Out of interest there is a Grand Slam bomb on display at Kelham Island Museum in Sheffield; unfortunately it does not have the tail fins attached. Can be seen in the photo here: Sheffield Industrial Museums Trust - Kelham Island Museum, Abbeydale Industrial Hamlet, Shepherd Wheel - Collections and Research -2 Collections: Kelham Island Museum -3 The Grand Slam Bomb The museum also has a Spitfire crankshaft on display and the awesome River Don Engine, a 12000 horsepower steam engine that saw service rolling armour plate for battleships: Sheffield Industrial Museums Trust - Kelham Island Museum, Abbeydale Industrial Hamlet, Shepherd Wheel - Collections and Research -2 Collections: Kelham Island Museum -1 The River Don Engine
Blimey they are big aren't they. I recently read a book on 617 Squadrons attacks on the Tirpitz using Tallboys. Does you know of any online accounts of the use of Grandslam bombs, ie. the effects on structures? I did a quick search but couldn't find much.
New book out recently, Barnes Wallis's Bombs. A must have buy. Excellent and talks about the structural effects on places such as the U-boat pens in Bergen etc as well as the bomb developement.
That sounds perfect thanks Kitty, I'll have to buy a copy, being an engineer myself I'm interested in technical details of the structural damage (yawn!). I found some internet stuff on the Bielefeld Viaduct raid and some of the U-boat pens, but not much technical detail. Also found this about the Grandslam used as a "gate guard" at RAF Scampton, caused a bit of a panic! Grand Slam (Apologies if its been posted before).
I'm interested in technical details of the structural damage (yawn!). I found some internet stuff on the Bielefeld Viaduct raid and some of the U-boat pens, but not much technical details A little info on the RAF Tallboy raids on the Brest U-boat Pens. The Pens at Brest underwent three attacks by Lancasters of 617 Squadron, each aircraft carrying one 12,000lb Tallboy bomb. The bombs were dropped from an altitude of 16,350 to 18,500 feet, the centre of the shelter being the selected as the aiming point, the fuses being set for 11 seconds delay on the first mission and 0.5 seconds delay on the others. In the first attack on 5 August 1944, seventeen Lancasters were dispatched and thirteen dropped their bombs over the target, obtaining five direct hits; in the second on 12 August, eight on the eleven aircraft dispatched dropped their bombs over the target, obtaining three direct hits; and in the third, on 13 August when only five of the twenty-eight Aircraft dispatched dropped their bombs over the target, they obtained one direct hit and two near misses. Altogether, of the twenty-six Tallboy bombs aimed at the Brest shelter, nine scored direct hits and there were two near misses. It is not possible to distinguish between the damage caused bt the differently fused bombs, but clearly in each case they penetrated and came to rest before detonation took place. Of the nine direct hits, four did not penetrate the roof, leaving craters approx 9 metres in diameter and 3 metres deep. Two of these hits were above walls and caused little scabbing, the other two caused scab holes which were about as large as the craters. Most of the scab material remained suspended from the roof by the reinforcing rods. In five instances the craters and scab holes joined and produced holes through the roof with average diameters of about 5 metres. The damage done inside was suprisingly small as the blast evidently spent itself in tearing through the concrete. No damage was sustained by the U-boats within and that only four persons were killed in the attackes, three of them being on the roof and the other inside one of the pens. The two near misses produced craters in the ground of nearly 30 metres diameter but did not result in any shock blast or fragmentation damage to external walls.
Its quite amazing actually. The book goes into detail about the pen constructions and how the bombs failed to cause significant damage. Aparently the pens had a double layer roof with a gap between. Most of the bombs went through the upper roof, but then exploded harmlessly in the space between that and the one underneath. Really quite fascinting, and I have no engineering background at all. As to the Bielfeld Viaduct, the large crater that swallowed up the viaduct itself is now the central lake of a large country park.
