re: #256 Nojay UK

The Polish EOD team were apparently using an underwater robot to deflagrate the charge in the bomb i.e. burn it out of the casing. They weren’t trying to “defuse” it since the original fuze had failed in the first place. Most bomb disposal operations on old bombs involve extracting the explosive charge by deflagration or steam injection since the fuzes are usually rusting lumps of scrap after the passage of sufficient time. They did take the precaution of evacuating residents from the area around the canal before attempting this operation. Wise.

The explosive charge in a Tallboy bomb was about 2.2 tonnes of Torpex, a compound with a high brisance. It was originally concocted for torpedo warheads as the name indicates. It used aluminium powder as an accelerant (just like modern rocket boosters) and unusually it was melted and cast into the Tallboy and Grand Slam bomb casings for maximum explosive energy and mechanical stability on impact.

I’m still a little surprised this bomb’s charge high-ordered during the attempt at deflagration. It’s possible the charge’s chemistry may have degraded a little over the 75 years or so since it was poured and become unstable.

Trivia note: The bomb bay dimensions of the B-52 were originally set by a requirement that it be able to carry the Grand Slam bomb internally and not, as often assumed, by the dimensions of early atomic bombs, which were much smaller.