Talk:HMS Thunderer (1872)

Exploded gun on [[HMS Thunderer (1872)]]

 * Moved from my user talk:

"...the left 12.5-inch gun in the forward turret exploded during gunnery practice". Histories state that this was in fact a 12.5 inch gun bored to 12 inches, designated "12-inch 38-ton gun". Your thoughts ? It wouldn't make sense to have different calibre main guns. Rod. Rcbutcher (talk) 04:41, 27 April 2016 (UTC)
 * Winfield & Lyon, p. 255, state that the source of Thunderer's guns being 12 inch vice 12.5 inch is from King's report on European navies, but they say 12.5, as does Parkes. Conway's, OTOH, says 12 inches. Sadly, Campbell doesn't start his series on British guns until the 1880 models. Do any manuals say that there was a 12-inch 38-ton gun?--Sturmvogel 66 (talk) 05:36, 27 April 2016 (UTC)
 * 1879 Treatise on the Construction and Manufacture of Ordnance in the British Service (i.e. before the explosion), states under 12-inch 35-ton gun : "Two 38-ton guns, Nos. 2 and 3 [sic] on board HMS "Thunderer", retain the calibre of 12" temporarily". I read elsewhere (still trying to find it again) that the problem was one of supply : over-supply of 12.5 inch, underesupply of 12-inch, hence the expedient of lining down (or completing as 12-inch) two 12.5 inch guns. Rcbutcher (talk) 09:53, 27 April 2016 (UTC)
 * 1921 Robertson, Evolution of Naval Armament, refers to Thunderer's two forward 12-inch 38-ton guns with new hydraulic action, one of which exploded in 1879... Rcbutcher (talk) 10:12, 27 April 2016 (UTC)
 * Brassey 1882 "The British Navy" vol II, page 82, goes into great detail about the 12-inch 38-ton gun explosion... "the bores having been specially kept to this size, instead of the usual twelve and a half inches of ordnance of that weight, in order that the same projectiles might be used for the guns in the fore-turret, and for those weighing 35 tuns in the aft turret". Rcbutcher (talk) 10:37, 27 April 2016 (UTC)
 * I just noticed that Winfield & Lyon state that the ship had four 12.5-inch guns, not just in the forward turret like everybody else. Hmmm....--Sturmvogel 66 (talk) 05:38, 27 April 2016 (UTC)
 * This belong on the article talk: page, not here. I'll move it over. Andy Dingley (talk) 09:28, 27 April 2016 (UTC)


 * I've no sourcing on what Thunderer had herself. Some general points though:
 * 'calibre' is more than diameter. The weight of shell can vary a lot within the same bore diameter and this affects range and effectiveness against armour more. 12 to 12.5 could be a large or a small difference. Some "12 in" guns could also vary a lot, depending on the model.
 * Pre-dreadnoughts deliberately used a range of calibres. This could even include "light" and "heavy" guns within the same calibre, on the same ship. I think this was a US approach more than UK. Many wing turrets though had a reduced maximum charge compared to a centreline turret, because of the risk of blast damage to the superstructure.
 * AIUI, Thunderer did only have one main gun calibre: the guns were built on differing 35-ton and 38-ton barrels owing to their availability (they are massive forgings and slow to produce), but the 38-tonners were then bored undersize to match the 35-tonners so that the ship had a consistent calibre from the service and ballistics point of view.
 * Yes, see Brassey 1882 above. Rcbutcher (talk) 05:01, 28 April 2016 (UTC)
 * Is there a source for Thunderer's guns definitely having been built for her, rather than being Palliser conversions of earlier MLs?
 * What ramming machinery was fitted? The Engineer article suggests that the problem was a fault in the depth indicator for hydraulic ramming gear, thus not indicating that the rammer had hit a second charge.
 * What's the purpose of the millboard disc above a Palliser shell? A fireable weather tompion? Andy Dingley (talk) 10:05, 27 April 2016 (UTC)


 * A simple point on the start of the above; "Histories state that this was in fact a 12.5 inch gun bored to 12 inches". That seems unlikely unless bored and sleeved down. SovalValtos (talk) 10:18, 27 April 2016 (UTC)
 * No, I think it was simply a brand new forging for a 12.5" 38 ton, but only ever bored out to 12". Andy Dingley (talk) 10:24, 27 April 2016 (UTC)

Power operated turrets
This is a mess. Nearly ever source seems contradictory.

Can we get good (i.e. primary archive sources) to clear up any of the following: Andy Dingley (talk) 10:51, 28 April 2016 (UTC)
 * Were both turrets initially power traversed? Was this done by steam, or by hydraulics?
 * Was the fore turret built with power, never powered, or converted after building (1874)?
 * What was powered, and what was powered in the fore turret that wasn't powered in the aft? Traverse, elevation, ramming, recuperation, shell lifts?
 * Were there hydraulic shell lifts fitted? To one or both?
 * How many elevation trunnions were there? I suspect that all guns had a manual elevation gear which worked the trunnion on the recoilling carriage. There may also have been a second trunnion (similar to that used for Inflexible), where the slideway frame of the carriage could also be raised and lowered by hydraulics, just for loading.
 * What were the tasks of the turret crew and how did this change in the 48-28 demanning after the power operation of the fore turret?
 * I'm pretty sure that both of the turrets were traversed with steam and initially worked by hand. The hydraulic gear fitted to the fore turret while fitting out or shortly afterwards elevated, rammed and lifted the shells and gun, AFAIK. I'm a bit dubious that the recuperation was hydraulic that early, but that's not anything I've studied specifically. I think that the rest of your questions can only be answered from the manuals for the gun and turret, if any survive.--Sturmvogel 66 (talk) 14:32, 28 April 2016 (UTC)
 * By "recuperation" here I mean a hydraulic ram to run the guns back out again after they had recoiled and stopped moving (rather than pulley blocks or a geared rack), not the hydro-pneumatic recuperators that would take another few decades. Andy Dingley (talk) 15:22, 28 April 2016 (UTC)
 * Ah, thanks for clarifying what you meant; that I don't know.--Sturmvogel 66 (talk) 15:31, 28 April 2016 (UTC)
 * "steam traverse" has been used as a contemporary shorthand for "power traverse" (i.e. as opposed to hand-working it). The mechanism was actually a hydraulic motor, with hydraulic pressure generated from a steam engine and pump, outside the turret. I see no evidence or sourcing for the turrets being worked directly with a steam engine. In particular, I have never seen any ship fitted with steam pipes to a turret or gunhouse, and any fixed steam engine would thus have to be mounted to the non-rotating barbette, making the working of a large turret (captained from within the turret) awkward, or at least involving obvious equipment outside the turret. Andy Dingley (talk) 18:09, 9 May 2016 (UTC)