Post by 2nd Bat on Jan 3, 2016 14:10:48 GMT -5
In recent news WW2 bombs in European cities continue to be discovered and in some cases explode randomly and continue to kill and maim people. 70 years after they were dropped! I did not know how time released bomb fuses worked and certainly didn't think they might release their firing pins decades later but they can and do!
During the war about 5 to 10 percent of the iron bombs dropped on targets in Europe had time release fuses. There were two reasons for time delayed fuses. One, so the bombs could penetrate deeper into a target for more destructive power and two, to cause casualties among rescue workers, firefighters and onlookers. (Terror weapons). One means for creating the time delay was to place a spinning pinwheel at the rear of the bomb between the fixed fins we commonly see on iron bombs. This pinwheel drives a long screw that in the course of falling, pierces a canister containing acetate which slowly melts through a series of layers holding back the detonating pin. The number and thickness of the layers determines the duration of the time delay which can, by design, be hours or even days.
The reason some of these bombs didn't explode is they pierced soft ground and with their rear fins torn off button hooked in the soil ending up with their nose cone pointing upward. The released acetone therefore dripped down away from the spring activated firing pin. These detonators are only now getting released as normal corrosion of the surrounding metal gives way. In recent cases 70 years later. Interestingly seventy to eighty years seems to be a consistent fatigue point so spontaneous surprise explosions are increasing.
Even today there are bomb disposal units in most major european cities and their work remains extremely dangerous. Usually these bombs are discovered at construction sites but increasingly cities are mulling over post bombing recon photos which in some cases reveal specific locations where bombs struck but didn't detonate. The duds that are turned upward are almost always found at a depth of 14 feet.
To add further complexities to recovery efforts, allied bombs with fuse delays were often rigged with
boobytrap trigger mechanisms as well.
During the war about 5 to 10 percent of the iron bombs dropped on targets in Europe had time release fuses. There were two reasons for time delayed fuses. One, so the bombs could penetrate deeper into a target for more destructive power and two, to cause casualties among rescue workers, firefighters and onlookers. (Terror weapons). One means for creating the time delay was to place a spinning pinwheel at the rear of the bomb between the fixed fins we commonly see on iron bombs. This pinwheel drives a long screw that in the course of falling, pierces a canister containing acetate which slowly melts through a series of layers holding back the detonating pin. The number and thickness of the layers determines the duration of the time delay which can, by design, be hours or even days.
The reason some of these bombs didn't explode is they pierced soft ground and with their rear fins torn off button hooked in the soil ending up with their nose cone pointing upward. The released acetone therefore dripped down away from the spring activated firing pin. These detonators are only now getting released as normal corrosion of the surrounding metal gives way. In recent cases 70 years later. Interestingly seventy to eighty years seems to be a consistent fatigue point so spontaneous surprise explosions are increasing.
Even today there are bomb disposal units in most major european cities and their work remains extremely dangerous. Usually these bombs are discovered at construction sites but increasingly cities are mulling over post bombing recon photos which in some cases reveal specific locations where bombs struck but didn't detonate. The duds that are turned upward are almost always found at a depth of 14 feet.
To add further complexities to recovery efforts, allied bombs with fuse delays were often rigged with
boobytrap trigger mechanisms as well.