Shell transport - opening in the floor

Discussions on the fortifications, artillery, & rockets used by the Axis forces.
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Joined: 08 Jan 2011 11:46
Location: Norway

Re: Shell transport - opening in the floor

Post by Janef » 12 Oct 2017 14:32

juestr wrote: I suppose when talking about the similar onboard hoist systems, you think about the transport from land to the store rooms in the bottom of the ship?

It seems that you agree with me that the influence of wear is so important that the barrels for "normal" operation had to be relined after 10% wear = predefined rounds/cal.. Ships had to go back to the shipyard. What about the turrets on land? Is the relining possible without the crane and in relative short time?
The aim of this discussion was to know if there was a lot of time possible for the refilling of magazines - at the contrary to e.g. the situation of Maginot turrets
Remember that when a ship went into dry-dock (out of water maintenance) at least all the powder (Vorkartuschen und Hauptkartuschen) had to be unloaded. For Gneisenau going into dry-dock in Kiel i February 1942 this was not done because of the large amounts of ice in the harbour and the difficulty in getting the ammunition barges alongside the ship. The rest of the story is known. Because of this they had this loading/unloading system.

In respect of wear of a gun barrel the word wear (Verschleiss) is not a good description. The problem arise with the erosion of the first part of the rifling (Rohrabnutzung). This means that the shell is rammed further away from the powder charge. For a 28 cm this results in the shell beeing 300 mm forward of the new barrel position (For the 40,6 cm we talk about 460 mm)
The amount of powder is constant, therefore the enlarged chamber volume results in a lower chamber pressure and hence a lower muzzle velocity. A loss of muzzle velocity results in a shorter range, the shot dispersion will not be influenced. A 28 cm SKC/34 new gun at 40 degrees elevation (maximum in theses turrets) will reach 40900 meters. A gun having reached its 10% reduction in muzzle velocity will only fire 33970 meters (reduction 6930 meters).

As for turrets on land experts from Krupp and the responsible MAZA had to travel to the site, bringing cranes and equipment. Turret armor had to be removed and the old liner would be removed and the new liner put in place. The reserve liners for large calibre guns as these were made for a spesific barrel serial number and were not interchangeable. The work would take some time.
As for time - offloading and onloading ammunition was a work that went on 24/7.
It makes no sence comparing land fortresses operating against an attacking ground force against naval operations. The operational use of the guns are quite different - a keyword here is heating of the barrels.


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