Ordnance – Cartridge feeding – Movable chamber
Patent
1991-10-15
1993-07-27
Bentley, Stephen C.
Ordnance
Cartridge feeding
Movable chamber
F41A 928
Patent
active
052312445
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention concerns an open breech weapon.
The field to which the present invention applies is that of small and medium calibre automatic weapon systems; more specifically open breech weapons intended for the firing of telescoped ammunition.
2. Related Art
In a conventional automatic weapon, the rounds to be fired must be inserted into a breech longitudinally. This process is effected by means of mechanisms displaced by high amplitude alternative translation movements. The insertion travel is greater than or equal to the length of the ammunition. This configuration gives rise to significant translation speeds and acceleration which significantly limit the firing rate. As the breech of this type of weapon always consists of a bored hole manufactured inside a single-piece component, there is no other alternative but for ammunition to be inserted longitudinally.
An open breech consists of at least two parts which move with respect to each other and the assembly of which forms a cavity of the same shape as the round to be fired. Generally open breech weapons have a cylindrical rotor which has one or more grooves parallel to its axis at its edge, the shape of which is the same as that of a round. This rotor rotates inside a race which has lateral openings such that the ammunition can be fed and that empty shells can be ejected. Closure of the breech with respect to the firing location is provided by the race or by a moving part. The rounds fired in this type of weapon are almost always triangular in section and have curved sides and the radius of the curve on the sides is equal to the radius of the rotor. This design enables lateral feeding of the rounds. Low amplitude translation movements result, thus giving the possibility of much faster firing rates.
Other significant advantages result source, volume/useful weight ratio to a maximum, which is a particularly useful feature for the integration of the weapon into an aircraft, for example, when it is known that the aircraft carrying capacity is limited and precisely defined.
Moreover, telescoped ammunition offers excellent projectile protection against outside attack and also, more importantly, from impacts. It is thus well suited to pointed ammunition and under-calibrated ammunition while dispensing with the requirement for protective caps. Conversely, as a result of the swelling of the shell after firing and the friction therefrom, the rotation of the rotor becomes difficult and absorbs a lot of energy. This problem has been approached in various ways.
The French patent 164601 published under number FR1603956 proposes a mechanism for ammunition without shells which is driven in an oscillating movement and can fire either telescoped rounds or classical no-shell rounds. The seal against combustion gases is provided by means of one or more intermediate parts in conjunction with the smooth rotor surfaces and uses the pressure developed by the gases in some configurations.
The following problems in this system are present: a seal with parts which are not locked in firing position as the system's basis, said position thus possibly being unfixed and sensitive to contamination, especially in the version used with classical ammunition designs. This fault prohibits the use of such a weapon, for example, on board an aircraft, where a large number of no-shell rounds could be located in the immediate proximity of the casing and thus of any propellant gas leaks. An explosion risk would thus result.
The patents published under numbers FR1159282, FR1604264 and U.S. Pat. No. 2,847,784 all concern telescoped ammunition with triangular shell shapes intended to reduce friction caused by to the swelling of the shell after firing. The patent published under number FR1159282 describes a weapon consisting of a rigid casing frame in which a rotating cylindrical rotor with machined cavities of the same shape as the shell is disposed. Between the frame and the rotor, there is a moving part with a cylindrical side facing
REFERENCES:
patent: 467089 (1892-01-01), Forbes
patent: 2317579 (1943-04-01), Bacon
patent: 2970521 (1961-02-01), Bell et al.
patent: 3446113 (1969-05-01), Dardick
patent: 3782242 (1974-01-01), Angell et al.
patent: 4123962 (1978-11-01), Williams
Clouvel Pierre M. A.
Simon Georges H.
Bentley Stephen C.
Giat Industries
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