Bucket of Sunshine Question - Yellow Sun

[Fonsini]

Not OpSec (in my opinion) just in case you were concerned.

Some time around 1956, the UK being somewhat backed into a corner in terms of weapon development due to the McMahon act and the resultant lack of US cooperation (until it was repealed in 1958) and needing a Megaton range weapon, came up with what is arguably the worst nuclear weapon design in history, the Green Grass device. Installed in either a Yellow Sun or Violet Club casing this bomb had so much fissile material fashioned into a thin outer shell combined with a large central void, that any simple collapse of the shell could potentially result in a prompt critical reaction and a partial detonation, even without a neutron initiator. In other words simply dropping it off the cradle could potentially remove an RAF base from the map. The RAF were given 5 of them, and they regarded that as 5 too many.

As a safety feature the central void of the bomb was filled with ball bearings which were held in place by a simple plastic plug, when removed the ball bearings trickled out into a large bucket and the bomb was technically armed or at least "dangerous". This process apparently took around 30 minutes unless it was freezing, in which case they would often lock together and refuse to budge, and technicians were understandably loathe to hit the casing with a hammer.

It's a long time ago, and with only 5 of the nightmarish things ever made this is something of a stretch, but did anyone on V Force ever come across one of these cold war terrors, any tales to share ?

[Pontius Navigator]

Not personally but my boss at Wittering, Billie Wells did.

He says at one time the ball bearings were emptied and rather than landing in a bucket ran all over the dispersal.

Of course to get them out the hole was at the bottom and of course you could not stuff them back. I believe the bomb had to be rotated to get them back in. Said quickly that sounds OK.

But that means offloading the live bomb.

Then it was not a simple issue of dropping them back in as the impact could . . .

Then of course it was necessary to ensure they were properly packed. To that end a secret tool, a 76z item, a Tools, Puddling was used to gently tamp them down.

Woe betide anyone that lost one of these tools though you could get one from Barrack Stores provided you didn't say what it was for.

In Barrack Stores it was a C class item aka Handles, Broom.

I think a friend of mine might know some more.

[Just This Once...]

There was a lot more than 5 Green Grass warheads, over 30 of them were deployed. The weapons were stored upside down after the first inadvertent ball bearing cascade.

[Just This Once...]

I should add that the ball bearings were fed into a rubber bag which lowered itself into place under its increasing weight. There was no risk of anything beyond expensive damage if the balls were dropped in.

The bomb was not really live with the balls removed so lowering the weapon onto its cradle without them fitted didn't really add any risk from manhandling or (heaven forbid) being dropped. The true risk was from fire which could puddle the enriched uranium and the balls added some much needed protection. They would also mitigate the risk of an unplanned HE explosion triggering a more sunny event, but clearly any explosion with radioactive shrapnel would not be fun.

[Fonsini]

There was a lot more than 5 Green Grass warheads, over 30 of them were deployed. The weapons were stored upside down after the first inadvertent ball bearing cascade.

Quite right, I stand corrected. There were 5 Green Grass physics packages installed in 5 early Violet Club bomb casings, and these were later transferred to Yellow Sun Mk1 casings in addition to 32 new builds for a total of 37 before the switch to an American design (US W28/ UK Red Snow) in the Mk2 version.

Pontius - I was hoping this would fall in your bailiwick.

[Pontius Navigator]

JTO, thanks, that detail was omitted by my boss.

Red Snow was also known as Unit 10,000. An one oddity, the same capsule was installed in Blue Steel but fitted in the opposite direction (180 degrees).

[Octane]

Would these have been devices tested at Woomera in Australia?

[ozleckie]

I was posted to Cottesmore Armoury in 1961 just as YS1 was replacing Blue Danube. YS1 was definitely user unfriendly. The collapse of the chamber which the ball bearings occupied was a vital part of the chain reaction which is why the balls were there.From memory when the bombed up aircraft went to 30 minutes readiness the bomb was lowered and rolled over and the balls removed.When the readiness returned to 40 minutes the balls were replaced. It was not unknown for some damage or problem to occur in all this and so another serviceable aircraft would have to be bombed up.
On a Mickey Finn exercise we were at our Boscombe Down dispersal when the bomb carrier was damaged and so a pantechnicon was despatched from somewhere in Kent complete with police escort and the bomb was returned by road. YS1 also required heating blankets to keep the temperature stable so the poor armourer who checked it every hour did not get much sleep. YS2, when it came along, was a much more user friendly way to end it all.

[Pontius Navigator]

Octane, no, Christmas Island. It was also Orange Herald that my uncle dropped. https://en.m.wikipedia.org/wiki/Operation_Grapple.

Green Grass, the YS1 warhead, was developed from OH.

Not Woomera which was rocket testing but Maralinga

https://en.m.wikipedia.org/wiki/Nuclear_weapons_tests_in_Australia

[ricardian]

Seen recently on FarceBook

https://scontent-lhr3-1.xx.fbcdn.net/v/t1.0-9/27971653_10155374132833157_2952059060297944509_n.jpg?oh=cc76 fa515e1c41d78127fb5dc6e4d985&oe=5B080DF3

[Vendee]

Love it :ok:

[NutLoose]

Haynes have missed "drop it" off the list for the Bruggen armourers.

[NutLoose]

Maralinga nuclear testing: Australia?s Hiroshima ? families speak out (http://www.news.com.au/lifestyle/real-life/news-life/the-secret-destruction-of-australias-hiroshima/news-story/9eabf722dbe2f87e03a297c2a348a8e1)

[glad rag]

Haynes have missed "drop it" off the list for the Bruggen armourers.

Well hmmm ok but a Laarbruch it was 1/1 with the snowfalls...

[Peter G-W]

I remember 27 Sqn dropped one in 1990.