Armstrong Gun

The Armstrong Gun is a type of large rifled gun first manufactured in England in 1855. It was designed by Sir William Armstrong and manufactured by the Elswick Ordnance Company and the Royal Arsenal at Woolwich.

History

In 1854 Armstrong approached the Secretary of State for War, proposing that he construct a rifled breech-loading 3-pounder gun for trial. Later increased in bore to 5-pounder, the design performed successfully with respect to both range and accuracy. Over the next three years he developed his system of construction and adapted it to guns of heavier calibre.

Armstrong's system was adopted in 1858, initially for "special service in the field" and initially he only produced smaller artillery pieces, 6-pounder (2.5 in/64 mm) mountain or light field guns, 9-pounder (3 in/76 mm) guns for horse artillery, and 12-pounder (3 inches /76 mm) field guns.

Armstrong did not consider his system suited to heavier guns but higher authorities had him develop a 20-pounder (3.75 inches /95 mm) field gun, a 40-pounder (convert|3.75|in|mm) siege gun, and a 110-pounder (7 inches /180 mm) heavy gun. The Royal Navy used all these guns and all except the 20-pounder saw service in New Zealand.

Armstrong system

Armstrong's guns were constructed of wrought iron and used a "built-up" construction, comprising a tube holding the bore on to which were shrunk smaller tubes, a breech, and a trunnion ring. The guns' rifling was on the "polygroove" system; the bore of the gun had 38 grooves along its length with a twist of one turn per 38 calibres. The cast iron shells were similar in shape to a Minié ball and were coated in lead. This permitted the grooves to bite into the projectiles and impart the required spin.

An innovative feature which is more usually associated with 20th-century guns was what Armstrong called its "grip", which was essentially a squeeze bore; the last 6 inches of the bore at the muzzle end was of slightly smaller diameter, which centered the shell before it left the barrel and at the same time slightly swaged down its lead coating, reducing its diameter and slightly improving its ballistic qualities.

The breech loaders used a vertical sliding block, which had a conical copper-ringed plug which sealed the firing chamber, to close the breech. To hold both block and plug tightly in place the guns used a breech screw.

Armstrong guns in action

The British used Armstrong guns extensively to great effect in the Second Opium War. As reported by the translator Robert Swinhoe, after the British attack on the Chinese fort at Pehtang:

Numbers of dead Chinese lay about the guns, some most fearfully lacerated. The wall afforded very little protection to the Tartar gunners, and it was astonishing how they managed to stand so long against the destructive fire that our Armstrongs poured on them; but I observed, in more instances than one, that the unfortunate creatures had been tied to the guns by the legs." [Robert Swinhoe, Narrative of the North China Campaign of 1860 (London: Smith, Elder & Co, 1861) p. 105.]

Return to muzzle-loading guns

In 1863 an Ordnance Select Committee met to consider the merits of muzzle-loading and breech-loading guns. In 1864, even before they had concluded their investigations, the Government stopped the manufacture of Armstrong breech-loaders. When the Committee finally reported, in August 1865, they announced that:

However, their report did admit that Armstrongs' guns, while more expensive, were undoubtedly safer in that while it was not uncommon for cast iron muzzle-loaders to burst (see below), not one Armstong gun had ever done so. (Furthermore, gunners could clear a hangfire from the breech; when the 100-ton gun (see below) at Napier of Magdala Battery hung fire, a gunner had to be lowered head-first down the bore to attach an extractor to the shell.)

Despite a further report which remarked on the advantages of breech-loaders, cost dominated the proceedings and the Committee finally announced that "The balance of advantages is in favour of muzzle-loading field guns" and in 1870 Britain reverted from breech-loading ordnance to muzzle-loading. [cite web | last = Ruffell | first = WL | authorlink = | coauthors = | title = The Gun - Rifled Ordnance: Whitworth | work = The Gun | publisher = | date = | url = http://riv.co.nz/rnza/hist/gun/rifled2.htm | format = | doi = | accessdate = 2008-02-06]

To allow rifling to be used with muzzle-loaders, Armstrong proposed in 1866 a new system whereby the shells had studs on the outside, which aligned with grooves in the barrel of the cannon.However, tests conducted in 1859 with the Armstrong 40-pounder, and again in 1869 with the Armstrong rifled 100-pounder had demonstrated that neither rifled cannon were capable of penetrating 4 inches of armor, even at as little as 50 yards. In the wake of these tests, the Armstrong guns originally equipping the HMS Warrior and HMS Black Prince were removed and replaced with conventional 68-pounder smoothbore cannon, which had been shown to have a better armour-piercing ability than had the Armstrongs.

100-ton guns

In 1876 Armstrong offered the British Admiralty a 100.2-ton gun with a bore of 450mm or 17.76in. The Admiralty rejected the design so instead Armstrong offered manufacturing rights to Italy. The Italians constructed several of the guns and fitted four of them in each of the new battleships "Duilio" and "Dandalo".

The British government, realizing that these Italian warships with their convert|22|in|mm of armor would be impervious to Malta's defensive weapons, hastily commissioned guns of even greater caliber of 160-tons and then 220-tons. When it became apparent that these specifications were beyond the capabilities of contemporary manufacturing technology, the British instead ordered four of the 100-ton guns for service at Gibraltar and Malta.

In Gibraltar, they installed one at Victoria Battery and one at Napier of Magdala Battery. At Valetta in Malta, they installed one at Sliema (Fort Cambridge) to the north of the harbor and one at Kalkara (Fort Rinella) to the east of the harbor. To house the Maltese guns the British used purpose-built forts that each cost £18,890 to construct.

While they had ordered their guns first, the Italians did not receive their guns until after the British Navy had installed theirs. One of the guns on the "Duilio" burst at Spezia in 1880, as did the gun at Victoria Battery. Two of the British guns survive to the present, the one at Napier of Magdala Battery and the one at Fort Rinella.

The 100-ton guns were the largest muzzle loading guns ever built. Not long after their manufacture and installation engineers designed new breech loading systems that made the muzzle loaders obsolete.

Description

Each gun weighed convert|100.2|LT|MT, had a barrel convert|30|ft|3|in|m long and a bore of convert|17.72|in|mm. The bulk of the bore, convert|30|ft|3|in|m, was rifled, greatly increasing the accuracy of the gun relative to smoothbores. A powder charge of convert|450|lb|3|kg of prism black powder could propel a convert|450|lb|3|kg shell up to convert|8|mi|km. The muzzle velocity was convert|1540|ft|3|m per second (approx. convert|1200|mph|km/h), and the shell could penetrate convert|24.9|in|mm of iron. Even so, the Italian government conducted tests in 1876 using its own 100-ton guns that proved that the 22 inch armor of its battleships would be able to withstand the guns.

At Fort Rinella the battery had a crew consisting of a battery commander and a master gunner, with nine gunners. Twelve men dealt with the ammunition, three manned the rangefinder, while there were also a trumpeter, a storeman, a lampman and a fatiguedn man. A telephonist maintained communications with the other battery at Fort Cambridge and a control station at Fort St. Elmo. If the telephone line was damaged, there was a backup semaphore and heliograph. It was intended that one gun should fire while the other was reloading, with a rate of fire of one round every four minutes; an attempt was made at Gibraltar to increase the rate of fire, which caused one of the guns to split its barrel. [cite book | last = Farrugia | first = Mario | authorlink = | coauthors = | title = Fort Rinella and Its Armstrong 100-Ton Gun | publisher = Midsea Books | date = 2006 | location = | pages = | url = | doi = | id = | isbn = 9993239909]

To enable the crew to load and traverse the massive gun, each gun had a steam engine that fed high-pressure steam to a hydraulic accumulator. It took three hours to generate the required head of steam from a cold start.

ee also

* 12 pounder 8 cwt Armstrong gun
* 100-pound breech-loaded naval cannon
* Artillery
* Cannon
* Rifled breech loader

Notes

Further reading

* Jack Beeching, "The Chinese Opium Wars" (1975), ISBN 0-15-617094-9
* Erik Ringmar, [http://ringmar.net/europeanfury/ "Fury of the Europeans: Liberal Barbarism and the Destruction of the Emperor's Summer Palace"]

External links