NORTH SEA class
In 1917, the North Sea class (N.S.) entered service, and they would be the last of non-rigid type airships in the Royal Naval Air Service (RNAS). These blimps were developed to replace the previous classes and apply all the lessons learned until then. The required capabilities were that it should be able to conduct 24 hours patrols, carry a large reserve of fuel, enough space to accommodate two crews and have great reliability. This class was larger than Coastal class, its streamlined envelope had a gas capacity of 10,000 m3, was powered by two Rolls-Royce Eagle petrol engines of 250 hp each and had four fins in the rear side to command the ship. Initially the crew was housed in two enclosed cabins made of duralumin, suspended by wires under the envelope. In the front was the piloting post, communications area and resting area. The rear cabin or “engineer’s cabin”, housed the controls for the engines and a space that allowed cooking. In 1918 some improvements were made in the North Sea class, mainly in the control cabins, which were unified in a single unit. The engines were replaced by a 240 hp Fiat direct drive engines that greatly increasing its reliability. A total of 14 North Sea class airships were built, of which the NS-14 was sold to the US Navy at the end of 1918. The NS-7 was the last non-rigid airship in service with the RAF, performing more than 450 flight hours until October 25, 1921, when it was finally retired.
NORTH SEA class gallery and more info