Following the trials and design
success of HMA No. 9, it was agreed that the Zeppelin threat had
to be tackled head on; the Admiralty required more ships. There
were initial problems at the Admiralty with regards to change
of staff and also general opinion regarding rigid airships, as
the successful non-rigid programme was expanding rapidly. However
in June of 1915, along with the Vickers Company, three new contractors
were selected to produce rigid ships.
The three new contractors
were Beardmore, Armstrong and Whitworth and finally Shorts Brothers.
All three companies were to become famous in the world of aviation.
By October 1915 the drawings were approved and three ships were
ordered. By December the pace of design and the requirement for
big ships had increased dramatically and a further sixteen ships
had been budgeted for by the Admiralty. All of these ships were
to become known as the 23 Class, which were in effect stretched
versions of the original No. 9. The designs were seen in essence
as modified versions of No.9, with an extra bay inserted in the
middle of the ship. A gun platform was added to the top of the
ship designed to take a two pound gun and two Lewis machine guns.
The platform was surrounded by 18 inch sanctions carrying lifelines.
These sanctions could be extended to double the height in order
to carry a canvas windscreen. Three other Lewis guns were to be
fitted at the extreme tail, in the control car further aft and
on the top walking way.
The bomb load was to be greater than that of HMA 9 but none was
actually specified. The ships each possessed an external keel,
to the same pattern as the No. 9. The cabin being 45 feet long
contain crew accommodation, a wireless room and a bomb room. From
the keel further aft were three gondolas which were suspended
below and accessible by open ladders.
The ship gondolas also contained
airtight buoyancy bags in case the ships had to alight on water.
This was a technical requirement of all ships since HMA 1 - the
Mayfly. With this rapid expansion of the requirement for airship
production, there were a few problems in that so far, only one
company had actually built a ship and hence had all the facilities.
In April 1916
the Government approved for a total fleet of 10, 23 class ships,
but this was later modified in the light of further design technology
available from Germany. The later ships becoming the R23X class
and the R31 class.
HMA 23 was the first to be completed, and hence the designation
of the class of ships. There were a number of delays in the initial
constructions and the ship was completed on 26th August 1917.
This led to the order of the R26 as Vickers had the space available
to build the ship. On lift and trim trials, the HMA 23 was found
to have a disposable lift of only 5.7 tons due to the machinery
being two tons heavier than originally estimated. Five weeks later
the HMA 25 was completed and her tests gave almost identical results.
Although not unexpected, the figures were disappointing and 2
weeks later on the 18th October the Admiralty decided that the
design must be altered. On the day of the decision the HMA 24
was also tested and found to be mysteriously two thirds of a ton
heavier than her sister ships, with a lift of only 5.1 tons. The
alterations to the ships included the removal of dynamos and bomb
frames and many other items which were deemed not necessary were
ordered that modifications be carried out at once to R.26, which
was still in the early stages of construction, while the other
three ships were to be modified similarly but, of necessity, over
a longer period and slightly less drastically. The measures to
be undertaken were aimed at lightening the airships by the elimination
of all unnecessary weight. In addition to removal of the dynamos,
buffer wheels and bomb frames, many other small items not considered
essential were either taken out or replaced with lighter equipment.
The folding tables which had been intended for the keel cabin
were never installed and the original plan of fitting a two-pounder
gun on the top platform was also discarded. The rear car was replaced
by a smaller and lighter one containing an engine with direct
drive to a single two-bladed propeller 13 feet 6 inches in diameter.
As there was now no space for the auxiliary controls, these were
transferred to the keel cabin.
Some of these modifications had already been carried out on the
first three ships, while others followed in due course. Together
they effected a marked, if not substantial, improvement to the
R.26, on which
Vickers could not begin work until No 9 had left Barrow, arrived
much later. All the recommended modifications were incorporated
in the course of her construction. Although built more quickly
than the others, in only about a year, she did not fly until March
The last of the class was R.26. (The Admiralty decided on 18th
December 1917, that all future rigid airships should have the
prefix R before their number.) Apparently the only one of her
class to incorporate all the design changes, she was commissioned
on 22nd April 1918, and stationed at Howden. During tests she
was found to have a disposable lift of 6 1/4 tons, a top speed
of 54 mph and a ceiling of 3,500 feet. It was also discovered
that if the engines were stopped at 53 mph the speed fell to 18
mph in two minutes, so great was the drag. By the end of the year
she had flown 191 hours and 29 minutes, of which the highlights
were a flight with No 23 over London on 25th October and a patrol
of 40 hours 40 minutes on 4th/5th June, when she was commanded
by Major T . This was the longest flight yet by a British rigid,
beating No 23's previous record, set up a few days earlier, by
32 minutes. Later in the year she was transferred to Pulham and,
commanded by Major Watt, she supervised the surrender of German
submarines at Harwich on 20th November 1918.
In January 1919,
R.26 flew a further 6 hours 18 minutes, and then had her bows
specially strengthened before being experimentally moored out
in the open, using the "three wire system". She had
a tendency to assume a tail up attitude, But this was overcome
by fastening sandbags to the after guys, and she survived for
over a week without harm. Then the weather worsened, rain soaked
her envelope and a snowstorm finally beat her into the ground.
Her cars were removed, allowing her to float again, but it was
soon found that the damage she had sustained was too severe for
repairs to be worthwhile. On 24th February the order was given
for her to be scrapped and her official deletion followed on 10th
the success of HMA No. 9, further ships were ordered by the
Admiralty. Along with the Vickers Company, three new contractors
were required to produce rigid ships. The Vickers Company had
already proven themselves with the design and construction of
No. 9 and were the only company with any experience of building
a large ship.