No. 9r - Design and Development

Design and Development

Plans to build a second rigid airship to follow on from the ill-fated HMA No. 1 (His Majesty's Airship No. 1) Mayfly had been agreed between the British Government and the Admiralty, but although the political situation in Europe was worsening the Government was uncertain as to whether a replacement would be required. Eventually, a conference was called with the Admiralty on 19 June 1912 to consider resuming the programme again.

At that time the non-rigid airship programme was proving to be more successful than the 'rigids' had been, and at this meeting not only was it agreed to expand the non-rigid programme, but also to resume the HMA No. 9 project. The firm of Vickers Ltd at Barrow-in-Furness, Cumbria, who were responsible for the creation of Mayfly, were asked to design an improved class of ship incorporating all that was then known about the successful German rigid airships designed by Count Zeppelin; however, the proposed classes would have to be built in existing facilities.

Vickers' airship department had been disbanded after the Government failed to keep it supplied with work following the Mayfly project. Consequently a new department was constituted in April 1913, and the original design team, including their chief designer H. B. Pratt and his assistant Barnes Wallis, was re-assembled.

HMA No. 9, or No. 9r ("r" for "rigid") as she would be referred to, would have to be limited to the size of the Zeppelins as the technology was based in part on secret French plans of Z IV, which had force landed in France on 3 April 1913. However, Z IV's design was already three years old, but other than the information on what the German designers had planned there was little else to go on, and as a result work proceeded slowly at first. 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 Admiralty had insisted that No. 9r was to be built much stronger than contemporary German airships because she would have to be handled by novice crews until some officers and men gained experience with rigid airships, and like Mayfly, she was designed with watertight cars.

Propulsion was provided by four 180 hp (130 kW) Wolseley engines, mounted in pairs on each of two external gondolas, one fore and one aft. These drove swiveling propellers mounted on massive extension shafts. This innovative feature assisted takeoff and landing, and is an early example of thrust vectoring in an aircraft.