With
the experience gained from the HMA 23 class, the further enhancements
were passed on to the new HMA 23X class ships.
The 23X class was a development
of the 23 class, itself often seen as merely an improvement to
the No 9 design, however there were some radical changes and lessons
learnt. Four of the class were originally planned, with numbers
running consecutively from R.27 to R.30, but following the downing
of the L-33 virtually intact, the British were able to re-think
the programme and R.30 were cancelled in order to concentrate
resources on the new R.33 class. R28 enjoyed a reprieve and it's
construction was transferred to Vickers, but then it was cancelled
to make way for Barnes Wallis' much more advanced R80 design.
R.27 its predecessors in that
minor modifications to the shape of the hull gave it slightly
more gas capacity, but more important was the elimination of the
external keel corridor. The function of this feature was to distribute
the weight of fuel tanks, ballast bags and similar items. Designers
and airship officers alike grew conservative afte the loss of
HMA No.1 due to hull failure, which was largely the result of
the removal of it's external keel in order to generate desperately
needed lift. As a result, there wa an insistence upon the retention
of external keels in the 23 class for safety. In reality, with
proper design, a heavy external keep was unnecessary. C.I.R. Campbell
realised this and untimatley succeeded in convincing those with
the ability to authorise his proposal that removal of the keep
could be safely accomplished in his 23X class proposal. It's absence
did result in a considerable saving of weight without causing
any significant loss of strength and aslo to improved manoeuvrability.
The various loads were concentrated at the bulkheads
The various loads were concentrated
at the bulkheads and suspended from the radial wiring which maintained
the hull in its correct polygonal shape. It is important to stress
that what Campbell accomplished with R27 and R29 was not just
the removal of an external keel, but the elimination of
the keel altogether. Only an internal corridor,
not an internal keel, was provided to allow the crew to travel
between the cars. This was never attempted with any other rigid
airship design.
Compare
the 23 Class with the 23X Class.
Graphic copyright N Regamey
An internal corridor which
allowed the crew to travel between the cars was formed by inverted
U-shaped ribs positioned above the two lowest longitudinal girders,
the surrounding gasbags being appropriately shaped. The corridor
also gave access to the ballast bags and petrol tanks. The latter
were interconnected by a long, wide aluminium tube running underneath
them, an arrangement which helped with refuelling and could be
used in an emergency to jettison fuel.
The four engines were again
Rolls Royce Eagle V12 designs, but they were the later Series
6 models, which produced 300 hp at full revolutions. The engine
arrangement was the same as that used originally for the 23 class
ships, with pairs of swivelling propellers in the forward and
after gondolas and twin engines driving fixed propellers in the
midship car. The radical and original decision to do without a
normal keel was fully vindicated when the first trials were held.
Not only were the two airships able to turn more quickly than
their forerunners, but the real benefit was found when the lift
and trim tests were held; the disposable lift was more than 8
1/2 tons, much better than any previous British airship and allowing
a more effective bomb load to be carried as well as sufficient
fuel for extended cruising. One handicap common to both ships,
as well as to their predecessors, was the absorbent nature of
the hull's outer covering of doped linen; a few hours of rain
could add around a ton of water to the weight.
Command
and commissioning
R.27 was commissioned on 29th
June 1918, under the command of Major P.Ommaney. She was immediatley
deployed upon anti-submarine patrol duties, completing fice flights
in two weeks. On August 12th she encountered a German U-boat and
bombed it, but it managed to escape (this incident has invariably
been confused with R29, which had another, more successful U-boat
experience). FN source. Unfortunately, R27 had a very brief career.
Howden
Fire and Final Life
On 16th August she was in
the hangar at Howden at the same time that some American riggers
were helpfully trying to make a new airship as a give to their
British hosts by attaching a spare SS Zero car to a disused envelope
(This airship has often erroneously been referred to as SSZ-23).
While they were completing the job some petrol was either spilt
into the ca or petrol fumes were ignited (both versions of the
cause have been documented)
This was in turn ignited a
little later by a spark when an unsuspecting operator came to
test the W/T (Wireless) equipment. The flames, fed by both fuel
and gas, expanded within seconds into a conflagration that totally
destroyed not only the makeshift blimp and R.27, but also SSZ.38
and SSZ.54, which had been moored nearby.
The envelope's of SSZ-62 and
SSZ-63 burned but their cars were not damaged at all. The hangar
itself survived, although with badly damaged roof. Several other
airships stationed at Howden that day survived, although most
were not in this shed. One airman who failed to get out in time
lost his life.
More
details can be found in our R 23 Exapanded research area
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