The Short Empire was a medium-range four-engined monoplane flying boat, designed and developed by Short Brothers during the 1930s to meet the requirements of the growing commercial airline sector, with a particular emphasis upon its usefulness upon the core routes that served the United Kingdom. It was developed and manufactured in parallel with the Short Sunderland maritime patrol bomber, which went on to serve in the Second World War; a further derivative that was later developed was the piggy-back Short Mayo Composite.
The development of the Short Empire had been heavily influenced by its primary customer, Imperial Airways, who had originally developed the requirements to which it was initially ordered and designed from. Imperial Airways, and its successor, the British Overseas Airways Corporation (BOAC), along with Qantas and TEAL, operated the type in commercial service. Upon entering service, the Empire routinely flew between the British mainland and Australia and the various British colonies in Africa and Asia, typically carrying a combination of passenger and mail cargoes; the Empires were also used on various other routes, such as on the service between Bermuda and New York City.
The Empire also saw military service during the Second World War. The Royal Air Force (RAF), Royal Australian Air Force (RAAF), Royal New Zealand Air Force (RNZAF), and briefly the Royal Canadian Air Force (RCAF) used the type to conduct various military operations, particularly as an airborne platform for anti-submarine patrols and for general transport duties.
Development
Origins
During the 1930s, global demand for air travel was consistently and rapidly growing. Thus, keen to grow their share of this emerging market, British airline Imperial Airways was keen to expand and sought the latest technology to do so. In particular, Imperial Airways' technical advisor, Major Robert Hobart Mayo developed a specification for a new type of aircraft to serve both passenger and freight requirements throughout the world. This specification sought an aircraft that would be capable of carrying up to 24 passengers in spacious comfort along with adequate room for airmail or freight while simultaneously being capable of a cruising speed of and a range of at least ; the capacity for an extended range of to serve the North Atlantic route was also stipulated. According to aviation author Geoffrey Norris, at the time, it was considered to be impossible to construct a land-based aeroplane of such size and weight that still possessed acceptable landing/take-off performance, thus it was determined that a flying boat would be required.
Early on, it was apparent that Short Brothers, who had previously developed and produced several large flying boats for Imperial Airways and the Royal Air Force (RAF) which had proven to be sound designs in terms of performance and safety, would be a frontrunner to fulfil the requirement. However, Shorts was hesitant to build such an aircraft, due to the necessary advances involved, straight from the drawing board without the production of a preceding prototype, and thus requested to be allowed the time to build such an aircraft; this was rejected by Imperial Airways, stating that such a delay was not permissible. In 1935, Imperial Airways announced the placement of an order for 28 flying boats of an as-of-yet undesigned type, weighing 18 tonnes each; the order was reportedly hailed as being "one of the world's boldest experiments in aviation", while sceptics referred to the decision less favourably as being a 'gamble'.
A design team led by Arthur Gouge set about designing what would become the Empire. It was quickly determined that, in order to possess the sufficient clearance between the tips of the propellers and the water, the wing would need to be in a high mounted position; initially to be housed in a hump above the fuselage for sufficient height, the fuselage depth was instead increased, providing more internal volume than required but enabling a lighter and stronger integration of the cantilever wing with the fuselage. Shorts' own convention for wide planing bottomed hulls for their flying boats was overturned as the 18-tonne weight would generate excessive drag with such a configuration; following a series of water tank experiments, a new type of planing bottom with a reduced beam deemed suitable. The basic aerodynamic design was derived from the smaller Short Scion Senior floatplane, which served in all but name as a half-scale prototype for the Empire and for its sibling, the military-orientated Short Sunderland.