Short S.23 Empire

Short S.23 Empire
source
Name	Short S.23 Empire
Type	Long-range flying boat
Manufacturer	Short Brothers
First flight	1936
Introduced	1938
Retired	1952
Primary user	Imperial Airways
Produced	1936–1945
Number built	43

Short S.23 Empire was a British long-range four-engined flying boat developed in the 1930s for transoceanic passenger and mail routes. Conceived by Short Brothers and ordered by Imperial Airways and later operated by British Overseas Airways Corporation, the type linked intercontinental services between London, Cape Town, Sydney, and Singapore before and after Second World War. The design combined metal hull developments from Short Mayo Composite experimentation with aerodynamic refinements influenced by contemporary work at Hawker Aircraft and Supermarine.

Development and design

Development began after Imperial Airways sought replacement for the Short Calcutta and Short Kent to serve the Imperial Airways Empire routes. Chief designer Arthur Gouge at Short Brothers led a team influenced by research at the National Physical Laboratory, the Royal Aircraft Establishment and aerodynamicists from Handley Page. The S.23 featured a high-mounted wing, four Rolls-Royce Kestrel-series inline engines or Wright Cyclone radials depending on production block, a stressed metal hull incorporating corrosion-resistant alloys developed from trials with Short S.8 Calcutta, and accommodations comparable to lounges on the RMS Queen Mary and cabins envisaged by Frank Whittle-era planners.

Sea-keeping used hull form data from testing at the Marine Aircraft Experimental Establishment and the Portsmouth Dockyard, while structural load factors reflected findings from A.V. Roe and Company and de Havilland studies. Navigation equipment included radio ranges and direction-finding sets originally supplied by Marconi Company and later augmented with long-range aerials compatible with Pan American World Airways and Qantas operations. Passenger layout balanced sleeping berths, dining saloons and separate compartments inspired by contemporary liners such as RMS King George V.

Operational history

Imperial Airways introduced the S.23 on scheduled services from Foynes and Eastleigh to Nouméa, Khartoum, Dar es Salaam and Melbourne. During peacetime operations the type connected with shipping lines including Peninsular and Oriental Steam Navigation Company and mail contracts with the Royal Mail. With outbreak of the Second World War, many S.23s were impressed by the Royal Air Force and re-designated for transport and maritime reconnaissance roles, cooperating with units like Coastal Command and operating from bases including Hamilton (Ontario), Foynes, and Christchurch, New Zealand.

Postwar, a number of aircraft re-entered civil service with British Overseas Airways Corporation on routes linking Foynes–Shannon–Lisbon and longer sectors to Singapore and Sydney in partnership with Qantas Empire Airways and Pan American World Airways code-sharing. The S.23 provided relief during reconstruction efforts in regions administered by United Nations Relief and Rehabilitation Administration and participated in evacuations associated with crises near Palestine and Malta. Withdrawal followed as landplane designs from Avro and Lockheed became dominant and new airports such as Heathrow expanded.

Variants

- S.23 Mk I: Initial production for Imperial Airways with Rolls-Royce Pegasus or similar powerplants used on early Empire flying boats, outfitted for transoceanic mail and first-class passengers. - S.23 Mk II: Militarised conversions for Royal Air Force service with photographic equipment and provisions for stretch-range fuel tanks, supporting Coastal Command and ferry units. - S.23 Mk III: Postwar civil refits operated by British Overseas Airways Corporation with updated navigation sets from Marconi, improved interior fittings influenced by BOAC transatlantic configurations, and alternative engines supplied by Wright Aeronautical. - Transport and freighter conversions: Modified by workshops at Short Brothers and maintenance depots at Felixstowe to carry freight and relief supplies during operations coordinated with British Red Cross and International Red Cross and Red Crescent Movement.

Operators

- Imperial Airways - British Overseas Airways Corporation - Royal Air Force (multiple squadrons under Coastal Command and ferry groups) - Qantas Empire Airways (through joint services) - Pan American World Airways (operational cooperation on long-range routes) - Royal Australian Air Force (limited wartime use) - Royal New Zealand Air Force (occasional wartime operations) - Private and government operators in Portugal and South Africa for specialist duties

Accidents and incidents

Several S.23s were lost in wartime operations during navigation-heavy missions near Norfolk Coast, the Bay of Biscay, and the approaches to Freetown. Notable incidents involved forced sea landings owing to weather systems studied by the Met Office and engine failures traced to supply chain issues affecting Rolls-Royce and Wright Aeronautical parts. Some airframes were salvaged and returned to service after repairs at facilities like Cowes and Belfast, while others were written off and their hulls repurposed or scrapped at yards associated with Vickers-Armstrongs.

Technical specifications

- Crew: flight crew plus radio and engineer positions, comparable to complements of Pan American Clipper crews - Capacity: passenger accommodation and mail/parcel capacity aligned with contracts from the Royal Mail and liner-class standards used by P&O and Cunard - Powerplant: four engines (variants used Rolls-Royce and Wright types) as per production batch agreements with Air Ministry procurement rules - Performance: cruising and range figures developed to match transoceanic sectors between Foynes, Darwin, and Sydney and to interface with flying boat terminals at Lympne and Pembroke Dock - Construction: all-metal hull and fabric/metal control surfaces with corrosion treatment techniques derived from projects at the National Physical Laboratory and testing at Marine Aircraft Experimental Establishment