Date: 19:37 UTC 15/05/1957
Type: Air drop @2400 m
Short Granite was dropped by a Valiant B1 bomber piloted by Wing Commander K. Hubbard. Detonated after 52 sec of free fall. This was Britain's first test of a radiation implosion thermonuclear bomb design. The device, named Green Granite Small, weighed 10,000 lb and used a modified Red Beard primary (called "Tom") and a lead-encased lithium deuteride secondary (called "Dick"). Most of the yield was from the secondary, providing evidence of successful radiation implosion, but the yield was far below the predicted value (about 1 megaton was expected).