Bomb Fuse

An open Secret – the Patent for a Bomb Fuse

Patents may contain valuable information – patents are not secret, they are published for everyone to learn from – but this is not always appreciated. During the Blitz on London in World War II, the first generation of bombs dropped caused a particular problem: the bombs could explode on impact or remain unexploded on the ground – they could be set either to explode immediately or after a time delay.

Of course, British bomb disposal officers would come to defuse those bombs which had not exploded immediately but to begin they had to learn how the bombs worked (many brave men lost their lives in this dangerous work – at one stage their life expectancy was just seven weeks on the job).

A pity that no one thought to look in the Patent Office Library at that time: the patent covering the bomb fuse. GB376128 had been published in 1932. It was the invention of Herbert Rühlemann working for Rheinische Metallwaaren und Maschinenfabrik in Germany. Eventually the patent was discovered but by then the Luftwaffe was dropping a different bomb on London and no patent covered the details of that bomb.

Below is shown figure 9, which either causes a bomb to detonate on impact or after a delay.