8.8 cm KwK 36

A captured Tiger I tank fitted with the 8.8 cm KwK 36

The 8.8 cm KwK 36 L/56 (German: 8,8 cm Kampfwagenkanone 36 L/56) was an 88 mm tank gun used by the German Army during World War II. This was the primary armament of the PzKpfw VI Tiger I tank. It was developed and built by Krupp.

Design

The KwK 36 was derived from the 8.8 cm FlaK 36 anti-aircraft gun by adapting/modifying it to the limited space available in tank turrets. Parts of the KwK 36 were built to practically the same design as the 7.5 cm and 5.0 cm guns already used in German tanks. The breech ring was square in section and 320 millimetres (13 in) on a side. The breech block was of vertical falling wedge type and operated semi-automatically, meaning that after firing the empty cartridge case was automatically ejected, while the breech cocked itself and remained open, ready to receive the next round.

The "L56" in the designation is a traditional measurement for artillery pieces. "L" refers to the length of the interior of a gun tube (or "barrel") in proportion to the size of its bore, an important metric in determining a gun's relative performance for its bore size. The inside diameter of a gun tube is considered one caliber. The designation "L56" means the barrel is 56 calibers long, or 56 times 88 mm = 4,928 mm; almost 5 metres (16 ft). Thus, it is not an absolute unit of measurement; it is a proportionate one, and thus is rarely used while considering overall dimensions. Rather, it is used to denote how much velocity a gun will generate for its bore size. The longer the tube is in relation to its bore, the higher the muzzle velocity it can generate. A longer gun barrel allows the expanding gas from the shell's charge to act on the projectile longer than a short barrel, imparting it more velocity and force. For the Tiger II's 8.8 cm KwK 43 L/71, 71 times 88 mm is 6248 mm, over 6 metres (20 ft) long. Shorter tubes are most useful for indirect fire, such as howitzers or infantry support. For anti-armour purposes using traditional solid shot, a long to very-long tube is needed, to generate the necessary velocity.

Performance

8.8 cm KwK 36 at Base Borden Military Museum

The KwK 36 was very accurate and high-powered, and its high muzzle velocity produced a very flat trajectory. This allowed its gunners a higher margin of error in estimating range.

In British firing trials during the war, a British gunner scored five successive hits from 1,200 yards (1,100 m) at a 16 by 18 inches (41 by 46 cm) target. Another five rounds were fired at targets moving at 15 miles per hour (24 km/h), and, although smoke obscured the gunners' observation, three hits were scored after directions given by the commander. The sighting system resulted in excellent firing accuracy for the 8.8 cm KwK 36 gun on the Tiger I.^[1]

Capability

The gun's performance was highly dependent on distance to target and type of ammunition loaded. For kinetic penetration, the speed of the projectile upon impact is crucial, and cumulative effect of air resistance decreases the velocity of the shell as the distance to the target increases. The accuracy achieved during controlled test firing to determine the pattern of dispersion gives a greater accuracy than the variation expected during practice firing on a range due to differences between guns, ammunition and gunners; both at precisely known distances.^[2] Due to errors in estimating the range and many other factors, the probability of a first shot hit under battlefield conditions was much lower than at the firing range. Observing the tracer from the first round in battle, the average, calm gunner might achieve the firing range accuracy shown in the second column with the second round fired at the same target. ^[2]

This gun used the same size 88 x 571R mm cartridge employed by the Flak 18/36/37, although modified for electrical priming.

Panzergranate 39 (PzGr. 39)

Finnish training chart for KwK 36, shows an 88 mm PzGr. 39 (APCBC round).

• Type: Armour-piercing, capped, ballistic cap (APCBC) projectile with explosive filler and tracer.
• Projectile weight: 10.20 kg (22.5 lb)
• Muzzle velocity: 773 m/s (2,540 ft/s)
• Explosive filler: 0.059 kg (0.13 lb)

Penetration figures given for an armoured plate 30 degrees from vertical

		Hit probability versus 2.5 x 2 m target [2]
Range	Penetration	Test bed	Firing range
100 m	132 mm	100%	100%
500 m	110 mm	100%	100%
1000 m	99 mm	100%	93%
1500 m	91 mm	98%	74%
2000 m	83 mm	87%	50%
2500 m	n/a	71%	31%
3000 m	n/a	53%	19%

PzGr. 40 (APCR)

• Type: Armour-piercing, composite rigid (APCR) projectile had a sub-calibre tungsten core.
• Projectile weight: 7.30 kg (16.1 lb)
• Muzzle velocity: 930 m/s (3,100 ft/s)

Penetration figures given for an armoured plate 30 degrees from vertical

		Hit probability versus 2.5 x 2 m target [2]
Range	Penetration	Testbed	Firing range
100 m	171 mm	100%	100%
500 m	156 mm	100%	100%
1000 m	138 mm	99%	80%
1500 m	123 mm	89%	52%
2000 m	110 mm	71%	31%
2500 m	n/a	55%	19%

Hl.39 (HEAT)

• Type: high explosive anti-tank (HEAT) round with a shaped charge.
• Projectile weight: 7.65 kg (16.9 lb)
• Muzzle velocity: 600 m/s (2,000 ft/s)

Penetration figures given for an armoured plate 30 degrees from vertical

		Hit probability versus 2.5 x 2m target [2]
Range	Penetration	Testbed	Firing range
100 m	90 mm	100%	100%
500 m	90 mm	100%	98%
1000 m	90 mm	94%	62%
1500 m	90 mm	72%	34%
2000 m	90 mm	52%	20%

Sprgr. L/45 (HE)

• Type: high explosive (HE) round
• Projectile weight: 9.3kg (20.5 lb)
• Explosive filler: 0.9 kg of amatol (3765 Kilojoules)^[3]

Penetration comparison

See also

• 8.8 cm KwK 43 L/71 - the direct successor to this gun, and the one mounted on the Tiger II
• 8.8 cm Flak 18/36/37/41, the prominent anti-aircraft and anti-tank weapon the 8.8 cm KwK 36 is often confused with.

References

Bibliography