16-inch Armour Piercing Shot
By Richard Henry, Curator, Military Collection, DITSONG: National Museum of Military History.
The British Admiralty ordered two new Battleships for the Royal Navy in December 1922. These were called the Nelson Class, named after Admiral Horatio Nelson. Their mass and size was restricted by the Washington Naval Treaty to a maximum dry tonnage of 35 000 tons and 16-inch guns. They were sometimes referred to as the “Cherry Tree” class as they had been cut down by Washington. The two ships were christened HMS Nelson and Rodney.
The keels were laid down on 28 December 1922. The firm Armstrong Whitworth & Co built the Nelson at the High Walker shipyard on the River Tyne, northern England. She was launched in September 1925 and commissioned in August 1927. The Rodney was built by Cammel Laird at the Birkenhead shipyard on the River Mersey, launched in December 1925 and commissioned in December 1927.
Not to exceed the maximum tonnage they had a unique layout with the nine 16-inch guns in three turrets all forward of the bridge. Armour plating was also reduced but in places over the main magazine, control positions, and waterline belt it had sloped armour up to 360 mm thick. The deck had a single plate of 159 mm thick to protect against plunging shells and aircraft bombs. Non vulnerable areas had minimal armour plating.
FIgure 1: Both battleships served extensively in the Atlantic, Mediterranean, and Indian oceans during the Second Word War. The Rodney was made famous by her role in the sinking of the German battleship Bismarck in May 1941.
THE SOUTH AFRICAN CONNECTION
On 25 March 1941, the Battleships HMS Nelson and Revenge as well as the light cruisers Edinburgh and Cairo and sixteen destroyers escorted twenty troopships with 528 000 troops from Britain to the Middle East.
On Wednesday 16 April 1941 at 8:45 HMS Nelson tied up alongside the Duncan Dock in Cape Town. The next day she was visited by General JC Smuts. It is thought that as a gift the Nelson donated one of her 16-inch projectiles. On 19 April at 8:00 HMS Nelson sailed from Cape Town for Durban. At 14:00 off Dyer Island she fired her main guns.
On Tuesday 22 April at 10:30 Nelson arrived off Durban; at 13:30 she entered the dry dock in Durban for her annual maintenance. The maintenance was complete by 3 May 1941 and the Nelson left the Durban dry dock and berthed in Durban. On 10 May at 14:30 the Nelson along with the aircraft carrier Eagle with Swordfish aircraft from 813 and 824 squadrons on board as well as the heavy cruiser Hawkins sailed from Durban. As the three ships passed through the harbour entrance large crowds had gathered on the breakwaters to wave goodbye. ‘The Lady in White’ Perla Gibson, sang in her soprano voice which was amplified by a ship’s megaphone while the three ships returned to Cape Town arriving on 12 May at 19:00. The next day at 8:00 the Nelson and Eagle sailed from Cape Town for St Helena in search of the German commercial raider Atlantis.
FOR THE WAR MUSEUM
In mid-1942 the War Museum had collected a few exhibits, but a letter dated 17 March 1943 written by the Officer Commanding the South African War Museum, Captain Bellwood to Commander Scheepers (Navy) at Defence Headquarters states “As far back as May 29, 1942, I have been trying to obtain historic and interesting objects which will help the SA War Museum show the part played by the South African Naval Service.” Bellwood also states that the SA War Museum has no naval exhibits and requests help in obtaining naval trophies, souvenirs and equipment.
This seems to suggest that by 29 May 1942, the SA Naval Service had a selection of interesting naval equipment in their possession, most probably at Simon’s Town where they were being used for demonstration and instruction purposes.
The Royal Navy and South African Naval Service exhibited material at the Liberty Cavalcade, Green Point Common, Cape Town, from 25 March to 1 April 1944. After the Cavalcade in Cape Town, the UDF exhibition, as well as the naval exhibition travelled by train to Bloemfontein, Kimberley and then Durban. The last cavalcade, the “Speed for Victory Fair”, was held at the Witwatersrand Agricultural Showgrounds in Milner Park, Johannesburg, from 25 November to 2 December 1944. After this cavalcade, many of the exhibits became part of the fledging South African War Museum holdings. The 16-inch projectile is listed on the inventory of exhibits compiled by Captain WA Bellwood, Officer Commanding of the War Museum, in July 1945. This list of objects was used during the handing over of the Museum to Bellwood’s successor, Maj JA de Wet.
The main armament on the Nelson and Rodney was nine Breech Loading 16-inch Mark 1 guns. There were three guns in each of the three gun turrets. These were the only Royal Navy battleships with this configuration. The guns were of 45 calibres, meaning 45 times the bore of 16 inches, which equates to a length of 60 foot (18 m).
A total of 29 of these guns were manufactured by Armstrong Whitworth & Company at Elswick, on Tyne, Vickers at Barrow-in- Furness, William Beadmore & Company at Dalmuir and the Royal Gun Factory at Woolwich. Eighteen of the guns were mounted on the battleships while the other 11 were repaired. The high muzzle velocity of the projectile wore out the barrels quite quickly and effected accuracy, leading to a large dispersion pattern. After firing between 200-250 projectiles they needed re-rifling.
SPECIFICATIONS OF BL 16-INCH MK 1 GUN
16-inches (406 mm)
Rate of fire:
1 round per min
Effective firing range:
32 000 m at a 32-degree elevation
Maximum firing range
36 375 m
By the 1850s it was found that high explosive shells had little effect on the thick armour plating of the enemy ships. High explosive shells only caused some damage to light infrastructure.
A new projectile or solid shot, able to penetrate the thick armour of the enemy ship was required. If the side armour of a ship could be penetrated it could lead to the ship taking in water and after multiple strikes, it could be sunk. The Rodney fired 380 projectiles at the Bismarck before it sank.
Armour piercing projectiles were at first forged and the nose specially quenched with water to make it extremely hard. The problem now was that the hard projectile could shatter on impact.
A softer penetrating nose cap transferred energy from the tip of the shell to the sides of the projectile, thereby helping to reduce shattering. The penetrating cap also deformed on contact which aided the “sticking “to the target armour plate on contact, which reduced the projectile from bouncing off in glancing shots when striking at an oblique angle.
During the Second World War (1939-1945), armour piercing projectiles / shot used alloyed steels containing a mixture of nickel, chromium and molybdenum.
Later amour piercing projectiles were fitted with a small bursting charge which would explode once the projectile or shot had penetrated the enemy ship.
THE ARMOUR PIERCING SHOT MARK 1B ON DISPLAY
This shot, with a penetrating cap, had a mass of 929 kg. Inside the projectile was 23.2 kg of TNT, which would explode after penetration.
The shot did not have a standard brass cartridge case contacting the propelling explosives. This would be too large to handle and manoeuvre and rather expensive. Rather the projectile was loaded into breech, rammed into the barrel and six charge bags, each with a mass of 37.4 kg and containing SC 280 explosives as the propellant. This total of 224 kg of propelling charge when fired built up a pressure of about 3 200 kg per cm squared in the gun breech. This pressure ensured that this 929 kg shot left the 18 m barrel as a muzzle velocity of about 788 m/s (depending on how worn the barrel was).
The trajectory of the shot and the range it would fly was dependent on the set elevation of the gun. The higher the elevation (up to 40 degrees), the greater the range. The effect and armour penetration of the shot, however, was dependent on the angle of the projectile strike and the strike velocity. See table below:
Side Armour Penetration
Deck Armour Penetration
18 290 m
27 420 m
32 000 m
The longer the range, the longer the time of flight of the projectile. To hit a ship traveling at say 20 knots (37km/h) the gunnery officer had aim ahead of the target, how much was dependent on the range and projectile flight time. It had to be calculated how far the enemy ship would travel during the fight time. A few examples are given below.
18 290 m
27 420 m
32 000 m
Figure 2: A 15-inch Capped Ballistic Capped Armour Piercing Shell with explosive charge (in darker yellow).
THE EFFORT REQUIRED IN LOADING THE PROJECTILE
When the Nelson or Rodney prepared for sea, a total of 900 armour piercing projectiles would be loaded into the hull, 100 projectiles for each gun. These were stored in an upright position on a rotating projectile handling platform below each gun turret. That is 300 projectiles per gun turret.
A further 5 400 charge bags, each weighing 37.4 kg were also loaded. Below each gun turret, towards the bottom of the ship is the magazine. In the magazine, the 1 800 charge bags for each gun turret were stored in separate racks. Each section of rack was sealed off the other to reduce the risk and damage from a fire or explosion.
Of the full crew compliment of 1 361 men, a total of three officers and 294 men were involved in preparing and firing the nine guns. One officer and 98 men per gun turret of three guns were required.
The majority of the 98 men required to service each gun turret worked either in the charge bag magazine and/or the projectile handling platform.
Six charge bags (37.4 kg each) were taken from the magazine and loaded into a charge bag chute which hoisted the bags up to the gun room inside the gun turret.
An operator electrically turned the outer projectile handling platform or carousel. This brought one of the upright standing projectiles closer to the projectile pusher hoist. The task was to now move the projectile from the outer ring to the inner ring. A cable was placed around the projectile and wrapped around a powered capstan. The capstan turned and at the same time pulled the projectile onto the inner turnstile and into position for the pusher hoist.
In the gun turret the gun was lowered to a five degree elevation and the breech opened. The projectile arrived in the gun room in an upright position nose first. It stopped when it got to the cradle behind the gun. The projectile in the cradle was then hydraulically lowered to line up with the breech of the gun. A hydraulic rammer operator rammed the projectile into the breech. The rammer was then withdrawn.
The gun was now ready to receive the six charge bags. Three bags were rolled from the chute in the gun room and placed in the cradle; another three bags were removed and loaded into the cradle. The six charge bags were rammed slowly into the breech. The breech was closed and the gun rose to the required elevation. The gunnery officer then checked all systems and the gun room officer confirmed them. The gun was fired, sending a 929 kg projectile on its way to the target. Each gun in the three-gun turret was elevated, loaded and fired separately. The same procedure was repeated for each of the nine guns.
Figure 3: Loading a 16–inch projectile into the turret handling platform. 16-inch Armour Piercing Shot On Display at DITSONG: National Museum of Military History; From HMS Nelson, 1941.
As the projectile loading in the handling rooms required 50 seconds, the maximum sustained rate of fire was one round per gun and was theoretically every 50 seconds. The actual firing rate was more likely to be every 65 seconds.
The visit of HMS Nelson to Cape Town in April 1941 and the meeting with Prime Minister, General JC Smuts was instrumental in the fledging War Museum in Johannesburg, eventually obtaining one of these 16-inch projectiles.
- Bellwood, WA Inventory of Exhibits War Museum, dated 16 July 1945.
- Bellwood, WA South African War Museum Organisation files 1-7.
- http://rapidttp.co.za/waratsea/nelson.html article by Marsh, J, HMS Battleship Nelson