Saturday, 11 January 2020

One half mass times velocity squared

I'm partial to both military history and physics and so was delighted when they were combined in the latest Royal Armouries talk, which was on the development of very large guns since the Crimean War, with (some) reference to the science behind them. Subjects covered ranged from Mallet's Mortar to the Iraqi Supergun, via the Paris gun, Gustav and Dora and the V3.

Mallet's achievement was perhaps the most impressive, given that he started more or less from scratch in his application of the scientific method to the problem which he faced; namely how to destroy the fortress at Sebastopol, the task which was to eventually be completed by Schwerer Gustav nearly a century later. He successfully reverse engineered the required shell size (anticipating Barnes Wallis in his calculations), overcame the problem of circumferential stress in the barrel, and used a modular design for ease of transport. All he didn't manage was to complete the task before the war ended; the gun was never fired in anger.

The weapon that really caught your bloggist's attention was the Pariser Kanone, not least because its range was so great that when aiming they had to take account of the rotation of the earth, a subject which of course has often featured here before. According to the speaker, Paris moved four miles between the gun being fired and the shell landing; it was not a precision weapon.

One interesting analogy used was that the kinetic energy of a projectile leaving the barrel of a WWI 7.5cm field gun (i.e. those included in my Square Bashing games) was equivalent to that of an articulated lorry travelling at 100 mph.

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