Big Bang : Tallboy bomb

**LINK** https://www.bbc.co.uk/news/world-europe-54522203

See also: **LINK** https://en.wikipedia.org/wiki/Tallboy_(bomb)

MichaelG.

One of the Wallis inventions. It’s likely not widely known that the good old Lancaster was able to, and readied for, the delivery of the atomic bombs at the end of WWII. It required a big push by the Americans to build a plane of their own to deliver them. I believe in-air refuelling was needed for the Lancaster and this was developed for the task. The A-bombs were slightly lighter (by about half a ton) than the tall boy bombs.

That is one big bad boy. Or it was.

Steve.

Was is now the correct term, apparently it has gone off, without casualties fortunately.

John

Wasn't there an even bigger Grand Slam that Wallis designed late in WW2?

Thor

Wallis originally proposed a 12 ton bomb, much earlier than the Tall Boy; he also provided a design for a plane to deliver it.

He was certainly considered a ‘crank’, at the time, where inventions were concerned, thinking far ‘out of the box’. A genius really, among those proposing radical suggestions for war-time weaponry. Like his original spherical ‘bouncing bomb, the final designs were much modified (the bouncing bomb developed into a cylinder) but his basic ‘shake the targets to destruction’ was well founded.

This may well be an apocryphal story but the Tallboy and Grand Slam bombs were the only bombs that the bomber crews were instructed to bring home if they couldn't find the target rather than dump due to the cost of each bomb. High grade steel for the case that wouldn't brake up on impact and some fancy machining on the nose of the weapon.

Another story in a similar vein was the "gate guardian" at an RAF base (Scampton?), a Tallboy that was thought to have been deactivated but was in fact still live!

John

The raid where it was dropped was against the Lutzow - everybody these days seems to call it a cruiser. It was only ever that on displacement alone. It was slower than most cruisers and threw a broadside twice the weight of a normal 'heavy' cruiser's. It was originally one of the three Panzerschiffs, but ironically not very well armoured.

Back in the day they were called 'pocket battleships'.

Shortly after the war ended, I remember going out with my dad, and travelling up 'Caistor High Street', a B road running up the Lincolnshire Wolds. I still have a vague memory of bombs being stacked on the verges of the road, and thought it was just a false memory. With the joys of the internet, I was able to find out that bombs from RAF Ludford Magna were indeed stored on the side of the road!

In the early eighties I worked in Bremen Germany, I visited the U-Boat bunker at Rekum, [ Valentin-Rekum U-Boat Bunker ]. If you can find it on Google maps its on the river Weser and the top of the bunker is full of craters, I was told that after the war it was used by these large bombs as a target but the concrete is so tough that it could not be breached. I have just googled the bunker and a web site is up and running, haven't seen it yet.

Bob

I had the pleasure of meeting Barnes Wallis in a village hall in Surrey, where he gave a talk on the Dambusters and his boucing bomb. A very interesting man who then still felt the burden of the aircrew lost during that mission.

On the subject of A bombs, modern ones are considerably lighter than the originals.

I know the Polish bomb squad gave a 50:50 chance of successfully de-fusing the thing but one wonders how much protection was put in place before they started. The bomb was only about 100 yards from a major ferry crossing (the two ramps in the video clip). The little dock to the left of the explosion was a U-boat pen (Google maps and earth are very good).

I find the explosion interesting. The plume of water and resulting waves were very symmetrical suggesting the bomb was in very good condition and had no seriously corroded.

JA

Re: protection mentioned above. Everybody in the radius of 2500 metres evacuated and in the radius of 3000m not allowed outside. And of course ferry crossing shut for the most of the day. They did realise there's a high risk since divers weren't around when device was remotely set off.

I'll say the whole action well prepared and all the details are available on website (in Polish language) Link . Worth having a look even just for photos.

Tom

"We've got to be at the pub by five guys so lets just set that sucker off"

"Anyone want fresh fish for tea tonight?"

.

Thanks for the link, Tom

DeepL seems to make a decent job of Polish to English translation.

MichaelG.

As far as I know, the tall boys and grand slam casings were manufactured in the USA, as the UK didn't have the capability at the time.

All good stuff, I love a bit of Dambuster history.

there is some Grand-slam stuff on Wiki too:

**LINK**

Possibly the high-spec steel came specially from the USA, but the casings were forged by Vickers-Armstrong in Sheffield.

Some interesting notes here: **LINK**

https://www.barneswallisfoundation.co.uk/life-and-work/munitions-design/

MichaelG.

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Edit: and here: http://www.sirbarneswallis.com/Links.htm

Edited By Michael Gilligan on 14/10/2020 18:09:55

The reason the Lancaster was considered as a vehicle for the atomic bomb was that it was originally thought that a plutonium-fuelled bomb could use a similar gun-type mechanism to that used for the uranium-fuelled Little Boy design (used for the Hiroshima bomb).

Plutonium 239, being more prone to spontaneous fission than Uranium 235, required a higher velocity for the projectile in a gun-type weapon, so that the two sub-critical masses formed by projectile and target would come together and attain super-criticality before they had time to start a pre-detonation 'fizzle'. This was attained by lengthening the barrel. The resulting weapon (called Thin Man) could, at the time, only be accommodated in the Lancaster's lengthy bomb bay. Contemporary American aircraft, like the B-17 had a pair of shorter bays, though the up-coming B-29 could be modified to carry it.

Further research revealed that manufacturing impurities in the Pu-239 made it even more prone to pre-detonation than had been supposed and the Thin Man would have to be impossibly long to work. Efforts were therefore concentrated on the more complicated, but more efficient, and safer*, Fat Man implosion bomb.

More here: https://en.wikipedia.org/wiki/Thin_Man_(nuclear_bomb)

*The idea of a safe nuclear weapon seems a little strange, but the gun-type design could be accidentally detonated from a single failure point. Getting the implosion bomb to work at all was sufficiently difficult that it had a degree of intrinsic safety to work with.