The R38 class (also known as the A class) of rigid airships was designed for Britain's Royal Navy during the final months of World War I, intended for long-range patrol duties over the North Sea. Four similar airships were originally ordered by the Admiralty, but orders for three of these (R39, R40 and R41) were cancelled after the armistice with Germany and R.38, the lead ship of the class was sold to the United States Navy in October 1919 before completion. On 23 August 1921, R-38 was destroyed by a structural failure while in flight over the city of Hull and crashed into the Humber estuary, killing 44 out of the 49 crew aboard.[2] At the time of her first flight she was the world's largest airship.[3]