erimental stage, is being persevered with, and the
intention is that it will gradually supplant the other S.S. classes.
It is calculated that it will equal if not surpass the C Star ship in
endurance, besides being easier to handle and certainly cheaper to
build.

"COASTAL" AND "C STAR" AIRSHIPS

The urgent need for a non-rigid airship to carry out anti-submarine
patrol having been satisfied for the time with the production of the
S.S. B.E. 2C type, the airship designers of the Royal Naval Air Service
turned their attention to the production of an airship which would have
greater lift and speed than the S.S. type, and, consequently, an
augmented radius of action, together with a higher degree of
reliability. As the name "Coastal" or "Coast Patrol" implies, this
ship was intended to carry out extended sea patrols.

To obtain these main requirements the capacity of the envelope for this
type was fixed at 170,000 cubic feet, as compared with the 60,000 cubic
feet and, later, the 70,000 cubic feet envelopes adopted for the S.S.
ships. Greater speed was aimed at by fitting two engines of 150
horse-power each, and it was hoped that the chances of loss owing to
engine failure would be considerably minimized.

The Astra-Torres type of envelope, with its system of internal rigging,
was selected for this class of airship; in the original ship the
envelope used was that manufactured by the French Astra-Torres Company,
and to which it had been intended to rig a small enclosed car. The
ship in question was to be known as No. 10. This plan was, however,
departed from, and the car was subsequently rigged to the envelope of
the Eta, and a special car was designed and constructed for the
original Coastal. Coastal airship No. 1 was commissioned towards the
end of 1915 and was retained solely for experimental and training
purposes. Approximately thirty of these airships were constructed
during the year 1916, and were allocated to the various stations for
patrol duties.

The work carried out by these ships during the two and a half years in
which they were in commission, is worthy of the highest commendation.
Before the advent of later and more reliable ships, the bulk of
anti-submarine patrol on the east coast and south-west coast of England
was maintained by the Coastal. On the east coast, with the prevailing
westerly and south-westerly winds, these airships had many long and
arduous voyages on their return from patrol, a