Blackburn Kangaroo from the left |
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The Blackburn Kangaroo was a land based maritime reconnaissance aircraft that entered service in small numbers in 1918.
The Kangaroo was a direct descendent of two earlier Blackburn designs. The twin boom Blackburn T.B. of 1915 had been designed as an anti-Zeppelin aircraft, but had suffered from poor performance. Its wing layout, with a very long upper wing and smaller lower wing had been inherited by the Blackburn G.P. (General Purpose), a design for a maritime patrol floatplane that had reached the prototype stage in 1916. The G.P. had a long slender fuselage, widely separated floats and carried a crew of three.
One of the reasons it hadn’t been ordered into production was a decision by the Air Board to use land based aircraft for maritime patrol duties. Seaplanes and floatplanes did have the advantage that they could land on the sea (although often not successful in rough seas) but the heavy floats used up much of their carrying capacity and they relied on suitable sea conditions to be able to take off. The Rolls Royce engines used in the second of the two G.P.s were reliable enough to be used in land based maritime patrol aircraft. A land based version of the G.P. was thus ordered into production, as the Blackburn R.T.1 Kangaroo (Reconnaissance-Torpedo 1)
The Kangaroo used the same fuselage and wings as the G.P. It thus had a long slender fuselage, with a small lower wing and large upper wing, and a biplane tail with twin rudders. It had dual purpose ailerons, which could be used as ailerons or lowered to use as landing flaps.
The airframe was wooden with a fabric covering. The G.P. had used sheet metal fittings, but these were replaced on the Kangaroo by forged fittings, which were stronger. The engine nacelles were moved from their position on the lower wing of the G.P. into a position in the wing gap, supported by struts. New honeycomb radiators were mounted at the front of the engines. The rudders were made larger. The fixed undercarriage had two separate units, each carrying two wheels. There was no suspension on the undercarriage but the large tyres gave some spring. On the ground it looked rather ungainly with the tall undercarriage raising the nose very high above the ground.
Although the Kangaroo had been designed to carry a torpedo between the wheels, that was never done. Instead it could carry one 520lb or four 230lb bombs in an internal bomb bay carried between the main spars of the lower wing. Four smaller bombs could be carried on racks under the fuselage. It carried a crew of three – gunner/ observer/ bomb aimer in the nose, pilot in a cockpit eight ft back from the nose and rear-gunner/ wireless operator behind the wings. It was given night flying and wireless equipment as standard. It was powered by two 250hp Rolls-Royce Falcon II engines giving it a top speed of 98mph at sea level.
The prototype Kangaroo, B9970, went to the Aeroplane Experimental Station at Martlesham Heath on 3 January 1918 for three weeks of official trials and tests against the long range Avro 529. On 19 January the undercarriage of the Kangaroo collapsed, but it was soon repaired and the tests were completed by 27 January. A number of problems were uncovered. The twin rudders were difficult to operate, partly because of the type of controls but also because the control wires went through the rear cockpit and could easily be trodden on. The fuselage wasn’t rigid enough so the rear fuselage would twist when coming out of a steep turn. The forward fuselage was so slender the gunner couldn’t get down low enough to actually use his gun. The rear gun had a very limited field of fire because of the massive biplane tail.
Originally it had been planned to order 50 Kangaroos, starting with a first batch of twenty. After the reports from Martleham Heath production stopped after the first 20 aircraft. Some changes were made – the fuselage was made stronger, and no more twisting was reported. Shock absorbers were installed on the undercarriage. The front fuselage was raised to give the gunner more space and his gun raised by 9in. The last 15 aircraft used a slightly more powerful 270hp Falcon III.
By the time the Kangaroo entered service the RAF had been formed. Ten aircraft went to No.246 Squadron on the River Tees, and between 1 May 1918 and the Armistice these aircraft flew 600 hours over the North Sea. They sighted twelve U-boats, attacked eleven, sank one and damaged four. The sinking came on 28 August 1918 when Lt E.F. Waring and Lt.H.J. Smith spotted U.C.70 sitting on the bottom near Runswick Bay and achieved a near miss with their 520lb bomb. The submarine was then finished off by HMS Ouse.
All off the surviving Kangaroos were sold off after the war. Blackburn themselves purchased the aircraft in best condition. Others went into private hands. These aircraft were used for commercial joyriding, making quite a profit carrying small numbers of passengers on their first flights, and for limited freight and postal services. Most had left service by the mid 1920s.
Engine: Two Rolls Royce Falcon II or III
Power: 250hp or 270hp each
Crew: 3
Span: 74ft 10.25in
Length: 44ft 2in
Height: 16ft 10in
Empty weight: 5,284lb
All-up weight: 8,017lb
Max speed: 98mph at 6,500ft
Climb Rate: 480ft/ min
Service ceiling: 10,600ft
Endurance: 8 hours
Armament: One 520lb or four 230lb bombs
Bomb load: Two Lewis machine guns
Blackburn Kangaroo from the Right 
Nose of Blackburn Kangaroo