North Sea or N.S. airship was originally designed to act as a
substitute for the Rigid, which, in 1916, was still a long way
from being available for work of practical utility. From experience
gained at this time with airships of the Coastal type it was thought
possible to construct a large Non-Rigid capable of carrying out
flights of twenty-four hours' duration, with a speed of 55 to
60 knots, with sufficient accommodation for a double crew.
main requirements fall under four headings:
Capability to carry out flights of considerable duration.
The necessary lift to carry an ample supply of fuel.
Adequate arrangements to accommodate the crew in comfort.
these could be fulfilled the authorities were satisfied that ships
possessing these qualifications would be of value to the Fleet
and would prove efficient substitutes until rigid airships were
available. The North Sea, as may be gathered from its name, was
intended to operate on the east coasts of these islands.
first ship, when completed and put through her trials, was voted
a success, and the others building were rapidly pushed on with.
When several were finished and experience had been gained, after
long flights had been carried out, the North Sea airship suffered
a partial eclipse and people were inclined to reconsider their
favourable opinion. Thus it was that for many months the North
Sea airship was decidedly unpopular, and it was quite a common
matter to hear her described as a complete failure. The main cause
of the prejudice was the unsatisfactory design of the propelling
machinery, which it will be see,, later was modified altogether,
and coupled with other improvements turned a ship of doubtful
value into one that can only be commended.
envelope is of 360,000 cubic feet capacity, and is designed on
the Astra-Torres principle for the same reasons as held good in
the cases of the Coastal and C Star. All the improvements which
had been suggested by the ships of that class were incorporated
in the new design, which was of streamline shape throughout, and
looked at in elevation resembled in shape that of the S.S. airship.
Six ballonets are fitted, of which the total capacity is 128,000
cubic feet, equivalent to 35.5 per cent of the total volume. They
are fitted with crabpots and non-return valves in the usual manner.
rigging is of the Astra-Torres system, and in no way differs from
that explained in the previous chapter. Nine fans of the internal
rigging support the main suspensions of the car, while similar
fans both fore and aft provide attachment for the handling
guys. Auxiliary fans on the same principle support the petrol
tanks and ballast bag.
gas and six air valves in all are fitted, all of which are automatic.
ripping panels are embodied in the top lobe of the envelope.
N.S. ship carries four fins, to three of which are attached the
elevator and rudder flaps. The fourth, the top fin, is merely
for stabilizing purposes, the other three being identical in design,
and are fitted with the ordinary system of wiring and kingposts
to prevent warping.
petrol was originally carried in aluminium tanks disposed above
the top ridges of the envelope, but this system was abandoned
owing to the aluminium supply pipes becoming fractured as the
envelope changed shape at different pressures. They were then
placed inside the envelope, and this rearrangement has given every
the envelope of the N.S. is rigged a long covered-in car. The
framework of this is built up of light steel tubes, the rectangular
transverse frames of which are connected by longitudinal tubes,
the whole structure being braced by diagonal wires. The car, which
tapers towards the stern, has a length of 85 feet, with a height
of 6 feet. The forward portion is covered with duralumin sheeting,
and the remainder with fabric laced to the framework. Windows
and portholes afford the crew both light and space to see all
that is required. In the forward portion of the car are disposed
all the controls and navigating instruments, together with engine-telegraphs
and voice pipes. Aft is the wireless telegraphy cabin and sleeping
accommodation for the crew.
complete electrical installation is carried of two dynamos and
batteries for lights, signalling lamps, telephones, etc. The engines
are mounted in a power unit structure separate from the car and
reached by a wooden gangway supported by wire cables. This structure
consists of two V-shaped frameworks connected by a central frame
and by an under-structure to which floats are attached. The mechanics'
compartment is built upon the central frame, and the engine controls
are operated from this cabin.
the original power units two 250 horse-power Rolls Royce engines
were fitted, driving propellers on independent shafts through
an elaborate system of transmission. This proved to be a great
source of weakness, as continual trouble was experienced with
this method, and a fracture sooner or later occurred at the universal
joint nearest to the propeller. When the modified form of ship
was built the whole system of transmission was changed, and the
propellers were fitted directly on to the engine crankshafts.
a later date 240 horse-power Fiat engines were installed, and
the engineers' cabin was modified and an auxiliary blower was
fitted to supply air to the ballonets for use if the engines are
the N.S. ship as modified the car has been raised to the same
level as the engineers' cabin, and all excrescences on the envelope
were placed inside. This, added to the improvement effected by
the abolition of the transmission shafts, increased the reliability
and speed of the ship, and also caused a reduction in weight.
leading dimensions of the ship are as follows: length, 262 feet;
width, 56 feet 9 inches; height, 69 feet 3 inches. The gross lift
is 24,300 lb.; the disposable lift, without crew, petrol, oil,
and ballast, 8,500 lb. The normal crew carried when on patrol
is ten, which includes officers.
in the case of the Coastal, a gun is mounted on the top of the
envelope, which is approached by a similar climbing shaft, and
guns and bombs are carried on the car.
ships have become notorious for breaking all flying records for
non-rigid airships. Even the first ship of the class, despite
the unsatisfactory power units, so long ago as in the summer of
1917 completed a flight of 49 hours 22 minutes, which at the time
was the record flight of any British airship. Since that date
numerous flights of quite unprecedented duration have been achieved,
one of 61 1/2 hours being particularly noteworthy, and those of
upwards of 30 hours have become quite commonplace.
the Armistice one of these ships completed the unparalleled total
of 101 hours, which at that date was the world's record flight,
and afforded considerable evidence as to the utility of the non-rigid
type for overseas patrol, and even opens up the possibility of
employing ships of similar or slightly greater dimensions for
6 appeared several times over London in the summer months of 1918,
and one could not help being struck by the ease with which she
was steered and her power to remain almost stationary over such
a small area as Trafalgar Square for a quite considerable period.
flights referred to above were not in any way stunt performances
to pile up a handsome aggregate of hours, but were the ordinary
flying routine of the station to which the ships were attached,
and most of the hours were spent in escorting convoys and hunting
for submarines. In addition to these duties, manoeuvres were carried
out on occasions with the Fleet or units thereof.
the foregoing observations it must be manifest that this type
of ship, in its present modified state, is a signal success, and
is probably the best large non-rigid airship that has been produced
in any country.
ships departed from the use of aeroplane technology for the gondolas
and their own design and layout was created. There were two main
one for the engine, and one for the Command Cabin. These were
often joined together by a small walkway slung below the tri-lobe
envelope. The enclosed control cabins enabled the airships to
have a longer endurance as it gave the crews some comfort, with
sleeping quarters and cooking facilities. The kitchen
cooking facilities were heated by the exhaust gasses, piped through
from the engines.
of the most famous NS class ships were NS7 & NS8. Both of
these ships were based at Rosyth in Scotland and at the end of
the war, they escorted the surrendered German fleet back to Rosyth