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 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 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.

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. 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.


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: 4 (pilot, navigator, bomb-aimer/gunner and midships gunner)
Length: 54 ft 0 in (16.46 m)
Wingspan: 88 ft 0 in (26.82 m)
Height: 19 ft 4 in (5.89 m)
Empty weight: 9,632 lb (4,369 kg)
Max takeoff weight: 19,020 lb (8,627 kg)
Powerplant: 1 × Napier Cub X-16 water-cooled piston engine, 1,000 hp (750 kW)
Propellers: 2-bladed fixed-pitch propeller

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

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



*