Original caption: In the summer of 1942, experiments were made in using the hollow-charge principle against tanks. Captain Terrell explains in his book "Admiralty Brief" the method of using the hollow-charge was to place the explosive behind a cone of steel and fire the explosive. The cone had to be a certain pitch from the base of the apex, and within certain limits the thickness of the steel used in the cone was important. The result was that the cone, by reason of the heat and direction of the explosion, would project forward a jet of molten metal at about 7000 feet per second. This remarkable phenomenon of the projection of this molten jet of metal was that it would converge inot a point just like the rays of light passing through a burning glass and concentrating at a particular place. At this point of concentration the penetrating power of the molten jet was quite astounding and a hollow-charge could be easily contained with its explosive in a 35-pound bomb, would penetrate and make a clean hole through eight inches of steel. Could this principle be employed against the pressure hull of a German submarine so as to flood and sink it? Preliminary trials were carried out at Whitchurch, Bucks, but the shape of the cone gave difficulty. Torpex was the explosive used. Next, trials were carried out off the Welsh coast against full scale models of the pressure hull of the captured submarine U.570, but they showed that the depth charge was a more lethal weapon than the hollow-charge bomb. Improvements were made, and in July 1942, the bomb inflicted lethal damage on the models, but for several months, difficulty was experienced in fusing the bomb. However, two attacks on German submarines by hollow-charge bombs of the final design, dropped from Hudson aircarft of Coastal Command were made early in 1943, and were believed to have resulted in the sinking of the U-Boats. It was soon after decided that the new Torpx-filled depth-charges were more effective, and the hollow-charge bomb project was dropped.
Air-dropped 35lb anti-submarine hollow-charge bomb, complete with nose fuze, but minus the cylindrical nose attachment