Landships II

James H · Legend

German "Toffee Apple" Mortar?

Lothianman · Colonel

I was taught to check such assertions by seeing if the sums make sense, using the Fermi Piano Tuner method (lots of little assumptions where the errors cancel out).

85kg, knock off the stick and you have a sphere weighing 80kg. Assume it is cast solid HE at a density of, I guess (for obvious reasons I don't want to google), 2500 kg/cubic metre. That gives a volume of 0.032 cubic metres.

A sphere has volume 4/3 x pi x radius cubed - say 4 x cube of the radius.

So the cube of the radius is 0.008 cu m. The cube root of that is the radius = 0.2m = 20cm. It'll be a bit smaller in reality because the cast iron is about 7000 kg/cu m (admittedly counteracted if you fill it with loose powder).

35 cm (say) diameter seems about right ...

mad zeppelin · Commander in Chief

5.3 cm Bombenkanone L/19 in Sappenlafette, proposed by Krupp in 1909 - but only one experimental model was ever built.

The weight of the projectile was given as 85 kg, this does, however, not specify how much explosives it contained.

Before the war, Krupp tried to sell internationally, but nobody would buy it. The German army ordered Rheinmetall Minenwerfer. So, eventually, the project was discontinued.

James H · Legend

Brilliant, Citizens. I thank you. Confirmation can be found in this remarkable piece of work: http://ediss.sub.uni-hamburg.de/volltexte/2013/6126/pdf/Dissertation.pdf , a 500-page dissertation on German mortars of WWI. Our chum is from p116 onwards. Weight of shell: 85kg, indeed.

But if it never went into production, how could Eye-Witness have observed it in action, and where did the detailed photos and diagrams come from if it was in German hands?

mad zeppelin · Commander in Chief

James H wrote:
But if it never went into production, how could Eye-Witness have observed it in action, and where did the detailed photos and diagrams come from if it was in German hands?

Photographed pre-war on an international armaments fair by the French and - like so many other pre-war items erroneously - distributed as picture of actual German war material in 1914/15, when images of the real stuff were not yet available.