The Saunders-Roe SR.A/1 was a prototype flying boat fighter aircraft designed and built by British seaplane manufacturer Saunders-Roe. It was the first jet-propelled water-based aircraft in the world. The concept behind the SR.A/1 originated during the Second World War as a reaction to Japan's successful use of military floatplanes and the emergence of the turbojet engine. Saunders-Roe presented an initial proposal of their jet-powered seaplane concept, then designated SR.44, to the Air Ministry during mid-1943. In April 1944, the Ministry issued Specification E.6/44 for the type and supported its development with a contract for three prototypes. Development was protracted by Saunders-Roe's work on other projects, the war having ended prior to any of the prototypes being completed. On 16 July 1947, the first prototype made its maiden flight. The SR.A/1 was evaluated by the Royal Air Force (RAF), who concluded that the design was incapable of matching up to the performance of land-based designs. Despite interest from foreign governments, including the United States, no orders for the SR.A/1 materialised. As such, it never entered volume production or saw service with any operators. While interest in the SR.A/1 programme was briefly revived following the start of the Korean War, the aircraft was considered to be obsolete by that point and was again rejected. The SR./A.1 was directly inspired by the modest successes experienced by the Imperial Japanese Navy in using seaplane fighters, such as the Nakajima A6M2-N (an adaptation of the Mitsubishi Zero) and the Kawanishi N1K. Seaplanes had performed successfully during both of the world wars although, according to author H. F. King, their achievements were often not highly publicised or well known. Prior to the introduction of the Gloster Gladiator, every British shipborne fighter was designed with an interchangeable wheel-or-float undercarriage. In theory, seaplanes were ideally suited to conditions in the Pacific theatre of the Second World War, and could turn any relatively calm area of coast into an airbase. Their main disadvantage came from the way in which the bulk of their flotation gear penalised their performance compared to other fighters. Both immediately prior to and during the war, Britain made very little use of seaplane fighters, instead relying upon aircraft carriers and land-based fighters as the basis of their military operations, despite the concept having remained popular with other powers, including Japan, Italy, and France. Proposed seaplane conversions were produced for both the Hawker Hurricane and the Supermarine Spitfire to meet operational needs in the Norwegian Campaign, but were largely curtailed following the rapid German victory in this theatre. No quantity production of seaplane fighters followed. It was in this backdrop that British seaplane manufacturer Saunders-Roe recognised that the newly developed turbojet engine presented an opportunity to overcome the traditional performance drawbacks and design limitations of floatplanes. By not requiring clearance for a propeller, the fuselage could sit lower in the water and use a flying boat-type hull. The prospective aircraft's performance when powered by Halford H.1 engines was projected to be 520 mph at 40,000 ft. Saunders-Roe speculated that, as floatplanes could have staging grounds nearer to their objectives than land-based counterparts, both the time and effort involved in mounting missions, particularly offensive ones, could be reduced. Early jet aircraft were typically restrained in terms of their range due to the high fuel consumption involved, a factor which could be overcome by bringing forward their staging areas, something which a floatplane would be readily capable of doing. Re-basing to virtually any body of water could also be performed with little in the way of setup or ground preparation, according to the company. For more development details, click here.
