This is a Tallboy bomb, 12,000 lbs, designed by Barnes Wallis with numerous unusual features to allow it to penetrate deep into the groud (or water) around the target before exploding. Its streamlined, elongated shape allowed it to achieve high terminal velocity. Slightly canted tail fins imparted spin that stabiized its attitude. The nose was hardend steel and the casing was another special steel to keep the bomb intact on impact. Three detonators and a timer in the tail made misfires unlikely. It was usually dropped by a Lancaster from 18,000 feet. About 854 were hand-built, so expensive that they were not jettisoned if not used but brought back and landed.

December 17, 2015