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The Short Empire was a four-engined monoplane transport flying boat, designed and developed by Short Brothers during the 1930s to meet the requirements of the British Empire, specifically to provide air service from the UK to South Africa, Singapore and Australia in stages. It was developed in parallel with the Short Sunderland maritime patrol bomber, which served in the Second World War along with the piggy-back Short Mayo Composite.

Key Information

Imperial Airways, as the primary customer, developed the requirements to which it was ordered and designed. Imperial Airways, and its successor, the British Overseas Airways Corporation (BOAC), along with Qantas and TEAL, operated the type in commercial 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 passengers and mail. The Empires were also used between Bermuda and New York City.

The Empire saw commercial and military service during the Second World War, for anti-submarine patrols and as a transport. The Royal Air Force (RAF), Royal Australian Air Force (RAAF), and Royal New Zealand Air Force (RNZAF) used the type.

Development

[edit]

Origins

[edit]

During the 1930s, demand for air travel was rapidly growing. The British national flag airline Imperial Airways sought to fully expand air service across the British Empire. Imperial Airways' technical adviser, planned a specification for a new type of aircraft to serve passenger and freight requirements throughout the world.[2] This required an aircraft to carry 24 passengers in comfort, as well as airmail or freight while having a cruising speed of 170 mph (270 km/h), a normal range of at least 700 mi (1,100 km) and the capability for an extended range of 2,000 mi (3,200 km) to cross the North Atlantic.[2] At the time, and for various reasons, including technical and operational, it was determined that a flying boat would be required.[2]

Short Brothers had previously developed successful large flying boats for Imperial Airways and the Royal Air Force (RAF), and was the frontrunner to fulfil the requirement.[2] Shorts was reluctant to build straight from the drawing board without a prototype, however this was rejected by Imperial Airways, which was desperate to replace obsolete types then in service that were unable to provide the full service needed.[2] In 1935, Imperial Airways announced an order for 28 flying boats of an as-of-yet undesigned type, weighing 18 tonnes each. The order was claimed by the British press as being "one of the world's boldest experiments in aviation".[2]

A design team led by Arthur Gouge created the Empire. To have adequate clearance between the propellers and the water, the wing needed to be as high as feasible and was initially to be attached to a hump above the fuselage as on the Martin M-130, but the fuselage height was instead increased, providing more internal volume than required but enabling a lighter and stronger integration of the cantilever wing to the fuselage.[2]

Following water tank experiments, a simplified-vee planing bottom with a much higher length to beam ratio than was common at the time was chosen.[2] The aerodynamic and hydrodynamic properties were tested on the smaller Short Scion Senior floatplane, which served as a half-scale prototype for the Empire and its sibling, the military's Short Sunderland.[3]

Shorts developed its own machinery to produce the necessary T-shaped Hiduminium alloy lengths that comprised the main spar.[4] A specialised and patented flap, known as Gouge flaps after its creator, caused only a small increase in drag, while the wing's lift coefficient was increased by 30 percent, the landing speed reduced by 12 per cent, and no trim changes were needed.[2]

Initial production

[edit]

On 4 July 1936, the first Empire built, registered G-ADHL, named Canopus, made its first flight with Shorts' chief test pilot, John Lankester Parker at the controls.[5] Early flights were relatively trouble-free, and Parker was satisfied with its performance and handling.[5] On 17 September 1936, G-ADHL first flew for Imperial Airways, with the final proving flight to Marseille, France took place on 22 October 1936.[6] The first series of the Short Empires, the S.23, could carry five crew, 17 passengers, and 4,480 lb (2,030 kg) of cargo at a maximum speed of 174 kn (322 km/h; 200 mph) and was powered by four 920 hp (690 kW) Bristol Pegasus Xc radial engines.[7]

The second Empire and the first of the long-range models, registered G-ADHM, named Caledonia, made its first flight on 15 September 1936 and was delivered to Imperial Airways on 4 December 1936.[6] From September 1936 onwards, one aircraft was produced per month and typically each aircraft's delivery occurring right after its first flight.[6] The Empire was officially known as the C-class by Imperial Airways and each aircraft operated by them was given a name beginning with the letter C.

On 26 February 1938, the final three Empires of the initial order placed by Imperial Airways – Coorong, Coogee and Corio were diverted from Imperial Airways and delivered to the Anglo-Australian Qantas Empire Airways.[8] In late 1937, Imperial Airways placed a follow-on order for another 11 Empires. When combined with the original order of 28, this had the distinction of being the largest order by a single customer placed for a British civil aircraft at that time.[9] While the first three aircraft of the additional order were of the typical S.23 class, intended for Qantas Empire Airways, the rest had a number of detail changes and were designated the S.30.[10] Short's Rochester factory produced all 43 Empires built.

Further development

[edit]

The S.30 series was fitted with four Bristol Perseus XIIc sleeve valve engines in the place of the Pegasus engines. the 890 hp (660 kW) Perseus engines were each 85 lb (39 kg) lighter and 17.3% more fuel efficient, but developed less power.[10] The airframe was strengthened, mainly by using heavier gauge sheeting on the fuselage and wings. The maximum takeoff weight increased to 46,000 lb (21,000 kg) with a corresponding range of 1,500 mi (2,400 km), the S.30 had a similar performance to the preceding S.23s.[10]

The first of the S.30 flying boats was registered G-AFCT and named Champion.[10] In December 1938, the second S.30 aircraft registered G-AFCU, named Cabot became the first of the revised series to fly. The last three aircraft of this order, initially named Captain Cook, Clare and Aotearoa, were renamed and re-registered for use by TEAL.[10] In 1939, a final S.30 flying boat, registered G-AFKZ and named Cathay, was delivered to Imperial Airways in late March 1940.[10]

Four flying S.30 series flying boats, Cabot, Caribou, Clyde and Connemara, were equipped with in-flight refuelling equipment and extra fuel tanks to provide scheduled transatlantic airmail service. The aircraft was to take off light and, once airborne, take on extra fuel to reach an all up weight of 53,000 lb (24,000 kg), giving the aircraft a range of over 2,500 mi (4,000 km). The extra fuel reduced payload to 4,270 lb (1,940 kg) against the 6,250 lb (2,830 kg) of the standard aeroplane. The refuelling was performed by three converted Handley Page Harrow bombers, one operating out of Ireland and two out of Newfoundland.

In 1939, Imperial Airways placed a further follow-on order for a modified S.30, designated the S.33.[10] This series had the same construction as its predecessors, but the new Pegasus XI engine, a development of the powerplant used by the original S.23 series, was used. Out of these three final aircraft, only two, named Clifton and Cleopatra, would be completed and delivered to the newly renamed British Overseas Airways Corporation (BOAC).[10]

The S.26, designated as the G-class by BOAC, was a substantially larger development of the Empire flying boat, and an entirely new aircraft, albeit of similar configuration.[11] It was roughly 15 percent larger, as well as using the much more powerful Bristol Hercules radial engine and a further improved hull design. It was intended to be used on the north Atlantic route.[11] The three that were built were immediately impressed into military service during the Second World War.[12]

Design

[edit]
Short S.23 Empire G-ADHM, Caledonia, on its beaching gear at Felixstowe, Suffolk, England, September 1936

The Short Empire flying boat was a clean high-wing monoplane, initially powered by four wing-mounted Bristol Pegasus Xc radial engines which drove de Havilland-built variable-pitch propellers.[13] The engines were each enclosed within NACA cowls and mounted ahead of the leading edge of the wings. This allowed portions of the leading edge adjacent to the engines to be hinged forward to be used as platforms to maintain the engines.[14]

The Pegasus Xc engines each produced 910 hp (680 kW) on takeoff, decreasing to 740 hp (550 kW) at an altitude of 3,500 ft (1,100 m).[15] Alternative engines were installed with both greater and reduced power outputs. Initial aircraft had a 40,500 lb (18,400 kg) gross weight, however, by 1939, many aircraft had been strengthened, for an increased gross weight of 53,000 lb (24,000 kg).[16] Its useful load included 600 imp gal (2,700 L; 720 US gal) of fuel (weighing 4,560 lb (2,070 kg)), 44 imp gal (200 L; 53 US gal) of oil, assorted equipment (weighing 3,340 lb (1,510 kg)), along with the payload and five crew (weighing 8,200 lb (3,700 kg)).[4] The S.23 series achieved a top speed of 200 mph (320 km/h) at an altitude of 5,500 ft (1,700 m) along with a cruising speed of 165 mph (266 km/h) and a minimum flying speed of 73 mph (117 km/h).[6]

The wings had a flush-riveted Alclad covering with Frise-type ailerons and the internally-developed Gouge flaps, the latter of which were actuated by an electric motor connected via a gearing system and screw jacks, allowing the flaps to be lowered in 60 seconds and raised in 90 seconds.[4] Large cylindrical 325-gallon fuel tanks were in the wings, between the inner and outer engines. On long-range variants of the aircraft, additional fuel tanks were added in the wings, up to three containing 280 gallons, 325 gallons, and 175 gallons in each wing. Sections of the wing leading edge alongside the nacelles folded down to be engine servicing platforms. Tip floats were carried on struts attached to the main spar and featured shock absorbers to reduce impact forces being transmitted to the wings.[4]

The hull used the same steps as earlier designs, but had a much finer beam to length ratio, and employed Shorts' traditional construction methods. The structure used a combination of Z-shaped stringers and I-shaped girders to form triangular sections that ran along the chines where the fuselage sides meet the planing bottom.[17] To simplify manufacturing and to maximize usable internal volume, only a simple single curvature on the hull was employed that didn't require the use of a press for most of the airframe. On previous Shorts' flying boats, a more complex S-shaped curvature and a sudden reduction in beam just above the chines had been employed instead.[17]

S.23 Empire G-AETV, named Coriolanus, moored at Pinkenba on the Brisbane River, 1939

The 17 ft (5.2 m) deep hull accommodated two decks, the upper deck forming a lengthy compartment divided into sections to accommodate 3,000 lb (1,400 kg) of freight and mail along with a storage space and a ship's clerk's office. This office contained controls such as electrical fuseboxes and circuit switches, ventilation controls, and fuelcocks.[17] The lower deck contained a large marine compartment containing an anchor, a pair of drogues, a mooring bollard and a boat hook, along with a ladder to the cockpit. The forward passenger saloon was aft of the mooring compartment and was followed by a central corridor flanked by the toilets and galley, a mid-ship cabin, a spacious promenade cabin, and finally an aft-cabin, each stepped to a different height.[18] The cabins could be fitted with seating or sleeper bunks. Near the rear of the aircraft, an additional freight and mail compartment extended into the rear fuselage.[18]

The flying crew was seated in a spacious bridge with the captain and co-pilot seated side-by-side while the radio operator sat behind the captain, facing the rear.[17] The flight deck was well equipped and included an autopilot while flying instrumentation included a Hughes turn indicator, compass, and variometer, a Sperry artificial horizon and heading indicator, a Kollsman sensitive altimeter, a Marconi radio direction finder, a Smiths chronometer, and an attitude indicator.[15] The radio operator had Marconi shock-proof radio sets for transmitting and receiving while the retractable direction-finding loop antenna could be rotated for visual or aural homing.[15]

While designed as civil aircraft, examples of the type would not only see military service but were specifically refitted for this purpose. In 1941, two Empire flying boats – Clio and Cordelia were modified at Shorts' Belfast facility with gun turrets in dorsal and tail positions, bomb racks extending out of slots cut in the fuselage sides as on the Sunderland, and air to surface vessel (ASV) radar equipment installed on the top and sides of the fuselage.[19] They were used by Coastal Command. More extensive military use was made of the Empire's military counterpart, the Short Sunderland.

Operational history

[edit]
Empire flying boat, G-ADVD, named Challenger, at her moorings in the Townsville Harbour, Queensland, December 1938

On 8 February 1937, one of the Empire flying boats, Castor, conducted the first regular flight, flying from Calshot, Hampshire, England to Alexandria, Egypt.[20] This flight, which covered a distance of roughly 2,300 miles (3,700 km) non-stop, showed that Britain could move military material to its overseas bases by air.[21] On 18 February 1937, Caledonia, the first of the Empires built, flew the same Calshot-Alexandria route; it was able to traverse the route non-stop at an average speed of 170 mph.[20]

On 5 July 1937, the first crossing of the Atlantic by an Empire flying boat was conducted.[20] On an experimental basis, Caledonia, piloted by Captain W N Cummings, flew a 1,993 miles (3,207 km) route from Foynes on the River Shannon, Ireland west to Botwood on the Bay of Exploits, Newfoundland. On the same day, an American Sikorsky S-42 flying boat flew the opposite direction.[20] Caledonia took just over 15 hours (including a period spend searching for a landing spot), flying at an altitude of 1,500 to 5,000 ft (460 to 1,520 m) to cover 1,993 miles (3,207 km)—an average speed of about 130 mph (210 km/h). On its return flight, conducted on 22 July 1937, Caledonia flew the same route in the opposite direction in a time of 12 hours; in comparison to the competing Sikorsky S-42, the Empire was able to traverse the overall route faster.[20]

Several more survey flights of the Atlantic were made by Caledonia and Cambria. In August 1937, Cambria conducted the east–west flight in 14 hrs 24 min. In 1937, Cavalier was shipped to Bermuda and, after reassembly, started a service between there and New York City on 25 May 1937.[22]

The Short Empire was designed to operate along the Imperial Airways routes to South Africa and Australia, where no leg was much over 500 miles (800 km). After the design of the Empire had been finalised and production had commenced, it was recognised that, with some pressure from the United States, it would be desirable to offer a similar service across the Atlantic. The range of the S.23 was less than that of the equivalent American-built counterpart in the form of the Sikorsky S-42, and as such it could not provide a true transatlantic service. Two boats (Caledonia and Cambria) were lightened and furnished with long-range tanks; both aircraft were used in experimental in-flight refuelling trials in order for them to conduct the journey; these modifications came at the cost of being able to carry fewer passengers and less cargo.

The first TEAL aircraft, ZK-AMA, named Aotearoa, at Auckland, New Zealand

In an attempt to manage the Atlantic crossing, an alternative 'piggy-back' approach was trialled. This concept had been strongly advocated for by Imperial Airways' technical adviser, Major Robert Hobart Mayo, as a means of significantly increasing both range and payload, and had been well received by both the airline and the British Air Ministry, the latter of which placed an order with Shorts.[23] Using the S.21 design (based on the S.23) as the carrier, a smaller four-engined floatplane, the Short S.20, was mounted upon its back; the most obvious difference between the S.21 and regular S.23 aeroplanes was the additional superstructure to carry the floatplane.[24] Only a single example was built of the S.21 carrier aircraft, named Maia, and of the S.20, named Mercury. Together, they were known as the Short Mayo Composite.[25][24]

On 21 July 1938, a successful mid-air launch of Mercury was executed off the west coast of Ireland while carrying a 600 lb payload of mixed cargo and mail; it arrived at Montreal, Canada, 2,860 miles (4,600 km) 22 hrs 22 min later, having achieved an average speed of 141 mph (227 km/h).[24] In further flights, the Empire-Mercury combination went on to set a number of long-distance records; one such flight was conducted on 6 October 1938, flying from Dundee, Scotland to Orange River, South Africa, covering 6,045 miles (9,728 km) in 42 hrs 5 min.[26] However, in spite of the demonstrated merits and workability of the concept, the outbreak of the Second World War resulted in the effective termination of all development work. During wartime, there was interest in the concept using alternative land-based aircraft to deliver Hawker Hurricane fighter aircraft for aerial protection over the mid-Atlantic.[11]

After Italy entered the Second World War in June 1940, it became impossible for mail to be safely flown between Britain and Egypt (and thus onto Australia) via the Mediterranean. Accordingly, a new "Horseshoe Route" was established that ran from Auckland/Sydney via Cairo (following the old "Eastern Route") to Durban, South Africa, and thence by sea to Britain. This was restricted after the loss of Singapore in February 1942 to being between Durban and Calcutta, India.

Wartime experience in operating the type at overload weights resulted in the realisation that the Empires could take off at considerably higher weights than the conservative maxima provided by Shorts and, although the last Empire crossings to America were made in 1940 (by Clare and Clyde), many more flights were made on the long, demanding and vital over-water Lisbon-Bathurst flights.[citation needed]

Variants

[edit]
Qantas Short C Class Empire flying boat VH-ABB Coolangatta, ca. 1940

42 "C Class" Short Empire flying boats were built, including 31 S.23s, nine S.30s and two S.33s.[1]

  • S.23 Mk I : powered by four 920 hp (690 kW) Bristol Pegasus Xc poppet valve radial engines. 27 built.[1]
  • S.23 Mk II Bermuda : powered by four 920 horsepower (690 kW) Bristol Pegasus Xc poppet valve radial engines. 2 built.[1]
  • S.23 Mk III Atlantic : powered by four 920 hp (690 kW) Bristol Pegasus Xc poppet valve radial engines. two built.[1]
  • S.23M : two converted from impressed S.23 Mk I, with an ASV radar, armed with two Boulton Paul gun turrets and depth charges.
  • S.30 Mk I : powered by four 890 hp (660 kW) Bristol Perseus XIIc sleeve valve radial engines. One built.[1]
  • S.30 Mk I (Cathay) : powered by four 920 hp (690 kW) Bristol Pegasus Xc poppet valve radial engines. One built.[1]
  • S.30 Mk II New Zealand : powered by four 890 hp (660 kW) Bristol Perseus XIIc sleeve valve radial engines. One built.[1]
  • S.30 Mk III Atlantic : powered by four 890 hp (660 kW) Bristol Perseus XIIc sleeve valve radial engines. Four built.[1]
  • S.30 Mk IV New Zealand : powered by four 890 hp (660 kW) Bristol Perseus XIIc sleeve valve radial engines. Two built.[1]
  • S.30M : two converted from impressed S.30 Mk III Atlantic for ASV trials and transport duties.
  • S.33 : powered by four 920 hp (690 kW) Bristol Pegasus Xc poppet valve radial engines. Two completed, third example scrapped when 75% complete.[1]

Many S.23, S.30 & S.33 were re-engined during the war with 1,010 hp (750 kW) Bristol Pegasus XXII poppet valve radial engines.[1]

Accidents and incidents

[edit]

Most accidents involving the aircraft occurred during landing and were generally attributed to pilot error. For pilots trained on smaller less sophisticated aircraft judgement of height was difficult due to the high cockpit of the Empire, as well as the concept of using flaps to manage speed.[27] With time improved familiarity reduced the accident rate. Once in service the structure was found to be weak in places, especially on the planing bottoms, which led to later models employing thicker gauge skins on the hull and wings.[27]

24 March 1937
G-ADVA Capricornus of Imperial Airways crashed in the Beaujolais mountains in Central France, during the inaugural Southampton to Alexandria scheduled service.[28]
27 November 1938
G-AETV Calpurnia of Imperial Airways crashed on landing on Lake Habbaniya, Iraq with the loss of four lives.[29]
21 January 1939
G-ADUU Cavalier of Imperial Airways ditched in the Atlantic Ocean due to carburettor icing affecting all four engines. The aircraft subsequently sank with the loss of three lives. Ten survivors were rescued by the American tanker Esso Baytown.[30]
14 March 1939
G-ADVB Corsair (under Capt E.S. Alcock, brother of John Alcock) foundered during a forced landing on the Dungu River. After 10 months' salvage work, and one failed take-off attempt, it was flown off the river on 6 January 1940.[31]
1 May 1939
G-ADVD Challenger of Imperial Airways crashed on landing in Mozambique Harbour with the loss of two lives.[32]
February 1941
G-AFCX Clyde of BOAC was wrecked in a gale at Lisbon, Portugal.[33]
29 December 1941
G-ADUX Cassiopeia of BOAC crashed after striking debris on takeoff from Sabang, Indonesia, killing four.[34]
30 January 1942
G-AEUH Corio of BOAC was shot down by seven Japanese fighter aircraft and crashed off West Timor, killing 13 of the 18 people on board. The aircraft was owned by BOAC, but was operated by Qantas.
28 February 1942
G-AETZ Circe of Qantas was shot down 170 nmi (320 km) south of Java by Mitsubishi G4M "Betty" aircraft of the Imperial Japanese Navy with the loss of all on board.[35][36]
22 April 1943
G-AEUB (VH-ADU) crashed off Port Moresby, with 18 survivors.[37]

List of aircraft

[edit]
Empire G-AFBK, Coolangatta, June 1936
Empire G-AFKZ, Cathay, at Vaal Dam, South Africa, circa 1942
Empire G-ADUV, Corsair, moored on the lake at Gwalior, India
Empire ZK-AMA, Aotearoa, flying above Auckland, New Zealand
Empire G-ADUV, Cambria, taking off from the Nile at Rod El Farag flying boat base, Cairo
Empire G-ADUV, idling in the water
Empire G-ADUT, Centaurus photographed in flight from a Beech Staggerwing
List of aircraft[19]
Registration Name Operator
S.23
G-ADHL Canopus Imperial Airways/BOAC
G-ADHM Caledonia Imperial Airways, later BOAC
G-ADUT Centaurus Imperial Airways, to Royal Australian Air Force (RAAF) in 1939 (as serial A18-10)
G-ADUU Cavalier Imperial Airways. Crashed 21 January 1939
G-ADUV Cambria Imperial Airways, later BOAC
G-ADUW Castor Imperial Airways, later BOAC
G-ADUX Cassiopeia Imperial Airways, later BOAC
G-ADUY Capella Imperial Airways
G-ADUZ Cygnus Imperial Airways
G-ADVA Capricornus Imperial Airways
G-ADVB Corsair Imperial Airways, later BOAC
G-ADVC Courtier Imperial Airways
G-ADVD Challenger Imperial Airways
G-ADVE Centurion Imperial Airways
G-AETV Coriolanus Imperial Airways, later BOAC, to QANTAS in 1942 (as registration VH-ABG)
G-AETW Calpurnia Imperial Airways.
G-AETX Ceres Imperial Airways, later BOAC
G-AETY Clio Imperial Airways, later BOAC, to Royal Air Force (RAF) in 1940 (as AX659). Crashed 22 August 1941
G-AETZ Circe Imperial Airways, later BOAC
G-AEUA Calypso Imperial Airways, to QANTAS in 1939 not used directly, to RAAF (as serial A18-11)
G-AEUB Camilla Imperial Airways, later BOAC, to QANTAS (as VH-ADU)
G-AEUC Corinna Imperial Airways, later BOAC
G-AEUD Cordelia Imperial Airways, later BOAC, to RAF in 1940 (as AX660), returned to BOAC in 1941 (as G-AEUD)
G-AEUE Cameronian Imperial Airways, later BOAC
G-AEUF Corinthian Imperial Airways, later BOAC
G-AEUG Coogee Imperial Airways, to QANTAS in 1938 (as VH-ABC), to RAAF in 1939 (as A18-12)
G-AEUH Corio Imperial Airways, to QANTAS in 1938 (as VH-ABD), to Imperial Airways in 1939 (as G-AEUH)
G-AEUI Coorong Imperial Airways, to QANTAS in 1938 (as VH-ABE), to Imperial Airways in 1939 (as G-AEUI)
G-AFBJ Carpentaria Imperial Airways not used, to QANTAS in 1937 (as VH-ABA), to BOAC in 1942 (as G-AFBJ)
G-AFBK Coolangatta Imperial Airways not used, to QANTAS in 1937 (as VH-ABB), to RAAF in 1939 (as A18-13)
G-AFBL Cooee Imperial Airways not used, to QANTAS in 1937 (as VH-ABF) to BOAC in 1942
S.30
G-AFCT Champion Imperial Airways, later BOAC
G-AFCU Cabot Imperial Airways, to RAF in 1939 (as V3137).
Destroyed 5 May 1940
G-AFCV Caribou Imperial Airways, to RAF in 1939 (as V3138).
Destroyed 6 May 1940
G-AFCW Connemara Imperial Airways
G-AFCX Clyde Imperial Airways, later BOAC
G-AFCY Captain Cook Imperial Airways, to TEAL in 1940 (as ZK-AMC Awarua). Sold as obsolete in 1948[38][39]
G-AFCZ Australia then Clare Imperial Airways, to TEAL in 1940 (as ZK-AMB), later to BOAC
G-AFDA Aotearoa Imperial Airways, to TEAL in 1940 (as ZK-AMA). Sold as obsolete in 1948[40][39]
G-AFKZ Cathay Imperial Airways, later BOAC
S.33
G-AFPZ Clifton BOAC April 1940, to RAAF (as A18-14), to QANTAS in 1942 (as VH-ACD). Crashed January 1944.
G-AFRA Cleopatra BOAC May 1940, 1st Service 5 June 1940 Poole to Durban. Final Service ended 5 November 1946 at Poole. Scrapped 1946.

Operators

[edit]
Short S.23 Cooee of Qantas—this aircraft is also pictured at the top of the page while later serving with BOAC, as G-AFBL
The third TEAL aircraft, ZK-AMC, named Awarua, circa 1940

Civil operators

[edit]
 Australia
 New Zealand
 United Kingdom

Military operators

[edit]
 Australia
 United Kingdom

Specifications (Short S.23)

[edit]

Data from The Encyclopedia of World Aircraft,[41] The Short Empire Boats[24]

General characteristics

  • Crew: 5 (2 pilots, navigator, flight clerk and steward)[42]
  • Capacity: [42]
    • 24 day passengers or 16 sleeping passengers
    • 1.5 ton of mail
  • Length: 88 ft 0 in (26.82 m)
  • Wingspan: 114 ft 0 in (34.75 m)
  • Height: 31 ft 9+3⁄4 in (9.696 m)
  • Wing area: 1,500 sq ft (140 m2)
  • Empty weight: 23,500 lb (10,659 kg)
  • Gross weight: 40,500 lb (18,370 kg)
  • Powerplant: 4 × Bristol Pegasus Xc radial engines, 920 hp (690 kW) each

Performance

  • Maximum speed: 200 mph (320 km/h, 170 kn)
  • Cruise speed: 165 mph (266 km/h, 143 kn) [43]
  • Range: 760 mi (1,220 km, 660 nmi)
  • Service ceiling: 20,000 ft (6,100 m)
  • Rate of climb: 950 ft/min (4.8 m/s) [43]

See also

[edit]
External videos
video icon Compilation of statistics and footage on the Short Empire flying boats
video icon Period amateur video of an Empire in Sumba, Indonesia, in 1937
video icon British Pathé newsreel of a Empire Flying Boat flying the first experimental flight from Sydney to Southampton

Related development

Aircraft of comparable role, configuration, and era

Related lists

Notes

[edit]

References

[edit]
[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Short Empire

View on Grokipedia
from Grokipedia
The Short Empire was a medium-range, four-engined flying boat designed and built by in the 1930s specifically to meet ' requirements for long-haul passenger and mail transport across the , featuring a high-wing configuration with a streamlined hull and capacity for up to 24 passengers. Developed in response to a 1935 order from for 28 aircraft without a , the Short S.23 Empire—often referred to as the "C-Class"—first flew on 3 July 1936 as the Canopus, powered by four XC radial engines each producing 920 horsepower (686 kW), enabling a maximum speed of 200 mph (322 km/h), a cruise speed of 165 mph (265 km/h), and a range of approximately 760 miles (1,223 km) while carrying a 3.5-ton . Its all-metal stressed-skin construction, cantilever wing with powered flaps, and luxurious interior—including multiple cabins, a steward's pantry, and options for sleeping berths—marked it as a pioneering luxury airliner for routes spanning , , , and , with the first commercial service commencing on 8 February 1937 on the to route. By early 1938, 25 units had been delivered to and three to Empire Airways, with additional orders in 1937 bringing total production to around 42 aircraft across variants, though only 27 S.23 models were completed before shifted priorities. During the war, most surviving Empires were impressed into military service by the Royal Air Force (RAF), (RAAF), and (RNZAF) for , transport, and reconnaissance duties, often fitted with and defensive armament; notable losses included Corio shot down by Japanese fighters on 30 January 1942 and Circe by a on 28 February 1942, with seven wartime losses recorded for the S.23 variant. The design's influence extended to the wartime , and post-war, remaining civil examples continued limited operations with (BOAC) until 1947, when they were fully retired in favor of land-based aircraft. Variants such as the S.30 (with engines for extended range) and S.33 (increased weight capacity) further adapted the type for diverse roles, underscoring its role in bridging the empire's vast distances during a pivotal era of aviation history.

Development

Origins

In the early 1930s, , the designated British carrier for international services, sought to expand its long-distance operations across the Empire, necessitating more capable aircraft than existing models like the Short Calcutta and flying boats. These earlier designs, while effective for shorter routes, lacked the capacity and range for reliable transoceanic travel. In early 1934, approached with a proposal for a new four-engine flying boat capable of carrying 24 passengers in comfort, along with 1.5 tons of mail and freight, over a minimum range of 700 miles at a cruising speed of around 160 mph. This specification aimed to support the airline's ambitious network linking Britain to key destinations in , , and , primarily via the Eastern route through the Mediterranean and or the African route southward. Short Brothers, a pioneering firm in flying boat construction since the First World War, responded promptly to the proposal with a detailed tender by late June 1934. Drawing on experience from military designs like the reconnaissance flying boat, the company emphasized an all-metal configuration with four engines to enhance reliability and safety over remote oceanic expanses, where emergency landings might be required. Chief designer Arthur Gouge incorporated innovative features such as a high-aspect-ratio wing and a streamlined hull with a narrow planing bottom to minimize drag, influenced in part by observations of modern monoplanes like the during the 1934 . This approach marked a shift from the structures of prior generations, prioritizing efficiency for the demanding routes. In January 1935, placed an order for 28 S.23 "C-class" Empire flying boats at a cost of approximately £37,800 each, proceeding directly to production without building separate prototypes to accelerate development. The design process accelerated without extensive preliminary testing, as the airline urged rapid development to meet operational deadlines; the first aircraft, G-ADHL , was slated for its maiden flight in 1936 from . This contract underscored the strategic importance of the project in bolstering Britain's aerial links to its global possessions.

Production

The Short S.23 Empire flying boats were manufactured at ' Rochester factory in , , between 1936 and 1938, where the hulls and major components were constructed before transport to the nearby for launch, followed by final assembly, engine installation, and water trials at the Felixstowe seaplane base. This facility, expanded in the early to handle large flying boat production, enabled a steady output rate of approximately one aircraft per month once full-scale manufacturing began in late 1936. The first three aircraft were G-ADHL , which completed its on 3 July 1936; G-ADHM Caledonia, which flew on 15 September 1936; and G-ADUV , which followed in early 1937, with all three entering commercial service on routes during 1937 after certification and route proving. Of the initial 28 S.23 ordered by , 25 were delivered to them and 3 diverted to Airways. Further contracts in 1937 added three more S.23 to , bringing the total S.23 production to 31 aircraft, with additional units of the S.30 variant for (), culminating in 42 flying boats completed across all variants by 1940. Pre-World War II production encountered challenges from material shortages, particularly aluminum and specialized alloys prioritized for military rearmament, which occasionally delayed component fabrication despite the factory's efficient processes. Wartime demands further shifted resources after , requisitioning completed for RAF use and halting civilian output, with each S.23 costing around £37,800 to £50,000 in pounds depending on configuration and escalation in material prices.

Experimental adaptations

One notable experimental adaptation of the Short Empire involved its modification into the lower component of the , developed in collaboration between engineer Major Robert H. Mayo and ' chief designer Arthur Gouge to enable long-range mail delivery without intermediate stops. The carrier aircraft, designated (G-ADHK), was a modified S.23 Empire flying boat with strengthened structure, additional fuel tanks, and a dorsal pylon for mounting the upper component, the (G-ADHJ), which featured four VI engines and streamlined floats for reduced drag. This piggy-back configuration allowed the Mercury to take off fully loaded from the Maia's back at high altitude, conserving fuel for extended range; the first successful in-flight separation occurred on February 6, 1938, over the . The Short-Mayo system proved effective in range extension trials, culminating in the first commercial non-stop east-to-west on , , when Mercury was air-launched from Maia over , , and flew 2,930 miles to Boucherville, near , in 20 hours and 20 minutes, carrying 274 pounds of . Subsequent operations included multiple experimental flights across the Atlantic, with Mercury completing at least three such crossings in under the composite setup, as well as a record non-stop flight from , , to the Transvaal, , covering over 6,000 miles in after further fuel capacity enhancements. The mechanism relied on electromechanical release for separation at approximately 3,000 feet, enabling the Mercury to glide and then climb on its own power, achieving effective ranges up to 2,500 miles for payload delivery without the need for . Parallel experimental efforts focused on in-flight refueling to extend the Short Empire's transatlantic capabilities for services, utilizing modified S.30 long-range variants such as Cabot (G-AFCU) and Caribou (G-AFCT), which featured reinforced airframes for 53,000-pound gross weights, stripped interiors, and additional fuel tanks. These trials, conducted by in collaboration with Flight Refuelling Ltd., employed a looped-hose system where converted Harrow bombers trailed a hose with a drogue-like loop, which the Empire's trailing captured and reeled in for connection to onboard tanks; demonstrations began in 1938 over and expanded to transatlantic routes in 1939. Between , , and Gander or Botwood, Newfoundland, Cabot and Caribou completed eight round-trip flights—totaling 16 one-way transatlantic segments—under winter conditions, with each refueling taking about 15 minutes at 6,000 to 8,000 feet altitude and enabling non-stop legs of 1,550 to 1,680 statute miles in 10 to 11 hours. The S.30 variants also underwent modifications for enhanced performance in long-range mail delivery experiments, including increased fuel capacity and aerodynamic refinements to support higher cruise altitudes around 8,000 feet for efficiency, as demonstrated in pre-war trials aimed at reliable transoceanic operations. Although neither the Short-Mayo composite nor the refueling system entered routine operational service due to the onset of and the shift to priorities, these adaptations provided valuable data on range extension techniques, influencing subsequent developments during the war, such as Flight Refuelling Ltd.'s looped-hose applications for RAF .

Design

Airframe and hull

The Short Empire flying boat featured an all-metal cantilever monoplane airframe, constructed primarily from aluminum alloys such as duralumin and Alclad to provide strength and lightness while resisting the corrosive effects of marine environments. The structure utilized stressed-skin construction with Z-section stringers, I-beam keels, and channel-section frames in the hull, riveted together with flush-fitting rivets (approximately 250,000 for the hull) over thousands of square feet of light-alloy sheet. The wings employed extruded T-section spars made from Hiduminium R.R.56 alloy, supplemented by tubular N-girders and Z-section stringers, also covered in Alclad stressed skin for durability. This design allowed for a high-mounted gull wing configuration with a span of 114 feet (34.75 m), incorporating a high-lift aerofoil section up to 20% thick at the root, which enhanced lift and structural integrity without external bracing. The hull adopted a narrow-beam, two-stepped planing bottom with a deep-V forward section transitioning to a modified V-shape amidships, featuring chines to control spray and a forward-raked main step aft of frame 20/21 for efficient water displacement during . This hydrodynamic form reduced drag compared to earlier wide-bottomed Short designs, enabling stable planing at speeds up to 26 knots while minimizing porpoising, though it required careful handling in rough water to avoid damage to the 16-18 SWG . The planing bottom and chines were plated with aluminum sheet for corrosion resistance, with fittings at high-stress points; some components coated with for additional protection without adding significant weight. The overall hull measured 88 feet (26.82 m), with a bare hull weight of approximately 5,900 pounds (2,676 kg), contributing to an empty weight of around 23,500 pounds (10,659 kg). Stability on water was ensured by wingtip stabilizing floats, which served as sponsons with 5,000 to 6,000 pounds of each, positioned to prevent lateral without the drag penalties of hull-mounted sponsons. These detachable floats, constructed from DTD 275 clad aluminum sheet, were interchangeable between types and included single steps for hydrodynamic efficiency. The wings integrated tanks—one main 325-gallon cylindrical unit per , positioned between the inner and outer nacelles—for center-of-gravity balance, with total standard capacity of approximately 650 imperial gallons, scalable up to 1,800 gallons in long-range configurations using auxiliary tanks. Tail surfaces followed a conventional arrangement, with fabric-covered elevators and a to maintain directional control, all mounted high on the hull to clear spray. The reached 40,500 pounds (18,370 kg), balancing the airframe's structural limits with operational payloads.

Powerplant and propulsion

The Short Empire flying boat was powered by four XC nine-cylinder air-cooled radial engines, each rated at 920 horsepower for takeoff, mounted in streamlined s on the high-mounted cantilever wing. These engines drove Hamilton three-bladed variable-pitch propellers with a of 12 feet 9 inches, allowing optimized performance for takeoff and cruise through adjustable blade angles. The design incorporated long-chord cowlings with adjustable flaps to regulate airflow over the cylinders, facilitating efficient and easy access for maintenance. The fuel system featured large cylindrical tanks integrated into the wing structure between the inner and outer engines, with a standard capacity of approximately 650 imperial gallons of 87-octane aviation fuel in the main tanks, supporting operational ranges suited to empire routes. Auxiliary tanks could be added in the wings or hull for extended missions, increasing total capacity to enable flights up to 1,800 miles, though these were fitted selectively based on route requirements. Oil capacity stood at 44 imperial gallons, stored in tanks within the engine nacelles, with coolers positioned in the wing leading edges to maintain lubrication under varying loads. Across variants, engine selections evolved for improved efficiency and altitude performance. Later S.23 models incorporated XXII engines, delivering 1,000 horsepower each through enhanced supercharging, while the S.30 and S.33 series adopted XC sleeve-valve radials rated at 890 horsepower, better suited for higher-altitude operations due to their design advantages in reduced drag and improved . Reliability was enhanced by features such as dual ignition systems with screened harnesses to mitigate electrical interference over water, and Eclipse starters with booster coils for dependable cold-weather ignition.

Cabin and operational features

The Short Empire flying boat employed a two-deck hull configuration to optimize space for both crew and passengers during extended transoceanic flights. The upper deck primarily served crew functions, featuring an enclosed for the captain and first officer, alongside dedicated spaces for the and , with the steward's quarters nearby to facilitate service. This layout allowed for efficient navigation and communication operations, including rooms equipped for long-range radio contact essential to Empire routes. The lower deck focused on passenger comfort, divided into forward and aft cabins seating up to 24 individuals in adjustable reclining chairs during daytime operations, complemented by a central dining lounge and baggage compartments. For overnight segments on 10- to 14-hour legs, the arrangement converted to sleeping berths for 16 passengers, promoting rest amid the journey's demands. Amenities such as a midships galley enabled the preparation of hot meals, while lavatories and a promenade area enhanced the onboard experience, reflecting the era's emphasis on luxury air travel. Operationally, the aircraft supported a standard crew of five—comprising two pilots, a , a flight handling radio duties, and a steward—ensuring comprehensive management of flight and needs. Navigation relied on radio aids for position fixes over remote waters, supplemented by safety provisions like launch systems, drogues, and distress signals stored in the forward marine compartment to mitigate ditching risks. Mail carriage capacity reached 1.5 tons (approximately 3,300 pounds), underscoring the Empire's dual role in transport and imperial services.

Operational history

Commercial service

The Short Empire flying boats entered commercial service with in late 1936, with the first regular operations commencing on the Mediterranean leg of the Horseshoe Route from to in 1937. This route, which looped southward via the Nile, Red Sea, and to connect Britain with its African and Asian territories, was soon extended eastward to and beyond. By March 1938, services reached , enabling partnerships with Empire Airways to operate the leg from to starting in July 1938. Further extension to occurred in April 1940 through collaboration with (), linking to . A key milestone was the inauguration of the first scheduled service on 12 1938 by the aircraft (G-ADUT), which had previously conducted a 1937 survey flight. These operations highlighted the Empire boats' role in elite and diplomatic travel, with luxurious accommodations for up to 24 passengers. During , following the merger of into (BOAC) on 1 1940, the fleet continued civilian mail and passenger runs across the Atlantic and . BOAC's Horseshoe Route from to and onward through to persisted until February 1942, supporting essential connectivity. The introduction of the Short Empire dramatically shortened travel times, reducing the journey from Britain to to 8 days and 23 hours by , compared to several weeks by . One-way fares to stood at approximately £160 in , inclusive of meals and accommodations, making accessible to affluent s and travelers. Pre-1940 operations logged significant passenger miles, with 14,732 eastbound and 15,041 westbound miles between the and in alone, contributing to over 5,000 passengers carried by early 1939. In wartime, BOAC adapted several Empire boats for continued civil use, including paint schemes to mitigate threats on Atlantic and African routes, where they delivered critical aerogrammes and airgraphs despite heightened risks. These efforts maintained vital and links, with like Caribou and Clyde undertaking transatlantic flights carrying up to 454 kg of per starting in August 1939.

Military employment

At the outbreak of in , numerous civil Short Empire flying boats operated by and other carriers were impressed into service with the Royal Air Force's Coastal Command to support patrols, troop and supply transport to and the , and ferry operations across oceanic routes. These aircraft, drawn from the existing civil fleet, provided an immediate capability for long-range maritime tasks where purpose-built military flying boats were still being scaled up. To adapt the Short Empire for combat roles, selected airframes underwent modifications including the installation of Air-to-Surface Vessel (ASV) radar for detecting submerged U-boats, .303-inch machine guns mounted in nose and dorsal Boulton Paul four-gun turrets for defensive armament, and underwing bomb racks capable of carrying up to six 450-pound depth charges for anti-submarine attacks. At least two aircraft—Clio (G-AETY, serial AX659) and Cordelia (G-AEUD, serial AX660)—were converted to the S.23M standard at ' Belfast facility in 1941 and assigned to Coastal Command squadrons for operational trials. In the Pacific theater, the Royal Australian Air Force (RAAF) impressed several and Empires, such as Coogee (VH-ABC, A18-12), Coolangatta (VH-ABB, A18-13), Centaurus (G-ADUT, A18-10), and Calypso (G-AEUA, A18-11), equipping some with extended fuel tanks for extended-range missions; while specific (RNZAF) units operated Sunderlands primarily, impressed Empires supported auxiliary transport in the region under joint Commonwealth efforts. Key operations included long-range patrols over the Atlantic Ocean, with bases such as in serving as critical staging points for anti-submarine sweeps against German U-boats; for instance, the Empire Clare (G-AFCZ) operated from West African waters before its loss in September 1942 en route from Bathurst, . Evacuation missions proved vital, exemplified by the RAF's Coorong (G-AEUL) conducting seven flights in April-May 1941 to rescue approximately 235 personnel from German-occupied , while RAAF Empires evacuated civilians and troops from Japanese-threatened areas like , , and —contributing to an air bridge that transported thousands of Dutch refugees via Broome, , in early 1942, with total evacuees exceeding 8,000 across all means. Supply runs sustained isolated Allied outposts, with RAAF aircraft delivering munitions and personnel to forward bases in , including and Milne Bay. More than ten Empires were lost to enemy action across these theaters, including Corio (A18-14) shot down by Japanese fighters off on 30 January 1942 with five survivors, Centaurus destroyed on the ground at Broome during a raid on 3 March 1942, and two others sunk in the same attack alongside thirteen other flying boats, contributing to around 100 fatalities. By 1943, as more advanced types like the entered widespread service, the Empire's frontline roles diminished, with surviving airframes reassigned to training units for aircrew familiarization in flying boat operations and second-line duties such as communications and search-and-rescue.

Post-war retirement

Following the conclusion of , (BOAC) phased out its Short Empire flying boats from commercial operations, with the final services on routes including to to ceasing in early 1947. These aircraft were replaced by land-based types such as the , which offered lower operating costs and required less specialized waterfront infrastructure amid post-war economic constraints. The shift was driven by escalating maintenance expenses for flying boat bases and vessels, which exceeded £1 million annually for BOAC by 1947, compounded by the absence of renewed government subsidies for Empire air mail services that had previously supported the fleet. Most of the surviving Empire fleet met its end through scrapping at key operational sites. In the , several were dismantled at Hythe, including G-ADVB Corsair in 1947. In , aircraft like Qantas's (VH-ABA) were broken up at Rose Bay in 1948, despite efforts by enthusiasts to preserve it for display. No significant commercial reuse occurred due to the high per-aircraft upkeep demands and outdated performance relative to emerging landplanes. The two Short S.30 Empires operated by (TEAL) in , ZK-AMA and ZK-AMC Awarua, were withdrawn from service in June 1947 after completing their last flights. ZK-AMC was sold by tender later that year, with its hull repurposed as a clubhouse for the Hobsonville Yacht Club before eventual disposal; ZK-AMA was stored at RNZAF Hobsonville and later converted into a at Mechanics Bay in , operating in that role into the late 1950s until scrapped. Although the Empire's hull and powerplant innovations informed later Short Brothers designs like the post-war Solent flying boat, none of the original aircraft were preserved, marking the definitive end of their operational legacy by 1948.

Variants

S.23 Empire

The Short S.23 Empire served as the primary civil transport variant of the Short Empire flying boat series, with a total of 31 aircraft constructed between 1936 and 1938, with 25 for Imperial Airways and 6 for Qantas Empire Airways. Powered by four Bristol Pegasus XC nine-cylinder radial engines, each delivering 920 horsepower, the S.23 was optimized for medium-range operations, accommodating up to 24 passengers in a comfortable cabin layout while achieving a standard range of approximately 760 miles at cruising speed. Compared to the prototype Canopus (G-ADHL), production S.23 models featured refinements such as a more robust all-metal stressed-skin construction and electric Gouge flaps on the high wing for better low-speed handling and takeoff performance on water. These changes enhanced overall stability and operational reliability for the demanding routes spanning , , and . The production run included aircraft with British civil registrations ranging from G-ADHL to G-AEVA, with all examples bearing names beginning with "C," such as (G-ADHL), Caledonia (G-ADHM), and Cambria (G-ADUV); these boats formed the backbone of ' fleet, enabling scheduled passenger and mail services across the . Some S.23s were fitted with optional auxiliary fuel tanks, extending the range to around 1,000 miles for specific longer legs while maintaining a service ceiling of 20,000 feet (6,100 m) to navigate typical operational altitudes.

S.30 and S.33 Empires

The S.30 Empire II represented an evolution of the standard Short Empire flying boat, optimized for challenging environmental conditions. Nine aircraft were constructed between 1939 and 1940, primarily to Imperial Airways specifications for extended operations on hot-weather routes. These featured four XIIC sleeve-valve radial engines, each delivering 890 hp (664 kW), which offered improved efficiency and reliability in high-temperature environments compared to the poppet-valve engines of earlier models. The installation reduced drag and enhanced performance in tropical climates, enabling service on African and Indian routes, with a still-air range of approximately 705 nautical miles (1,305 km) while achieving a higher service ceiling of 20,000 ft (6,100 m). Operated initially by and later by BOAC during wartime, the S.30 fleet supported vital tropical services, including the West African route from to , where they contended with extreme heat exceeding 50°C, corrosion, and extended takeoff requirements. Several units, such as G-AFCU Cabot and G-AFCV Caribou, were impressed into RAF service in , receiving minor adaptations like added armor plating, Lewis machine guns for defense, and bomb racks for maritime , without significant structural modifications to the base airframe. Some S.30s also participated in in-flight refueling trials, incorporating specialized systems such as hydraulic locking mechanisms and sliding valves to facilitate mid-air fuel transfer. The S.33 variant was a rarer adaptation, with only two units completed in 1940 out of three ordered, comprising Clifton (G-AFPZ, c/n S.1025) and Cleopatra (G-AFRA, c/n S.1026). Retaining the Bristol Pegasus XC radial engines at 920 hp (690 kW) each—similar to the S.23 but with potential upgrades to the 1,010 hp (753 kW) Pegasus XXII in service—these aircraft emphasized durability through a strengthened fuselage and increased hull plating for buoyancy and operational resilience. The third airframe (c/n S.1027) was scrapped while approximately 75% complete due to shifting production priorities. Delivered to BOAC for commercial duties, the S.33s saw limited frontline use, primarily on routes, with finishes applied for wartime conditions; both were eventually transferred to military operators like the RAAF. One example, VH-ACD (Clifton), was lost in a training accident off on 18 January 1944, resulting in no fatalities but ending its career. The surviving unit was retired and scrapped post-war, marking the end of S.33 operations by the mid-1940s.

Incidents and accidents

Pre-war incidents

The Short Empire flying boats experienced several incidents during their pre-war commercial operations, primarily involving navigation errors, pilot misjudgments, and challenging environmental conditions, resulting in the loss of at least eight aircraft and 19 fatalities between 1937 and 1939. On 24 March 1937, ' G-ADVA crashed into the Mountains near Ouroux, , while en route from to . The struck terrain during a descent through snow clouds over mountainous country, killing five of the 14 people on board due to a navigation error in poor . On 1 October 1937, ' G-ADVC Courtier crashed during landing in Faliron Bay off , . The flying boat broke apart on impact in calm conditions, resulting in three passenger fatalities out of 13 on board; the aircraft sank. On 5 December 1937, ' G-ADUZ Cygnus crashed shortly after takeoff from Harbour, , during a flight from to . Incorrect flap settings caused the flying boat to porpoise and stall into the sea, resulting in two fatalities (a crew member and a passenger) and injuries to six others among the 13 on board. On 27 November 1938, Imperial Airways' G-AETW Calpurnia crashed into the desert near Lake Habbaniyah, Iraq, while approaching for landing in a sandstorm at night. The captain descended too low to maintain visual contact with the ground, leading to a collision with terrain that destroyed the aircraft and killed all four occupants. In early 1939, additional incidents highlighted ongoing challenges. On 21 January 1939, Imperial Airways' G-ADUU Cavalier ditched in the Atlantic Ocean approximately 285 miles southeast of Port Washington due to engine failure from carburetor icing, sinking with three fatalities (two passengers and one crew) out of 13 on board; ten survivors were rescued. On 12 March 1939, Imperial Airways' G-ADUY Capella suffered hull damage from a collision with floating debris while taxiing at Batavia (now Jakarta), Indonesia; all eight occupants evacuated safely before it partially sank, but the aircraft was damaged beyond repair and written off. On 1 May 1939, Imperial Airways' G-ADVD Challenger ditched off Lumbo, Mozambique, after porpoising on a second landing attempt in rough seas, severing the cockpit and killing two crew members while injuring four others; the aircraft was lost. On 12 June 1939, G-ADVE struck the water out of control during landing in strong winds at Calcutta, India, sinking the flying boat with no fatalities among the eight on board. These events underscored mechanical reliability and weather-related risks in the early fleet.

Wartime incidents

During , the Short Empire flying boats, originally designed for civilian service, faced significant risks when repurposed for military transport and evacuation duties, particularly in the Pacific theater where they operated without defensive armament or armor plating. These vulnerabilities exposed them to enemy air attacks and operational hazards, resulting in at least ten losses to combat action and operational causes during the war, contributing to around 18 total wartime attrition and over 60 fatalities. On 30 January 1942, the BOAC-operated G-AEUH Corio was shot down by Japanese Zero fighters while evacuating civilians from , , to Broome, . The aircraft crashed into the sea off the southern coast of , killing 13 of the 19 people on board; five survivors, including the captain and first officer, were rescued by a Dutch vessel. This incident highlighted the lack of defensive capabilities, as the unarmed flying boat was unable to evade the attacking fighters. Another major combat loss occurred on 28 1942, when BOAC's G-AETZ was shot down by a Japanese bomber over the during an evacuation flight from Tjilatjap, Java, to Broome, . All 18 occupants perished in the crash, marking one of the deadliest single incidents for the type during the war. The attack demonstrated the flying boats' susceptibility to long-range enemy and bombing in contested maritime routes. On 3 March 1942, a Japanese air raid on Roebuck Bay at , destroyed several moored flying boats, including RAAF's A18-10 (ex-G-ADUT) and BOAC's G-AEUC . The attack sank or severely damaged the , contributing to 16 fatalities across the raid from and bombing (from all involved). This event illustrated the risks of basing the unarmored boats in forward areas vulnerable to surprise aerial assaults. Other notable wartime losses included the operational crash of BOAC's G-AEUF Corinthian on 22 March 1942 near Darwin, , after striking floating debris during landing, with all crew rescued and no fatalities; the RAAF's A18-12 Coogee crash on 27 February 1942 near , killing 6; and Qantas' VH-ADU Camilla on 22 April 1943 near , . En route from , , the aircraft encountered poor weather and navigational difficulties, leading to a stall and heavy impact into Hood Lagoon; 13 of the 15 aboard died. Investigations attributed the incident to adverse conditions compounded by the demands of long overwater flights without advanced aids. Additional losses, such as G-ADUX Cassiopeia on 29 December 1941 at Sabang (4 fatalities) and G-AFCX Clyde wrecked in a at in February 1941, further highlighted operational hazards. Post-incident inquiries, including those by Australian civil aviation authorities, emphasized systemic issues like crew fatigue from extended patrols and inadequate for night and overwater , prompting recommendations for enhanced and modifications despite the aircraft's origins. These losses collectively accounted for over 60 fatalities and influenced the transition to more militarized designs like the for postwar service.

Operators

Civil operators

The primary civil operator of the Short Empire flying boat was , which placed an initial order for 28 S.23 variants in 1936 to serve on Empire Air Mail Scheme routes. These aircraft, such as G-ADHL Canopus and G-ADUT Centaurus, were based primarily at Hythe in the and Rose Bay in , entering service from February 1937 for passenger, , and freight transport. In 1939, merged into (BOAC), which continued operating the fleet—now numbering around 25 aircraft—until the end of the war, with most retired or scrapped by 1947. Qantas Empire Airways operated six S.23 Empire flying boats, with three (Coorong, Coogee, and Corio) diverted from Imperial's order and delivered in 1938, plus three additional units acquired later. Notable examples included VH-ABD Corio, VH-ABA Carpentaria, VH-ABB Coolangatta, and VH-ABF Cooee, based at Rose Bay, Sydney, and used from July 1938 for passenger and mail services linking Australia to England via surveys and regular flights until retirement in 1947. Tasman Empire Airways Limited (TEAL) acquired three S.30 Empire variants in 1940 for trans-Tasman operations between and . These were ZK-AMA (ex-G-AFDA), ZK-AMB (ex-G-AFCP), and ZK-AMC Awarua (ex-G-AFCY), based in and , providing passenger and mail services from April 1940 and later supporting surveys until all were withdrawn in 1947. Across all civil operators, a total of approximately 42 Short Empire flying boats (S.23 and S.30 variants) were allocated to commercial service, with the majority serving the network before post-war retirement by 1948.

Military operators

The impressed several Short Empire flying boats for service with Coastal Command, converting them for long-range and roles from 1939 onward. These aircraft were based in the and later in , with over 15 utilized in operations by squadrons including No. 240 and No. 320. By 1944, most had been phased out, returned to civil operators or scrapped. The Royal Australian Air Force impressed four Short S.23 Empire flying boats: one from (A18-10) and one from (A18-11) in September 1939, plus two from (A18-12 and A18-13) in June 1940, along with one leased from BOAC (A18-14) in March 1942, for transport and general duties. These were primarily operated by No. 11 Squadron RAAF in the Pacific and regions, with some support from No. 33 and No. 41 Squadrons, conducting evacuations and patrols from bases including Darwin and until 1943. All were released for civil use or destroyed by war's end in 1943–1944.

Specifications

General characteristics (Short S.23)

The Short S.23 Empire was a four-engined flying boat designed primarily for civil and transport, with provisions for military adaptation in select variants. It featured a crew of five, comprising two pilots, a , a (or flight clerk), and a steward to manage needs during flights. The accommodated up to 24 s (or 17 with increased load) and up to 4,000 lb (1,814 kg) of and freight in daytime configuration, for a total of approximately 7,000 lb (3,175 kg), or alternatively carried freight and in cargo operations. Key structural dimensions included a of 88 feet (26.82 m), a of 114 feet (34.75 m), and a of 31 feet 10 inches (9.70 m), with a wing area of 1,500 square feet (139.35 m²) supporting its high-wing layout. Weights were approximately 23,500 pounds (10,659 kg) empty and 40,500 pounds (18,370 kg) at maximum takeoff. Power was provided by four XC radial engines, each delivering 920 horsepower (686 kW). In military configurations, such as the S.23M variant, the aircraft was fitted with ASV radar, two .303-inch (7.7 mm) four-gun machine gun turrets for defense, and provisions for six depth charges for anti-submarine roles.
CharacteristicSpecification
Crew5 (2 pilots, navigator, radio operator, steward)
Capacity24 passengers (or 17 with increased mail) and up to 4,000 lb (1,814 kg) mail/freight; total payload ~7,000 lb (3,175 kg)
Length88 ft (26.82 m)
Wingspan114 ft (34.75 m)
Height31 ft 10 in (9.70 m)
Wing area1,500 sq ft (139.35 m²)
Empty weight23,500 lb (10,659 kg)
Max takeoff weight40,500 lb (18,370 kg)
Powerplant4 × Bristol Pegasus XC radial engines, 920 hp (686 kW) each
Armament (optional, military variants)2 × four-gun .303 in (7.7 mm) machine gun turrets; provisions for 6 × depth charges

Performance (Short S.23)

The Short S.23 Empire flying boat was engineered for reliable performance on medium-range oceanic routes, with a maximum speed of 200 mph (322 km/h) achieved at 5,500 ft (1,680 m). Its maximum cruising speed was 165 mph (266 km/h) at 11,000 ft (3,350 m), enabling efficient operations while carrying up to 24 passengers and mail. The standard range with full and totaling 9,200 lbs (4,173 kg) was 760 miles (1,220 km) in still air, sufficient for key legs of the Empire air mail scheme. For extended missions, auxiliary fuel tanks could boost the range to approximately 1,870 miles, as configured in long-range variants of the S.23 class. The aircraft's service ceiling reached 20,000 ft (6,100 m), providing clearance over typical weather systems encountered on transcontinental flights. At , it attained a of 950 ft/min (4.8 m/s) in coarse pitch, supporting quick ascents after water takeoffs. Fuel consumption at cruising speed averaged around 130 gallons per hour. With standard tanks of 652 gallons, this provided about 5 hours for the baseline range of 760 miles. Auxiliary tanks extended operational to up to 10 hours or more for longer sectors. Compared to contemporaries like the , the S.23 excelled in payload-range balance for oceanic services, facilitating faster survey times on routes such as the North Atlantic.

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  17. https://nfhwa.org/hythes-flying-boat-history/
  18. https://www.britairliners.org/airliners-article?title=short-brothers%25E2%2580%25A6the-forgotten-tra&id=42
  19. https://www.gracesguide.co.uk/Short_Mayo_Composite
  20. https://www.aviastar.org/air/england/short_mayo.php
  21. https://www.govinfo.gov/content/pkg/GOVPUB-D301-PURL-LPS47711/pdf/GOVPUB-D301-PURL-LPS47711.pdf
  22. https://flyingboatmuseum.com/early-aviation-experiments-to-achieve-nonstop-transatlantic-flight/
  23. https://ntrs.nasa.gov/api/citations/19930090518/downloads/19930090518.pdf
  24. https://www.seawings.co.uk/images/EmpireProfilebookgal/Flying%20Empires%20Book.pdf
  25. https://pdhonline.com/courses/m490/m490handout.pdf
  26. https://www.gruppofalchi.com/files/Profile-Publications-Aircraft-084---Short-Empire-Boats.pdf
  27. https://caspir.warplane.com/aircraft/serial-search/aircraft-no/200001524
  28. https://wondersofworldengineering.com/flying-boats.html
  29. https://www.wondersofworldaviation.com/mobile/flying-boats.html
  30. https://airpages.ru/eng/uk/s23.shtml
  31. https://www.ssarkansan.com/american-hawaiian-in-wwii/honolulan/raf-no-204-squadron
  32. https://visit.museum.wa.gov.au/broome-flying-boats-1942
  33. https://www.gracesguide.co.uk/Short_Brothers:_S.30_Empire
  34. https://www.airhistory.net/aircraft/22389/Short-S-30-Empire
  35. http://www.century-of-flight.freeola.com/Aviation%20history/coming%20of%20age/imperial/short%20s30%20empire.htm
  36. https://www.gracesguide.co.uk/Short_Brothers:_S.33_Empire_Flying_Boat
  37. https://www.baaa-acro.com/aircraft/short-s33-empire-flying-boat
  38. https://www.baaa-acro.com/aircraft/short-s23-empire-flying-boat
  39. https://asn.flightsafety.org/wikibase/342313
  40. https://www.baaa-acro.com/crash/crash-short-s23-empire-flying-boat-athens-3-killed
  41. https://asn.flightsafety.org/wikibase/342284
  42. https://asn.flightsafety.org/wikibase/342273
  43. https://asn.flightsafety.org/wikibase/342208
  44. https://www.baaa-acro.com/crash/crash-short-s23-empire-flying-boat-near-habbaniya-lake-4-killed
  45. https://asn.flightsafety.org/wikibase/342193
  46. https://www.baaa-acro.com/crash/crash-short-s23-empire-flying-boat-atlantic-ocean-3-killed
  47. https://asn.flightsafety.org/wikibase/342184
  48. https://www.baaa-acro.com/crash/crash-short-s23-empire-flying-boat-batavia
  49. https://pacificwrecks.com/aircraft/short/index.html
  50. https://asn.flightsafety.org/wikibase/341546
  51. https://pacificwrecks.com/aircraft/short/circe.html
  52. https://asn.flightsafety.org/wikibase/341509
  53. https://pacificwrecks.com/aircraft/short/A18-10.html
  54. https://www.awm.gov.au/visit/exhibitions/alliesinadversity/japanese/broome
  55. https://assets.simpleviewinc.com/simpleview/image/upload/v1/clients/australiasnwtourism/Broome_Air_Raid_1942_Embassy_of_the_Kingdom_of_the_Netherlands_f8780613-a1d9-468e-ac3e-3403fb5d58cd.pdf
  56. https://pacificwrecks.com/aircraft/short/corinthian.html
  57. https://asn.flightsafety.org/wikibase/341481
  58. https://asn.flightsafety.org/wikibase/341039
  59. https://pacificwrecks.com/aircraft/short/camilla.html
  60. https://asn.flightsafety.org/wikibase/341602
  61. https://www.teal.co.nz/tasman-empire-airways-limited
  62. http://www.adf-serials.com/research/empireflyingboats.pdf
  63. http://www.aviastar.org/air/england/short_empire.php
  64. https://pacificwrecks.com/aircraft/short/tech.html
  65. https://www.aussieairliners.org/shortfb/g-advd/gadvd.html
  66. https://media.defense.gov/2010/Sep/29/2001309638/-1/-1/0/AFD-100929-015.pdf
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