Cutaway model of a Swiss 30x170 HS-831 HEI-SD cartridge.
Quote: (from Tony Williams website)
This was a Hispano-Suiza development from the 1950s, but has a connection to an earlier round as the base dimensions are exactly the same as the Hotchkiss 25x163, surely not a coincidence. The gun was originally known as the HS-831(pict.05) but was renamed the Oerlikon KCB when the companies merged around 1970. It has exclusively been used in the anti-aircraft role, in both land-based and naval mountings. The cartridge cases were originally of brass but these are now rare, and steel cases are much more common.
In the late 1960s the case design was adopted for the British Army's Rarden AFV cannon, but the material reverted to brass. Rarden and KCB ammunition are not qualified as interchangeable.
End quote
The cartridge was also used in the French AMX 13 DCA anti-aircraft tanks (pict.06). It had a range of 5000 mtrs, with a firing rate of 300 Rpm per gun.
The cartridge:
The cartridge has a green lacquered steel shellcase. In the base, a brass magazine type firing cap assembly is screwed in.
The projectile body is made of drawn and machined mild steel. It has a sintered iron driving belt. The projectile body is filled with a pressed in high explosive incendiary charge.
The fuze has the stamped in markings: HS 602 62 on the lower edge of the fuze body.
Functioning of the fuze:
The fuze is build-up of an aluminium fuze housing (1 ) , in which an aluminium inner housing (2 ) is placed, containing the centrifugal safety segments (9 ) and the brass chamfered ring (5 ) for the mechanical self-destruct mechanism. The hammer pin (3) is crimped into the nose.
The base plug (14 ) houses the rotor safety disc (10 ) , that keeps the firing cap out of line (green line) with the firing pin (6 ).
Upon firing the projectile, two forces occur; inertia, forcing the loose parts in the fuze in backward position, and the centrifugal force which throws all loose parts outward.
The two springs (12 ) pressing on the shafts of the rotor (10 ) keep it pressing on the slider disc (13 ) before firing and so form the transport safety. The rotor houses the firing cap (in the green line)
When the projectile accelerates, the flat underside of the rotor is pressed even harder upon the slider disc (13), fixating it is in its position. When the speed of the projectile is constant, the centrifugal force takes over. The firing pin spring (8 ) in the spring housing (7 ), pushes the firing pin housing (6 ) downward. The centrifugal force throws the four balls (4 ) outward onto the chamfered edge of the brass ring (5 ), thereby lifting the firing pin assembly upward a little. As long as the combined force of the four balls swung in the chamfered edge is larger than the force of the spring (8 ) pushing downward, it will keep the firing pin afloat. At the same moment the foil roll at the base of the safety segments (9 ) unrolls , allowing the two segments to move outward and enable the firing pin to move down in case of impact or self-destruct.
The rotor (10) is kept fixated by a interrupted ring (11) that falls into a groove on the circumference of the rotor. The centrifugal force will bend the ring (11) open, allowing the rotor (10 ) to rotate freely. The rotor will rotate from the green line into the centerline of the projectile. While rotating, the rotor allows the slider disc (13) to slide to the side, opening the flame hole into the detonator.
The two springs (12) enshure the rotor can be lifted slightly when rotating. This to prevent the slider disc (13 ) from becoming wedged during movement.
Upon impact, the hammer pin (3 ) hits down on the spring housing (7 ) which pushes down the firing pin (6 ) into the firing cap in the rotor, exploding the projectile. The four balls (4 ) are pushed back into the firing pin housing (6 ) during the proces.
If no target is hit, a moment will appear that the speed of the projectile drops, as well as the number of revolutions. As soon as the firing pin spring (8 ) overcomes the force of the four balls (4 ) in the chamfered edge of the brass ring (5 ) , it will push the balls back into the firing pin housing, allowing the firing pin to move into the firing cap in the rotor disc, exploding the projectile in the self-destruct mode.
Regards, DJH
Quote: (from Tony Williams website)
This was a Hispano-Suiza development from the 1950s, but has a connection to an earlier round as the base dimensions are exactly the same as the Hotchkiss 25x163, surely not a coincidence. The gun was originally known as the HS-831(pict.05) but was renamed the Oerlikon KCB when the companies merged around 1970. It has exclusively been used in the anti-aircraft role, in both land-based and naval mountings. The cartridge cases were originally of brass but these are now rare, and steel cases are much more common.
In the late 1960s the case design was adopted for the British Army's Rarden AFV cannon, but the material reverted to brass. Rarden and KCB ammunition are not qualified as interchangeable.
End quote
The cartridge was also used in the French AMX 13 DCA anti-aircraft tanks (pict.06). It had a range of 5000 mtrs, with a firing rate of 300 Rpm per gun.
The cartridge:
The cartridge has a green lacquered steel shellcase. In the base, a brass magazine type firing cap assembly is screwed in.
The projectile body is made of drawn and machined mild steel. It has a sintered iron driving belt. The projectile body is filled with a pressed in high explosive incendiary charge.
The fuze has the stamped in markings: HS 602 62 on the lower edge of the fuze body.
Functioning of the fuze:
The fuze is build-up of an aluminium fuze housing (1 ) , in which an aluminium inner housing (2 ) is placed, containing the centrifugal safety segments (9 ) and the brass chamfered ring (5 ) for the mechanical self-destruct mechanism. The hammer pin (3) is crimped into the nose.
The base plug (14 ) houses the rotor safety disc (10 ) , that keeps the firing cap out of line (green line) with the firing pin (6 ).
Upon firing the projectile, two forces occur; inertia, forcing the loose parts in the fuze in backward position, and the centrifugal force which throws all loose parts outward.
The two springs (12 ) pressing on the shafts of the rotor (10 ) keep it pressing on the slider disc (13 ) before firing and so form the transport safety. The rotor houses the firing cap (in the green line)
When the projectile accelerates, the flat underside of the rotor is pressed even harder upon the slider disc (13), fixating it is in its position. When the speed of the projectile is constant, the centrifugal force takes over. The firing pin spring (8 ) in the spring housing (7 ), pushes the firing pin housing (6 ) downward. The centrifugal force throws the four balls (4 ) outward onto the chamfered edge of the brass ring (5 ), thereby lifting the firing pin assembly upward a little. As long as the combined force of the four balls swung in the chamfered edge is larger than the force of the spring (8 ) pushing downward, it will keep the firing pin afloat. At the same moment the foil roll at the base of the safety segments (9 ) unrolls , allowing the two segments to move outward and enable the firing pin to move down in case of impact or self-destruct.
The rotor (10) is kept fixated by a interrupted ring (11) that falls into a groove on the circumference of the rotor. The centrifugal force will bend the ring (11) open, allowing the rotor (10 ) to rotate freely. The rotor will rotate from the green line into the centerline of the projectile. While rotating, the rotor allows the slider disc (13) to slide to the side, opening the flame hole into the detonator.
The two springs (12) enshure the rotor can be lifted slightly when rotating. This to prevent the slider disc (13 ) from becoming wedged during movement.
Upon impact, the hammer pin (3 ) hits down on the spring housing (7 ) which pushes down the firing pin (6 ) into the firing cap in the rotor, exploding the projectile. The four balls (4 ) are pushed back into the firing pin housing (6 ) during the proces.
If no target is hit, a moment will appear that the speed of the projectile drops, as well as the number of revolutions. As soon as the firing pin spring (8 ) overcomes the force of the four balls (4 ) in the chamfered edge of the brass ring (5 ) , it will push the balls back into the firing pin housing, allowing the firing pin to move into the firing cap in the rotor disc, exploding the projectile in the self-destruct mode.
Regards, DJH
