HMA No. 1 - Design

Design

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; 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.

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, Mayfly being the first rigid airship to do so. She had an impervious outer cover, a simplified cruciform tail, 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.

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.