With the experience gained from the HMA 23 class, the further enhancements were passed on to the new HMA 23X class ships.
Design and Construction
R.29 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 was 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 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 realised this and ultimately succeeded in convincing those with the ability to authorise 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 improved manoeuvrability.
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.
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 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.
Armstrong Witworth had been given the contract for the R29, and had originally produced the HMA 25. As the shed at their Barlow works was a double shed, they could begin construction on the R29 beside the partially completed HMA 25. By the time the No.25 had made its first flight at the end of 1917, the R29 was taking shape under construction next to it. The R29 took flight not long after, on 29th May 1918, and was delivered in June 1918 to East Fortune in Scotland.
Service Life
R.29 was the most successful British wartime rigid, being the only one to successfully 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.
She 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 the convoy was comprised of 34 ships alone.
U-Boat Challenge – UB 155
It is widely but incorrectly believed that 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.
On 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 signalled 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.
Then 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.
Although 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.
Final 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.
She 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.