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

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[Seaspriter]

The effect of a Grand Slam detonating at
ground level in the open. .... Lincoln Cathedral, which dates back to 1250, would have been flattened.

That is one powerful bomb. Shudder the thought of losing lives and the beautiful Lincoln Cathedral -- it is also the church my ancestors attended in the 1500s.

The Grand Slam story reminds me of a bomb episode on a more miniature scale, but very close to me -- my existence on this planet was the result of unexploded bombs:

Headline: U.S. Minelayer Beat Off Four Suicide Plane Attacks
New York Herald Tribune, August 4th, 1945
FELLED THREE PLANES OFF OKINAWA; FOURTH FLED SMOKING

Washington, Aug 3, (UPI) – The Navy told today of the exploits of the new destroyer-minelayer Harry F. Bauer, which shot down three suicide planes and drove a fourth away seriously damaged without itself suffering a scratch.
The Bauer previously had shot down four other enemy planes in single attacks upon larger formations of which the minelayer was a member. In this attack, she was the sole target of four enemy suiciders.
The action took place at Okinawa on Sunday, April 29th. Three Japanese single engine fighters and a two-motored bomber suddenly came out of the clouds and headed straight for the Bauer, which was on an isolated patrol station.
The bomber came in first, and the ship’s main battery let loose. The enemy plane exploded in mid-air, and a single parachute opened as the bomber plunged into the sea.
The next plane came in low and fast, and the Bauer’s gunners saw their hits flaming from the plane. But it kept coming. Finally the pilot lost control and the plane executed a snap roll and plunged into the sea. The bomb exploded as the plane hit the water, shaking the minelayer sharply but inflicting no damage.
The second fighter headed for the ship but was forced away by the Bauer’s accurate fire and circled briefly out of range. At the same time the last enemy plane headed in for the small ship.
Again accurate fire hit the fighter, which burst into flames and then aimed in a death-plunge straight for the Bauer. It cleared the ship’s stacks by a scant ten feet to crash into the sea. The bomb let go as it struck the water, and the Bauer was again shaken, but unhurt. The surviving plane fled, leaving a trail of smoke behind.

Headline: DEATH LURKS UNDERFOOT
by Richard J. O’Keefe, Philadelphia Inquirer War Correspondent (June 30, 1945)

SHIP HELD UNEXPLODED JAP BOMB 17 DAYS AFTER BATTLE

Aboard a fast carrier, Halsey’s Third Fleet, June 30th – A local Navy man is an officer aboard the destroyer minelayer Harry F. Bauer which shot down 13 Kamikaze planes in action off Okinawa and learned today that for 17 days since the battle they had been literally walking with death underfoot. He is Lt. (jg) Robert B. Lynch, (Combat Information Officer) , who will remember for the rest of his days that three threads on a bomb fuse probably was all that prevented him from becoming another name on the Navy Department casualty lists.
BOMB IN FUEL TANK
Unnoticed during the heat of battle, a 550-pound aerial bomb from a kamikaze hit the ship. The kamikaze released the bomb just moments before crashing into the ship amidships with a glancing blow. The bomb pierced the hull and fell into a fuel tank without exploding. The unexploded bomb was discovered when the flooded fuel tanks of the destroyer were emptied. The hole in the tank had been believed caused by shrapnel.
3 THREADS FROM DEATH
No one with sufficient experience in defusing bombs was aboard the destroyer, and a hurry call was sent for Lt. Charles M. Rupprecht of Englewood, N.J. air ordnance officer aboard one of Halsey’s Third Fleet carriers. The Lieutenant, who is over six feet tall, removed the bomb on June 30th. He worked alone for four hours in the bottom of the tank, removing the tail and nose fuses of the bomb and fitting a hoist to it so it could be lifted from the ship. Later examination of the fuses belied the ordnance officer’s state that his job was “just routine.” It was found that three threads in each fuse were all that prevented the firing pins from dropping on the charges. Apparently the kamikaze pilot released the bomb just a moment too late to arm the bomb. Had the arming propeller turned another second, the bomb would have become armed, dropping the firing pins on the charges. Had the pins dropped, the bomb would have exploded and probably caused the loss of the destroyer and all its crew, other ordnance officers said.
UNEXPLODED TORPEDO
During the battle, the destroyer was also pierced by an aerial torpedo, which entered the port bow and passed through the starboard bow, also without exploding. The “tail” of the “fish” was left hanging inside the ship, and discovered when the ship was surveyed for repairs.
Lt. Lynch is the son of Mrs. Mildred Lynch, 86 Strathmore Road, Cranston, and the husband of Mrs. Robert B. Lynch, 5 Legion Way, Cranston. -30-

[browningautorifle]

22,000Lb Grand Slam

I thought you were going to tell us you found one for your collection...

[Aussie48]

I thought you were going to tell us you found one for your collection...

Thank heaven he hasn't

Dick

[CINDERS]

Gads foiled again Batman! Now I heard there was a............

[Peter Laidler]

I'm surprised that they didn't just steam the TNT stuff out the original bomb once they'd got the filler plate (?) off - or whatever it was they took off to inspect. I doubt whether it was fuzed. Someone has made an exact replica of a bouncing bomb. Maybe Airfix could do a full size Grand Slam replica

[CINDERS]

Now there's a thought PL the instructions would be pretty easy just 2 halves but the bleedin' glue would set you back a pretty penny!

Steaming out explosives ~ they used to do that with the aerial mines the Germans dropped was to steam the explosive out after cutting a hole in the mine casing it was called tree-panning, there were a few types the Germans dropped ~ magnetic or acoustic, magnetic & acoustic in one then as the Mine disposals got good at it delousing the damn things.
Then they introduced George with photoelectric cells under the rear dome the only way into the bomb which had to be removed first to get inside so as soon as sunlight hit it bang no more mine disposal officer they assembled it in filtered sunlight so the only way to defeat the damn thing was in total darkness.(This mine also had the very first printed circuitry board in it)
They used phosphor bronze tools on the magnetic mines and were very very careful with acoustics each movement of the keeper rings was measured in fraction of inches one disposal chap lost his life when a lorry got through somehow and the noise and vibrations set it off, if you look at a pic of a WWII German acoustic mine it has one giant ear.
Next lot they put in a thing called a ZUS-40 which grabbed the fuse from inside the mine so any attempt to remove the fuse would set off the ZUS - 40 and fire the mine they defeated this item 2 ways with a very long string to pull the fuse out where a trap was suspected or drill small holes and fill the fuse area with pure alcohol and sugar which when the alcohol evaporated the sugar crystals stopped the booby trap from activating.


Some of the things these chaps did well they deserved the Victoria cross but as they were RNVR vollunteers they could only get the George cross just a couple of ones for you, being lowered into an empty gasometer to delouse a magnetic/acoustic mine standing knee deep in tar with no hope of escape.
Working on a mine fuse hanging upside down with the fuse out of sight on a barge full of munitions and the fuse ran he beat the fuse by the slimiest of margins having to use a tool to stop it running as you only had 17 seconds to run 400 yards its lethal zone whilst upside down! with no hope of escape.
Being on the mud flats with a live acoustic and thinking it was dead and dragging the test chain over it to test it but someone took some chain and they were within the lethal zone as the chain mounted the mine it detonated just as he said "See I told you it was dea......" it bent his knees 90 degrees the wrong way.
They disposed of mines under water as well.
The one they could not defeat very well was the oyster mine which went up with the passing of a ship and the underwater pressure wave it created moving through, there were lots of other mines as well that scared even the Germans who made them.
One character was the civilian professor who devised allot of methods in dealing with these treacherous things and was often seen with his lady secretary taking notes with a helper working on the mines they were called The Holy Trinity until one day all three were atomized by a mine that got them all.
HMS Vernon was the place they were taken to when safe to pull right down and look at (a spoof ship) it was a base workshops, or at a quarry with a ships name as another red herring where they were safely detonated.
All this in "Softly Tread The Brave" By Ivan Southall I highly recommend this book to read

There is another called "Open the Ports" a sequel to the above book which is set during and after the war to open up the ports in Europe of which it was deemed so highly dangerous that it was not officially sanctioned by the military..........they were only reserves who did this task!

[browningautorifle]

Make a sand mold and cast it from solid lead...

[Flying10uk]

The filler plate on a Grand Slam bomb is accessed after removal of the tail section of the bomb which is made of a much lighter gauge sheet metal than the actual bomb casing containing the explosive. The filler plate is just a circular steel plate with holes round the edge for bolting it to the rear of the bomb casing. I found out this information by looking at several Grand Slam bombs in museums such as the Brooklands Museum, surrey. Its a shame the above bomb casing wasn't saved.

[browningautorifle]

Agreed, but for them to try to boil the explosive out would have taken a considerable amount of work they obviously weren't interested in...too bad though.