(2x 5 man watches)
250hp (Rolls Royce Eagle)
later changed to 260hp
Fiat A12 Six Cylinder
230lb (100kg) bombs on racks
5 machine guns, one mounted on a gun platform on t her top
of the envelope
Designed as a long duration
patrol airship, the North Sea class airship was the largest non-rigid
built by Great Britain during WW1. The North Sea or N.S. class
airship was originally designed to act as a substitute for the
rigid airships, 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.
The requirements for the specification
of the new type of ship fell 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.
If 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 the British Isles and main bases sited therefrom.
The Admiratly signed off the developement specification and construction
was approved on January 1916 of six of the new North Sea class
ship was undetaken at the RNAS Kingsnorth
Airship Station on the north Kent coast, in the river Thames
estruary and was the largest non-rigid designed in Britain up
to that time.
There was at first some discussion
as to whether the the Astra Torres or the Parseval type of envelope
would be the better, but the principles behind the design of the
latter, were not fully understood in this country. Copies could
be and had been made, but any enlargements or modificatrions would
require a re-design of the trajectory rigging bands which were
a feature on the German airship. This was a dangerous undertaking
and, so the Astra Torres pattern which had been adapted without
trouble for the Coastal ships, was again chosen
The form used for the new
design was not only larger than before, but more streamlined,
looking quite similar in outline to the earlier and smaller Submarine
Scout or SS class of ships.
The first ship, designated
N.S.1 was assembled and tested at RNAS Kingnorth and undertook
her first trial flight on 1st February 1917. The trials were voted
a success, and the other five ships construction were rapidly
continued 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 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.
The envelope of 360,000 cubic
feet capacity, and 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 were fitted with crabpots
and non-return valves in the usual manner.
The rigging is of the Astra-Torres
system, and in no way differs from that on the earlier Coastal
class ships. 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.
- Four gas and six air
valves in all are fitted, all of which are automatic.
- Two ripping panels are
embodied in the top lobe of the envelope.
The N.S. ship carries four
fins, to three of which are attached the elevator and rudder flaps.
The fourth, the top fin, is smaller and for stabilizing purposes,
the other three being identical in design, and are fitted with
the ordinary system of wiring and kingposts to prevent warping.
The 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 satisfaction.
These ships departed from
the use of aeroplane technology for the gondolas and their
own design and layout was created. There were two main cars, 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.
Stung below the envelope of
the N.S. the Control car is a long fabric 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 of the
control car was covered with duralumin sheeting, and the remainder
covered with fabric laced to the framework. The front windows
and in the rear, side portholes afford the crew both light and
space to see all that is required. In the forward portion of the
car are all the controls and navigating instruments, together
with engine-telegraphs and voice pipes linking the to the engine
car and upper gun platform. Aft is the wireless telegraphy cabin
and sleeping accommodation for the crew.
A complete electrical installation
was provided on board by two dynamos and batteries for lights,
signalling lamps and telephones. The engines were mounted in a
power unit structure separate from the car and reached by a rather
precarious wooden gangway supported by wire cables. This structure
consisted of two V-shaped frameworks connected by a central frame
and by an under-structure to which floats are attached. The mechanics'
compartment was built upon the central frame, and the engine controls
operated from this cabin.
In 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. Later,
when a modified form of ship was built the whole system of transmission
was changed, and the propellers were fitted directly on to the
engine crankshafts. Th problems with the Rolls Royce engines later
gave the decision that these be replaced by 260 horse-power Fiat
engines, and the engineers' cabin was modified and an auxiliary
blower was fitted to supply air to the ballonets for use if the
engines are not running to maintain the shape of the envelope.
The Crew Organisation
The normal crew comprised
two watches of five necessary for extended patrols
and consisted of a Captain and Second Officer, a Coxswain and
Second coxswain, two W/T (Wireless Telegraph) Operators, two Engineers
and two Air Gunners. The Captain was in overall command of the
vessel, and was assisted by the Second Officer in navigating,
maintaining height, and regulating gas pressure. The "Air
Gunners" main task was to act a look-outs whilst on patrol.
There was always on Lewis gun mounted on the rear of the ar that
could be used for attacks on submarines or for sinking mines.
The Air Gunners also acted as cooks and could fry or heat stew
in a pot or pan headted by the exhaust gasses from the engines.
The Coxswain was responsible
for the rest of the crew, and for the care and maintenance of
the ship whilst on the ground. He or the Second Coxswain steered
the vessel in flight from a position at the very front of the
control car. During patrols, the Air Gunners took on the duties
of look-outs and also acted as cooks
The 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. As
with the case of the Coastal class airship, a gun was mounted
on the top of the envelope, which is approached by a similar climbing
shaft, and guns and bombs are carried on the car.
The NS class ships became
notorious for breaking all flying records for non-rigid airships.
Even the first ship of the class, despite the unsatisfactory power
units, 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
After the Armistice the NS
11 had completed an unparalleled flight of some 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 commercial
N.S. 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.
The flights were not in any
way stunt performances to pile up a large aggregate of hours to
prove the ability of the larger class of ship or the success of
an airship, 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.
From 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.
Of the fifteen ships, 7 were
allocated at some time in their service life to RNAS
East Fortune to assist in patrolling the North Sea.
Two of the most famous NS
class ships were NS.7 & NS.8. 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. The NS 7 had onle
of the longest careers of the NS Class spanning from May 1918
and speninf most of her working life based at East Fortune Airship
base in Scotland, and then her final days at Howden in Yorkshire.
The NS.7 final flight was on 25th Octoer 1921. The NS.7, under
the command of Captain H. C. Irwin, who was later to command the
R 101, undertook towing and landing trials wth H.M.S. Furious,
and was land the N.S.7 on the deck of the aircraft carrier on
7th July 1919.
The record Breaker and Tragedy
NS11 was the eleventh North
Sea class airships ordered by the Royal Navy for the Royal Naval
Air Service, but by the time NS11 was delivered in September 1918,
the Royal Naval Air Service had been amalgamated with the Royal
Flying Corps to form the RAF.
As with all of the North Sea Class ships, the the airship was
built and tested at RNAS Kingsnorth. Prior to the accident, she
had made voyages of more than 1000 miles (1600 km) over the North
Sea, setting a world record for non-rigid airships. On 9th February
1919, was based at the RNAS
Longside the N.S.11 left the ground at 14:00 with a crew of
9, and Captain W. K.F.G Warneford in command. The ship flew out
over and undertool a patrol reaching up to the Ornkney Islands,
and across the Moray Firth, undertaking photography of the captured
German Fleet, then down past East Fortune and Berwick then around
the Norhumberland Cost.
Captain Warnefoot reported:
the flight no trouble of any kind whatsoever was experienced,
except one slight defect in the engines, and on coming down, the
rudder and elevator controls were examined and not a trace of
wear was found anywhere, despite the fact that one rudder control
had been in for about 150 hour flying previous this, including
the flight of 61 hours.
It is considered
that it would be impossible to get a ship to be more reliable,
as from the time she was commissioned (September 1918) to the
present date there have been no replacements of an kind except
elevator and rudder controls.
gave no trouble at all, except the magneto drive stripped on the
starboard engine. New parts were picked up from East Fortune and
replaced the port engine has now run 350 hours and given no trouble
of any kind.
The N.S. 11 returned to base
on 13th February and landed at 18:50 with a total duration of
the flight of 100 hours and 50 minutes, covering some 2,300 miles,
equivalent to an astounding duration of just over 4 days in the
air. The Captains' report gave a condition of the 9 crew members
on board and concluded that:
crew were in no way fatigued, except for the 1st Engineer who
had to perform a great deal of heavy work, such as starting up
the engines, etc. When he had started up one engine single handed,
he was so fatigued that he collapsed and fell off the rail, but
fortunately, he was caught by a piece of 5cwt wire between the
rolling guys and recovered himself."
This single flight of the
N.S. 11 broke the previous record of 61 hours, or two and a half
days, performed by the same ship and personnel,
11 Final Flight
NS11 had taken off from RAF
Pulham Airshp Station in Pulham St Mary, Norfolk, around midnight
on the night of 14 July 1919 and was heading over the North Sea
on a mine-hunting patrol. In the early hours of 15 July, she was
seen to fly beneath a long "greasy black cloud" off
the village of Cley next the Sea on the Norfolk coast when locals
reported an abnormal noise from her engines (which may have suggested
she was experiencing engine trouble).
She was returning towards
the coast and reportidly some 5 miles off the coast of Cromer
in Norfolk, when she exploded into a ball of flames, causing a
vivid glare lasting for several minutes as the burning airship
descended, plunging into the sea after a second explosion. At
approximately 01.45 a massive explosion was heard out to sea,
carrying as far as Holt, and along the coast the Wells and Cromer.
Eyewitnesses report " Mr Stangrooms bedroom lit
up bright as day, as did those of the Greens and the
Kayes at Blakeney". The glare lasted for a few minutes,
and then a maroon flare was let off, calling out the Cley Lifesaving
Rocket Brigade. As the streets of Blakeney filled with people,
Mr Green roused his father, who was coxwain of the Blakeney lifeboat.
They estimated the wreckage
to be five or six miles offshore, and ran to the quay to summon
fellow lifeboatmen; but it was low water, and they discovered
the lifeboat was stranded high and dry. The officers at
RNAS Pulham Airship Station were unaware of the disaster until
someone from the Eastern Daily Press office in Norwich telephoned
to see if there was any comment about the explosion.
None of the nine crew members
on board the airship survived. The Sheringham lifeboat was launched
but its crew could only find a small part of the aluminium wreckage.
Tragecally, all nince crew members were lost.
The accident occurred less
than 48 hours after the airship R34 arrived at RAF Pulham after
a successful double-crossing of the Atlantic Ocean, including
the first-ever east-west crossing by air.
The findings of the official
Court of Enquiry were inconclusive, but amongst other possibilities
it was thought that a lightning strike may have caused the explosion
Nothing more had been found
by the time that seven minesweepers dropped anchor off Cromer
pier on the Friday night in readiness for dragging operations.
Divers were present in case any large parts of the airship were
information please see our N.S.
11 Special Edition Dirigible Magazine (Summer 1994)
more requirements put on the Airship Service to provide more
aerial cover for shipping, the final designs of the non-rigid
culminated with the most efficient ships, the North Sea Class.
The US - North Sea Ship
One North Sea Class ship was destined for use in America. The
Aircraft Record card is for NS 14, built at Kingsnorth in late
1918 with Wheelwright modified cars.
She made flying trials on 14 December, 1918, and was then deflated
and shipped to the USA. Her subsequent history is a bit hazy but
this is what we have researched:
Packed up and shipped to America for
US Navy, 22 April, 1919.
Given Navy Bureau serial number A5580.
Sent to Wingfoot Lake N A S, Suffield, Ohio, for evaluation.Arrived
on 17 May. Not inflated.On 13 December, transferred to Hampton
Roads, Norfolk, Virginia.
Arrived on 30 January, 1920.
Subsequent US Navy history unknown.
Turned over to US Army 22 September, 1925.
Stricken from the Navy List 28 January, 1926.
So far no records have come to light to determine whether this
ship was ever inflated and flown in the United States. We would
be interested to know if NS 14 was ever flown in the US and if
you have any information on this then please contact