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R 27 (HMA 23X Class)

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 hence R.28 and R.30 were cancelled in order to concentrate resources on the new R.33 class.

Statistics:
Length 539ft
Diameter 53ft
Speed 57mph
Engines 4 x 300hp
Volume 990, 000cft


R.27 differed from their 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, and only secondarily to strengthen the hull, so its absence in the two 23X ships was intended to effect a considerable saving of weight without causing any significant loss of strength and also to improve manoeuvrability. The various loads were concentrated at the bulkheads and suspended from the radial wiring which maintained the hull in its correct polygonal shape.


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.


R.27 was commissioned on 29th June 1918, and flew 89 hours 40 minutes in service commanded by Major Ommaney before coming to a disastrous end.

On 16th August she was in the hangar at Howden at the same time that some riggers were helpfully trying to make a new airship by attaching a spare SS Zero car to a disused envelope. While they were completing the job some petrol was spilt into the car; it was not mopped up. The spilt petrol was ignited a little later by a spark when an unsuspecting operator came to test the WIT 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 hangar itself survived, although badly damaged. One airman who failed to get out in time lost his life.

 

 

 

Shown here is the R27 in Howden shed with 3 Coastal class ships before the fire.


 


Related ships: HMA 1, HMA 9, HMA 23, Airship Movie Page

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