Germany
28 cm/52 (11") SK C/28
Updated 28 December 2008

This weapon was used on the famous Panzerschiffes or "Pocket Battleships" Lützow (ex-Deutschland), Admiral Scheer and Admiral Graf Spee.  The turrets were fitted with RPC only for elevation.

The shells used for these guns had inferior ballistic characteristics when compared to those for the later 28 cm SK C/34.  "These guns had 28 cm Psgr.m.K. L/3,7 armor-piercing projectiles, which were more or less a 'warmed-over' Krupp 28 cm Psgr.m.K. L/3,4 post-1911 World War I AP projectiles with a slight decrease in weight, a blunter nose, a thicker AP cap and a more pointed windscreen to increase range.  They were still just as poor at oblique-angle impact as their older brothers, having the same '0.5-caliber-KC-penetration-at-500 mps-and-30°-obliquity' specification as did the pre-World War I design.  Both the older projectile and this newer one barely met that requirement.  These guns also had a very blunt-nosed SAP-type Common projectile (Spgr.m.Bdz) with only light AP penetration ability, though the blunt nose shape gave it good thin-deck (British and French 'Treaty' cruisers) penetration at long range, which was probably what it was for." -- Nathan Okun

  The construction of this weapon was similar to that of the 28 cm SKC/34, but the jacket was in one piece.

All German 28 cm guns had an actual bore diameter of 28.3 cm (11.1").

WNGER_11-52_skc28_Graf_Spee_stern_pic.jpg

Stern 28 cm/52 Turret on Admiral Graf Spee in mid-1939
U.S. Naval Historical Center Photograph # NH 80897

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Gun Characteristics
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Designation 28 cm/52 (11") SK C/28
Ship Class Used On Lützow (ex-Deutschland) Class
Date Of Design 1928
Date In Service 1930
Gun Weight 106,262 lbs. (48,200 kg)
Gun Length oa 583.27 in (14.815 m)
Bore Length 547.4 in (13.905 m)
Rifling Length 449.25 in (11.411 m)
Grooves (80) 0.128 in deep x 0.265 in (3.25 mm x 6.72 mm)
Lands 0.173 in (4.4 mm)
Twist Increasing RH 1 in 50 to 1 in 35
Chamber Volume 9,764 in3 (160 dm3)
Rate Of Fire 2.5 rounds per minute
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Ammunition
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Type Cartridge - Bag
Projectile Types and Weights APC L/3,7 - 661.4 lbs (300 kg)
HE L/4,2 base fuze - 661.4 lbs. (300 kg)
HE nose fuze - 661.4 lbs. (300 kg)
Bursting Charge APC L/3,7 - 14.55 lbs. (6.6 kg)
HE L/4,2 base fuze - 35.27 lbs. (16.0 kg)
HE L/4,2 nose fuze - 48.06 lbs. (21.8 kg)
Projectile Length APC L/3,7 - 41.2 in (104.7 cm)
HE L/4,2 base fuze - 46.8 in (118.8 cm)
HE L/4,2 nose fuze - 46.8 in (118.8 cm)
Propellant Charge Fore:  79.4 lbs. (36.0 kg) RPC/38 (16/7.2)
Main:  156.6 lbs. (71.0 kg) RPC/38 (16/7.2)
Total main cartridge weight:  417.8 lbs. (189.5 kg)
Muzzle Velocity APC - 2,986 fps (910 mps)
Others - N/A
Working Pressure 20.3 tons/in2  (3,200 kg/cm2)
Approximate Barrel Life 340 rounds
Ammunition stowage per gun 120 rounds (see Note 2)
Notes:

1) These guns, like most large caliber German guns, used a "fore charge" which was propellant in a silk bag, and a "main charge" which was propellant in a brass case.  The brass case helped to seal the breech of the gun.

2) This is the design figure.  "German Warships 1815-1945" says that the actual outfit ranged from 105 to 120 rounds.  Admiral Graf Spee carried 100 rounds per gun during her war cruise.  Her outfit consisted of 200 AP, 200 HE Nose Fuze and 200 HE Base Fuze rounds.  Of these, 414 were fired during the Plate River battle - all 200 HE Nose Fuze rounds, 184 HE Base Fuze and 30 AP rounds, leaving her with 170 AP and 16 HE Base Fuze rounds at the close of the action.  She scored seven hits and one damaging near miss on HMS Exeter while HMS Ajax received one hit and one glancing blow and HMNZS Achilles escaped with a single damaging near-miss, a total of about 2.7 percent.  Although this hit percentage was better than that recorded by the British and New Zealander crews, it was disappointing to the Germans, who blamed Capt. "Langsdorff's torpedo officer's tendency to over zigzag" - Eric Grove.

3) Fore and Main charges were rammed together.

4) APC and HE ballistic caps had a radius of 8.5 calibers.  The tangent of the ballistic cap to the shell body was inclined at 5 degrees, which resulted in a projectile with a short overall length.

5) Actual Projectile designations were as follows:
   APC L/3,7 - Pz.gr. L/3,7 (mhb)
   HE L/4,2 base fuze - Spr.gr. L/4,2 Bdz (mhb)
   HE L/4,2 nose fuze - Spr.gr. L/4,2 Kz (mhb)

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Range
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Elevation
With 661 lbs. (300 kg) APC
Striking Velocity
Angle of Fall
1.9 degrees
5,470 yards (5,000 m)
2,467 fps (752 mps)
2.4
4.5 degrees
10,940 yards (10,000 m)
2,005 fps (611 mps)
6.0
8.0 degrees
16,400 yards (15,000 m)
1,617 fps (493 mps)
11.8
2.5 degrees
21,870 yards (20,000 m)
1,335 fps (407 mps)
21.4
18.6 degrees
27,340 yards (25,000 m)
1,181 fps (360 mps)
34.2
26.3 degrees
32,810 yards (30,000 m)
1,158 fps (353 mps)
46.4
36.4 degrees
38,280 yards (35,000 m)
1,247 fps (380 mps)
56.0
40.0 degrees
39,890 yards (36,475 m)
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Mount / Turret Data
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Designation Three-gun Turrets
   Lützow (ex-Deutschland) (2):  Drh LC/28
Weight  590 tons (600 mt)
Elevation -10 / +40 degrees
Elevation Rate 8 degrees per second
Train about +150 / -150 degrees
Train Rate 6 degrees per second
Gun recoil N/A
Loading Angle +2 degrees
Notes:

1) Turrets had electric training, auxiliary elevation, auxiliary hoists but otherwise they were hydraulically powered by two electrically driven pumps in each turret using a water / glycerine pressure medium.  Main gun elevation was by hydraulic cylinder driving the elevation arc by a rack and pinion.

2) Each gun was served by a shell cage which picked up the charge cage on its way to the gunhouse.  The hoists came up between the guns and the shells were transferred to the loading tray by rammers.  The shell hoist for the left gun came up between the left gun and the center gun.  The other two cages came up between the center and right gun.  The charge cage carried the fore charge on the bottom and the main charge on top.  The fore charge was loaded by hand and then the main charge rammed in behind it.  There were also auxiliary hoists for each gun.  The auxiliary hoist for the center gun came up behind the gun and had a tiltable cage.  The other auxiliary hoists came up behind and to the side of the guns, with the shells and main charges being transported by overhead gear.

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Data from
"Naval Weapons of World War Two" by John Campbell
"German Warships 1815-1945" by Erich Gröner
"The Price of Disobedience:  The Battle of the River Plate Reconsidered" by Eric Grove
"The Big Gun:  Battleship Main Armament 1860-1945" by Peter Hodges
"German Capital Ships of World War Two" by M.J. Whitley
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Special help from Richard Worth and Nathan Okun