The scientists at Aldermaston had not yet mastered the design of thermonuclear weapons. They produced a new design, called Round A. Another trial was scheduled, known as Grapple X. Round A was dropped on 8 November 1957. To save time and money, the target was off the southern tip of Christmas Island rather than off Malden Island, just from the airfield where 3,000 men were based. This time the yield of exceeded expectations. Round A was a true hydrogen bomb, but it used a relatively large quantity of expensive highly enriched uranium.