Blackburn Cubaroo

https://en.wikipedia.org/wiki/Blackburn_Cubaroo

The Blackburn T.4 Cubaroo was a prototype British biplane torpedo bomber of the
1920s. Built by Blackburn Aircraft and intended to carry a large 21 in (533 mm)
torpedo, the Cubaroo was one of the largest single-engined aircraft in the world
at the time of its first flight.

In 1921, the British Air Ministry issued Specification 8/21 to Blackburn for a
Coastal Defence Torpedo Aeroplane, the resulting design being designated the T.4
Cubaroo. Due to the change of policy in the Air Ministry to favour a
twin-engined design a new sepcification was issued in 1922, the British Air
Ministry drew up Specification 16/22, for a long-range torpedo bomber capable of
carrying a 21 in (533 mm) torpedo (which was at the time thought capable of
sinking the largest warship) over a range of 800 mi (1,300 km). 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 engine. 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 engines.

In order to carry the heavy (over 2,000 lb/907 kg) torpedo over a long range,
the Cubaroo was massive. With a wingspan of 88 ft (27 m), 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 to accommodate the Cub
engine, and was fitted with folding, two-bay wings. In order to allow the
torpedo to be carried, the Cubaroo was fitted with a main undercarriage
comprising two sets of two wheels, with the torpedo being carried on a crutch
between the two sets of wheels.


Role
Torpedo Bomber

Manufacturer
Blackburn Aircraft

Designer
F A Bumpus

First flight
1924

Status
Prototype

Primary user
Royal Air Force

Number built
2

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 bombers, 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.

Specifications (Cubaroo)

General characteristics
Crew: four – pilot, navigator, bomb-aimer/gunner and midships gunner
Length: 54 ft 0 in (16.46 m)
Wingspan: 88 ft 0 in (26.83 m)
Height: 19 ft 4 in (5.89 m)
Empty weight: 9,632 lb (4,378 kg)
Max. takeoff weight: 19,020 lb (8,645 kg)
Powerplant: 1 × Napier Cub 16-cylinder water-cooled X-type engine, 1,000 hp (746
kW)

Performance
Maximum speed: 100 kn (115 mph, 185 km/h)
Range: 1,565 nmi (1,800 mi, 2,900 km)
Endurance: 10 hours
Service ceiling: 11,800 ft (3,600 m) absolute

Armament

3 × .303 in (7.7 mm) Lewis Guns in midship gunners cockpit and at beam hatches
1 × 21 in (533 mm) naval torpedo

or
4 × 551 lb (250 kg) bombs




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