Cutaway model of a 7,5cm “patroon granaatkartets met tijd-schokbuis No.5 “Cartridge shrapnell with a time-impact fuze No.5, as used in the “Gun 7 field “ (Kanon 7 veld) with the Dutch artillery prior to WW2. In 1904 the gun was taken into service with the Dutch army, it had a max. Range of 6.500 mtrs. In 1926 the gun was modernised, which resulted in a max. range of 10.000 mtrs. With the mobilistaion in 1939 the Dutch army had 280 pcs. of 7 veld available for use.
The projectile body is made of steel. On top of the body a steel cap is screwed with fine thread. This cap serves as the lock up cap for the schrappnell balls charge, a centering device for the flamepipe and a threaded cap to receive the time-impact fuze No.5. The lower end of the flame pipe is centered by the expulsion flange. Below the expulsion flange a expulsion charge, existing of gunpowder No.2 is placed. The flame pipe is filled with tablets of black powder -9mm in diameter, 14 mm long and with a 3mm diameter hole- that boost the flame of the time-impact fuze No. 5 when travelling down. The space between the cap and the expulsion charge is filled with lead balls in cast resign.
Before firing the projectile, the fuze is set on the desired fuze activation distance after which the projectile is fired. At appr. 150 mtrs. before the target, the fuze is activated. The flame travels down the pipe into the expulsion charge which ignites. The expulsion flange is now pushed upward up to the moment where the fine thread of the cap is ripped of and the charge of lead balls is projected forward (in airburst), the projectile body serving as a kind of barrel. The rotation of the projectiel enshures the balls are thrown outward so a conical shaped pattern of dispersion of balls appears.
The shrappnel projectile is meant primarally against groups of –dug in and non dug in- troops as well as unarmoured targets.
Functioning of time impact fuze No.5:
The fuze has two inertia activated firing caps which are placed in inertia cylinders. The upper firing cap is held in place by means of a brass cup with two outward bend lips (green) that keep the firing cap in upper postion. A spring on top of this cylinders prevents it from moving forward. Upon firing the projectile, inertia moves the firing cap afterward, bending the lips on the cup inward. The firing cap is moved into the firing pin below it. This ignites the pyrotechnic powder mechanism.
The lower firing cap cylinder is kept away from the firing pin above it by a brass cylinder that also rests on a brass cup with two outward bend lips (also green). Upon firing of the projectile, inertia throws down the ring , bending the two lips inward. The firing cap is now free to move forward into the firing pin upon impact, only held away from another by a creep spring. This part of the fuze is the impact activated fuze.
The distance is set by rotating the lower ring by means of a key. The division is in mtrs. ranging from 0-5600 mtrs with 50 mtrs. divisions.
The groove in the lower ring –housing the black powder path- is interrupted for about one cm. Rotating this part above the flash hole of the magazine shuts off the time function, leaving the impact function only. This position can be recognized by the + on the outside of the lower ring being set above the zero set line on the outer rim of the body. Rotating the lower ring into the 5600 mtrs. direction ring will lengthen the path of black powder to be burned. The upper ring is fixed by means of two pins and cannot rotate. It has a flash-through hole that passes the flame of the upper firing cap directly into the lower ring. If the black powder in the lower ring is burned up, it will end in the flash hole of the powder magazine below it (containing black powder No.2) in the lower fuze body. This will activate the projectile below the fuze.
The setting shown in this cutaway is 0 mtrs, this however is the best setting to explain the functioning of the fuze.
The shellcase used is the “ Kardoes Mg. Van 7 veld” shellcase Brass Gun 7 field. The main charge exists of “RB vlamvrij pijpen 206x6/5” Smokeless and Flameless sticks 206mm long , 6 mm outer diameter with a 5 mm diameter hole. In the base of the shellcase a percussion primer No.2 is screwed. In contrast to the HE projectile that has a seperate charge, the shrappnel projectile is a fixed cartridge. On top of the powder charge a cartboard closure cap is placed.
Length of the shellcase: 277 mm
Length of projectile: 267 mm
Length of complete cartridge: 509 mm
Regards DJH
The projectile body is made of steel. On top of the body a steel cap is screwed with fine thread. This cap serves as the lock up cap for the schrappnell balls charge, a centering device for the flamepipe and a threaded cap to receive the time-impact fuze No.5. The lower end of the flame pipe is centered by the expulsion flange. Below the expulsion flange a expulsion charge, existing of gunpowder No.2 is placed. The flame pipe is filled with tablets of black powder -9mm in diameter, 14 mm long and with a 3mm diameter hole- that boost the flame of the time-impact fuze No. 5 when travelling down. The space between the cap and the expulsion charge is filled with lead balls in cast resign.
Before firing the projectile, the fuze is set on the desired fuze activation distance after which the projectile is fired. At appr. 150 mtrs. before the target, the fuze is activated. The flame travels down the pipe into the expulsion charge which ignites. The expulsion flange is now pushed upward up to the moment where the fine thread of the cap is ripped of and the charge of lead balls is projected forward (in airburst), the projectile body serving as a kind of barrel. The rotation of the projectiel enshures the balls are thrown outward so a conical shaped pattern of dispersion of balls appears.
The shrappnel projectile is meant primarally against groups of –dug in and non dug in- troops as well as unarmoured targets.
Functioning of time impact fuze No.5:
The fuze has two inertia activated firing caps which are placed in inertia cylinders. The upper firing cap is held in place by means of a brass cup with two outward bend lips (green) that keep the firing cap in upper postion. A spring on top of this cylinders prevents it from moving forward. Upon firing the projectile, inertia moves the firing cap afterward, bending the lips on the cup inward. The firing cap is moved into the firing pin below it. This ignites the pyrotechnic powder mechanism.
The lower firing cap cylinder is kept away from the firing pin above it by a brass cylinder that also rests on a brass cup with two outward bend lips (also green). Upon firing of the projectile, inertia throws down the ring , bending the two lips inward. The firing cap is now free to move forward into the firing pin upon impact, only held away from another by a creep spring. This part of the fuze is the impact activated fuze.
The distance is set by rotating the lower ring by means of a key. The division is in mtrs. ranging from 0-5600 mtrs with 50 mtrs. divisions.
The groove in the lower ring –housing the black powder path- is interrupted for about one cm. Rotating this part above the flash hole of the magazine shuts off the time function, leaving the impact function only. This position can be recognized by the + on the outside of the lower ring being set above the zero set line on the outer rim of the body. Rotating the lower ring into the 5600 mtrs. direction ring will lengthen the path of black powder to be burned. The upper ring is fixed by means of two pins and cannot rotate. It has a flash-through hole that passes the flame of the upper firing cap directly into the lower ring. If the black powder in the lower ring is burned up, it will end in the flash hole of the powder magazine below it (containing black powder No.2) in the lower fuze body. This will activate the projectile below the fuze.
The setting shown in this cutaway is 0 mtrs, this however is the best setting to explain the functioning of the fuze.
The shellcase used is the “ Kardoes Mg. Van 7 veld” shellcase Brass Gun 7 field. The main charge exists of “RB vlamvrij pijpen 206x6/5” Smokeless and Flameless sticks 206mm long , 6 mm outer diameter with a 5 mm diameter hole. In the base of the shellcase a percussion primer No.2 is screwed. In contrast to the HE projectile that has a seperate charge, the shrappnel projectile is a fixed cartridge. On top of the powder charge a cartboard closure cap is placed.
Length of the shellcase: 277 mm
Length of projectile: 267 mm
Length of complete cartridge: 509 mm
Regards DJH
