S.S. ZERO
The original S.S. Zero was built at a south-coast station by Air Service labour, and to the design of three officers stationed there. The design of the car shows a radical departure from anything that had been previously attempted, and as a model an ordinary boat was taken. In shape it is as nearly streamline as is practicable, having a keel and ribs of wood with curved longitudinal members, the strut ends being housed in steel sockets. The whole frame is braced with piano wire set diagonally between the struts. The car is floored from end to end, and the sides are enclosed with 8-ply wood covered with fabric.
Accommodation is provided for a wireless telegraphy operator, who is also a gunner, his compartment being situated forward, amidships is the pilot and abaft this seat is a compartment for the engineer.
The engine selected was the 75 horse-power water-cooled Rolls Royce, it being considered to be the most efficient for the purpose. The engine is mounted upon bearers above the level of the top of the car, and drives a four-bladed pusher propeller.
The car is suspended from an envelope of 70,000 cubic feet capacity, and the system of rigging is similar to that in use on all S.S. ships. The petrol is carried in aluminium tanks slung on the axis of the envelope, identically with the system in use on the S.S.P's. The usual elevator planes are adopted with a single long rudder plane.
The speed of the Zero is about 45 miles per hour and the ship has a theoretical endurance of seventeen hours; but this has been largely exceeded in practice.
The original ship proved an immediate success, and a large number was shortly afterwards ordered.
As time went on the stations expanded and sub-stations were added, while the Zero airship was turned out as fast as it could be built, until upwards of seventy had been commissioned. The work these ships were capable of exceeded the most sanguine expectations. Owing to their greater stability in flight and longer hours of endurance, they flew in weather never previously attempted by the earlier ships. With experience gained it was shown that a large fleet of airships of comparatively small capacity is of far more value for an anti-submarine campaign than a lesser fleet of ships of infinitely greater capacity. The average length of patrol was eight hours, but some wonderful duration flights were accomplished in the summer of 1918, as the following figures will show. The record is held by S.S.Z. 39, with 50 hours 55 minutes; another is 30 hours 20 minutes; while three more vary from 25 1/2 hours to 26 1/4. Although small, the Zero airship has been one of the successes of the war, and we can claim proudly that she is entirely a British product.