Blackburn
Iris
Raul Colon
Email:rcolonfrias@yahoo.com
The R.B.1,
codenamed ‘Iris’ was the first flying boat design and
development project undertaken by the Yorkshire-based
Blackburn Aeroplane and Motor Corporation, Ltd. The design
of the Iris-I was the direct result of the Royal Air Force's
desire to fill its maritime reconnaissance arm with a long
range platform. A pre-design specification request was
delivered to Blackburn in early 1925.
Only one year after the specification, the company was able
to produce a workable aircraft fully loaded. On the morning
of June 26th, 1926, the first prototype, R.B.1-I took to the
air in its maiden flight. The Iris-I was an all wooden,
three engine flying boat that utilized a distinctive biplane
tail elevator on its upper plane and three rudders. The
aircraft needed a five men flight crew. The two pilots sat
on a side-by-side, open cockpit in the top front of the
fuselage. The rest of the crew also sat in an open cockpit
placed in the rear area, behind the wing structure.
Following a brief evaluation period, engineers at Blackburn
decided to replace the provisional wooden hull for an all
metal one. There are also some minor modifications performed
on the Iris-I’s three Rolls Royce Condor IIIB piston
engines. The resulting type was called model R.B.1A-II. It
employed a more powerful power plant, the same RR Condor
engines, but with an augmented in-line fuel distribution
mechanism.
Overall, five versions of the Iris were produced between
1926 and the fall of 1932. All types employed the same
airframe profile. Versions I through III were fitted with a
Rolls Royce Condor engine, while IV utilized an Armstrong
Siddeley Leopard III radial piston engines and type V
carried three Rolls Royce Buzzard II MS piston motors. The
final three produced Iris (III, IV and V) made it to full
operational status, with the RAF’s 209 Squadron, in early
1930. At the time of their deployment, the Iris had the
distinction of being the largest operational flying boat in
the world.
Despite a very good service record, the Iris is most
famously remembered by a lone flight. In September 28th,
1928, British Under Secretary of State for Air, Sir Philip
Sassoon, took a 15,929km flight on an Iris-II. Sassoon and
his party took off from Felixstowe and flew to Karachi to
inspect RAF’s units deployed in the Island of Malta, Iraq
and Egypt. The whole inspection flight took sixteen days, an
impressive achievement for those times.
Power Plant:
Three Rolls Royce 570hp Condor Engines (other variants are
described above)
Wingspan: 29.57m
Length 20.54
Height: 7.77m
Total Wing Area: 207.07m(2)
Maximum Take off Weight: 13,376kg
Top Speed: 190kph
Serviceable Ceiling: 3,230m
Operational Range: 1,287km
Climb Rate: 184m per minute
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