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  • Writer's pictureroy blewett

Short S.25 Sunderland and S.45 Seaford

Updated: Jan 7, 2023

Solent 4 ZK-AMO was delivered to Tasman Empire Air Lines in 1949 and operated the Coral Route to South Pacific islands until its was donated to the Museum of Transport and Technology in 1961. It is now on display inside the purpose-build Aviation Hall, with Sunderland V NZ4115 nearby (Dec 22).

The Short brothers, Horace, Eustace and Oswald, established their eponymous company at Battersea in November 1908 to build balloons. They quickly spotted the potential for powered flight and were awarded a contract to build six Wright Flyers, which they did at a new factory at Leysdown. By 1910, the company had already outgrown the site and moved to Eastchurch. Soon after, Horace Short became involved in training the first batch of pilots for the fledgling Royal Naval Air Service, and this led to the development of the company’s first seaplane and construction of another factory, this one on the River Medway at Rochester.

Short Brothers were to become synonymous with seaplane development, producing a line of all-metal flying boats and, in 1934, Imperial Airways placed on order for 14 S.23 ocean-going boats, straight from the drawing board, for use on its Empire route to Australia. A year earlier, the Air Ministry had issued specification R.2/33 for a long range four-engine general purpose flying boat to replace an earlier Short Brothers product, the Singapore III. The company proposed the S.25 in competition with Saunders-Roe and began work on a prototype, drawing heavily on development of the S.23. With war in Europe on the horizon, the Royal Air Force (RAF) had begun a large re-equipment programme and with Rochester already working flat out, the Air Ministry built a new factory on Queen’s Island, adjacent to Harland & Wolff’s shipyard at Belfast Harbour. A new company, owned jointly by Short Brothers and Harland & Wolff was set up to manage it. In the meantime, the Air Ministry had awarded a production contract for the S.25, now known as the Sunderland. Large numbers were produced throughout the war, with the Hercules-powered version of the Sunderland adopting the designation S.45 and the name Seaford. The RAF continued to operate the Sunderland until 20 May 1959, while the Royal New Zealand Air Force did not retire its Sunderlands until 1967.

The type’s commercial career began during World War II, when Sunderlands were used by British Overseas Airways Corporation (BOAC) to keep important long haul routes open. BOAC’s use of the Sunderland led to development of the post-war Sandringham, work that kept the Queen’s Harbour factory busy well into the 1950s.

Finally, a word on construction numbers. Belfast-built aircraft have construction numbers prefixed with ‘SH’ (for Short Brothers & Harland), with those from the conversion line suffixed with a ‘C’. Aircraft built at Rochester before and after the war have c/ns prefixed with ‘S’; those built during the war were not allocated c/ns. No aircraft from the Windermere or Dumbarton production lines survives.

First flight: 16 Oct 37 (c/n S.803, K4774)

Production: 765, made up of 525 by Short Brothers (353 at Rochester, 137 at Belfast and 35 at White Cross Bay, Windermere) and 240 by Blackburn Aircraft at Denny shipyard, Dumbarton.

First delivery: 28 May 38, to the Royal Air Force (c/n S.861, L2159)

Last delivery: Nov 49, to T.E.A.L. (c/n SH.1556, ZK-AML)

Variants: Sunderland I - initial production version with 7-man crew and capacity for 2,000 lb ordnance load, powered by 4 Bristol Pegasus XXII radials (75 built at Rochester, including one prototype equipped initially with Pegasus Xs);

Sunderland II - developed version equipped with A.S.V. Mk.II radar and improved defensive armament, powered by Pegasus XVIIIs (68 built made up of 23 at Rochester, 15 and Belfast and 20 at Dumbarton; first flight 24 Apr 42);

Sunderland III - main production version based on Sunderland II with detailed aerodynamic improvements (475 built made up of 216 at Rochester, 64 at Belfast, 35 at Windermere and 160 at Dumbarton; first flight 28 Jun 41; 30 modified for BOAC use as Hythe-class, with austere bench and mattress seating);

Sunderland IV - Sunderland III powered by Bristol Hercules 19s, necessitating installation of larger fin and tailplane (2 built at Rochester; first flight 30 Aug 44);

Sunderland V - Sunderland II with A.S.V. Mk.IVc radar, powered by Pratt & Whitney R-1830 Twin Wasp radials (125 built made up of 17 at Rochester, 48 at Belfast and 60 at Dumbarton; first flight Mar 44);

Seaford 1 - production version of Sunderland IV (8 built);

Solent 2 (S.45A)- civil version of the Seaford 1 for BOAC as Salisbury-class, with accommodation for up to 34 day passengers on the lower deck and dining-saloon and bar on upper deck, powered by Hercules 637s (12 built at Rochester, first flight 11 Nov 46);

Solent 4 - Solent 2 with increased weight for Tasman Empire Airways Ltd, accommodation for up to 44 passengers on two decks and powered by Hercules 733s (4 built at Belfast, first flight 26 May 49).

Conversions: Sandringham 1 - Sunderland III with re-modelled nose and tail (a feature of subsquent conversions also), accommodation for up to 24 passengers on the lower deck and a dining-saloon and bar on upper deck (1 converted, first flight 28 Nov 45);

Sandringham 2 - Sunderland II/III converted with accommodation for up to 45 passengers on upper and lower decks, powered by R-1830-92 Twin Wasps (4 converted, of which 2 subsequently converted to Sandringham 3);

Sandringham 3 - Sunderland III converted with accommodation for up to 21 passengers on the lower deck and a dining-saloon and bar on upper deck, powered by R-1830-92 Twin Wasps (5 converted, including 2 from Sandringham 2);

Sandringham 4 - Sunderland III converted for Tasman Empire Airways Ltd with accommodation for up to 30 passengers and R-1830-90Cs (4 converted);

Sandringham 5 - Sunderland III converted as BOAC Plymouth-class and furnished only on the lower deck, with accommodation for up to 22 passengers and R-1830-90Ds (10 converted);

Sandringham 6 - Sunderland III converted for D.N.L. use in harsh Arctic climate with A.S.V. Mk.VIc radar and accommodation for up to 37 passengers on two decks (5 converted)

Sandringham 7 - Sunderland III converted as BOAC Bermuda-class as per Sandringham 5 but with accommodation for up to 30 (3 converted);

Solent 3 - Seaford 1 converted for BOAC, with accommodation for up to 39 passengers on two decks (7 converted 1949).

Short Sunderland survivors
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