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Bombing of the Tirpitz

Posted: Thu Jan 09, 2020 4:43 pm
by paul.mercer
I'm not sure where to place this post, but here it goes!
Watching a program about the sinking of the Tirpitz by 9 and 617 squadrons, it was suggested that the 'Tallboy' bombs achieved or went through the sound barrier on their way down and that the several 'near misses' could gave given severe damage to her hull - perhaps in the way that the 'bouncing bombs' did to the dams, it was also suggested that the great caverns carved out in the sea bed by the near misses was the reason she capsized.
I realise that Tirpitz was a powerfully built ship, but would a near miss have this effect on her hull? Also, I would have thought that the ones that did hit her a 6 ton bomb travelling at the speed of sound would very likely have gone right through her and out of the bottom of her hull and would have been enough to sink her straight away.
Any thoughts on these suggestions made in the program

Re: Bombing of the Tirpitz

Posted: Thu Jan 09, 2020 9:10 pm
by Dave Saxton
The mining effect from such large high explosive warheads could have been catastrophic. There was the potential for a torpedo exploding several meters under the keel type of effect. Nonetheless, the Tirpitz was subjected to severe under water explosions when it was attacked by the X-craft and also during the first tall boy near misses in Sept, and it came through less damaged than what one might expect.

As result of the X-craft charges the structural damage was limited to a few seams of the outer shell and flooding limited to a few wing tanks and the double bottom. A gland was damaged resulting in flooding into a shaft alley. It was the shock to the machinery that caused it to be immobilized. Likewise, the two near misses from bombs during the Sept Lancaster raid caused no flooding but damaged the machinery. It was eight days before the battleship could move by its own power.

The bomb that hit during the Sept. raid caused heavy damage to the ship's bow, though. This bomb passed through the bow flare and then exploded several meters below the bow. The structural damage was extensive, rendering the ship unseaworthy. The entire bow structure forward of the transverse armoured bulkhead was wrecked. When it transferred to Tromso the bow had to be reinforced with heavy steel girders first.

The Oct. 28th raid only achieved one near miss. This explosion caused a split in the shell plating aft and distorted the port side prop shaft causing minor flooding. The number two steering gear compartment was also flooded.

During the final raid it can only be guessed to what effect near misses had. The bombs that hit did not pass through the ship before detonating. One hit adjacent to turret Bruno but it is not known what effect it had. One hit midships on the aircraft catapult and exploded on the main armoured deck deck slope over the wing tanks. The explosion obliterated the wing tanks, the main armoured belt, and the armoured bulkhead, over an area of 14 meters opening up the boiler rooms to the sea and causing the ship to capsize. A third hit next to the port aft 5.9" turret exploding inside the ship, furthering the flooding of the port side.

Re: Bombing of the Tirpitz

Posted: Sat Jan 11, 2020 12:18 pm
by hans zurbriggen
Hello Mr.Saxton,
was it not the third hit that caused the detonation of the aft ammunition storage of Tirpitz ?


Re: Bombing of the Tirpitz

Posted: Sat Jan 11, 2020 3:10 pm
by Dave Saxton
Yes, it may have been the primary contributor, or a secondary contributor, but I don't think we know with much certainty.

Re: Bombing of the Tirpitz

Posted: Sat Jan 11, 2020 5:12 pm
by paul.mercer
Many thanks to you both those big bombs obviously did their job!

Re: Bombing of the Tirpitz

Posted: Wed Jan 15, 2020 12:24 pm
by wadinga
Fellow Contributors,

These "earthquake" bombs were not really designed for piercing armour, their casings were hardened for penetrating soil to result in undermining of structures. Penetration of concrete structures was just about achievable, eg U-boat pens. The cushioning effect of mud with water above actually minimised the mining effect, compared with the bouncing bomb/Highball which exploded at the bottom of the water column.

On a previous raid on Tirpitz an experimental weapon called the JW mine was dropped, slowed by a parachute. This device was intended to vary its buoyancy oscillating between the surface and bottom several times, with the hope it would hit the underside of the ship detonating and damaging keel and double bottom. It proved a failure.

A project to fill in the space under Tirpitz' keel was underway involving the emplacement of thousands of tons of sand, so as to prevent the sinking of the "Floating Battery" and allow her guns to defend Tromso even if she were sitting on the bottom, but the work was nowhere near complete when the ship rolled over. Several authors point out the original seabed survey failed to identify a significant depression in the anchorage floor in which the locals liked to fish, and which accommodated the superstructure as the ship rolled over to 135 degrees.

All the best