differed from its predecessors in that minor modifications to
the shape of the hull had given them slightly more gas capacity,
but more important was the elimination of the external keel corridor.
The function of this feature wasw primarily to distribute the
weight of fuel tanks, ballast bags and similar items. Designers
and airship officers alike grew conservative after the loss of
HMA No. 1 due to hull failure, which was largely the result of
the removal of its external keel in order to generate desperately
needed lift. As a result, there was an insistence upon the retention
of external keels in the 23 class for safety. In reality, with
proper design, a heavy external keel was unnecessary. C.I.R. Campbell
realized this and ultimately succeeded in convincing those with
the ability to authorize his proposal that removal of the keel
could be safely accomplished in his 23X class proposal. Its absence
did effect a considerable saving of weight without causing any
significant loss of strength and also to improved manoeuvrability.
The various loads were concentrated at the bulkheads and suspended
from the radial wiring which maintained the hull in its correct
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. The corridor was formed
Compare the 23 Class with the 23X Class.
The corridor 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
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.
R.29 was the most successful British wartime rigid, being the
only one to succvessfully engage an enemy U-boat. She was commissioned
on 20th June 1918, based at East Fortune and in a brief operational
career of less than five months flew 335 hours and covered an
estimated 8,215 miles.
Once she carried out a patrol of over 30 hours, twice more she
made a flight longer than 20 hours.
conducted at least: twenty-eight anti-submarine patrols, nine
convoy escorts, one Grand Fleet patrol, two search missions, investigated
four possible U-boat sightings, successfully bombed and assisted
in the destruction of one German U-boat, observed, investigated
and reported seven different sightings of floating wreckage and
oil patches, escorted at least fourteen destroyers, engaged in
an unknown number of drogue trials, and made at least two photographic
test flights. The total number of ships she protected is unknown,
but it must have been considerable. For example, reference to
her escorting convoy OZ61 on October 13th reveals that convoy
was comprised of 34 ships alone.
is widely but incorrectly believed R29 engaged three German U-boats
based upon an error made by researcher Robin Higham. Her flight
records are complete and reveal no evidence that she ever pursued
a U-boat until it ran onto a mine, so it is quite unknown how
this claim originated. The belief that she attempted to bomb another
U-boat, but that it got away, is based upon a true incident that
occurred with her sister ship R27. R29 in fact only engaged one
U-boat, but this encounter was quite successful.
Sunday 29th September, at about half past one in the afternoon
and in exceptionally calm conditions, R.29, captained by Major
G. M. Thomas, was escorting a convoy bound for Scandinavia when
a faint patch of oil was seen discolouring the water near Newbiggin
Point. A message, "Oil patch rising below me," was signaled
by Aldis lamp to HMS Ouse, one of the escorting destroyers, which
turned at once to help. Her captain could not see the slight evidence
that was apparent to the airmen high overhead and he signalled
for more information, "Drop light over it." In reply
the airship indicated the probable whereabouts of the submarine
by dropping not a flare but a 230 lb bomb, the destroyer joining
in the attack with two depth charges as the first explosion subsided.
R.29 dropped a second bomb and a calcium flare to mark the position
of the oil patch, at which point another destroyer, HMS Star,
joined with Ouse and two armed trawlers to add more depth charges
to the barrage. At half past two, HMS Star reported considerable
quantities of oil rising to the surface. destroyers then steamed
off to continue protecting the convoy.
A buoy was placed as a marker by one of the trawlers and a deep
depth charge was dropped, while R.29 remained on watch for more
than an hour. When she at last left to rejoin the convoy at four
o'clock large amounts of oil were still bubbling to the surface.
It was subsequently confirmed from intelligence reports that UB.115
had been destroyed in the attack.
British non-rigids had several engagements with German U-boats,
this was the sole success recorded by any British wartime rigid..
If the R29 had not been present, the UB-115 probably would have
gone undetected and it could have destroyed several ships with
a concurrent loss of life.
After the Armistice R.29 flew another 16 hours before May 1919,
when her midship car was replaced by a smaller and lighter type
containing only one engine driving a single propeller. In this
modified form she flew a further 87 hours, including a flight
in June over Edinburgh, Berwick, May Island and the Firth of Forth,
when she was accompanied by R.34.
was finally deleted in October, 1919, having covered an estimated
11,334 miles in service, more than any other British rigid up
to that time.