I would assume that the explosive was TNT. TNT actually takes some effort to detonate; this is why even artillery shells can be filled with it, an not explode during firing. TNT can also burn safely e.g if thrown into a fire in small amounts; you likely can even make a candle out of it.
The bomb likely had another, undetected detonator which was triggered, and it produced enough of a shock wave to make the TNT explode.
> The bomb likely had another, undetected detonator
That would be really poor bomb design. Bombs are designed to be stored inert near the airstrip, mounted to staged aircraft and armed quickly by inserting a primer/detonator. There would be one and only one per bomb. The detonator would certainly be removed first before trying to burn out.
Explosives usually become more unstable over time, sometimes forming pockets of primary explosives, which can detonate the bomb. See my sibling comment.
Edit: I'm completely mistaken! Some bombs in fact have multiple fuse pockets, so presumably, multiple fuses. Nonetheless, even with all fuses removed, UXB can still go off during disposal.
Well, poor or not, they did it, I found the American TM for german bombs of that era printed in the 50s and the SC250 definitely has a forward and after fuze pocket. Took 5, 17, 50, or 57 series fuzes.
Its wild that all this stuff from decades ago is online. You get used to not having any historical data about, well, historical events.
The type 17 fuze was a clockwork that could go 1.5 to 80 hours after landing. I could imagine something like that getting jarred into working again after a few decades...
Thanks for the correction! Yeah, I did some more digging and there are in fact some wacky designs. The single-fusing-element is more dominant in modern designs, but war is a crazy place.
The Germans would sometimes use a timed detonator on their bombs, intended to kill emergency services personnel who moved in after the raid and were fighting fires, aiding the wounded, etc. If you haven't seen it, the show "Danger UXB" from the early 80's is good.
You jest, but I believe some of these incidents have been caused by some sort of delay mechanism which gets stuck, until one day it is dug up or corrodes enough to unstick, at which point it goes off.
After I clicked reply and went to do a chore I thought to myself "I didn't talk about how it's been almost 80 years and it's unlikely to have been a timer." Doh.
The British just sent two waves of bombers one a few hours after the first to kill off the ambulances and firefighters. Seems like the Germans once again beat the British at their own disgusting tactics with better technology.
Also do you have a source other than a post-war tv show? Im getting a lot of unrelated search results when trying to confirm that timed fuses were used this way. Typically timed fuses were used to make the bomb explode before reaching the ground so it wouldn't just blow dirt into the air but would actually collapse lots of roofs etc. mis-set timers could hurt rescue personnel but i havent heard that that was even intended by the Germans.
These were not proximity fuses, but fuses with clockwork timers designed to delay hours or days until they exploded. This turns them into area denial weapons. Militaries use them to this day (but with modern electronics) on targets like airfields.
Early "proximity" fuses like you're talking about (not the later radar VT fuses developed by the British & Americans, first used at the Battle of the Bulge) had mechanical timers with delays of only a few seconds to account for the planned height of the aircraft when dropped. Many of the men awarded the George Cross for their UXB work encountered them after they malfunctioned (If you ever have the chance to visit the UK Imperial War Museum, it's highly recommended.)
> Seems like the Germans once again beat the British at their own disgusting tactics with better technology.
Check your timeline. The German bombing campaign against the civilian population of major British cities started in early September 1940 (mom spent many nights sheltering in the family's Anderson Shelter from the German bombs). Retaliatory bombing in occupied Europe & Germany by the British didn't begin until the next year.
I was asking for a source that those were actually used on british cities. That article sounds like bombs that were supposed tk detonate not the ‘ambulance killers’ you say were used.
>When explosive devices failed to detonate
From wikipedia:
The Royal Air Force began bombing military targets in Germany, such as docks and shipyards, in March 1940, and began targeting Berlin in August 1940.
Im sorry Churchill’s unpopular warmongering killed so many of your people.
Your commentary here and in your post above has been incredibly insightful. I was reminded of the 1967 USS Forrestal fire, when I had recalled reading that the ships captain and ordinance handlers were extremely worried about loading old bombs aboard the ship. Your explanations gave much further context to what was likely happening in that ordinance that gave those men such concern. Thanks!
> Specialists started the process by using a robot to cut the fuse and trigger at about 17:30 GMT on Thursday, but abandoned this when water from the cutting process destabilised part of the sand barrier.
> A decision was then made to switch to a slow burn technique, which was being carried out when the device exploded.
This is what we were taught on seismic crews too. It is generally okay and safe to burn sticks of dynamite (TNT) but just make sure you don't whack them really hard trying to put it out. The energy required to make it explode was supplied by a blasting cap which took a small electrical voltage to cause it to pop, roughly a half volt if I remember right (40 years ago so no guarantees.) You didn't want to disturb the blasting caps but you could toss the sticks of TNT anywhere with no consequences.
The bomb likely had another, undetected detonator which was triggered, and it produced enough of a shock wave to make the TNT explode.