RML 17.72 inch gun

Infobox Weapon
name= RML 17.72 inch gun


caption=The only remaining Malta 100 t (17.75 in) gun is at Fort Rinella. The other gun's demolition was so costly that this one was retained and is still visible today, although painted with a non-original colour.
origin= UK
type=howitzer
is_ranged=
is_bladed=
is_explosive=
is_artillery=yes
is_vehicle=
is_missile=
is_UK=yes
service=1877-1906
used_by=
wars=
designer=
design_date=
manufacturer=
unit_cost=
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number=
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spec_label=
weight=103 tons
length=
part_length=bore : convert|362.9|in|m (20.48 calibres)
action=
width=
height=
diameter=
crew=
cartridge=HE, AP, Shrapnel, convert|2000|lb|kg|sigfig=4Text Book of Gunnery, 1902. Table XII, Page 337]
caliber=convert|17.72|in|mm|sing=on|sigfig=4
action=
rate=
velocity=convert|1548|ft/s|m/s [Firing 2000 lb projectile with 450 lb Prism powder propellant. Text Book of Gunnery, 1902. Table XII, Page 337.]
range=
max_range=6,600 yards
feed=
sights=
breech=
recoil= 1.75 m
carriage=
elevation= 10° 30'
traverse=150°

The RML 17.72 inch gun ("100-ton gun") was an Armstrong British model mounted in fortifications at Malta and Gibraltar as well as on two Regia Marina battleships.

Origins

Around 1870 the largest gun made by UK firms was the 320 mm RML (rifled, muzzle loading) gun, with a mass of 38.6 tons and a 371 kg projectile, capable of piercing 414 mm of mild steel at 1,830 meters. This weapon was adequate to the needs of the time, but the progress of gun technology was very rapid. French industries soon made a 420 mm, 76 ton gun. This led the Royal Navy to ask for a 81 ton gun.

Armstrong, the main British artillery producer, began a project for creation of an even larger weapon, a 457 mm gun, also called '100 ton'. It was proposed to the Royal Navy, but rejected because it was considered too heavy and costly.

Meanwhile, after the reunification of Italy, the Regia Marina began an innovative program to field the best and most powerful battleships of the time, the first of them being the "Duilio" class, armed with 380 mm guns. They were already very powerful, but in February of 1874 when the UK started to build the HMS "Inflexible", armed with 406 mm guns, Italian admirals called for even more powerful guns, to hold the lead in battleship design.

Armstrong was ready to sell those guns, with a contract for eight units, enough to arm the "Duilio" and her sister "Dandolo". This happened 21 July 1874.

This contract shocked British authorities, as they had the Malta naval base to defend. At that time, (after the Suez Canal), Malta was the most important British base in the Mediterranean. Even if many coastal fortresses were armed, even with 320 mm guns, this left Malta poorly defended against a possible attack from "Duilio"-class ships. This was a worrying problem also because Crispi called Malta 'Italia irredenta' ('Unredeemed Italy').

The British feared that the "Duilios" could reach Valletta port and start to fire on their fortresses, destroying them one after the other, while keeping outside the effective range of the fort's guns (these battleships were also well protected). But the requests made by the British Army had no effect on London bureaucracy, and until the "Duilio" was launched in May 1876, no decision was made.

At that time, the Royal Navy started to take care of this issue (already signalled by the British Army) and asked for a gun capable of piercing 914 mm steel at 914 m. Several design were proposed for immense guns of 163, 193 and 224 tons.

In December 1877, Simmons, chief of Malta defenses, was called to London to discuss this issue and he asked for four guns comparable to "Duilios" at 3,000 yards. Strangely enough, apparently nobody had thought to forbid Armstrong to sell to Italy these much-feared weapons that were completed and sold regularly, rather than embargoed.

Due to the emergency, it was decided that it would be simpler to quit designing the bigger guns and buy the same weapons as the "Duilios", because, generally, a land fortress with the same caliber guns has an advantage compared to a ship.

Four guns were requested in March 1878 and construction was started in August, while in the meantime "Duilio" had conducting sea trials since 1877.

100 t gun description

These new artillery pieces were enormous weapons for their time (their weight was comparable to the "Iowa"-class 406/50 mm), even though the barrel was quite short. They were muzzle-loading guns, with rifled tube and rigid mount. Only decades later there were manufactured bigger guns than these ones.

The gun was 9.953 m long, or 20.49 caliber. Its maximum diameter was 1.996 m, but it reduced to 735 mm at the muzzle. The construction was very complex, with several structures containing one another. The internal barrel was 9.220 m long.

Firing was mechanical or electrical, with an optical system for aiming. Projectiles were of three types, all weighting 907 kg and 449.6 mm diameter:
*AP Pallister, 1.120 m long, steel forward section, capable to pierce 536 mm at 1,829 m. with a 14.5 kg explosive internal charge.
*HE Common, 1.232 m long, had a thinner walls and so, 35.4 kg HE
*Shrapnel: 1.143 m long, with a charge of only 2.3 kg HE but also 920 bullets of 113.4 grams each.

Projectiles could be exploded by timer or via 15-second fuses.

Launch charges were polygonal, with 399 x 368 mm maximum width and length. They were made of 51 kg 'Large Black Prism' propellant, and four or five were needed for every shell fired at maximum power.

Projectiles could be fired only once every four minutes. Muzzle velocity was 472 m/s and maximum elevation was 10° 30' (direction was 150 degrees). At maximum charge (204 kg?) and maximum elevation it could achieve only 5,990 m range, but at that distance it could still pierce 394 mm of steel (it is not clear if it was mild or hardened).

The weight of the mount was: 103,888 kg (gun), 20,680 kg (mobile mounts with 18 wheels), 24,118 kg (platform) and 2,032 kg (base). The platform was sloped at 4 degrees to slow the recoil.

The recoil was 1.75 m and two hydraulic pistons in the rear part of platform absorbed the rest of energy. Rotation was obtained with chains powered by hydraulic systems, and another hydraulic system was used for elevation.

Crew was 35, including 18 for ammunition depots.

ervice

The career of these guns was not impressive, as no Italian battleship had ever threatened Malta. When Gibraltar commanders heard of these big guns they asked for some, and obtained them: two of the four ordered for Malta were delivered there.

The first battery was Napier of Magdala, on Rosia Bay, and the second, called Victoria, was placed one kilometer north.

Construction started in December 1878, with the first ready in 1883 and the second in 1884. At that time, the "Duilio"-class ships had been operational for around seven years, leaving a gap in Malta defenses.

The first gun was transported by HMS "Stanley" (a special cargo vessel) adapted for the task and delivered on 19 December1882. The second was delivered on 14 March 1883. These two guns were ready on their mounts on July and September 1883.

The first firings took place in 1884, but the weapons were not fully operational until 1889 due to hydraulic system problems.

The Malta guns were placed on Fort Rinella, completed in 1884, and Fort Cambridge, ready in 1880. The first ammunition load comprised all the models available, included 50 AP and 50 HE. Shrapnel, once fired, was not replaced, being considered not so effective (also because it had 0.3% HE).

"Stanley" delivered two guns: Rinella received its on 31 July 1883 and mounted it 12 January 1884, and Cambridge respectively on 16 September 1882 and 20 February1884.

The work to make these machines serviceable was so great that until 1885 there were no firing tests. Between 1887 and 1888 the activity was stopped due the need to rework hydraulic systems, but nevertheless these guns were considered quite reliable, serving for more than 20 years.

Another problem took place: during firing trials on5 March 1880, one of "Duilio's" guns cracked while firing at the maximum charge. At the suggestion of the British Army, it was officially established that the maximum practical charge was 204 kg and not 255.

One of the British guns was also cracked: Napier gun, during a fire trial, had the barrel cracked, it this case because the crew managed to fire one shot for every 2.5 minutes. This wrecked gun was not easily repairable; it was used as a foundation for a building, and was replaced with the other, because Fort Napier was deemed more effective. The Malta guns were phased out in 1906, as was Napier's. They had fired their last shots several years before, in 1903 and 1904. During the First World War the guns at Malta were claimed to have been ready for use when SMS "Goeben" was known to be nearby. Although the 100 t guns were powerful, they would have been totally outclassed by modern weapons: the range and rate of fire were too low, as modern 280-305 mm guns had over 15-20 km range and the rate of fire of one shot every 30 seconds. "Goeben" would have had no difficulty firing against Malta guns, if needed.Napier and Rinella's guns are still intact. They were too costly to demolish and were left as junk, then later restored to acceptable condition. The 'pink' paint was added only recently; originally they were not painted at all.

Rinella Fort also exists today, although it is abandoned. It was 71 m by 66 m, with an external wall 6 m tall. There were two floors, the lower had an ammunition depot, and also shaft motors to power the hydraulic systems. The large fixed barrette that contained the gun was 127 mm thick iron, with several 510 mm windows to reload the gun (by muzzle) with special reloading systems, directly from the ammunition depots in the lower floor.

ee also

Notes

References

* [http://cgsc.cdmhost.com/u?/p4013coll11,230 Text Book of Gunnery, 1902. LONDON : PRINTED FOR HIS MAJESTY'S STATIONERY OFFICE, BY HARRISON AND SONS, ST. MARTIN'S LANE]
* Caruana, Joseph, "The British 100 t guns", Storia militare magazine n.22, July 1995.
* Handbook for RML 17.72 inch gun, 1887, HMSO publications.
* Q. Huges, "Malta: A Guide to the Fortifications" and "Britain in the Mediterranean: the defense of her Naval stations"