No. 9r
| No. 9r | |
|---|---|
 |
|
| Role | Experimental airship |
| National origin | United Kingdom |
| Manufacturer | Vickers Ltd |
| Designer | H. B. Pratt and Barnes Wallis |
| First flight | 27 November 1916 |
| Number built | 1 |
HMA No. 9r was a rigid airship designed and built by Vickers at Walney Island just off Barrow-in-Furness, Cumbria. It was ordered in 1913 but did not fly until 27 November 1916 when it became the first British rigid airship to do so. It was dismantled in June 1918 after being flown for around 165 hours, mainly for experimental purposes.
Plans to build a second rigid airship to follow the unsuccessful HMA No. 1 (His Majesty's Airship No. 1) Mayfly were agreed by the Committee for Imperial Defence in early 1913, and that Vickers should be asked to design an improved class of ship incorporating all that was then known about the Zeppelins. Vickers' airship design department had been disbanded following the failure of the Mayfly, consequently a new department was formed when the original design team was reassembled with H. B. Pratt recruited as chief designer. Pratt had been working at Vickers while the Mayfly was being constructed and had predicted that it was not structurally sound and subsequently left the company. Pratt in turn hired Barnes Wallis, whom he had met while both were working for the shipbuilding firm of J. Samuel White, as his assistant. The initial order for the new ship was placed on 10 June 1913, with the final plans being agreed at the end of the year, and a formal contract was signed in March 1914.
The initial specification called for an airship with a disposable lift of 5 tons (5080 kg) capable of flying at 45 mph (72 km/h) and maintaining an altitude of 2,000 ft (610 m) for 30 minutes; however, the required load was later reduced to 3.1 tons (3150 kg). The hull was cylindrical for most of its length and was constructed from 17-sided transverse frames with a triangular section keel underneath. Two gondolas were suspended from the keel, the forward one containing the control compartment and two of the engines, the aft containing an emergency control station and the remaining pair of engines. In addition there was a radio cabin and a mess space for the crew within the keel structure, which also contained the fuel and ballast tanks. Propulsion was provided by four 180 hp (130 kW) Wolseley engines, mounted in pairs in the gondolas. Like Mayfly, it was designed with watertight cars so that it could be operated from water. The design was based in part on French plans of Z IV which had landed in France on 3 April 1913 following an accidental incursion into French airspace, permitting a thorough examination.
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