and to extend the duration of pressure in the barrel. This enables the capacity of the weapon to be increased without needing to dimension the barrel more powerfully.
• the countermass body When the countermass body is divided into a number of smaller bodies, these bodies can be caused to accelerate consecutively in the barrel, beginning from the rear.
• an expan ⁇ ding nozzle form optionally combined with decreasing inlet area from body to body rearwardly in the countermass, the highest pressure drop and the greatest acceleration is obtained on that countermass body which is located furthest to the rear in the barrel at each moment in time.
• This consecutive acceleration sequence further improves the ability of the countermass to reduce the brief maximum pressure while, at the same time, maintaining a relatively high gas pressure over a longer period of time than when using a conventional countermass.

Landscapes

• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• General Engineering & Computer Science (AREA)
• Toys (AREA)
• Aiming, Guidance, Guns With A Light Source, Armor, Camouflage, And Targets (AREA)
• Carbon And Carbon Compounds (AREA)
• Saccharide Compounds (AREA)
• Electron Beam Exposure (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Priority Applications (3)

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

Country Status (9)

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Citations (2)

Family Cites Families (5)

• 1990
  • 1990-01-29 SE SE9000302A patent/SE467594B/sv not_active IP Right Cessation
• 1991
  • 1991-01-29 JP JP3503926A patent/JPH05504613A/ja active Pending
  • 1991-01-29 AU AU72292/91A patent/AU643756B2/en not_active Ceased
  • 1991-01-29 CA CA002073988A patent/CA2073988A1/en not_active Abandoned
  • 1991-01-29 US US07/916,088 patent/US5285713A/en not_active Expired - Fee Related
  • 1991-01-29 EP EP91903255A patent/EP0592399A1/en not_active Withdrawn
  • 1991-01-29 WO PCT/SE1991/000064 patent/WO1991011672A1/en not_active Application Discontinuation
• 1992
  • 1992-07-24 FI FI923373A patent/FI923373A0/fi not_active Application Discontinuation
  • 1992-07-28 NO NO922969A patent/NO174021C/no unknown

Patent Citations (2)

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