BRITISH 

SUPER-HEAVY

GUNS 

BY NJM CAMPBELL

PART I

The guns discussed in this article, that were actually mounted in British ships, are limited to the four RML mounted in the battleship Iinflexible completed in 1881, the two 16.25in BL mounted in the battleships Ben'bow of 1888, and Victoria and Sans Pareil of 1890-1891, the single 18in BL mounted in the battlecruiser Fürious of 1917 and the monitors General Wolfe and Lord Chve, as rearmed in 1918, and finally the nine 16in BL Mark 1 mounted in the battleships Nelson and Rodney of 1927. This is a small total when compared with the 128-15in BL mounted at one time or another in 22 ships, but the guns of 16in or over actually mounted in ships tell but a part of the story of such weapons. Also included are, the 17.7in RML mounted at Gibraltar and Malta, the 16in BL built for Russia in 1914-1917, which ended its days as the first British süper-velocity 8in, the 16in BL Mk II and III intended for the Lion class, ships caticelled because of the 1939 1945 war, and the 16in BL Mark IV project for the redesigned Von class of the immediate post World War Two period. Besides these there are the four 18in/45 cal guns of 1920-1921, each of which was of different construction and three "of which were actually begun. Lastly the 1885 1 1886 project to reinforce the Portsmouth defences by four 17in/41 cal BL may be noted, though there is more than a touch of fantasy about this as it would have been virtually impossible to build these guns at that date and it is exceedingly improbable that they would have functioned in a satisfactory way if they had been constructed.

161N RML MARK 1

The origins of this gun go back to July 1873 when the Admiralty requested the War Office, at that date responsible for the supply of naval guns, to prepare a design for a 60 ton gun, 22ft 4in in overall length. The largest gun actually in British service at this time was the 12in/35 ton. At a meeting on 21 October 1873 a design for a 75 ton 16in of the above length, to fire a 16501b projectile with a 3001b black powder propellant charge, was discussed and a requirement to pierce 20in of wrought iron at 1 000yds was mentioned; the Italian battleship Duilio, laid down in April 1873, would have armour of this thickness, as also, it was erroneously believed, would the Russian battleship Petr Veliki, launched in August 1872. On 26 November 1873 a less ambitious design was produced for a 60 ton 15in gun, still 22ft 4in long, firing a 13501b projectile with 2301b charge. Finally, on 11 March 1874, the manufacture of an experimental gun of about 75 tons - on a later estimate 80 tons - was approved. This was to have a 24ft bore and was to be tried successively at 14, 15 and 16in cal - when bored to 16in, it was expected to give an MV (muzzle velocity) of 1400ft/sec with a 1650lb projectile and a 3001b propellant charge. It took 18 months to complete this gun, as enlarged plant had to be acquired at Woolwich, and meanwhile the Inflexible, which was to mount 4 of these guns when the design had been settled, had been laid down on 24 February 1874.

The experimental gun was eventually bored to 14.5in, not 14in, and rifled on the unsatisfactory but usual RML system with 11 grooves, studded projectiles and the twist increasing from zero to 1 in 35 at the muzzle. It was 'proved' on 17 September 1875 attaining an MV of 1550ft/sec with a 12601b projectile and a 2401b charge. After further firings it was bored to 15in and rerifled, then chambered to 16in and finally bored to 16in and rerifled. It should be noted that in the later firings copper gas-checks were used. These were rimmed discs attached to the base of the projectile; the rim expanded into the rifling grooves on firing so that the serious erosion from powder gases escaping past the projectile was greatly reduced. After a total of 166 rounds the gun was examined on 30 December 1876 and it would found that the steel tube had cracked in a rifling groove for a length of 55 to 85ins from the bottom of the bore. This was thought to be due to holes drilled and tapped for the fitting of crusher gauges to measure the pressures in the bore on firing.

However, firings continued, with some further development of the crack, and the gun was then chambered to 18in diameter and attained an MV of 1600ft/sec with a 17001b projectile and 4251b charge. By June 1877 the total of rounds fired was 274 but, though the Inflexible had been launched on 27 April 1876 and construction of all 4 of her guns was under way in March 1877, important details were as yet unsettled. In particular it had not been decided whether to abandon the studded projectile in favour of an improved gas- check combined with shallower but more numerous rifling grooves, a system to be known as polygroove. Accordingly the first of the Inflexible's guns was bored to 15.5in and given polygroove rifling but troubles with excessive pressures and shells ,setting up' occurred so it was not until August 1878 that it was recommended that this system should be used with a bore of 16in. It had been decided a year previously that the guns were to be chambered. The Inflexible's 4 guns were completed in 1880-1881 and this much delayed ship was finally ready in October of the latter year. Two more guns completed in 1881-1.882 were mounted in a twin turret at Dover and one more, intended as reserve for the Inflexible, was completed in 1885-1886 to give, with the original experimental gun, a total of eight.

All were built at the Royal Gun Factory Woolwich which at that date had a monopoly of gun construction for the British Services. The 16in RML was built on what was known as the Fraser two layer modification. There was a steel W tube which was heat-treated and quenched in oil but not tempered, and over this a wrought iron breech piece, 1B coil, 2B coil and B tube were shrunk. These were linked to one another by overlapping bayonet type joints. The C coil, incorporating the trunnion ring, was shrunk over the breech piece and part of the 1B coil and the cascable screw, which contained the axial vent, was screwed into the breech piece and butted firmly onto the end of the W tube. The cascable and trunnion ring were wrought iron forgings while the other parts were built up by hammer welding two or more coils"themselves made by coiling wrought iron bar over a mandrel and hammer welding. No attempt was made to carry out the shrinking so as to give precise calculated stresses in the various layers. This construction was crude but cheap, and reasonably effective for relatively short guns, and gave better longitudinal strength than the more complex Armstrong construction used in the 17.72in RML. Details of the 16in RML Mark 1 were:

17.72 IN RML
16 IN RML

Weight 80 tons (average)

Length (oa) 26ft 9in (321in)

Length (bore) 18 cal (288in)

Diameter 72in (max) 25in (at muzzle)

Chamber size 59.6 x 18in, volume 14 600 cub in

Rifling length 227.4in twist 0 to 1 in 50 at muzzle, 33 grooves,

polygroove plain section 0. 1 x 1 in, lands 0.523in

Projectile weight 17001b (including

2 1 -Ilb gas check)

Charge 4501b prismatic black (4 x112.5), later 4501b prismatic brown Muzzle Velocity 1604ft/sec with black powder, 1540 with brown. 

Brown powder charges were approved in April 1885 as black powder was found to expand the A tube and, in one instance, to crack it. The two Dover guns, Nos 6 and 7, were identical to the others except for shorter trunnions. A report of 23 May 1888 shows no available reserve guns for Inflexible as No 4 had had to be replaced by No 8 and neither No 4 nor the original No 1 were yet repaired. Two years later it was suggested that the two Dover guns might be replaced by smaller BLs and transferred to the Navy as additional reserves but nothing came of it, perhaps because the trunnions would have had to be lengthened. The life of the 16in RML before relining was rather dubiously estimated at 350 rounds. The Inflexible's two twin turrets allowed 10' elevation and 2' to 5' depression depending on the training angle with fixed loacling positions at 9'35" depression. The hydraulic loading gear could accommodate a shell 60in long which gave ample margin as the longest common shell was a little under 5 1 in and the chilled iron Palliser AP (Armour Piercing) 43.45 to 43.7in. At 10' elevation the range at 1590ft/sec MV was 6730yds, reducing to 6430yds at 1540ft/sec. 

Inflexible at Malta in her early days.

The Itahan battleship Duilio.

The Inflexible took part in the bombardment of Alexandria on 11 July 1882. At that date her outfit per gun was 55 Palliser AP, each with a 161b black powder burster intended to explode on impact as there was no fuse, 15 nose fused cast iron common shell each with a 601b black powder burster, 5 shrapnel, containing 860-4oz shot, and 5 case, intended mainly for use against torpedo boats and containing 1920-8oz shot. Her total expenditure in the bombardment was 21 Palliser, 56 common and 11 shrapnel, all fired with full charges. The Palliser AP was unlikely to burst unless it struck a heavy gun or mounting and the effect of the other projectiles was much reduced by the near uselessness of the fuses for which the War Office authorities were responsible. Cast steel base fused common shell, with 112.75lb black powder bursters, did not become available until much later. The next heaviest RML in the British Navy was the 12.5in/38 ton so the 16in was by far the largest. It can be judged as an interesting and fairly satisfactory gun but of obsolescent type by 1881 when it entered service, as two years previously a 15.75in/21.8 cal Krupp BL had been demonstrated with good results at Meppen. It remains to add that the two Dover 16in and turret are still extant although declared obsolete in 1902. 17.72IN RML NMRK 1 The origins of this gun go back to the Duilio and Dandolo, two of the remarkable but not entirely satisfactory ships designed by Benedetto Brin for the Italian Navy. When authorised in 1872 it was intended that they should have four 35 ton guns but in 1873 this was increased to four 60 ton. Both ships were laid down in the first half of that year but in 1874, as a consequence of the intention to arm the Inflexible with four 80 ton guns, it was decided that the two Duilio's should each have four 100 ton guns. A contract to build 8 of these guns was placed with Armstrong's at Elswick in July 1874, though only one was to be made initially, the others following when the first had been found satisfactory. It must be noted that the Duilio was about 900 tons smaller than the 11 8 8 0 ton Inflexible and that her beam was only 64ft 8in compared with 75ft in the latter ship. She was clearly much overgunned as is shown by her ammunition outfit of only 35 rounds per gun.

The first gun, bored to 17in and not chambered, was sent to Italy for trials in July 1876 but, on satisfactory reports of the 80 ton gun, orders to proceed with the other 7 guns of the original contract had already been given on 23 June 1876. As an unchambered 17in, 1542ft/sec MV was attained with a 20001b projectile and a 3751b prismatic black charge. Other tests were satisfactory and the gun was returned to Elswick for boring to 17.72in and chambering. Further trials were carried out in March and April 1878 and the four guns for the Duilio were delivered in time for her to complete in January 1880, the Dandolo, which had been launched 26 months after the Duilio, following in April 1882. Meanwhile the British wished to increase the coast defences of Gibraltar and Malta and, as further 16in RMLs could not be delivered from Woolwich in reasonable time, it was decided to break their monopoly and order 4 of the 17.72in from Elswick which, at that time, had a far better equipped gun- making plant than Woolwich. These four guns were delivered in 1882-1883 and a further three guns were made for Italy (one for the pontoon Forte, which was part of the Spezia defences, and two reserve guns) giving a final total of 11 for Italy and 4 for Britain.

The construction was very different from that of the 16in RML. The steel 'A' tube was in two lengths joined by a steel ring, in halve s, over the j oint. Over the 'A' tube were shrunk 10 wrought iron coils, identified from the breech end as 2A, 213, 2C, 21), 2E, 21)1, 2E1, 2F, 2G and 2H. The 2D and 21)1 coils were thinner than the rest and had the 2E and 2E' coils shrunk over them. The next layer, which stopped 207.85in from the muzzle, comprised the 3A and 3B coils, the trunnion piece and the 3C coil. Finally there was a layer extending to the trunnions, consisting of the 4A', 4A and 4B coils. The cascable, which screwed into the 2A coil, contained the axial vent and was made from a wrought iron forging as was the trunnion piece. The various parts were shrunk to more precise limits than in the Fraser construction as it was attempted to give each the designed stress. The surface of some of the coils was serrated to give a better longitudinal
grip, but not all the coils had overlapping joints, and it was thought that the 'A' tube took by far the greatest part of the longitudinal stresses. Details of the
17.72in Mark 1 were:
Weight 102 tons (average)
Length (oa) 32ft 7.85in (391.85in)
Length (bore) 20.5cal (363in)
Diameter 76.45in (max) 29in (at
muzzle)
Chamber size 59.72 x 19.7in,
volume 17 049 cub in
Rifling length 302.88in, twist 1 in
105 to 1 in 50 at 2.88in from
muzzle then uniform, 28 grooves,
polygroove plain section 0.125 x
1.Iin, lands 0.888in
Projectile weight 20001b (including
241b gas check)
Charge 4501b prismaticl or
prismaticl black (4 x 11 N)
Muzzle Velocity 1548ft/Sec

It will be noted that the projectile was relatively light as, if scaled up from the 16in, it would have been about 23001b. Much heavier charges were used by the Italians and in trials 1725ft/sec MV was attained with a 20001b projectile and a 5731b charge but on 6 March 1880 one of the Duilio's guns pufled apart. The fracture ran from the front end of the parallel part of the chamber to the front end of the 4B coil just behind the trunnions. The charge on this occasion was 5 5 1 lb of Fossano powder, which had large irregular grains each containing a number of small high density pieces in a lower density material. Normally such a charge would have given about 17.4 tons/sq in but it was believed that the Fossano grains had broken into fine pieces which would have given a much higher pressure. The gun was repaired by building up on a new A tube and subsequently the Italians appear to have limited charges to 529 lb, which gave about 170Oft/sec MV, while in Britain a much smaller charge and lower performance was accepted.

The British projectües were of the same type as those for the 16in, the Paffiser AP being 48.6in long with a 321b burster and the cast iron common of the same length having a 781b burster. A later cast steel common shell had a 1941b burster and was 52.55in long.

The two Gibraltar guns were mounted at 'Victoria' and 'Napier' of Magdala's batteries and the two Malta guns at'Rinefla' and 'Cambiidge' batteries. They were in the usual type of coast defence carriage- with pivotted slide and not in turrets. All except the 'Victoria' guns were still operational in 1902 but were soon declared obsolete. One still survives at Gibraltar, on a reconstructed carriage and slide as an exhibit, and there is a second gun at Malta.

PART2

16.25IN BL MARK 1

The twelve guns of this type were all built at Elswick but the differences between them were such that the designation of Mk -1 was abolished in July 1892 and they were known individually by their serial numbers. The origins of this gun go back to March 1883 when the Admiralty decided to arm the battleship Benbow, laid down on 1 November 1882, with two 100 ton guns to be supplied by Armstrong instead of the four 13.5in guns of the original design. It must be noted that the four ships of the French Terrible class, of which the first had been launched in 1881, were to have two 16.5in, though of a short and not very powerful type, and that Armstrong had already built 17in 100-ton guns for the Italian navy, while Woolwich were having great trouble in designing and building much smaller BL (Breech Loading) guns. In April 1883 Armstrong sent the design, No 12746, of the 17in gun they were then making for the Lepanto, the second of the Italian 17in gun ships, to the Ordnance Committee. After discussion two more 17in designs were submitted, Nos 12866 and 12867. These had chambers only 84.5in long instead of 102in and No 12866 was 31 calibres instead of 27, while the weights were 113-116 tons, which the Admiralty objected to, in May 1883, as they did not wish the weight to exceed 100 tons. The Ordnance Committee therefore confined themselves to the Lepanto design, which they objected to on the grounds of too long a chamber, too short a gun and a jointed A tube.

The Admiralty then agreed to accept a weight of over 100 tons if this were essential and on 27 July 1883 Armstrong submitted design No 13375. This was for a 16.25in/30 cal gun with an 84.5in chamber, an improved method of jointing the A tube and a weight of 110-2' tons. With a 9001b charge and a 18001b projectile, the MV (muzzle velocity) was variously estimated at 2020 to 2127fs with a maximum pressure of 17 tons/sq in. After further discussion this design was altered to include a single piece A tube, at a price of 4 to 6 months delay, and on 16 September 1884 design No 15215, which incorporated this feature, was finally approved, orders for Benbow's two guns and one reserve having been placed on 16 February 1884. Slow burning cocoa powder SBC - was approved for the guns on 24 August 1886 and the charge weight was later fixed at 9601b.

The history of the twelve guns is now given under their serial numbers.

NOS 1 AND 2

The construction was: A tube/breech piece (taking breech block), 17 hoops extending to muzzle/ 1 long hoop and 10 short hoops/8 hoops/7 hoops. All parts were made from steel forgings. The breech piece was secured to the A tube longitudinally by a serrated metal ring and the hoops of the 3 outer layers were secured by shoulders, apparently with yellow metal run in. The foremost hoop of the outer layer was held by a serrated metal ring. As the Benbow had been launched on 15 June 1885 the two guns were required in 1886 but No 1 was not proved until 1887 when it was found that the projectiles were not being properly rotated due to the rifling grooves being only 0.04in deep, as in the Italian guns. Nos 1 and 2 were, however, too urgently needed for the grooves to be deepened and in Benbow's gunnery trials in April 1888 the projectiles were reported a~ steady in flight. Benbow was completed in June 1888 but in December it was directed that her guns should be limited to half charges and Nos 1 and 2 were eventually replaced by Nos 11 and 12 in about May 1894.

NO 3 

Intended as a reserve gun for Benbow this was returned to Elswick for the rifling to be deepened to 0.06in and for the shot seating to be altered to take a 16.5in diameter driving band. The gun was delivered in December 1888 and used for range table firings, but it developed flaws in the bore and was also found to droop 0.75in. Further firings extended the flaws and slight openings appeared between the exterior hoops. It was accordingly sent to Elswick to be fitted with a short bore liner and for some alterations to the hoops. This comprised replacing the 14 forward hoops of the first layer by 3 long hoops or tubes and the 5 forward hoops of the second layer by a single long hoop. The third layer, of 9 hoops, and the fourth layer, of 7 hoops, were not altered. Further experimental firings caused flaws to develop forward of the liner and it was decided to fit a full length liner, the design of which was approved in October 1896.

NO 4

 Completed with 0.06in ritling grooves and with a coned section at the start of the shot seating which gave a reduced MV of 2066fs at 14.5 tons/sq in pressure. After firing trials in the new battleship Victoria on 17 October 1889 it was found to have drooped by 0.7in with slight opening between hoops. As soon as the gun could be spared it was sent for strengthening which in this case comprised a long final hoop in the second layer replacing 5 short hoops and an additional short hoop beyond it. Ort re-proof in 1890 the droop increased from 0.3in to 0.75in with slight opening between hoops but further firing caused little change and it was accepted in September 1890 and sent to the Victoria's sister ship Sans Pareil. It was found to be oversize and a small amount had to be cut from the Sans Pareil's turret port to allow full depression.

NO 5 

Completed with 0.06in rifling grooves as were all the later numbers. This gun was built up on a softer A tube than usual and during proof in April 1889, and subsequent rounds fired with the gun turned over, developed a droop of 1.4in with a bend of 0.7in to one side. Openings of up to 0. 13 5in also occurred between the hoops. The Elswick authorities blamed this on the use of the usual proof carriage with the recoil not in the direction of the gun's axis. It was then mounted in Victoria but as after 12 rounds the droop increased to 2.5in there was nothing for it but to rebufld the gun on a new A tube, which was eventually decided upon 14 months later in December 1890. As rebuilt the hoops were as given for the short lined No 3 above except that there was one less short hoop in the second layer and the third layer comprised 2 fairly long and 4 short hoops. After reproof the gun was accepted in August 1892 and was sent to Malta as reserve gun.

NO 6 

After two proof rounds in May 1889 openings appeared between the hoops and the gun seemed to be bending. There was a delay until October 1889 when it was decided to return the gun to Elswick for the second layer to have a long final hoop in place of the 5 short ones. The altered gun was Proved and sent to Chatham for the Victoria, as a replacement for No 4 gun, by March 1890.

NO 7 

This gun was altered before delivery in the same way as No 6, passed proof in January 1890 and was sent to the Victoria as a replacement for No 5 gun. In August 1891 a crack appeared in the A tube face at the muzzle which extended 54in into the bore. This was removed at Malta later in the year by cutting back the gun by about half a calibre.

17in BL

NO 8

 This gun was completed, like the strengthened No 4, with a long final hoop in the second layer in place of 5 short hoops and a short hoop beyond it. It was slightly larger than No 4 and was sent for proof in September 1890 when openings were found to be developing between the chase hoops, but the gun still went to the Sans Pareil for gunnery trials in December 1890. Two 4-charge rounds were fired and it was then discovered that the foremost short hoop of the second layer had cracked through. The hoop was renewed at Woolwich and further rounds fired at the proof butts and at Shoeburyness, making a total of 18, but, as the separation of the hoops had increased and the gun now had a droop of 1.25in and was bent 0.95in to the right, it was rejected in March 1891. It was sent back to Elswick at the end of the year for the hoop to be cut off, from the muzzle to the thrust hands, the A tube straightened cold and the gun rebuilt with two long hoops in the forward part of the first layer and one in that of the second layer. It was however found necessary to use a new A tube. The gun was sent for re-proof in January 1894 when some movement of the outer hoops occurred and also some expansion of the bore and chamber. Two further rounds were fired in June which caused a little further expansion but it was decided to accept the gun in July 1894 and it was stored in England as a reservegun.

16.25in BL Mk I

NO 9 This was built to a different construction with A tube/breech piece (taking the breech block), 1 medium hoop, 2 short hoops, 2 long hoops or tubes, 1 short hoop, 1 long hoop or tube to the muzzle/1 long hoop, 4 short hoops, 1 long hoop/2 medium hoops, 1 short hoop, 1 medium hoop/7 short hoops. It passed proof in 1891 and was mounted in the Sans Pareil. A report of March 1898, when a total of 5 proof, 16 full, 40 practice and 18 reduced charges had been fired, shows that the first layer of hoops had then moved forward by a total of 0.26in.

NOS 10, 11 and 12

Ort 24 January 1890 the Admiralty approved that three more guns should be obtained from Elswick to an improved design provided that they were interchangeable with the other guns. Two Elswick designs, Nos 31305 without wire and 31306 with wire, dated 10 April 1890, were considered by the Ordnance Committee who recommended the wire design with some modifications. The Admiralty were concerned at the extra cost of £1000 for one wire wound gun or £2 100 for three, and also at the presence of wire in that part of the gun outside the Victoria class turrets, and asked

16.25in BL Nos 1 land 12

for the DGOF (Director General of the Ordnance Factories) to be consulted as the design differed considerably from that of the experimental 9.2in/40 and 13.5in/30 which had successfully been made at Woolwich. The DGOF produced design No 8514C3, in which the wire was kept within the Victoria's turret, and eventually the Ordnance Committee recommended that the three guns should be made to a modified Elswick design, No 31306C of 27 November 1890, unless any were made at Woolwich when 8514C3 was to be used. The Admiralty, who had postponed

ordering the guns on 20 November 1890, agreed on 4 February 1891 on the understanding that the guns would be interchangeable with earlier ones and that the War Office were responsible. It should be noted that the Admiralty became responsible for naval guns in 1888-89 but the 16.25in remained a War Office responsibility. For reasons of cost the Admiralty wanted at least one built at Woolwich but this was vetoed, without doubt correctly as Woolwich had enough troubles with smaller guns.

The Elswick works would give no delivery date for a wire wound 16.25in as they had no experience of winding guns of that size and eventually, on 25 September 1891, it was recommended that No 18 be built to a modification of the 10 April 1890 design No 31305C as some forgings were already partly machined, and that Nos 11 and 12 be built to 31305D which had a thinner A tube at the muzzle end to bring it within the then safety conditions for a burst A tube. In explanation it should be said that Elswick usually worked on the 16.25in well in advance of formal sanction. The drawings were sealed on 17 December 1891.

The construction was as follows: A tube/breech piece (taking breech block), 1B hoop, 2B hoop, B tube to muzzle/lC, 2C, 3C hoops/lD, 21), 3D hoops/jacket, E hoop machined for thrust rings. All hoops were long. There were screwed collars at the forward ends of the breech piece, 2C and E hoops where they were over the A tube, 1B and 3D hoops respectively.

No 10 was proved in 1893 and sent out to Malta as a reserve gun, while Nos 11 and 12, proved in the same year, both showed some expansion in the bore which was attributed by Elswick to a rather soft A tube and to the driving band which was considered to be excessively large. The expansion was worst in No 12 but was not very serious and the two guns replaced Nos 1 and 2 in Benbow in about May 1894.

It is clear that the 16.25in was an over- ambitious venture at a time when smaller guns such as the 12in/25 and 13.5in/30 had many troubles. Details were: Weight (including breeech fittings) 112 tons 15cwt 901b Weight (less breech fittings) 110 tons 12cwt 511b These figures apply to Nos 1 and 2. The individual weights for the later guns are not known. They are usually listed as 111 tons nominal.

The battleship Benbow, the first vessel to be fitted with the 16.25in gun. The weight involved meant only one gun could be mounted in each barbette instead of two as in the earlier ships of the Admiral class which carried 13.5in guns

Length (oa) 43ft 8in - 524in Length (bore) 30 cal - 487.5in Diameter 65.5in max, 28in min Chamber size 84.5 x 21.125 in, volume 28 660 cu in Rifling 397.2-397.4 in, Nos 1, 2 and 3 twist of 1 in 130 to 1 in 30 at 77.2 in from muzzle then uniform, Nos 4-12 1 in 60 to 1 in 30 at muzzle, 78 grooves, polygroove EOC section, 0.04 x 0.45in (in Nos 1 and 2) 0.06 x 0.45in (in Nos 3 to 12) lands 0.2045 in. As relined No 3 had Mk 111 rifling with 396.9in straight to 299.4in from muzzle then increasing to 1 in 30 at muzzle, 78 grooves, polygroove modified plain section, 0.06 x 0.42in, lands 0.2345in. Projectile weight 1800 1b Charge 960 1b slow burning cocoa SBC (8 x 1201b) Muzzle velocity 2087fs Design pressure 17tons/sq in

A charge of Mk 1 Cordite was considered but not adopted; 317' lb size 50 + 81b 6oz size 31 gave an MV of 2278fs at a pressure of 15.01 tons/sq in. The breech block was a cylindrical screw with 6 plain segments and a de Bange obturator. There was no carrier and the block, which was operated by hydraulic power, was normally kept at the fixed loading position as in the contemporary 13.5 and 12in guns. The mountings in all three ships allowed 13' elevation and 5' depression, with loading at maximum elevation, and the range at 13' was 12 400yds at the new gun NIV of 2087fs. The probable life was 104 full charges. The rate of fire was slow with 3 to 32'minutes between rounds but the 12in and 13.5in 'Admirals' were no faster, and it was not until the introduction of the improved 13.5in mountings in the battleships Nile and Trafalgar that the interval was reduced to about 2 minutes 10 seconds.

The ammunition outfit was 100, later 92, rounds per gun in Benbow and 80 in the Victoria and Sans Pareil. The proportions for 1892 were, in Benbow, 3 7 AP (armour piercing), 44 Common and 11 Shrapnel and in the other two 32 AP, 38 Common and 10 Shrapnel. lf available 20 of the AP were to be hollow steel shot. This had a maximum length of 59.31 in and was required to be 'substantially whole' after piercing a 20in compound plate backed by 6in wrought iron at normal impact and at a velocity of 2 100 fs. The chilled iron Palliser AP short was 43.57in long and the nose fuzed common and shrapnel 55in long. The forged steel common shell had a burster of 187211b of black powder and the later, and cheaper, cast steel common shell one of 1794'lb. The shrapnel shell contained 2330 4oz iron shot. Later a base fuzed pointed common was introduced; this was 5 7.3 5in long with a 1821b black powder burster. Figures dated 1890 give 582 in as the extreme length of shell for power loading but presumably it was found possible to accommodate the steel AP shot at its maximum length.

PROJECTED 17IN COAST DEFENCE GUN. 

The dreams of gun designers are excluded from this article but an exception has been made for the 17in/41 calibre of 1885-86. The intention was to construct two turrets each containing two of these 156 ton guns, as a reinforcement for the Portsmouth defences. One turret was to be located 400yds east of Horse Sand Fort and the other 400yds south of No Man's Land. No drawings of these turrets have been found but it seems probable that they would have resembled the Torre Umberto which was erected at Spezia by Armstrong. This hydraulically powered work completed in 1892 contained two 15.75in 119 ton Krupp guns firing a 20281b projectile at an MV of 1804fs and had a revolving weight of about 2000 tons of which 1400 tons was contributed by the cupola roof of Gruson chilled iron. In any event the cost of the Portsmouth turrets was considered prohibitive and the plan was altered to two forts each containing two guns on the usual single carriage and slide mounting. The whole project seems to have been abandoned in 1886.

Drawings of the gun show a liner extending from the forward end of the chamber to the muzzle inside the 1A tube and joined to it and the chamber liner by a curved threaded ring. There was a 2A tube over the chamber liner and this was joined to the 1 A tube by a shoulder. The line of the 2A tube was continued for about 14ft by wire and stop rings. Over this was shrunk a complete layer comprising the breech piece, into which the breech block screwed, and the 1 B to 7B hoops extending to the muzzle. A thick layer of wire was wound over that part of the breech piece which covered the chamber, shot location and part of the breech screw. This was continued by the 3C hoop which was partly over the forward end of the wire, the trunnion piece, 1 C and 2C hoops to a distance of 29ft 3in from the muzzle. Finally the jacket, and what appears to be a ring brazed to the 3C hoop, extended for 159.8in from a point 2in from the breech face. Details would have been:

Weight 156 tons
Length (oa) 61ft 1 lin - 743in 
Length (bore) 41.12 cal - 700in 
Diameter 69in max, 30in min 
Chamber size 100 x 27in 
Projectile weight 22401b 
Charge weight 17001b 
Muzzle velocity 2500fs 
Design pressure 18 tons

It is as well that no attempt was made to build this design.

161N GUN FOR RUSSIA, VICKERS PATTERN A 

The battleship Victoria fitting out during 1889/90. The left 16.25in gun has been fitted in her single turret but the right gun is still to be installed
The Victotia at Malta shortly after completion in 1890

This gun was begun in 1914 before the outbreak of the First World War and was proved at Eskmeals on 22 August 1917. It was originally intended as the prototype gun for a class of three projected 32 000 ton battleships to be built in Russia for the Black Sea Fleet and which were to be armed with three triple 16in turrets. Although wire wound guns were standard in Britain at that time, they had never been accepted by most foreign countries and Vickers had already built satisfactory wire free 1 Oin guns for the Russian cruiser Rurik and had an order for twenty-four 14in guns for the Borodino class battlecruisers. The construction of this gun, Vickers No 1712A known during the War as the '15 inch A', was thus very far from contemporary British practice. There were the usual tapered inner A and A tubes but with the favourite Vickers cannelured rings between the locating shoulders. Over the A tube were the B 1, B2 and B3 tubes reaching to the muzzle and over these the Cl and C2 tubes for about two thirds of the gun's length. The next layer comprised the jacket and a screwed collar and finally the breech ring. The breech screw, held by the carrier, worked in a breech bush which was screwed into the Cl tube. Details were as follows:

Weight (including breech mechanism) 107 tons 14cwt 
Length (oa) 60ft - 720in Length (bore) 43.65 cal - 698.45in 
Diameter 56.6in max, 27in min 
Chamber size 127 x 18.24in, volume 33 000 cu in Rifling 565.5in long, grooves 0. 12in 
deep - believed to have had the start of the rifling slightly coned so that the full depth was not attained for about 8in, a refinement present in the Vickers 10in and 14in guns for Russia. 
Centre of gravity 248.2in from breech face (loaded) 249.45in (unloaded) 
Projectile weight 24611b 
Charge weight 7321b NCT (Nitrocellulose tubular) Muzzle velocity 2485fs 
Working pressure 16.3 tons/sq in 

At proof an MV of 2513fs was recorded at a temperature of 69'F and a pressure of 16.6tons/sq in. This was with a 7341b NCT charge of grain size 15.2in long, 0.79in outside diameter and 0.283in inside diameter. It was anticipated that 2600fs would be reached with a 7651b charge and a pressure of 18.7 tons/sq in. The nearest comparable standard British gun of that time, the 15in Mark 1 of 42 calibres, weighed 100 tons including the breech mechanism, had a larger diameter chamber of 107.505 x 20.Oin and 30 590 cu in volume, was 68.5in diameter over the breech ring and had an unloaded centre of gravity 209.7in from the breech face. It fired a 19201b shell at an MV of 2472fs, with a 4281b MD45 cordite charge at 80'F and 20 tons/sq in working pressure. The performance of the Vickers 16in was very high relative to the gun's weight but the centre of gravity was far forward which would have meant large turrets, so that there was good reason for the 15in guns large breech ring. Unfortunately it is not know what the regularity of the 16in would have been with NCT but with MD45 its performance would have been drastically reduced, as is shown by the 14in for the Borodino class. This gun, the Vickers 14in Pattern U, was 50.4 cals in bore length, weighed 82 tons 281b with breech mechanism, had a 21940 cu in chamber and, with a 16481b shell, was designed to attain an MV of 2700fs using a 5401b NCT charge of 18.5 tons/sq in pressure. A few entered British service in 1918-19 as the 14in Mk VI and at this pressure with a 15861b shell the best that could be achieved with MD45 was a 3131b charge giving 2470fs MV.

In August 1917 the question of what to do with this gun arose, and there were discussions about its employment on land but its weight was considered too great. However, on 23 March 1918 the German long 2 1 cm guns began to shell Paris at about 70 miles range and the production of a similar weapon became an urgent matter. It was thus decided to convert the 16in into a 205mm - 8.07in 'super velocity' gun to be known as the 8in sub-calibre Mk I. The A tube was cut back 42in at the muzzle and it, and the inner A tube were extended for 267.45in past the original muzzle by a new 2A tube. The B3 tube was cut back by 182.05in and was continued to the new muzzle by a B4 tube, with a screwed external guide ring joining B3 and B4. A new full length rifled liner was inserted in the 2A and inner A tubes. The details of the rifling and projectile were based on what could be learnt from fragments of the German shells which had been picked up. Details of the gun were as follows: 

Weight (including breech mechanism) 138 tons 16cwt
Weight (less breech mechanism) 136 tons 19cwt 
Length (oa) 82ft 3.35in - 987.35in
Length (bore) 119.9 cal - 968in 
Chamber size 128.35 x 1 1.Oin, 
volume 11 500cu in 
Rifling uniform twist 1 in 45, 64 grooves 0.1005 x 0.198in, lands 0. 1 98in (The shell body and forward driving band were pre-rifled) 
Centre of gravity 333.5in from breech face (loaded) 333.85in (unloaded) 
Projectile weight 2491b 
Charge 3131b MD oval, 0.60 x 1.20in 
Muzzle velocity 4901fs 
Pressure 29.47tons/sq in

The conversion was completed in February 1919 and the above figures are those for the highest velocity reached in the trials. The wear at 1 in from the commencement of rifling was about 0.02in per round. Unfortunately the heat treatment of the very long liner had to be carried out with improvised equipment at Vickers and it developed a crack so that only six rounds were fired and the forging for the replacement liner, which was to be heat treated at Woowich who had equipment that would take it, had to be scrapped. Thus no more was done with the gun and it was scrapped in late 1928. All rounds had been fired from the proof mounting with muzzle support and the service mounting, which allowed elevation from 40 to 58', was never completed.

18IN MARK 1

The 18 in gun, Furios 1917
Furios with aircraft and flying off platform 1917

This gun was the heaviest ever completed in Britain and, except for the 18.1 guns of the Japanese battleships Yamato and Musashi, the largest mounted in any ship. It was originally intended for the light battlecruiser Fürious, laid down on 8 June 1915, which was to carry two 18in gun in single turrets fore and aft. Only the Armstrong works at Elswick could build a gun of this size without considerable difficulties and the two guns plus one spare were ordered in the Spring of 1915 to Elswick drawing 14237, RGF1 1349/1 being the official Woolwich drawing.

The first gun was proved at Ridsdale, the Elswick proving ground, in September 1916, the second followed in late 1916 and the third in early 1917. Since the days of the 16.25in the construction of British heavy guns had been much simplified by the use of wire winding. The 12in Mark VIII mounted in the Majestic class battleships, laid down from December 1893, had been the first standard British wire wound heavy gun and this had been followed by the 12in Marks IX to XII, the 13.5in Mark V and the 15in Mark 1, the two latter being highly satisfactory in most respects. Serious difficulties had arisen in the 12in Mark VIII, and also in the Mark IX, as a result of the inner A tube closing in near the muzzle "steel choke"- and also cracking. This was due to a great part of the longitudinal stresses in the inner A tube being concentrated at the foremost locating shoulder. Various expedients improved this by better stress distribution and the trouble was virtually eliminated by the introduction of a slow taper fit between the inner A and A tubes in the 13.5in Mark V of later manufacture. The earlier guns of this mark retained forward shoulders until relined. With tapered inner A tubes the locating shoulders were kept well to the rear of the gun.

In most respects the 18in, which was known as the 15in B during the war for reasons of secrecy, actually resembled an enlarged version of the 15in with a relatively small breech ring but there was an important difference in the breech mechanism. The standard Welin stepped screw block was used with 15 segments of which 3 were plain, but the Vickers 'pure couple' mechanism was replaced for reasons of excessive slam by the Elswick short arm mechanism. In this the breech screw withdrew through the carrier, which complicated the actuation of the lock but was fast acting, the time to open or close the 18in breech being 3 seconds with hydraulic power, and slam was much reduced. It may be noted that this mechanism would in all probability have been standard in the 15in if trials in E597, the experimental gun fitted with it, had not been delayed for too long by a failed A tube. A further unusual feature of the 1 8in was the 'slow cone' obturator. The construction of the gun was normal comprising: tapered inner A tube with 5 locating shoulders a little forward of the Chamber/A tube in which the breech bush (taking the breech block) was located/wire layers with necessary stop rings and fastenings/B tube and Jacket overlapping the rear end of B tube/breech ring. There was the usual shrunk collar on the rear of the A tube. Nickel steel was used for the various forgings except for the jacket and breech ring which were in unalloyed carbon steel.

To return to the history of the three guns, the Fürious had her two guns and mountings shipped in early 1917 but on 2 March 1917 it was decided to remove the fore turret and replace it by a flight deck. She commissioned on 26 June 1917 and on 17 October 1917 it was decided to replace the after turret by a second flight deck. Meanwhile Vice Admiral Bacon, in Command at Dover, had been told of the existence of these guns and that two would be available. In August 1917 lie proposed mounting them inside the shell of the Palace hotel at Westende, when that place should fall to the Army, and use them to bombard the German docks at Bruges and the Zeebrugge locks at about 36 000yds.

The 18 in BL Mk I

It soon became clear that the Army would not reach Westende quickly, if at all, and Bacon conceived the idea of mounting them in 12in gun monitors, whose guns were by then badly outranged by the German coastal batteries. Approval for this was given on 23 September 1917 but the mountings for Fürious had been designed to suit the roller path of the twin 15in turret and were actually heavier and of greater overall diameter. Thus new mountings for all three guns were ordered to be designed and built at Elswick. Although always called the 15in B Coast Defence or CD mounting, they were actually land bombardment mountings with a forward pivot and only 20' total training. There were various troubles but eventually the first was installed in General Wolfe training over the starboard beam aft and the second was similarly fitted in Lord Clive. The third mounting was to have been in Prince Eugene but this was cancelled. No 2 gun, originally in Fürious A turret, was shipped in General Wolfe on 9 July 1918 and removed to the Portsmouth gun ground on 14 December 1920 where it remained until scrapped and sold in July 1933. No 3 gun, the original spare, was shipped in Lord Clive on 7 September 1918 and removed to the Portsmouth gun ground on 11 October 1920. In January 1921 it was sent to Woolwich to be relined for experiments in connection with the proposed 18in/45 cal and when the relining was cancelled, in November 1921, remained at Woolwich until scrapped and sold in July 1933. No

1, the gun in Fürious Y turret, arrived at Portsmouth for the Prince Eugene on 13 September 1918 and was sent to the Silloth range for various trials in March 1920. lt had been intended that Elswick should reline the gun for experiments for the proposed 18in/45 but this was cancelled and in November 1921 it went to Elswick for relining to a 16in/45 cal Mark I. This was done by January 1924 and the gun was used for various trials until January 1942 when it was sent to Woolwich and eventually scrapped in July 1947.

The myth that the three guns were mounted at Singapore dies hard in the nature of myths and it was thought worthwhile to give their true history. Details were as follows:

Weight (including breech mechanism): 149 tons
Weight less breech inechanisin): 146 tons 4 cwt
Length(oa): 62ft0.15in-744.15in
L,ength(bore): 40cal-720.2in
Diameter: 72.5in max, 30.5in min, 32in over rnuzzle
Chambersize.- 127.05x23.85in,volume 51310cu in (The intended chamber dimensions were 125.8 x 24in but they were altered owing to a machining error)
Rifling: 585.42in long, uniform twist 1 in 30, 88 grooves, polygroove plain section,
dimensions not certain but believed 0.124 x 0.459 in with lands 0. 1835in
Centreofgravity: 250.5infrombreechface(loaded)
Projeetileweight. 33201b
Charge: 6301b MD45 (6 x 105) Supercharge 6901b MD45 (5 x 105 + 1 x 165)
Muzzle velocity: 2270ft/sec (with supercharge 2420ft/sec)
Designpressure: 18.0 tons/sq inch

The main fault was the low muzzle velocity for which the impracticability of making MD Cordite in a size greater than 45, due to the time taken to evaporate solvent and wartime conditions which prevented experiments with other grain forms or propellants, were responsible. Trials at Silloth in 1920 with the charge at a temperature of 49 15 0'F instead of the standard 80'F gave an MV of 2277ft/sec with 6601b of MD45 cordite and 2438ft/sec with 8201b of the new oval Ardeer Solventless (SQ cordite with an 0.32 x 0.64in section, the respective pressures and mean differences in muzzle velocity being 16.92 tons/sq in and 2.0 ft/sec with MD45 and 16.90 and 4.6 with SC.

In point of fact the supercharge could have been used as the standard full charge as wear was remarkably small and the gun could well have withstood the likely new gun, 80'F, pressure of 21 tons/sq in The only gun that did much firing, No 2 in General Wolfe, expended 60 proof and supercharges, 41 full and 2 reduced charges calculated as equivalent to 1611A6 full charges. The mean wear at lin from the commencement of the rifling was 0.379in compared with at least 0.45in for the same number of equivalent full charges in the 15in Mark 1.

The mountings for Fürious allowed 30' elevation and 5' depression giving a range, with 4crh (calibre radius head) shells and full charges, of 28 800yds. The monitor mountings allowed firing at 22' to 45' elevation and 8crh shells were used giving a range of 36 000yds with full charges and 40 1 00yds with supercharges. All these ranges are for new gun muzzle velocities as given above. Fürious had a war outfit of 120 rounds per gun, 60 being APC (Armour Piercing Capped) and 60 CPC (Common Pointed Capped). Length was limited to 77in but it would seem that this was not attained by the 4crh shells, the APC not exceeding 67.25 in and the CPC 75.7 in. The CPC burster was 243 1b black powder and that of the APC 119 1b lyddite. The monitors carried 60 rounds intended to be 8crh nose fuzed HE (High Explosive) with a maximum length of 8441in. These were however not delivered in time and they fired APC shells fitted with ballistic caps to give an 8crh head.

Stern view of General Wolfe in 1918, showing her fixed 18in Mk 1

In conclusion it must be regretted that this good but very heavy gun was never mounted in a suitable ship, although alternative designs for the Hood with this gun was considered.

181N/45 CALIBRE

Although none of these were completed, their history is important to the development of British heavy guns. In 1919 the Admiralty decided that the standard main armament of future battleships and if possible battlecruisers was to be the 18in/45. At the same time it was desired to reduce the weight and also the muzzle droop of future gun designs and it was hoped that this might be achieved by improved wire wound construction or by using a partly wire wound or wire free design. The possibility of obtaining a 30tons/sq in yield point from heavy forgings made in nickel chrome molybdenum steel would make it easier to solve these problems. Designs for all  three types of construction \eere called for from Elswick, Vickers and Woolwich and their designers produced 11, 13 and 13 designs respectively which were carefully considered by the Ordnance Committee. As a result 5 final designs were produced by the Royal Gun Factory (RGF), Woolwich. It was realised that the test programme on the partly wire wound and wire free guns would take a long time and that the first production guns would probably have to be made to the improved wire wound design. Orders for 18in No 5, the partly wire wound gun, and No 6, the wire free gun, were placed with Vickers and Elswick respectively on 22 December 1920, while No 4, the wire wound gun, was ordered from Woolwich on 20 January 1921. It was intended to order a second wire free gun in the following year, to be made on Krupp principles as far as they could be adapted to the use of bag charges, but this was never done. Krupp guns were built at that time by the precision shrinking of relatively short tubes and not as in No 6 above, where long tubes should be used.

It should be noted that only Elswich were suited for making 18in/45 guns in production as is shown in the following table of manufacturing limits, though Vickers and Woolwich could have made a few.

Works Maximum Diameter(breech end) Length (oa) Weight
ELSWICK 84in 73 ft 200tons
VICKERS 72in 70 ft 100 tons (150 possible)
WOOLWICH 72in 76 ft 120 tons (can be increased in emergency)

In the event the 18in/45, generally known as the 16in/50 for reasons of secrecy, was too large for the first new British ships which were to be battlecruisers and, as negotiations at the Washington Conference which had begun on 12 November 1921, madjit clear that 18in guns would be ruled out, the three prototype guns were cancelled on 30 January 1922.

No 4 would have been built on similar lines to the 18in Mark 1 but with the wire wound in one continuous length, a process known as taper winding. No 5 would have had an unwired chase with inner A, A and B tubes and the wire over the rest of the gun was not to have been taper wound, while No 6 would have had a chase, comprising inner A, A and B tubes, with the B tube continued by a C tube towards the rear where there was also the usual jacket. All would have had the Elswick short arm breech mechanism. The A tube forging weighed 57 tons.

There was never any intention of building 20 or 21 in guns and Sir Robert Hadfield of the famous steel company of that name was asked to stop talking about APC shells of this size.

Details of the three 18in/45 guns were:

Design  Wire RGF 11459  Part Wire RGF 11460A  No Wire RGF 11462
Weight (including breech mechanism) 134 tons l0cwt  134tons 15cwt  130tons
Diameter (max)  66in  66in  65.2in
Diameter (min)  29.6in 29.5in  29.0in
Centre of gravity from breech face (loaded) 276.8in 277.3in 271in
Droop  0.55in  0.51 in 0.48in

The following details were common to all:

General Wolfe taken at the same time as the previous photograph

Leugth(oa). 69ft5in-833in
Length(hore): 45cal-810in
Chambersize-. 147.3x22.14in,volume55,000cuin
Rifting: Not decided
Projectile weight: 29161b
Charge: About8101bMDoval(0.37x0.74in)
Muzzie velocity: Probably about 2650ft/sec
Design pressure: 20 tons/sq in

The triple mounting designed by Elswick would have given 40' elevation and 3' depression with an estimated rate of fire of one round per gun every 29 seconds. It will be noted that the projectile was very light. In August 1920 the intended new 18in APC with an 8crh, would have weighed 33201b with a length of 79.72in and a burster of 2.37% of the projectile weight. A maximum length of 92in would have been allowed to cover any HE design and also the possibility of increasing the weight to 40001b. Inadequate trials at oblique impact appeared to show that a 16881b 15in shell behaved better than the 19201b one. This

result was not substantiated by later trials but it was decided prior to these to fix the 18in/45 calibre shell at 29161b with a 22'% burster and a conical head - 6/co crh - the max length being taken at 82.66in to allow for HE.

Rifling details were to await 15in trials between a gun with the standard rifling of uniform twist 1 in 30 with 76 grooves, each 2.5 x land width, another gun similar but with a uniform twist of 1 in 40, as used in Italian 15in guns, and a third gun with a uniform twist of 1 in 30 and 100 grooves of equal width to lands, which was based on modified German practice.

16IN MARK 1

The nine 16inch Mk 1 guns of the battleship Nelson in 1940. Note the UP mountings on the roofs of B and X turrets.

The history of this gun goes back to January 1921 when it was determined that the proposed battlecruisers of the G3 type could not take a larger gun if they were to be able to use the drydocks at Rosyth, unless protection and/or speed were reduced or only 6 guns were accepted for the main arrnament. There was no time to experiment with alternative constructions and the first two guns were ordered from Elswick on 22 August 1921. The bulk orders for the GYs guns were placed on 25 October 1921, 13 going to Elswick, 9 to Beardmore and 14 to Vickers, who were also to make one to a special design. These orders except for that of August 1921, were cancelled with the GYs, and fresh orders were placed for the Nelson and Rodneys guns, Nos 3- 10 being ordered from Elswick, Nos 11-18 from Vickers, and Nos 19-23 from Beardmore, all on 11 December, 1922, while Nos 24- 29 were ordered from Woolwich two days later. One of the 18in Mark 1 guns had been relined to 16in, as previously noted, and also one of five Army 18in howitzers to be used for relatively low velocity trials such as those for the APC shells.

The construction resembled that of the proposed wire wound 18in/45 but the gun was relatively heavier. There was an inner A tube with a taper fit in the A tube and 2 rear locating shoulders. Next came a tape.r wound wire layer and over this the B tube and overlapping jacket. There was the usual breech ring over the jacket, breech bush located in the A tube, into which the breech block screwed, and a shrunk collar on the rear of the A tube. The Welin breech block was actuated by the American Asbury roHer cam mechanism for which Vickers had acquired the rights. No 1 gun was completed in March 1924 and No 2 followed in July but trouble was soon apparent. A light 20481b projectile had been chosen, of proportionately the same weight as the 18in/45 and the experimental 16881b 15in, and with a charge of 5501b of oval MD Cordite it was intended that the new gun (80'F) muzzle velocity should be

2715ft/sec. In March 1925 2670ft/sec was attained with a 5251b charge but wear was rapid with a loss of 1.5ft/sec per round, and the probable life was at most ,180 efc (equivalent full charges), too low for the British, though acceptable in some navies. Also accuracy was not very good and the rifling was damaged by the hammering of the short bodied, long headed projectile so that stripping occurred. These troubles were cured by reducing the muzzle velocity to 2575ft/sec which, as will be seen, was later slightly increased, and the rifling was also improved on relining.

The first three service guns, Nos 3,4 and 24 were completed with a chamber 11 8.5in long but later guns had a chamber of different form and 125.5in long. As the three short chamber guns were in Nelson's A' turret until February 1945, the nominal shell ramming distance was 7in less in this turret than in the others. The replacement of the 20481b shell bv one of 22501b was considered anä No 2 gun was relined in 1928-1929 with improved rifling and a chamber of 30 011 cu in instead of the standard 35 205 cu in. It was thought that a 5061b charge of solventless cordite, SC3 8 1, would give an MV of 2575ft/sec with the 22501b shell in this gun and a range of about 40 500yds at 40' elevation but financial stringencies prevented any change.

Details were as follows:

Weight (including breech mechanism): 108 tons
Weight (less breech mechanism): 106 tons
Length (oa): 61 ft 10.2in - 742.2in
Length (bore): 45 cal - 720in
Diameter: 65in max, 27in at muzzle
Chamber size: 125.5 x 19.9in (except Nos 3, 4, 24 - 118.5in long), volume 35 305 cu in.
Rifling: Mark 1 586.964in (except Nos 3, 4, 24 - 592.4in), uniform twist 1 in 30, 96 grooves, polygroove plaitisection 0.124 x 0.349in, lands 0.1745in; Mark 11 588.95in, uniform twist 1 in 30, 80 grooves, polygroove plain section 0.135 x 0.377in, lands 0.2513 in 
Centre of gravity: 245.4in from breech face (unloaded)
Projectile weight: 20481b
Charge: 4981b MD45 (6 x 831b) (later 495 SC280 (6 x 82-ilb)
Muzzle velocity: 2586ft/sec (with Mark Il rifling 2614ft/sec)
Design pressure: 20 tons/sq in (with Mark 11 rifling about 21.3)
As completed both Nelson and Rodney had Mark 1 rifling in all their guns but Nelson had 'B' and 'X' turrets changed to guns with Mark 11 rifling in May 1944, while 'A' turret did not receive these until March 1945.

As completed both Nelson and Rodney had Mark 1 rifling in all their guns but Nelson had 'B' and 'X' turrets changed to guns with Mark 11 rifling in May 1944, while 'A' turret did not receive these until March 1945.

In Rodney 'B' turret changed to two guns with Mk 11, and one with Mk 1 rifling in December 1937, while 'X' had three new guns with Mk 1 rifling in September 1938 and 'A' three with Mk 11 rifling in February 1942. This mixing was less serious than it might seem as the muzzle velocities tended to become similar as the guns wore. The triple mountings in Nelson and Rodney allowed 40' elevation giving a range, calculated for an MV of 2525ft/sec, of 38 400yds or about 39 900 at 260Oft/sec. The estimated life was about 250 efc and the intended rate of fire 2 rounds per gun per minute but the shell room arrangements and also the mountings gave a good deal of trouble originally. As a result the full salvo per minute rate for single ship practices from 1928 to 1933 showed a yearly average of 1.90 to 1.53 compared with 2.28 to 1.93 for 15in gun ships.

Unless bombardment was intended only APC shell was carried, this having a 6/ oo crh head and a length of 66.23in. The burster was 22'% of the projectile weight and, unlike most other heavy British APC shells, block TNT was used. During World War II'K'shell containing dyes for colouring the shell splashes was introduced and these weighed up to 20591b 5oz. The longest HE shell had a maximum length of 75.94in.

In conclusion it may be said that the 16in Mark I was a good gun which would have been better if the unfortunate decision to use a light shell had not been taken. It was the last British heavy gun to be built with wire winding.

16IN MARK II AND III

The sole difference between these

GENERAL ARRANGEMENT - 16 in eb Triple M& 1

1 . Counterbalance weight
2. Rammer engine casing
3. 'Chum'Ievers
4. Rangefinder
5. Telescopic rammer tube casing
6. Tilting tray
7. Position of breech at full depression(-Y)
8. Gunhouse roof support pillar
9. Rear collars
10. Recoil cylinder
11. Sliding pipes for hydraulics, air blast and
wash-out squirt to breech
12 Trunnion cap
13 Mantlet plate
14. Locking bolt
15. 'Walking' pipes to elevating structure
16. Training base toller
17. Turret clip
18. Elevating cylinder trunnion
19. Exhaust tank
20. Steam heating pipes
21. Cable winding gear
22. Turret drenching tanks
24. Hydraulic accumulator
25. Shell room (W turret')
26. Watertight door
27. Shell room rammer tray
28. Pivoting tray
29. Revolving shefl seuttle
30. Trunk guide roller
31. Cordite swinging tray
32. Central pivot
33. Cordite tilting hoppers
34. Shell bogie (in horizontal position)
35. Cordite rammer engine
36. Flash door
37. Cordite roller-conveyor
38. Triple cordite charges
39. Athwartships cordite roller-conveyor
40. Cordite stowage bay
41. Shell bogie (tilted upright)
42. Shell room (W turret)
43. Revolving shell scuttle
44. Cordite hoist trunk
45. Wash-out squirt air bottles
46. Training drive shaft
47. Shell striking down trunk
48. Air blast bottles
49. Training rack
.50. Centre gun shell hoist trunk
51. Left gun shell hoist trunk
52. Breech in full recoil at maximum elevation (+40')
53. Drive pinion and twin training pinion
54. Elevation buffer stop
55. Tilting engine
56. Gunhouse vents
A. Upper (foVsIe) deck
B. Main deck
C. Middle deck
D. Beam line
E. Lower deck
F. Platform deck
G. Inner bottom
H. Outer bottom

Drawing by Peter Hodges from his forthcoming book The Big Gun: Battleship Main Armament 1860-1945 to be published in 1980 by Conway Märitime Press.

Marks was that 11 had 3 rear and 2 forward shoulders where the jacket was located on the A tube, and 111 had 2 rear and 3 forward. The design went back to 1935 and was in most respects an enlarged version of the 14in Mark VII, to be mounted in the King George V class battleships, and the 15in Mark 11which was never made. Alternative designs with 16in guns were considered for the King George V class but it was not until the battleships Lion and Temeraire of the 1938 programme that ships with 16in guns were again laid down. The first gun, No 30, was ordered from Woolwich on 31 January 1938, and was followed by Nos 31 to 39, ordered from Royal Ordnance Factory, Dalmuir on 16 September 1938, and by Nos 40 to 57 from Vickers Armstrongs, Elswick, on 23 September 1938. The Lion and Temeraire, laid down respectively on 4 July 1939 and 1 June 1939, would each have had nine guns, as would their sister ships Conqueror and Thunderer of the 1939 programme. All four ships were suspended, to be cancelled later during the Second World War, and the gun orders were reduced to Nos 30 to 35 and 40 to 42. Of these No 30 and 40 to 42 were Mark 11 and Nos 31 to 35 Mark 111. Only Nos 30, 31, 32 and 40 were completed.

For preliminary trials it was determined in August 1935 that a standard 16in Mark 1 would give the desired performance with a 23751b projectile, an MV of 2475ft/sec at 70'F and a pressure of 20 tons/sq in with a 5241b charge of SC320, but the construction of the new 16in was very different to that of the former gun. In the Mark II and 111 there was an inner A tube with a 1 in 500 taper on the radius throughout, an A tube and jacket with a rectangular breech ring, a breech bush taking the Welin serew breech block and located in the A tube, and a shrunk collar on the A tube. The two locating shoulders for the inner A tube were 555 and 5 71 in from the muzzle. An Asbury roller cam breech mechanism was used and balancing weights were fitted to the breech ring to bring the centre of gravity near the breech end. This construction needed a heavy A tube and the forging weighed about 64 tons, the largest British gun forging, with a finished weight of 442'tons. The design was slightly modified in 1939 to permit a loose liner type of inner A tube to be used subsequently if desired. As noted above this construction was similar to that of the 14in Mark VII and both guns were mounted in a cylindrical cradle instead of the previous saddle and slide. This feature and also the type of construction date back to the experimental 12in/50cal Mark XIV completed in 1933.

Details of the 16in Mark 11 and 111 were as follows:

Weight (including breech mechanism): 118 tons 14cwt 841b (with balance weights 131 tons l cwt 84 1b)

Weight (less breech mechanism): 116 tons lcwt 841b

Length (oa): 6 1 ft 11. 3in - 743.3in

Length (bore): 45 cal - 720in

Diameter: 52in over jacket, 24in at muzzle

Chamber size: 129.4 x 19.Oin, volume 34 022 cu in

Ritling: 583.47in long, uniform twist 1 in 30, 80 grooves, polygroove plain section 0. 131 x 0.377in, lands 0.2513in

Centre of gravity: 226.24in from breech face with breech mechanism; (with balance weights 208.9in)

Projectile weight: 23751b APC 20481b HE - this latter was shorter than the original HE for 16in Mark 1 guns, and was to be used by Mark 1, 11 and 111 guns.

Charge: Estimated 520 1b SC350 in sixths

Muzzle velocity: 2475ft/sec at 70'F (probably about 2485ft/sec at 80'F, with 20481b shell about 260Oft/sec)

Design pressure: 20.5 tons/sq in

The triple mountings, of different design to those in the Nelson class, would have allowed 40' elevation. Range tables were never issued but, at 240Oft/sec, between 38 000 and 39 000 yards would have been reached. Shells were limited to 73in length by the mounting and, with a 6/12 crh head, the APC shell came within less than half an inch of this. The burster was 22'% of the total shell weight and 70/30 shellite was used. The design was a scaled up 14in and was expected to pierce 14in armour where the 14in shell would pierce -12in. The specification called for piercing 14in carburised and hardened armour at 30' to the normal and at striking velocities of 1770 and 210Oft/sec equivalent to 16 000 and 7000 yards.

The redesigned Lion apd Temeraire, which it-was proposed to lay down after the War, would not have had these guns but the 16in Mark IV, though the two Mark Ills Nos 31 and 32 were to be altered for trials as related below.

161N MARK IV

This, the last British naval heavy gun to be designed and dating from 1944-1945, was 45 calibres in bore length with a minimum new gun muzzle velocity of 2450ft/sec at 70'F. Otherwise it was a new departure with a loose barrel, a design pressure of 24 tons/sq in and it was to be flashless with the suitable propellant. The breech block was to open upwards and the weight of the projectile, which was

limited to 78in length, was to be determined by the best CP - that is the base fuzed HE - shell that could be designed within this length. Such a bombardment shell was expected to cause the maximum damage against light armour up to 3in thick. The APC shell, which now took second place, was to be of the same weight as the CP with the best possible performance against deck armour combined with a reasonable performance against heavy side armour. The 24ton design pressure would not normally have been reached, but would have allowed light shells to be fired at very high velocity; clearly this requirement came from the employment of some of the German heavy guns in this manner when firing across the Channel.

The redesigned Lion and Temeraire were each to have nine 16in guns in three triple turrets and new mountings were to be designed with a loading cycle of 20 seconds instead of the usual 30. The upward opening breech block was a feature of the Richelieu's 15in quadruple turrets and it would presumably have opened as the guns ran out after recoil as in the Richelieu. 'One shot' ramming was to be employed, it would seem with coaxial rammers as in the British 8in cruisers.

For preliminary trials, one of the 16in Mark Ills, No 31, was relined with a 27 000 cu in chamber for use with flashless propellant and an auto-frettaged loose barrel was ordered for No 32, though this conversion could not have been used at anywhere near the designed pressure.

The Lion and Temeraire were cancelled and all this work on the gun and mounting was abandoned.

Details are given of a Vickers Armstrong design, dated 6 July 1945, though this may well not have been the final design. Weight (including breech mechanism): 117 tons 17cwt Length (oa): 61ft 11.3in - 743.3in Length (bore): 45 cal - 720. 1 in Diameter: 52in over jacket, 25in muzzle swell, 24in minimum Chamber size: 113.4 x ? 1 7.9in, volume 26 000 cu in Charge: 610 lb (approx) flashless Design pressure: 24 tons/sq in

The loose barrel weighed 35 tons 2cwt, had an 0.Olin taper on the diameter and was to be auto-frettaged at 32 tons/sq in in order to obtain a yield point of 45 tons/sq in. This corresponded to the inner A tube and was easily the largest of British design. The A tube ended 188in from the muzzle, and there was a jacket, breech ring and removable breech bush weighing 1 ton 5cwt 281b. Rifling details remained to be decided.

This remarkable, if unbuilt, design concludes the story of very large British naval guns. Extreme performance was not aimed at in normal service, at least latterly, and attention was concentrated on reasonably long life, regularity and accuracy. There seems little doubt however that the two latter qualities could have been retained with a higher performance if a tubular grain propellant had been used instead of cord.

 

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