22,000Lb Grand Slam

[CINDERS]

Thought this would be some good reading;

Vintage News
Strangeness, 6 November 2015
The RAF discovered that a 15 year-old
‘Gate Guard’ Grand Slam bomb – was actually LIVE!!!!
Apparently when Lincolnshire County Council were widening the road past RAF Scampton’s main gate in about 1958, the ‘gate guards’ there had to be moved to make way for the new carriageway. Scampton was the WWII home of 617 Sqn, and said “gate guards” were a Lancaster…and a Grand Slam bomb.
When they went to lift the Grand Slam, thought for years to just be an empty casing, with an RAF 8 Ton Coles Crane, it wouldn’t budge. “Oh, it must be filled with concrete” they said. Then somebody had a horrible
thought …. No!….. Couldn’t be? … Not after all these years out here open to the public to climb over and be photographed sitting astride! …. Could it? …. Then everyone raced off to get the Station ARMO. He carefully
scraped off many layers of paint and gingerly unscrewed the base plate.
Yes, you guessed it, live 1944 explosive filling! The beast was very gently lifted onto an RAF ‘Queen Mary’ low loader, using a much larger civvy crane (I often wonder what, if anything, they told the crane driver), then driven slowly under massive police escort to the coastal experimental range at Shoeburyness. There it was rigged for demolition, and when it ‘high ordered’, it proved in no uncertain terms to anyone within a ten mile radius that the filling was still very much alive!
Exhaustive investigations then took place, but nobody could find the long-gone 1944, 1945 or 1946 records which might have shown how a live 22,000 lb bomb became a gate guard for nearly the next decade and a half. Some safety distance calculations were done, however, about the effect of a Grand Slam detonating at
ground level in the open. Apart from the entire RAF Station, most of the northern part of the City of Lincoln, including Lincoln Cathedral, which dates back to 1250, would have been flattened.

The Grand Slam was a 22,000 lb (10,000 kg) earthquake bomb used by RAF Bomber Command against
strategic targets during the Second World War. It was the most powerful non-atomic bomb used in the war.
Known officially as the Bomb, Medium Capacity, 22,000 lb, it was a scaled-up version of the Tallboy bomb
and closer to the original size that the bombs’ inventor, Barnes Wallis, had envisaged when he first developed his earthquake bomb idea. It was also nicknamed “Ten ton Tess”.
When the success [of the Tallboy bomb] was proved, Wallis designed a yet more powerful weapon… This 22,000 lb. bomb did not reach us before the spring of 1945, when we used it with great effect against viaducts or railways leading to the Ruhr and also against several U-boat shelters. If it had been necessary, it would have been used against underground factories, and preparations for attacking some of these were well advanced when the war ended. —
Sir Arthur Travers Harris (1947).

On 18 July 1943, work started on a larger version of the Tallboy bomb, which became the Grand Slam. As with the original Tallboy, the Grand Slam’s fins generated a stabilizing spin and the bomb had a thicker case than a conventional bomb, which allowed deeper penetration. After the hot molten Torpex was poured into the casing, the explosive took a month to cool and set. Like the Tallboy, because of the low rate of
production and consequent high value of each bomb, aircrews were told to land with their unused bombs on board rather than jettison them into the sea if a sortie was aborted.

After release from the Avro Lancaster B.Mk 1 (Special) bomber, the Grand Slam would reach near supersonic speed, approaching 1,049 ft/s (320 m/s), 715 mph (1150 km/h). When it hit, it would penetrate deep underground before detonating. The resulting explosion could cause the formation of a camouflet (cavern) and shift the ground to undermine a target’s foundation.
Unlike Tallboy, Grand Slam was originally designed to penetrate concrete roofs. Consequently, it was more effective against hardened targets than any existing bomb. The first Grand Slam was tested at the Ashley Walk Range in the New Forest, on 13 March 1945. By the end of the war, 42 Grand Slams had been dropped on active service
2

Information

Warning: This is a relatively older thread This discussion is older than 360 days. Some information contained in it may no longer be current.