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  1. #1
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    10,5 cm Sprenggranate L/4,4 for 10,5cm Flak 38/39

    Cutaway model of a “10,5 cm Sprenggranate L/4,4 mit gegossener sprengladung”, which translates as a “10,5cm High explosive shell L/4,4 with cast in explosive charge”.

    The shell was fired from the 10,5cm Flak 38/39. This gun was designed as competition for the 8,8cm Flak 18, but hardly showed any improvements over the Flak 18. As it was also more heavy than the Flak 18 the 10,5 cm Flak 38 often ended up on static mounts in Germany.
    The 10,5cm Flak 39 was the improved version of the 10,5cm Flak 38 where the electrically served gun laying system was replaced with a mechanical gun laying system.
    The 10,5cm C/33 ship gun was the naval version of the Flak 38, both using the same cartridges. The shellcase length in both cases is 769mm.

    The projectile body is formed by pressing a rod into a red hot piece of steel shaft , and machining to size the pressed projectile body after cooling down. A steel plug is screwed into the base. A lead gasket ring is placed between the base of the projectile body and the base plug, enshuring a gas tight seal. On top of the base plug a 5mm thick layer of magnesium kit (-white- ,a kind of polyester resign precursor) is cast which prevents the explosive charge that is cast in the projectile body from entering the thread of the base plug. On top of the magnesium kit a 1,55 kg charge FP02 (TNT) or FP 60/40 (60% TNT / 40% Amonium nitrate) is cast. In top of the shell body the Gr.Zdlg.C/98 NP (large booster charge C/98 Nitropenta) is placed, which ignites the main charge in the shell body.
    The drive belts are KPS which stands for “Kupfer Platiertes Stahl” which translates as Copper plated steel. A sheet of copper plate is connected to a sheet of steel plate by means of an explosive welding process. The newly formed layered plate is cut into strips that fit the grooves for the driving belts in the shell body and the driving bands are machined to the desired dimensions after pressing the driving belt strips into the grooves. The big advantage here is the saving of approximately 60% copper for driving band production, a strategic material of which there allways was a shortage in WW2 Germany. Later in the war, all 10,5 cm Flak shells had FES (Fe Sintered / Sintered iron) driving belts.

    When the shell is used in the anti aircraft role it is fuzed with the Zt.Z.S30 (30 seconds time fuze) or the Zt.ZS30 Fg (Fg means centrifugal weight driven). When used against ground targets it used the AZ23/28 impact fuze.

    The brass clad steel shellcase is 769mm long and is filled with 5,5 kg Diglykol powdersticks, 665mm long, 6,25mm in diameter with a 3mm hole through. These powderstick are placed in a linen bag at the base to which another linen bag is sewed containing 20 grams Nz.Man.NP 1,5x1,5x0,5mm (rifle powder), which served as ignition charge.
    In the base of the shellcase the electric primer C22 is screwed.

    Data:
    Projectile weight : 15,1 kg (33Lb 5 oz)
    Vo: 881 Mtr/sec (2.890 ft/sec)
    Max. ceiling: 11.400 mtr (37.401 ft)
    Effective ceiling: 9.450 mtr (31.003 ft)
    Range (ground targets) : 17.600 mtr (19.247 ft)

    Also added is a picture (pict 02) of three shells of the WW2 German heavy flak. It clearly shows the increase in calibre and cartridge size during the progress of the war.

    From left to right:
    -The 8,8cm Spr Gr.L/4,4 for the Flak18, 36/37. (cartridge length 930mm)
    -The 10,5 cm Spr.Gr. L/4,4 for the Flak 38/39. (cartridge length 1160mm)
    -The 12,8cm Spr.Gr. L/4,5 for the Flak 40. (cartridge length 1480mm)

    Regards, DJH.
    Attached Images Attached Images
    Last edited by pzgr40; 13th February 2020 at 07:09 AM.

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  3. #2
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    Quote Originally Posted by pzgr40 View Post
    The big advantage here is the saving of approximately 60% copper for driving band production, a strategic material of which there allways was a shortage in WW2 Germany. Later in the war, all 10,5 cm Flak shells had FES (Ferriet Eisen Stahl / Soft iron) driving belts.
    Just a small side note: "FES" = Sintereisen (FE - the chemical element iron, S = Sinter-) and both FES and KPS bands are an invention of 1918 when they had the same shortage of copper. So in 2nd WW the methods to save copper were already invented. But FEW ("Weicheisen" - soft iron) bands were added in 2nd WW for a few shells (15,2 cm for russian guns for example).

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  5. #3
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    Thanks for the added info, I will change it in the posting while I still can ....
    Regards, DJH
    Last edited by pzgr40; 13th February 2020 at 07:53 AM.

  6. #4
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    For KPS and FEW I have read following explanations in German WW2 manuals.
    KPS - Kupfer Panzer Stahl in D 420/150 (copper armoured steel)
    FEW - Walzeisen in D 435/3 (rolled iron)
    See images.
    Attached Images Attached Images
    Last edited by greif; 13th February 2020 at 10:46 PM.

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    Grzesio (14th February 2020), pzgr40 (14th February 2020)

 

 

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