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October 9

coastal cannon

Fortification of Poggio Rasu (Caprera, Sardinia). Probably a part of unidentified coastal cannon from the late 1800's (?) - Which cannon was that? Thanks! Etan J. Tal^(talk) 14:53, 9 October 2017 (UTC)[reply]

Not sure, but it could also be a gun mount, for something like the Gatling gun, with the mount being similar to this modern one: [1]. StuRat (talk) 15:46, 9 October 2017 (UTC)[reply]

Maxim gun and Gatling gun seem to be 'too small' for this pivot and were not in use by the Italians anyway. Etan J. Tal^(talk) 15:57, 9 October 2017 (UTC)[reply]

It may have been a Howitzer as these were very common for the time period, especially in coastal batteries. Howitzers are a sort of hybrid between a cannon and a mortar, with an intermediate length barrel for higher muzzel velocities than a mortar, but which are still used for veritcal (mortar-like) trajectories rather than more horizontal cannon-like trajectories. --Jayron 32 16:13, 9 October 2017 (UTC)[reply]

If this is on the landward side, it's probably a Swivel gun.--Ykraps (talk) 16:19, 9 October 2017 (UTC)[reply]

Swivel guns were in use much earlier and their range is much too short for coastal fortification. Etan J. Tal^(talk) 16:32, 9 October 2017 (UTC)[reply]

This seems to be a good source, where it states: "The cannons of Poggio Rasu Superiore, especially, were positioned to defend the Eastern side." (emphasis mine). The question still remains: what kind of cannon? Would "Big" suffice? 2606:A000:4C0C:E200:29AF:8B75:2D37:5BB4 (talk) 20:50, 9 October 2017 (UTC)[reply]

My question is 'Which sort of cannons'? In all the websites which I have searched there is no mentioning of the exact type of cannon which was in use in this specific fortification or in the many others on Caprera island. Etan J. Tal^(talk) 21:07, 9 October 2017 (UTC)[reply]

This emplacement is for a large gun such as a Parrott rifle or one of its successors. The ring was connected to the front of the carriage. The gun sat on the carriage and recoiled back along the carriage. The gun was aimed in azimuth by moving the back of the carriage along the semicircular tracks that can be seen in the picture. We cannot tell from the picture alone exactly how the carriage was designed. There were many variations. -Arch dude (talk) 22:09, 9 October 2017 (UTC)[reply]

Notice the wheels under the carriage rails. The wheels carry the back of the rails along the circular track. -Arch dude (talk) 22:17, 9 October 2017 (UTC)[reply]

It would help to have an indication of scale. What's the diameter of the cylindrical vertical hole in the center ? StuRat (talk) 22:30, 9 October 2017 (UTC)[reply]

Regretfully I did not measure this. I estimate it is about 4" in diameter, but I may be wrong... Etan J. Tal^(talk) 22:58, 9 October 2017 (UTC)[reply]

This site - http://www.sardegnafortificata.it/jkrasu.htm - indicates that there were 4 Krupp 280mm guns, and 2 Hotchkiss 57mm cannon (which I think was a version of the five barrelled revolving cannon) - see Hotchkiss gun for further links. Looking at the aerial photos of the fort, there is a large four gun battery in the upper fort, which would presumably have held the Krupp coastal guns, and a smaller two gun battery in the lower fort, which appears to show the semi-circular pattern in the original photo. That lower fort battery controls the road access to the fort on the landward site, so would be the logical position for rapid fire smaller weapons. Wymspen (talk) 11:55, 10 October 2017 (UTC)[reply]

Agreed; these are mounts for late-19th or early 20th century quick firing guns, which were introduced to counter the threat from torpedo boats. It seems more likely to me that the single-barrelled version was more probable, as the multi-barrelled type was a bit of a gimmick and not widely adopted if I recall correctly. The British-built version of the single 57 mm was called the QF 6-pounder Hotchkiss; our article shows the type of pedestal mounting which would have been bolted to the firing platform. The sloping masonry at the front was called a glacis-parapet, an innovation of the 1880s, and was designed to deflect the new high explosive shells upwards (our Twydall Profile article has some details). Alansplodge (talk) 12:30, 10 October 2017 (UTC)[reply]

The fort may have eventually had the Krupp 25 cm guns and the quick firing guns, but I think the emplacements in the picture were for some earlier type of large pivot gun. The semicircular tracks are diagnostic. The Krupps were way too large for this, and the quick-firers were pedistal-mounted with no need for a concrete track. A later upgrade to the Krupps would make sense as the late 19th century was a time of rapid evolution in cannons. -Arch dude (talk) 13:36, 10 October 2017 (UTC)[reply]

Probably right, however, I think the racer tracks were for an earlier weapon which was replaced by the QF guns. My opinion is that the present parapet overlays the previous mounting, but that's just a guess. Many 19th century forts had several changes of armament, necessitating rebuilding work each time. Alansplodge (talk) 15:27, 10 October 2017 (UTC)[reply]

The caption is now set to: Fortification of Poggio Rasu (Caprera, Sardinia). The pedestal was probably used for Hotchkiss 57 mm gun (QF 6-pounder Hotchkiss) or 57/43 Mod. 1887

QF 6 pounder Nordenfelt (both used by the Italian army). I thank you all for your cooperation! Etan J. Tal^(talk) 15:18, 10 October 2017 (UTC)[reply]