Short S.23 Empire Class / S.30 Empire Class
In 1935 the British government took the bold decision to carry all mail within the Empire at the ordinary surface rate. Combined with increasing passenger traffic, this called for a sudden expansion of Imperial Airways and the equally bold decision was taken to buy 28 of a totally new flying-boat, known as the C Class Empire, 'off the drawing board' from Short Brothers, at a cost of over £2,000,000. They were four engined cantilever monoplane with a hull of advanced lines.
Features included light-alloy stressed-skin construction; a cantilever high wing with electric Gouge flaps; four 685kW Bristol Pegasus Xc radial engines driving DH Hamilton two-position propellers; and a streamlined nose incorporating an enclosed flight deck for captain, first officer, navigator and flight clerk. A steward's pantry was amidships and in the normal configuration seats were arranged in front and rear cabins for 24 passengers. On long hauls sleeping accommodation was provided for 16, with a promenade lounge. On some routes experience showed that the mail capacity had to be raised from 1.5 to 2 tonnes, reducing the passenger seats to 17.
The prototype, the Short S.23 named Canopus, flew on July 4, 1936. Less than four months later, on October 30, it was in passenger service. Others followed at fortnightly intervals and by 1937 the fleet was already covering 113,196 miles per week on scheduled services.
The original C-Class boats had four 910 hp Bristol Pegasus engines and could carry 17 passengers, plus two tons of mail and freight for 810 miles at 164 mph. They were soon followed by seven more with 900 hp Perseus engines and double the range of the first batch.
All 28 were delivered, plus three for Qantas (Australia). Two were long-range boats with increased weight and transatlantic range. Eleven S.30s (eight for Imperial and three for Tasman Empire Airways) had 663kW Perseus XIIc sleeve-valve engines and greater range - the first four also being equipped for flight refuelling to greater weight. The final two boats were S.33s with increased weight and Pegasus engines.
On 5 August 1935, Imperial Airways began regular trans-Atlantic airmail flights using Short Empire flying boats which were refuelled in the air.
Short Empire ‘Cambria’, specially modified for trans-Atlantic operations
During World War II most of these great aircraft served on long routes all over the world. Four were impressed for RAF use with radar (two being destroyed in Norway in May 1940) and most were re-engined with the same 752kW Pegasus 22 engines as the Sunderlands (the derived military version). Their achievements were amazing: one made 442 crossings of the Tasman Sea, two evacuated 469 troops from Crete and one was flown out of a small river in the Belgian Congo in 1940. Others maintained schedules on the North Atlantic, between Britain and Africa, the dangerous Mediterranean route from Gibraltar to Malta and Cairo, and the Horseshoe route between Australia, India and South Africa. Most were retired in 1947.
The prototype completed 2,024,745 miles of safe flying in her ten years of service.
Engines: 4 x Bristol Pegasus XC, 790 hp / 686kW
Wing span: 114 ft 0 in (34.75 m)
Length: 88 ft 0 in (26.82 m)
Height: 31 ft 9.75 in (9.68 m)
Wing area: 139.35 sq.m / 1499.95 sq ft
Empty weight: 10659 kg / 23499 lb
Max TO wt: 40,500 lb (18,375 kg)
Max level speed: 200 mph (322 kph)
Cruise speed: 265 km/h / 165 mph
Ceiling: 6095 m / 20000 ft
Range: 1223 km / 760 miles
Engines: 4 x 910 h.p. Bristol Pegasus
Length: 88 ft. (26.82 m.)
Wing span: 114 ft (34.74 m.)
Weight empty: 23,500 lb. (10,660 kg.)
Max speed: 200 mph
Max cruise: 165 mph (265 kph)
Ceiling: 20,000 ft. (6,000 m.) fully loaded
Range: 800 miles (1,300 km.)
Pax cap: 24
Short S.23 Empire