Cutaway model of a 15/12,8cm Sprgr.42 TS (Treibspiegel). Translated in English: 15/12,8 cm High Explosive sabot shell Type 42.
The projectile was meant to be fired from the S.f.H.18 (Heavy field Howitzer 18), the purpose of the projectile design was to improve the range.
Description of the projectile:
The projectile has a cast steel body, machined to an outside diameter of 128 mm maximum. It is threaded in the nose to receive the gaine No.12 for the Np30 booster and to receive a fuze, in this case a AZ.23 Pr. The lower 30 mm of the projectile has a smaller diameter and has 6 holes with a 14mm diameter drilled at 60 degrees each, perpedidcular to the centerline of the projectile. Two protruding triangular grooves also go round this lower part , meant to secure the lower sabots.
Three lower sabots, 120 degrees each are placed around the lower part, secured in place with 3 long pins over the sabot division edge, and three short pins, each in the centre of the sabot.
The rolled on drivingband locks up the three sabots.
The upper sabot exists of a 2,5mm thick sheet metal cage, made of three 120 degrees segments with a weakening in the sabot division edge. Three holes are drilled in the side of the projectile body . After the ring has been placed over the projectile body, a steel ball is placed, half in the ring, half in the projectile’s body. Three screws lock up the steel balls, securing the ring to the shell.
The only purpose of this forward ring is to guide the projectile straight through the barrel, it therefore has the diameter of the lands of the gun’s barrel (148,5mm).
Length of the projectile without fuze is 552mm, with fuze 644mm.
Weight of the complete projectile is 31,05 kg. In flight, after discarding the sabots: 27,15 kg.
Vo.: 645m/sec.
After firing, the indents in the driving band weaken the connections between the sabots, the centrifugal force rips open the connections between the sabots (drivingband breaks) and these are discarded from the projectile body.
This means the calibre of the projectile is reduced from 150mm to 128mm, a 17% decrease in diameter. When calculating the surface area of both diameters, the frontal surface area of the shell has decreased 27% after discarding the sabots. This, together with the slim and boat tailed shape of the projectile greatly improves range.
The range of a normal SfH18 projectile is about 13,25 km, the 15cm SprGr 42 TS has a range of 18 km. This is an increase of 135% in range and a 184% increace in area coverage.
Five types of TS shells were manufactured for testing at Hillersleben testing range:
1* 15cm Sprgr.42 TS , mark2 , type with “geschosszapfen” (I have no translation for that) and modified charge. Tests were not completed at 28-01-1945
2* 15cm Sprgr.42 TS with three piece steel sabots. Up to 21-01-45, 600 shots were fired at the test range in Hillersleben. Tests are not complete yet. (type depicted in this posting)
3* 15cm Sprgr.42 TS L/5,5 with four sabots. With a projectile weight of 30,7kg and a sabot weight of 1,8kg . Tests were still in progress on 21-01-1945 at Hillersleben.
4* 15cm Sprgr.42 TS with six piece sabots. With a projectile weight of 29,60kg and a sabot weight of 1,7kg. Design by brandt , tests were still in progress on 21-01-1945.
5* 15cm Sprgr. TS with an eight piece sabot. Tests with these sabots from perlitic cast steel were not satisfying yet on 21-01-1945
The fuze used on this shell is the AZ23 Pr. (presstoff / pressed and baked bakelite).
Functioning of the fuze:
The fuze exists of a steel skeleton filled and surrounded with bakelite. This was done to replace strategic materials for fuzes like aluminium and brass that were scarce during ww2 in Germany. Functioning of the fuze: after firing the centrifugal weights between the firing pin and the firing cap block are thrown outward , thereby releasing both. These two parts are held apart by a spring. The screw in the side can be rotated 90 degrees, thereby enabeling the plate in the central firing channel to move out and open the central flame channel, giving no delay, or shut, and force the flame of the firing cap over the 0,15 sec delay channel. At impact the wooden hammer pin forces the firing pin in the firing cap. If the shell glances off a target , the firing cap block moves forward into the firingpin, caused by the negative acceleration. The flame reaches the black powder magazine, which ignites the detonator and the booster, exploding the main charge.
The detonator used is the Zdlg.36Np (Zundladung 36 Nitropenta / Booster 36 Nitropenta), an aluminium, round based bushing with a 108 grams load of nitropenta. The top of the booster is closed with a black plastic cap, on top of which a cork gasket is placed. Weight of the complete booster is 150 grams.
An oponential smokebox No.9 for observation purposes could be placed just below the gaine. The precence of a smokebox was stencilled on the base of the projectile; “oR” meaning ohne Rauchladung (no smokebox)
Regards , Pzgr40
The projectile was meant to be fired from the S.f.H.18 (Heavy field Howitzer 18), the purpose of the projectile design was to improve the range.
Description of the projectile:
The projectile has a cast steel body, machined to an outside diameter of 128 mm maximum. It is threaded in the nose to receive the gaine No.12 for the Np30 booster and to receive a fuze, in this case a AZ.23 Pr. The lower 30 mm of the projectile has a smaller diameter and has 6 holes with a 14mm diameter drilled at 60 degrees each, perpedidcular to the centerline of the projectile. Two protruding triangular grooves also go round this lower part , meant to secure the lower sabots.
Three lower sabots, 120 degrees each are placed around the lower part, secured in place with 3 long pins over the sabot division edge, and three short pins, each in the centre of the sabot.
The rolled on drivingband locks up the three sabots.
The upper sabot exists of a 2,5mm thick sheet metal cage, made of three 120 degrees segments with a weakening in the sabot division edge. Three holes are drilled in the side of the projectile body . After the ring has been placed over the projectile body, a steel ball is placed, half in the ring, half in the projectile’s body. Three screws lock up the steel balls, securing the ring to the shell.
The only purpose of this forward ring is to guide the projectile straight through the barrel, it therefore has the diameter of the lands of the gun’s barrel (148,5mm).
Length of the projectile without fuze is 552mm, with fuze 644mm.
Weight of the complete projectile is 31,05 kg. In flight, after discarding the sabots: 27,15 kg.
Vo.: 645m/sec.
After firing, the indents in the driving band weaken the connections between the sabots, the centrifugal force rips open the connections between the sabots (drivingband breaks) and these are discarded from the projectile body.
This means the calibre of the projectile is reduced from 150mm to 128mm, a 17% decrease in diameter. When calculating the surface area of both diameters, the frontal surface area of the shell has decreased 27% after discarding the sabots. This, together with the slim and boat tailed shape of the projectile greatly improves range.
The range of a normal SfH18 projectile is about 13,25 km, the 15cm SprGr 42 TS has a range of 18 km. This is an increase of 135% in range and a 184% increace in area coverage.
Five types of TS shells were manufactured for testing at Hillersleben testing range:
1* 15cm Sprgr.42 TS , mark2 , type with “geschosszapfen” (I have no translation for that) and modified charge. Tests were not completed at 28-01-1945
2* 15cm Sprgr.42 TS with three piece steel sabots. Up to 21-01-45, 600 shots were fired at the test range in Hillersleben. Tests are not complete yet. (type depicted in this posting)
3* 15cm Sprgr.42 TS L/5,5 with four sabots. With a projectile weight of 30,7kg and a sabot weight of 1,8kg . Tests were still in progress on 21-01-1945 at Hillersleben.
4* 15cm Sprgr.42 TS with six piece sabots. With a projectile weight of 29,60kg and a sabot weight of 1,7kg. Design by brandt , tests were still in progress on 21-01-1945.
5* 15cm Sprgr. TS with an eight piece sabot. Tests with these sabots from perlitic cast steel were not satisfying yet on 21-01-1945
The fuze used on this shell is the AZ23 Pr. (presstoff / pressed and baked bakelite).
Functioning of the fuze:
The fuze exists of a steel skeleton filled and surrounded with bakelite. This was done to replace strategic materials for fuzes like aluminium and brass that were scarce during ww2 in Germany. Functioning of the fuze: after firing the centrifugal weights between the firing pin and the firing cap block are thrown outward , thereby releasing both. These two parts are held apart by a spring. The screw in the side can be rotated 90 degrees, thereby enabeling the plate in the central firing channel to move out and open the central flame channel, giving no delay, or shut, and force the flame of the firing cap over the 0,15 sec delay channel. At impact the wooden hammer pin forces the firing pin in the firing cap. If the shell glances off a target , the firing cap block moves forward into the firingpin, caused by the negative acceleration. The flame reaches the black powder magazine, which ignites the detonator and the booster, exploding the main charge.
The detonator used is the Zdlg.36Np (Zundladung 36 Nitropenta / Booster 36 Nitropenta), an aluminium, round based bushing with a 108 grams load of nitropenta. The top of the booster is closed with a black plastic cap, on top of which a cork gasket is placed. Weight of the complete booster is 150 grams.
An oponential smokebox No.9 for observation purposes could be placed just below the gaine. The precence of a smokebox was stencilled on the base of the projectile; “oR” meaning ohne Rauchladung (no smokebox)
Regards , Pzgr40
