Yellow Sun (nuclear weapon)
| Yellow Sun | |
|---|---|
 A Yellow Sun at the Royal Air Force Museum Cosford (2011)
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| Type | Nuclear weapon |
| Place of origin | United Kingdom |
| Specifications | |
| Weight | 7,250 pounds (3,290 kg) |
| Length | 21 feet (6.4 m) |
| Diameter | 4 feet (1.2 m) |
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| Filling |
Uranium – Green Grass warhead |
| Blast yield |
400 kt (1,700 TJ) Green Grass warhead |
Uranium – Green Grass warhead
400 kt (1,700 TJ) Green Grass warhead
Yellow Sun was the first British operational high-yield strategic nuclear weapon. The name actually refers only to the outer casing; the warhead (or physics package) was known as "Green Grass" (in Yellow Sun Mk.1) and "Red Snow" (in Yellow Sun Mk.2). The ENI or electronic neutron initiator (generator) was Blue Stone.
The casing was some 21 feet (6.4 m) long, 48 inches (1.2 m) in diameter. The Mark 1 version with the Green Grass warhead weighed 7,250 pounds (3,290 kg). The Mk.2 version with the lighter 1,700 pounds (770 kg) Red Snow warhead had ballast added to maintain overall weight, ballistic and aerodynamic properties, and avoid further lengthy and expensive testing, and changes to the electrical power generating and airburst fuze.
Unlike contemporary U.S. bombs of similar destructive power, Yellow Sun did not deploy a parachute to retard its fall. Instead it had a completely flat nose which induced drag, thereby slowing the fall of the weapon sufficiently to permit the bomber to escape the danger zone. Additionally, the blunt nose ensured that Yellow Sun did not encounter the transonic/supersonic shock waves which had caused much difficulty with barometric fuzing gates which had plagued an earlier weapon, Blue Danube.
Electrical power was supplied by duplicated ram-air turbines located behind the twin air intakes in the flat nose. The earlier Blue Danube design had relied on lead–acid batteries which had proven to be both unreliable and to require time-consuming pre-flight warming.
Yellow Sun Stage 1 and Stage 2 were the original designations. Stage 1 was intended as an interim design to carry a one megaton Green Bamboo warhead of the "layer-cake" type thought similar to the Soviet JOE.4 and the US "Alarm Clock" concepts. These hybrid designs are not now regarded as truly thermonuclear, but were then thought to be a stepping-stone on the route to a fusion bomb. Stage 2 was to follow when a true thermonuclear warhead based on the Granite design became available.
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Wikipedia