Short S.81
The Short S.81 was an experimental British gun-carrying pusher biplane seaplane, ordered from Short Brothers by the British Admiralty in 1913 for use by the Royal Naval Air Service. The seaplane, manufacturers serial number S.81, was built at Eastchurch and allocated the military serial number "126". S.81 was delivered to Calshot on 25 May 1914 and accepted by the Navy on 2 June 1914. It had three-bay wings with overhanging upper wings, and was powered by a 160 hp (119 kW) Gnome rotary engine. It was first fitted with a 1½ pounder (37 mm) semi-automatic  Vickers quick-firing gun in July 1914. Tests with this gun showed that recoil was severe, with claims that firing the gun would induce a stall. It was fitted with a number of different guns for trials, testing a six-pounder (57 mm) Davis gun (an early recoilless gun) in 1915. In 1915 it had a dynamo and searchlight fitted. No longer needed for trials, it was deleted from the inventory in October 1915.