The Sopwith T.1 Cuckoo was a potentially promising torpedo bomber that was left down by its Sunbeam Arab engine, and was only just entering service at the end of the First World War.
The idea of using aircraft to carry torpedoes had been discussed before the outbreak of war in 1914, and Sopwith had designed a large seaplane, the Sopwith Special Seaplane, to test out the idea. However no powerful enough engine was found, and the Special never took off carrying a torpedo. The first successful torpedo drop came on 28 July 1914, from a Short Folder seaplane. In 1915 the Short 184 seaplane entered service, and this was just about able to carry a 14in torpedo. More torpedo carrying floatplanes were developed, but they all suffered from having to carry the heavy floats as well as the heavy torpedo.
By 1915 thought was beginning to turn to the idea of using a wheeled torpedo bomber, which would take off a floating flat decked barge. On 9 October 1916 Commodore Murray Sueter officially asked Sopwith to start work on a new torpedo bomber. This was to be a one man aircraft, with one version capable of carrying one 1,000lb torpedo and a second two torpedoes. Both were to carry fuel for four hours. It was expected that it would be launched by catapult.
Sopwith allocated the designation T.1 to the single torpedo aircraft and T.2 to the two torpedo version, although never started work on the T.2. By February 1917 they had produced the fuselage of the T.1, but by then Sueter had been moved to Italy and interest in the project appears to have dropped. In February 1917 the aircraft was seen by Wing Commander A.M. Longmore (later Air Chief Marshal Sir Arthur Longmore, and before that the man who had made that first torpedo drop), who expressed an interest in it and got the project revived.
The T.1 was somewhat similar to the contemporary Sopwith B.1 Bomber, of which two prototypes were produced. They were both large single seat biplanes powered by a 200hp Hispano-Suiza engine, but the T.1 would prove to be the better design.
The T.1 was a three bay biplane with folding wings, The wings folded backwards at the first interbay struts. The undercarriage was attached at the same point on the lower centre section. The widely spread wheels were attached without a cross bar, leaving space for the torpedo between them. It had a wingspan of 46ft 9in, making it significantly larger than the B.1 The pilot’s cockpit was in line with the trailing edge of the wing, with the fuel, oil and water tanks in front him (opposite to the layout on the B.1).
The prototype T.1 was competed in June 1917 and went to the Experimental Armament Depot at Grain in July 1917. It was test flown on 2 August, and then went on a tour of fleet bases, reaching East Fortune, Donibristle and Rosyth. On 2 November it was placed onboard HMS Furious but was back on shore on 10 November and back at Grain by 8 December.
On 18 January 1918 the aircraft was successfully tested with an 18in Mark IX torpedo. However at the same time a shortage of Hispano Suiza engines meant that the decision was made to swap to the 200hp Sunbeam Arab engine. This engine would prove to be problematic and would delay the service entry of the T.1
In the autumn of 1917 an order for 100 T.1s was placed with Fairfield of Glasgow and an order for 50 from Pegler of Doncaster. Neither company had any experience of building aircraft, and progress was slow. As a result the more experienced Blackburn company was given a contract for fifty more aircraft. By February 1918 the Admiralty expected the first four production aircraft to be delivered in April, and production to peak in July-August. A total of 200 were expected by the start of November 1918.
In April 1918 the first Arab powered aircraft underwent trials, and the Arab engine began to cause problems. The prototype had to make a forced landing while on its way to Grain for the trails. In tests it proved to be more nose heavy. During tests of take-off length and acceleration the prop shaft broke and the aircraft had to make a second forced landing. By the end of July only two aircraft were available out of the 100 that had been expected, and the engine was still causing problems.
Aircraft did slowly reach the navy. The aircraft completed type trials with torpedoes in mid-June 1918. The first production aircraft arrived on 1 June and by the end of August fourteen had reached the Torpedo School at East Fortune. The aircraft needed some minor modifications to the tail and a new radiator, but the engine was still the main problem.
As a result of all of these delays the T.1 wasn’t ready for service when the war ended. However work on the type continued. Only after the armistice did it become the Sopwith Cuckoo. A new engine, the Wolseley Viper, was chosen. Arab powered aircraft became the Cuckoo Mk I, the first Viper powered version the Cuckoo Mark II.
Once enough aircraft had reached No.201 Training Depot Station at East Fortune, torpedo dropping training began. The Cuckoo was felt to be the best torpedo bomber available at the end of the war, and was more manoeuvrable than its more modern rivals (the Short Shirl and Blackburn Blackburd).
Towards the end of the war plans were in place to use the new aircraft carrier HMS Argus as a specialist torpedo bomber carrier. No.185 Squadron, RAF, was formed at East Fortune on 21 October 1918 to operate on the Argus and by mid November it had twelve Cuckoos. However the armistice ended most interest in the torpedo bomber, especially in the RAF. No.185 Squadron was reduced to a cadre unit on 9 April 1919 and officially disbanded on 14 April.
However this didn’t end the Cuckoo’s career. On 31 December No.186 Squadron was formed using the members of No.185 who had been onboard the Argus. It was originally planned to use this squadron to carry out attacks in the Caspian Sea, but instead it was used for further experimental work with the Cuckoo. On 1 February 1920 it was renumbered as No.210 Squadron. On 1 April 1923 it was split into Nos.460 and 461 Flights, and at the same time the last Cuckoos left service.
A third version of the Cuckoo was produced, the Cuckoo Mk.III. This was powered by a 275hp Rolls Royce Falcon III engine and appeared in 1919. It was sent for trials at Grain on 11 September 1919.
Some work was done on converting the Cuckoo to carry bombs, and it was possible to fit two 500lb or four 230lb bombs in place of the torpedo. However the Air Board’s Technical Department pointed out that the aircraft wasn’t really suited to the role – it had a good forward view, needed for launching a torpedo, but poor downwards visibility. As a single seater the pilot would also have had to act as bomb aimer. One aircraft was converted to carry bombs, but the project was then abandoned.
In April 1921 a British Aviation Mission, led by Colonel the Master of Sempill was sent to Japan. Amongst the aircraft they took with them were six Viper-powered Cuckoo Mk IIs, which were used train the first generation of Japanese torpedo bomber crews.
Engine: Sunbeam Arab eight-cylinder water cooled engine
Span: 46ft 8in
Height: 10ft 8in
Empty Weight: 2,199lb
Loaded Weight: 3,883lb
Maximum Speed: 103.5mph at 2,000ft
Climb rate: 4m 0s to 2,000ft
Endurance: 4 hours