21 cm Kanone 39
Encyclopedia
The 21 cm Kanone 39 (K 39) was a Czech
-designed heavy gun used by the Germans in the Second World War. Two were built before the Germans occupied Czechoslovakia
in March 1939 and seized the rest of the guns and kept it in production for their own use, eventually building a total of 60 guns for themselves. They participated in Operation Barbarossa
, the Siege of Odessa, Siege of Leningrad
and the Siege of Sevastopol and were used on coast defense duties.
as a dual-purpose heavy field and coast defense gun in the late Thirties for Turkey
with the designation of K52. Only two had been delivered before the rest of the production run was appropriated by the Heer
upon the occupation of Czechoslovakia in March 1939.
Unlike the German practice of sliding block breech
es that required a metallic cartridge case to seal the gun's chamber against combustion gases, Škoda
preferred to use a interrupted screw
breech with a deBange obdurator to seal the chamber. This lowered the rate of fire, but had the great economic advantage of allowing bagged propellant charges that didn't use scarce brass or steel cartridge case when those metals were in short supply. The other unusual feature of the gun was that it used a monobloc auto-frettaged barrel. This was a single piece of steel that was radially expanded under hydraulic pressure. This had the advantage of placing the steel of the barrel under compression which helped it resist the stresses of firing and was simpler and faster to build since the barrel didn't require assembly as with more traditional construction techniques.
The box-trail carriage revolved on a turntable that sat on a ball race
on the firing platform and was capable capable of 360° traverse. The end of the carriage rested on rollers which rested on a metal track or rail. For transport the K 39 broke down into three loads, the barrel, the carriage and the firing platform with the turntable. Each of these was carried on a trailer with pneumatic tires. Emplacing the gun took six to eight hours, mainly to dig in and anchor the firing platform.
The story of the gun's development by the Germans is contradictory in the available sources. Hogg claims that the K 39/40 had only slight changes made, but that the K 39/41 added a muzzle brake
to control recoil. Gander and Chamberlain say that the K 39/40 and K 39/41 both had muzzle brakes with better performance than the original K 39 and that the K 39/41 was introduced to simplify production. A total of sixty were built for the Germans.
well forward on the shell and was fitted with a thin metal casing behind the driving band filled with a graphite mixture intended as a bore lubricant and to reduce wear. The 21 cm Gr 39 Be was an Czech-designed anti-concrete shell fitted with a base fuze, a ballistic cap
and the additive sleeve. It was filled with 8.1 kilograms (17.9 lb) of TNT. There was also an armor-piercing
, base-fuzed shell, the 21 cm Pzgr 39 of which little is known other than it had a filling of 2.8 kilograms (6.2 lb) of a PETN
/wax
mixture.
The K 39 used a three-part bagged charge that weighed a total of 37.5 kilograms (82.7 lb). The K 39/41 used a bagged charge with a total weight of 55 kilograms (121.3 lb) The base charge (Kleine Ladung) weighed 21.5 kilograms (47.4 lb) and had an igniter stitched to its base. The two increments (Vorkart) were lightly stitched together and enclosed in another bag tied at the top and with another igniter stitched to the base. The medium charge (Mittlere Ladung) consisted of the base charge and increment 2 while the full charge (Grosse Ladung) consisted of the base charge and both increments. The increments were loaded before the base charge.
767 was assigned to the Sixth Army of Army Group South
where it participated in the sieges of Odessa and Sevastopol. 768 was initially assigned to 4th Army of Army Group Center, but it was quickly transferred to Army Group North
to aid in the siege of Leningrad
. By the start of Case Blue in late June 1942 Artillery Battalion 767 had been converted to smaller guns, but 768 was assigned to the 18th Army of Army Group North
.
Seven K 39 guns were assigned to coast defense duties in Norway and nineteen K 39/40 guns were stationed in France (13) and Norway (6).
Czechoslovakia
Czechoslovakia or Czecho-Slovakia was a sovereign state in Central Europe which existed from October 1918, when it declared its independence from the Austro-Hungarian Empire, until 1992...
-designed heavy gun used by the Germans in the Second World War. Two were built before the Germans occupied Czechoslovakia
German occupation of Czechoslovakia
German occupation of Czechoslovakia began with the Nazi annexation of Czechoslovakia's northern and western border regions, known collectively as the Sudetenland, under terms outlined by the Munich Agreement. Nazi leader Adolf Hitler's pretext for this effort was the alleged privations suffered by...
in March 1939 and seized the rest of the guns and kept it in production for their own use, eventually building a total of 60 guns for themselves. They participated in Operation Barbarossa
Operation Barbarossa
Operation Barbarossa was the code name for Germany's invasion of the Soviet Union during World War II that began on 22 June 1941. Over 4.5 million troops of the Axis powers invaded the USSR along a front., the largest invasion in the history of warfare...
, the Siege of Odessa, Siege of Leningrad
Siege of Leningrad
The Siege of Leningrad, also known as the Leningrad Blockade was a prolonged military operation resulting from the failure of the German Army Group North to capture Leningrad, now known as Saint Petersburg, in the Eastern Front theatre of World War II. It started on 8 September 1941, when the last...
and the Siege of Sevastopol and were used on coast defense duties.
Development and design
It was designed by ŠkodaŠkoda Works
Škoda Works was the largest industrial enterprise in Austro-Hungary and later in Czechoslovakia, one of its successor states. It was also one of the largest industrial conglomerates in Europe in the 20th century...
as a dual-purpose heavy field and coast defense gun in the late Thirties for Turkey
Turkey
Turkey , known officially as the Republic of Turkey , is a Eurasian country located in Western Asia and in East Thrace in Southeastern Europe...
with the designation of K52. Only two had been delivered before the rest of the production run was appropriated by the Heer
Heer (1935-1945)
The Heer was the Army land forces component of the German armed forces from 1935 to 1945, the latter also included the Navy and the Air Force...
upon the occupation of Czechoslovakia in March 1939.
Unlike the German practice of sliding block breech
Breech-loading weapon
A breech-loading weapon is a firearm in which the cartridge or shell is inserted or loaded into a chamber integral to the rear portion of a barrel....
es that required a metallic cartridge case to seal the gun's chamber against combustion gases, Škoda
Škoda Works
Škoda Works was the largest industrial enterprise in Austro-Hungary and later in Czechoslovakia, one of its successor states. It was also one of the largest industrial conglomerates in Europe in the 20th century...
preferred to use a interrupted screw
Interrupted screw
An interrupted screw or interrupted thread is a mechanical device typically used in the breech of artillery guns. It was invented circa 1845....
breech with a deBange obdurator to seal the chamber. This lowered the rate of fire, but had the great economic advantage of allowing bagged propellant charges that didn't use scarce brass or steel cartridge case when those metals were in short supply. The other unusual feature of the gun was that it used a monobloc auto-frettaged barrel. This was a single piece of steel that was radially expanded under hydraulic pressure. This had the advantage of placing the steel of the barrel under compression which helped it resist the stresses of firing and was simpler and faster to build since the barrel didn't require assembly as with more traditional construction techniques.
The box-trail carriage revolved on a turntable that sat on a ball race
Ball bearing
A ball bearing is a type of rolling-element bearing that uses balls to maintain the separation between the bearing races.The purpose of a ball bearing is to reduce rotational friction and support radial and axial loads. It achieves this by using at least two races to contain the balls and transmit...
on the firing platform and was capable capable of 360° traverse. The end of the carriage rested on rollers which rested on a metal track or rail. For transport the K 39 broke down into three loads, the barrel, the carriage and the firing platform with the turntable. Each of these was carried on a trailer with pneumatic tires. Emplacing the gun took six to eight hours, mainly to dig in and anchor the firing platform.
The story of the gun's development by the Germans is contradictory in the available sources. Hogg claims that the K 39/40 had only slight changes made, but that the K 39/41 added a muzzle brake
Muzzle brake
Muzzle brakes and recoil compensators are devices that are fitted to the muzzle of a firearm or cannon to redirect propellant gases with the effect of countering both recoil of the gun and unwanted rising of the barrel during rapid fire...
to control recoil. Gander and Chamberlain say that the K 39/40 and K 39/41 both had muzzle brakes with better performance than the original K 39 and that the K 39/41 was introduced to simplify production. A total of sixty were built for the Germans.
Ammunition
Every shell used by the K 39 weighed 135 kilograms (297.6 lb). The original Czech 21 cm Gr 39 (t) high-explosive shell had both nose and base fuzes and a filling of 18.8 kilograms (41.4 lb) of TNT. The German equivalent, the 21 cm Gr 40 lacked the base fuze, had a copper driving bandDriving band
The driving band or rotating band is part of an artillery shell, a band of soft metal near the middle of the shell, typically made of gilding metal, copper or lead...
well forward on the shell and was fitted with a thin metal casing behind the driving band filled with a graphite mixture intended as a bore lubricant and to reduce wear. The 21 cm Gr 39 Be was an Czech-designed anti-concrete shell fitted with a base fuze, a ballistic cap
Shell (projectile)
A shell is a payload-carrying projectile, which, as opposed to shot, contains an explosive or other filling, though modern usage sometimes includes large solid projectiles properly termed shot . Solid shot may contain a pyrotechnic compound if a tracer or spotting charge is used...
and the additive sleeve. It was filled with 8.1 kilograms (17.9 lb) of TNT. There was also an armor-piercing
Armor-piercing shot and shell
An armor-piercing shell is a type of ammunition designed to penetrate armor. From the 1860s to 1950s, a major application of armor-piercing projectiles was to defeat the thick armor carried on many warships. From the 1920s onwards, armor-piercing weapons were required for anti-tank missions...
, base-fuzed shell, the 21 cm Pzgr 39 of which little is known other than it had a filling of 2.8 kilograms (6.2 lb) of a PETN
PETN
Pentaerythritol tetranitrate , also known as PENT, PENTA, TEN, corpent, penthrite , is the nitrate ester of pentaerythritol. Penta refers to the five carbon atoms of the neopentane skeleton.PETN is most well known as an explosive...
/wax
Wax
thumb|right|[[Cetyl palmitate]], a typical wax ester.Wax refers to a class of chemical compounds that are plastic near ambient temperatures. Characteristically, they melt above 45 °C to give a low viscosity liquid. Waxes are insoluble in water but soluble in organic, nonpolar solvents...
mixture.
The K 39 used a three-part bagged charge that weighed a total of 37.5 kilograms (82.7 lb). The K 39/41 used a bagged charge with a total weight of 55 kilograms (121.3 lb) The base charge (Kleine Ladung) weighed 21.5 kilograms (47.4 lb) and had an igniter stitched to its base. The two increments (Vorkart) were lightly stitched together and enclosed in another bag tied at the top and with another igniter stitched to the base. The medium charge (Mittlere Ladung) consisted of the base charge and increment 2 while the full charge (Grosse Ladung) consisted of the base charge and both increments. The increments were loaded before the base charge.
Operational history
The K 39 and its variants served as mobile artillery only with Artillery Battalions (Artillerie-Abteilungen) 767 and 768, each battalion being organized with 3 batteries, each with two guns. Both battalions were raised in April—May 1940, but it is unknown if either participated in the Battle of France. For Operation BarbarossaOperation Barbarossa
Operation Barbarossa was the code name for Germany's invasion of the Soviet Union during World War II that began on 22 June 1941. Over 4.5 million troops of the Axis powers invaded the USSR along a front., the largest invasion in the history of warfare...
767 was assigned to the Sixth Army of Army Group South
Army Group South
Army Group South was the name of a number of German Army Groups during World War II.- Poland campaign :Germany used two army groups to invade Poland in 1939: Army Group North and Army Group South...
where it participated in the sieges of Odessa and Sevastopol. 768 was initially assigned to 4th Army of Army Group Center, but it was quickly transferred to Army Group North
Army Group North
Army Group North was a German strategic echelon formation commanding a grouping of Field Armies subordinated to the OKH during World War II. The army group coordinated the operations of attached separate army corps, reserve formations, rear services and logistics.- Formation :The Army Group North...
to aid in the siege of Leningrad
Siege of Leningrad
The Siege of Leningrad, also known as the Leningrad Blockade was a prolonged military operation resulting from the failure of the German Army Group North to capture Leningrad, now known as Saint Petersburg, in the Eastern Front theatre of World War II. It started on 8 September 1941, when the last...
. By the start of Case Blue in late June 1942 Artillery Battalion 767 had been converted to smaller guns, but 768 was assigned to the 18th Army of Army Group North
Army Group North
Army Group North was a German strategic echelon formation commanding a grouping of Field Armies subordinated to the OKH during World War II. The army group coordinated the operations of attached separate army corps, reserve formations, rear services and logistics.- Formation :The Army Group North...
.
Seven K 39 guns were assigned to coast defense duties in Norway and nineteen K 39/40 guns were stationed in France (13) and Norway (6).