| HMA No. 1 "Mayfly" | |
|---|---|
| Mayfly at her mooring, Barrow-in-Furness (September 1911) |
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| Role | Aerial scout airship |
| National origin | United Kingdom |
| Manufacturer | Vickers |
| Designer | C. G. Robertson Lieutenant N. F. Usborne |
| First flight | Never flown |
| Status | Abandoned project; airship wrecked by winds on 24 September 1911 |
| Primary user | Royal Navy |
His Majesty's Airship No. 1, more commonly known as the Mayfly, was designed and built by Vickers, Sons and Maxim at their works in Barrow-in-Furness, Cumbria, England, as an aerial scout airship for the British Royal Navy. She was the first British rigid airship to be built, and was constructed in a direct attempt to compete with the German airship programme. When she was moved from her shed in Cavendish Dock to conduct full trials on 24 September 1911, she broke in two as a result of being subject to strong winds before she could attempt her first flight. Although Mayfly never flew, her brief career provided valuable training and experimental data for British airship crews and designers.[1]
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In July 1908, Captain Reginald Bacon, the Royal Navy's Director of Naval Ordnance, recommended that the Navy should acquire an airship that would compete with the success of the early German rigid airships designed by Count Ferdinand von Zeppelin.[2] The British Government agreed that a sum of £35,000 "should be allocated to the Admiralty for the building of a dirigible balloon",[1] and in March 1909 the armament firm of Vickers, Sons and Maxim advised that they could construct the ship for £28,000 (without goldbeater's skin gas-bags and varnished skin outer cover for which the Admiralty would be required to provide contractors), and that they would erect a constructional shed at their own expense in return for a 10-year monopoly on airship construction, similar to the submarine agreement they already had with the Crown. The contract was awarded to Vickers on 7 May 1909, with design responsibility divided between Lieutenant N. F. Usborne at the Admiralty and C. G. Robertson of Vickers; however, the 10-year monopoly clause was refused.[1][2]
Zeppelins of the time could fly 100 mi (160 km), carry a crew of 26, and reach an altitude of 5,400 ft (1,600 m) with an endurance of 12 hours; however, the Vickers design, designated HMA (His Majesty's Airship) No. 1 and known as the Mayfly, was intended to be moorable on water, carry wireless equipment, be capable of 40 kn (46 mph; 74 km/h) for 24 hours, have a ceiling of 1,500 ft (460 m), and carry a crew of 20 in comfort. The mooring was to be to a mast, a practise which the British were the first to adopt as standard, and Mayfly was the first of the rigid airships to be fitted with the mooring equipment in the nose of the ship.[1]
Mayfly was originally intended to be an aerial scout, and was designed along similar lines to the very early Zeppelins, but with some major modifications. She was 66 ft (20 m) longer than her German contemporary, LZ-6, and had a 50% greater volume. This gave her a correspondingly greater lift than LZ-6, and weight savings were achieved through the use of duralumin (a German product which Vickers had access to the patents for, but the Germans would not use until 1914) in Mayfly's construction rather than aluminium,[1] Mayfly being the first rigid airship to do so. She had an impervious outer cover, a simplified cruciform tail,[2] and with a head resistance of just 40% by comparison her shape was more streamlined than the contemporary Zeppelins, as well as the No. 9, 23 or 23X class which were to follow. An even more streamlined shape had been suggested for Mayfly, but it was rejected by the Admiralty, and it was not until 1917/18 that a truly streamlined ship was constructed; the R80.[1]
Propulsion was provided by two Wolseley 160 hp marine racing engines, each housed in a watertight hand-crafted mahogany engine car, one forward and one aft. Each engine drove a pair of 15 ft (4.6 m) diameter wooden propellers, mounted on either side of the gondolas, rotating at half engine speed.[1]
The construction shed (which doubled as a hangar) was designed by Vickers and built from the wall of Cavendish Dock at their "Naval Construction Yard" in Barrow, out to piles driven into the basin floor. It contained a float on which construction of the airship took place and which could be taken out of the shed together with the airship. Beginning in 1909, the work was due to be completed in August that year and the ship delivered two months later, but in June trouble occurred with driving the piles into the floor of the dock. Consequently, the shed was not completed until June 1910, at which point the actual construction of HMA No. 1 could begin. A screen was erected in the dock together with a newly designed 38 ft (12 m)-high floating mooring mast that was capable of withstanding a steady pull of 80 tons (70 tonnes). A large safety margin had been allowed – the maximum load the ship would exert on the mast was calculated to be approximately 4 tons (4 tonnes) in a wind of 80 mph (130 km/h).[1]
In preparation for the completion of Mayfly, crew training commenced on 25 February 1910, covering important skills such as working the rubber fabric 9carried out at Messrs Short Brothers works, Battersea, London), instructions in petrol engines at Vickers works, signals, instruction in aeronautics and meteorology.[1]
An entry in Handbook for HMA No. 1 noted that:[1]
"Two crews were used to look after the ship whilst out, as the work was new. They lived on board the airship and suffered no discomfort at all although no provision had been made for cooking or smoking on board. At night the temperature of the living space was a little above that of the outside air, but as the ship proved quite free from draughts in the keel and the cabin, it was anticipated that with suitable clothing, no trouble would be experienced from the cold."
The Admiralty's officer responsible for the design of HMA No. 1, Lieutenant N. F. Usborne, was selected as her Captain following the comments made by the Inspecting Captain of Airships, Captain Murray Sueter who said, "Lieutenant Usborne has conducted himself to my entire satisfaction. A very zealous and capable officer, he has worked hard in making himself an expert in aeronautical work. I strongly recommended him for promotion."[3]
Commander Edward Masterman, Officer Commanding, Naval Airship Section wrote, "It is no exaggeration to say that his [Usborne's] was the outstanding personality in the project. Nothing was decided without his advice and few things undertaken of which he disapproved. His was the knowledge, slight though it now appears, for undertaking the construction of a rigid airship larger than any existing, it was his brain and his drive which set matters going in the progress of this great experiment. He was the expert and revelled in so being."[3]
Throughout construction the Admiralty expressed their doubts about airships. The constructors modified the design even as it was built in order to meet specifications and when it appreared that the airship would be too heavy removed some of the structure to lighten her. This included the main keel. One of Vickers draughtsmen calculated this would cause her to break up.[4]
The finished Mayfly was the largest airship yet constructed.
Static trials commenced within the shed on 13 February 1911 when Mayfly's motors were run and her controls operated, but outdoor trials could not be conducted until the weather moderated and it was not until March that the crew were reported ready for launching.[1]
On Monday 22 May 1911, Mayfly was towed stern first from her very narrow shed for handling and mooring trials by boats attached by lines to her sides, then gradually swung out of Cavendish Dock and attached to the mooring mast. Whilst there, nine officers remained on board (having quarters in the keel and telephone communication between the cars) to conduct engine trials, but these were cut short due to radiator problems. On the following day she was subject to winds of 45 mph (72 km/h), and during the two nights she was out of the shed, searchlights were played across her so that her motions could be observed. Mayfly showed no signs of rising and it was discovered from calculations that she was too heavy, and that the removal of fixtures weighing some three tons would be necessary to enable her to become airborne.[1] It was decided to return her to the shed where the external keel, the anchor, and many other items were removed.[3] Consequently, she floated for approximately five hours with both gondolas around 4 ft (1.2 m) out of the water during which time the engineers were able to perform trimming trials.[1]
Whilst under cover, an improved system was devised for removing Mayfly from the shed. This consisted of a series of electric winches that could gently ease her out, even in windy conditions, and on 24 September 1911 it was decided to move Mayfly from her hangar for full testing. However, just as her nose cleared the hangar door, a sudden forceful beam-side gust caused the ship to lurch, and she was rolled virtually onto her beam ends. She eventually righted, and as she was being pivoted so that her nose would point back out to the dock, there were cracking sounds amidships and she broke in two. At that point she started to rise in an inverted "V" configuration, and the crew in the after gondola dived overboard as the stern portion rose up into the air. The two halves subsequently plunged into the water. Fortunately there were no fatalities, and the wreck was returned to the shed the same day.[1]
A court of inquiry's conclusion was that no-one could be attributed the blame for the incident, and that it would be reasonable to support the story that the squall was to blame. It was of such a force that later ships would have also been severely damaged if they had encountered it under the same tethered circumstances.[1] However, Commander Masterman is reported as stating unofficially that, "Mayfly was pulled in half by the handling party when someone forgot to release the lines that tethered the bows of the ship."[5] Furthermore, in an article entitled Twenty-One Years of Airship Progress Lt.Col. W. Lockwood Marsh wrote: "This accident, though the ship was undoubtedly weak, was directly due to a mistake in handling, one of the parties on a hawser continuing to haul in without noticing that the after car had fouled a buoy."[6]
Mayfly was the subject of much negative publicity about being a waste of taxpayers’ money,[3] and the future of Naval Airship operations was seriously questioned in the Admiralty.[1] Winston Churchill, who was First Lord of the Admiralty at the time later made the following House of Commons statement on 26 March 1913: "Altogether, compared with other navies, the British aeroplane service has started very well... I have a less satisfactory account to give of airships. Naval airship developments were retarded by various causes. The mishap which destroyed the May-fly, or the Won't Fly, as it would be more accurate to call it, at Barrow, was a very serious set-back to the development of Admiralty policy in airships."[7]
After being wrecked, Mayfly was abandoned and left to rot in her shed,[1] and on 31 March 1913, Sir Bolton Eyres-Monsell (who would himself later become First Lord of the Admiralty) made the following comment during a Commons sitting regarding the fate of Mayfly and the plight of Britain's airship strength: "The 'May-fly' broke three years ago, and nothing further has been done. In non-rigid airships, Germany has seventeen, and against that we have two very inferior ones and two on order, but we are not doing anything in this respect."[7]
Despite never having flown, the brief career of the aptly named Mayfly provided valuable training and experimental data for British airship crews and designers.[1]
Data from [1][2] (NB: sources do not agree on all values; and as Mayfly never flew, performance figures are theoretical. Engine data from[8])
General characteristics
Performance
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