Ammunition and explosives – Projectiles – Line carrying or filamentary material distributing
Patent
1992-06-16
1994-07-19
Brown, David H.
Ammunition and explosives
Projectiles
Line carrying or filamentary material distributing
F42B 1270
Patent
active
053298543
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a projectile for the dispersal of a load with time delay after firing from a launching tube with a hot gas under pressure. Such a projectile comprises a cylindrical casing with a first pressure chamber, formed by a portion of the casing together with a cross wall arranged in the casing and an external side wall provided with at least one supply opening for the hot gas to the first pressure chamber. The projectile further comprises a second pressure chamber, formed by a second portion of the casing, said cross wall and a piston axially movable with slide fitting in the casing, and the load, which stands in connection with the piston. A throttled gas connection is arranged between the first and second pressure chambers. The piston, under the effect of a built-up pressure in the second pressure chamber, is arranged to perform an axial movement firing the load out of the casing, but not until the pressure has reached a predetermined level.
Such projectiles are known for instance from Swedish patent No. 7802120-1, which describes a projectile for firing and dispersing a load consisting of a multiplicity of tightly packed, radar-reflecting strips in a casing. This projectile is fired from a launching tube by means of highly compressed pressure air which upon firing flows into the first pressure chamber via a check valve and flows thereafter at limited flow rate through the throttled gas connection into the second pressure chamber, where a gas pressure builds up to a predetermined level, which is determined by the shearing resistance in an interlocking pin that keeps said piston with the load in a starting position. When the gas pressure has become sufficiently high, the pressure force acting upon the piston in the axial direction brings about that the interlocking pin is sheared off, and the piston with the load is pushed out of the casing, thus enabling the load to be dispersed. The projectile that is described in Swedish patent No. 7802120-1 is therefore primarily intended to be fired with compressed air having the temperature of the surroundings, but it can also, from a constructive point of view, be fired with hot gas under pressure, such as detonation gas.
It is essential, however, that the time delay after the firing of the projectile from a launching tube can be predetermined with relatively great precision, which requires that the construction is such that the building up of the pressure in the second pressure chamber proceeds well-defined and with adjusted pressure increase per time unit.
If firing is effected with gas under pressure obtained through the detonation of a charge, naturally, the gas will initially have a relatively high temperature, and will also be mixed with a certain portion of more or less finely disintegrated particles. On firing, this hot gas flows into the first pressure chamber and there it is cooled off relatively quickly by the walls that form the pressure chamber, i.e. a first portion of the casing, the cross wall and the side wall, all usually made of metal. Thereby, the pressure in the second pressure chamber into which flows the relatively hot gas through said throttled gas connection will, as a function of time, have a relatively flat course, which makes it difficult to determine with the desired precision the desired time delay, which depends on the pressure increase to a predetermined, desired level.
In addition, due to the fact that the gas is mixed with particles, there is a risk that the throttled gas connection will be choked up.
The object of the present invention is therefore to obtain a projectile of the kind mentioned by way of introduction, which is suitable for firing with gas under pressure that is obtained by means of detonating a charge at which the time delay can be determined with good precision.
Such a projectile is characterized primarily in that a fibrous material with relatively good thermal conductivity is so arranged in the first pressure chamber that the pressure in the gas conducted to the first pressure chamber remai
REFERENCES:
patent: 4017100 (1977-04-01), Gehrig et al.
patent: 4322385 (1982-03-01), Goetz
patent: 4333402 (1982-06-01), Landstrom et al.
patent: 4578247 (1986-03-01), Bolieau
patent: 4858951 (1989-08-01), Lenzen
patent: 4944210 (1990-07-01), Flock et al.
patent: 4950458 (1990-08-01), Cunningham
Ellstrom Hans
Hanberger Soren
Komstadius Sven
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