The Blackburn T.4 Cubaroo was a prototype

British British may refer to: Peoples, culture, and language * British people, nationals or natives of the United Kingdom, British Overseas Territories, and Crown Dependencies. ** Britishness, the British identity and common culture * British English, ...

biplane

torpedo bomber A torpedo bomber is a military aircraft designed primarily to attack ships with aerial torpedoes. Torpedo bombers came into existence just before the First World War almost as soon as aircraft were built that were capable of carrying the weight ...

of the 1920s. Built by Blackburn Aircraft and intended to carry a large 21 in (533 mm)

torpedo A modern torpedo is an underwater ranged weapon launched above or below the water surface, self-propelled towards a target, and with an explosive warhead designed to detonate either on contact with or in proximity to the target. Historically, s ...

, the Cubaroo was one of the largest single-engined aircraft in the world at the time of its first flight.

Design and development

In 1921, the British

Air Ministry The Air Ministry was a department of the Government of the United Kingdom with the responsibility of managing the affairs of the Royal Air Force, that existed from 1918 to 1964. It was under the political authority of the Secretary of State ...

issued Specification 8/21 to Blackburn for a ''Coastal Defence Torpedo Aeroplane'', the resulting design being the T.4 Cubaroo. Due to the change of policy in the Air Ministry to favour a twin-engined design a new specification was issued in 1922, the British

drew up Specification 16/22, for a long-range torpedo bomber capable of carrying a 21 in (533 mm)

(which was at the time thought capable of sinking the largest warship) over a range of . Major F. A Bumpus, chief designer of Blackburn Aircraft submitted the design for the Blackburn T.4 Cubaroo, which was a large biplane powered by a single example of the new 1,000 hp (750 kW)

Napier Cub The Napier Cub was an unusual and very large experimental 16-cylinder 'X' pattern liquid-cooled aero engine built by the British engine company D. Napier & Son. The Cub was the only Napier 'X' engine design. First flown on 15 December 1922 ...

engine An engine or motor is a machine designed to convert one or more forms of energy into mechanical energy. Available energy sources include potential energy (e.g. energy of the Earth's gravitational field as exploited in hydroelectric power ...

. Avro also submitted a design against this specification, the Avro 557 Ava, which was a similarly large biplane, powered by two 600 hp (450 kW)

Rolls-Royce Condor The Rolls-Royce Condor aircraft piston engine was a larger version of the Rolls-Royce Eagle developing up to 675 horsepower (500 kW). The engine first ran in 1918 and a total of 327 engines were recorded as being built. Variants ''Note:'' ...

engines. To carry the heavy (over 2,000 lb/907 kg) torpedo over a long range, the Cubaroo was massive. With a wingspan of , it may have been the largest single-engine military aircraft in the world at the time and was fitted with the most powerful aircraft engine available, the Napier Cub, which was an unusual X-type engine which weighed over a ton excluding radiators. The Cubaroo, with a mainly metal structure, had a deep

fuselage The fuselage (; from the French ''fuselé'' "spindle-shaped") is an aircraft's main body section. It holds crew, passengers, or cargo. In single-engine aircraft, it will usually contain an engine as well, although in some amphibious aircraf ...

to accommodate the Cub engine and was fitted with

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, two-bay wings. To carry the torpedo, the Cubaroo was fitted with a main undercarriage comprising two sets of two wheels, with the torpedo being carried on a crutch between them.

Operational history

The first prototype (with serial ''N166'') flew in secrecy in the summer of 1924, proving to have good handling characteristics, with the engine not causing problems (the Cub had already been test flown in an Avro Aldershot testbed). It was then fitted with a metal, three-blade adjustable-pitch propeller and was delivered for testing at RAF Martlesham Heath but was written off after its undercarriage collapsed on 2 February 1925. A second prototype flew in 1925, but the Air Ministry abandoned the requirement for a torpedo bomber to carry the 21 in (533 mm) torpedo and lost interest in single-engine

heavy bomber Heavy bombers are bomber aircraft capable of delivering the largest payload of air-to-ground weaponry (usually bombs) and longest range (takeoff to landing) of their era. Archetypal heavy bombers have therefore usually been among the larges ...

s, so the second prototype Cubaroo was used as an engine testbed, flying with the experimental 1,100 hp (820 kW) Beardmore Simoon compression ignition engine.

Operators

Royal Air Force The Royal Air Force (RAF) is the United Kingdom's air and space force. It was formed towards the end of the First World War on 1 April 1918, becoming the first independent air force in the world, by regrouping the Royal Flying Corps (RFC) an ...

operated aircraft for evaluation and as a testbed only.

Specifications (Cubaroo)

References

External links

* {{Blackburn aircraft Cubaroo 1920s British bomber aircraft Single-engined tractor aircraft Biplanes Cancelled military aircraft projects of the United Kingdom Aircraft first flown in 1924